Valve movement of three species of North American freshwater mussels exposed to elevated carbon dioxide.

PubMed

Hasler, Caleb T; Hannan, Kelly D; Jeffrey, Jennifer D; Suski, Cory D

2017-06-01

Freshwater mussels are at-risk taxa and may be exposed to high levels of carbon dioxide (CO 2 ) because of the potential use of CO 2 to control the movement of invasive aquatic fish species. One potential behavioral response to a change in the partial pressure of CO 2 (pCO 2 ) may be altered valve movement. In this study, three species of mussels were fitted with modified sensors and exposed to two regimes of pCO 2 to define thresholds of impaired valve movement. The first experiment demonstrated that Pyganodon grandis were much more tolerant to rising pCO 2 relative to Lampsilis siliquoidea (acute closure at ∼200,000 μatm in comparison to ∼80,000 μatm). The second experiment consisted of monitoring mussels for 6 days and exposing them to elevated pCO 2 (∼70,000 μatm) over a 2-day period. During exposure to high pCO 2 , Lampsilis cardium were open for nearly the entire high pCO 2 period. Conversely, P. grandis were closed for most of the period following exposure to high pCO 2 . For L. siliquoidea, the number of closures decreased nearly 40-fold during high pCO 2 . The valve movement responses observed suggest species differences, and exposure to elevated pCO 2 requires a reactive response.

Coccolithophore community response to increasing pCO2 in Mediterranean oligotrophic waters

NASA Astrophysics Data System (ADS)

Oviedo, A. M.; Ziveri, P.; Gazeau, F.

2017-02-01

The effects of elevated partial pressure of CO2 (pCO2) on plankton communities in oligotrophic ecosystems were studied during two mesocosm experiments: one during summer 2012 in the Bay of Calvi, France, and another during winter 2013 in the Bay of Villefranche, France. Here we report on the relative abundances of coccolithophores versus siliceous phytoplankton, coccolithophore community structure, Emiliania huxleyi coccolith morphology and calcification degree. A pCO2 mediated succession of phytoplankton groups did not occur. During both experiments, coccolithophore abundance and community structure varied with time independently of pCO2 levels. Changes in the community structure were partly explained by the concentration of phosphate during the winter experiment. During the summer experiment, it was not clearly related to any of the parameters measured but possibly to changes in temperature. Phenological changes in the community and an attenuated response due to the low biomass building during the winter experiment could have masked the response to pCO2. E. huxleyi dominated the coccolithophore community in winter; it was not affected by elevated pCO2 at any time. In contrast, the abundance of Rabdosphaera clavigera, the dominant species in summer, increased with time and this increase was affected at elevated pCO2. Thus, a different coccolithophore community response based on species-specific sensitivities to pCO2 is still likely. Finally, elevated pCO2 had no traceable effect on E. huxleyi (type A) coccolith morphology or on the degree of coccolith calcification. Our results highlight the possibility that, in oligotrophic regions, nutrient availability, temperature or intrinsic phenological changes might exert larger constrains on the coccolithophore community structure than high pCO2 does solely.

Interactive effects of elevated temperature and CO2 levels on energy metabolism and biomineralization of marine bivalves Crassostrea virginica and Mercenaria mercenaria.

PubMed

Ivanina, Anna V; Dickinson, Gary H; Matoo, Omera B; Bagwe, Rita; Dickinson, Ashley; Beniash, Elia; Sokolova, Inna M

2013-09-01

The continuing increase of carbon dioxide (CO2) levels in the atmosphere leads to increases in global temperatures and partial pressure of CO2 (PCO2) in surface waters, causing ocean acidification. These changes are especially pronounced in shallow coastal and estuarine waters and are expected to significantly affect marine calcifiers including bivalves that are ecosystem engineers in estuarine and coastal communities. To elucidate potential effects of higher temperatures and PCO2 on physiology and biomineralization of marine bivalves, we exposed two bivalve species, the eastern oysters Crassostrea virginica and the hard clams Mercenaria mercenaria to different combinations of PCO2 (~400 and 800μatm) and temperatures (22 and 27°C) for 15weeks. Survival, bioenergetic traits (tissue levels of lipids, glycogen, glucose and high energy phosphates) and biomineralization parameters (mechanical properties of the shells and activity of carbonic anhydrase, CA) were determined in clams and oysters under different temperature and PCO2 regimes. Our analysis showed major inter-species differences in shell mechanical traits and bioenergetics parameters. Elevated temperature led to the depletion of tissue energy reserves indicating energy deficiency in both species and resulted in higher mortality in oysters. Interestingly, while elevated PCO2 had a small effect on the physiology and metabolism of both species, it improved survival in oysters. At the same time, a combination of high temperature and elevated PCO2 lead to a significant decrease in shell hardness in both species, suggesting major changes in their biomineralization processes. Overall, these studies show that global climate change and ocean acidification might have complex interactive effects on physiology, metabolism and biomineralization in coastal and estuarine marine bivalves. Copyright © 2013 Elsevier Inc. All rights reserved.

Does encapsulation protect embryos from the effects of ocean acidification? The example of Crepidula fornicata.

PubMed

Noisette, Fanny; Comtet, Thierry; Legrand, Erwann; Bordeyne, François; Davoult, Dominique; Martin, Sophie

2014-01-01

Early life history stages of marine organisms are generally thought to be more sensitive to environmental stress than adults. Although most marine invertebrates are broadcast spawners, some species are brooders and/or protect their embryos in egg or capsules. Brooding and encapsulation strategies are typically assumed to confer greater safety and protection to embryos, although little is known about the physico-chemical conditions within egg capsules. In the context of ocean acidification, the protective role of encapsulation remains to be investigated. To address this issue, we conducted experiments on the gastropod Crepidula fornicata. This species broods its embryos within capsules located under the female and veliger larvae are released directly into the water column. C. fornicata adults were reared at the current level of CO2 partial pressure (pCO2) (390 μatm) and at elevated levels (750 and 1400 μatm) before and after fertilization and until larval release, such that larval development occurred entirely at a given pCO2. The pCO2 effects on shell morphology, the frequency of abnormalities and mineralization level were investigated on released larvae. Shell length decreased by 6% and shell surface area by 11% at elevated pCO2 (1400 μatm). The percentage of abnormalities was 1.5- to 4-fold higher at 750 μatm and 1400 μatm pCO2, respectively, than at 390 μatm. The intensity of birefringence, used as a proxy for the mineralization level of the larval shell, also decreased with increasing pCO2. These negative results are likely explained by increased intracapsular acidosis due to elevated pCO2 in extracapsular seawater. The encapsulation of C. fornicata embryos did not protect them against the deleterious effects of a predicted pCO2 increase. Nevertheless, C. fornicata larvae seemed less affected than other mollusk species. Further studies are needed to identify the critical points of the life cycle in this species in light of future ocean acidification.

Warming and pCO2 effects on Florida stone crab larvae

NASA Astrophysics Data System (ADS)

Gravinese, Philip M.; Enochs, Ian C.; Manzello, Derek P.; van Woesik, Robert

2018-05-01

Greenhouse gas emissions are increasing ocean temperatures and the partial pressure of CO2 (pCO2), resulting in more acidic waters. It is presently unknown how elevated temperature and pCO2 will influence the early life history stages of the majority of marine coastal species. We investigated the combined effect of elevated temperature (30 °C control and 32 °C treatment) and elevated pCO2 (450 μatm control and 1100 μatm treatment) on the (i) growth, (ii) survival, (iii) condition, and (iv) morphology of larvae of the commercially important Florida stone crab, Menippe mercenaria. At elevated temperature, larvae exhibited a significantly shorter molt stage, and elevated pCO2 caused stage-V larvae to delay metamorphosis to post-larvae. On average, elevated pCO2 resulted in a 37% decrease in survivorship relative to the control; however the effect of elevated temperature reduced larval survivorship by 71%. Exposure to both elevated temperature and pCO2 reduced larval survivorship by 80% relative to the control. Despite this, no significant differences were detected in the condition or morphology of stone crab larvae when subjected to elevated temperature and pCO2 treatments. Although elevated pCO2 could result in a reduction in larval supply, future increases in seawater temperatures are even more likely to threaten the future sustainability of the stone-crab fishery.

Diel CO2 cycles reduce severity of behavioural abnormalities in coral reef fish under ocean acidification.

PubMed

Jarrold, Michael D; Humphrey, Craig; McCormick, Mark I; Munday, Philip L

2017-08-31

Elevated CO 2 levels associated with ocean acidification (OA) have been shown to alter behavioural responses in coral reef fishes. However, all studies to date have used stable pCO 2 treatments, not considering the substantial diel pCO 2 variation that occurs in shallow reef habitats. Here, we reared juvenile damselfish, Acanthochromis polyacanthus, and clownfish, Amphiprion percula, at stable and diel cycling pCO 2 treatments in two experiments. As expected, absolute lateralization of A. polyacanthus and response to predator cue of Am. percula were negatively affected in fish reared at stable, elevated pCO 2 in both experiments. However, diel pCO 2 fluctuations reduced the negative effects of OA on behaviour. Importantly, in experiment two, behavioural abnormalities that were present in fish reared at stable 750 µatm CO 2 were largely absent in fish reared at 750 ± 300 µatm CO 2 . Overall, we show that diel pCO 2 cycles can substantially reduce the severity of behavioural abnormalities caused by elevated CO 2 . Thus, past studies may have over-estimated the impacts of OA on the behavioural performance of coral reef fishes. Furthermore, our results suggest that diel pCO 2 cycles will delay the onset of behavioural abnormalities in natural populations.

Short term exposure to elevated pCO2 and hypoxia affects the cellular homeostasis of grass shrimp, Palaemonetes pugio

EPA Science Inventory

Estuarine organisms are adapted to frequent changes in temperature, salinity, pH, and dissolved oxygen (DO) levels. The high productivity of an estuary contributes to large changes in environmental conditions, with organismal respiration enhancing hypoxic zones, and elevating pCO...

Molecular mechanisms underlying the physiological responses of the cold-water coral Desmophyllum dianthus to ocean acidification

NASA Astrophysics Data System (ADS)

Carreiro-Silva, M.; Cerqueira, T.; Godinho, A.; Caetano, M.; Santos, R. S.; Bettencourt, R.

2014-06-01

Cold-water corals (CWCs) are thought to be particularly vulnerable to ocean acidification (OA) due to increased atmospheric pCO2, because they inhabit deep and cold waters where the aragonite saturation state is naturally low. Several recent studies have evaluated the impact of OA on organism-level physiological processes such as calcification and respiration. However, no studies to date have looked at the impact at the molecular level of gene expression. Here, we report results of a long-term, 8-month experiment to compare the physiological responses of the CWC Desmophyllum dianthus to OA at both the organismal and gene expression levels under two pCO2/pH treatments: ambient pCO2 (460 μatm, pHT = 8.01) and elevated pCO2 (997 μatm, pHT = 7.70). At the organismal level, no significant differences were detected in the calcification and respiration rates of D. dianthus. Conversely, significant differences were recorded in gene expression profiles, which showed an up-regulation of genes involved in cellular stress (HSP70) and immune defence (mannose-binding c-type lectin). Expression of alpha-carbonic anhydrase, a key enzyme involved in the synthesis of coral skeleton, was also significantly up-regulated in corals under elevated pCO2, indicating that D. dianthus was under physiological reconditioning to calcify under these conditions. Thus, gene expression profiles revealed physiological impacts that were not evident at the organismal level. Consequently, understanding the molecular mechanisms behind the physiological processes involved in a coral's response to elevated pCO2 is critical to assess the ability of CWCs to acclimate or adapt to future OA conditions.

Ocean Acidification Affects the Phyto-Zoo Plankton Trophic Transfer Efficiency

PubMed Central

Cripps, Gemma; Flynn, Kevin J.; Lindeque, Penelope K.

2016-01-01

The critical role played by copepods in ocean ecology and biogeochemistry warrants an understanding of how these animals may respond to ocean acidification (OA). Whilst an appreciation of the potential direct effects of OA, due to elevated pCO2, on copepods is improving, little is known about the indirect impacts acting via bottom-up (food quality) effects. We assessed, for the first time, the chronic effects of direct and/or indirect exposures to elevated pCO2 on the behaviour, vital rates, chemical and biochemical stoichiometry of the calanoid copepod Acartia tonsa. Bottom-up effects of elevated pCO2 caused species-specific biochemical changes to the phytoplanktonic feed, which adversely affected copepod population structure and decreased recruitment by 30%. The direct impact of elevated pCO2 caused gender-specific respiratory responses in A.tonsa adults, stimulating an enhanced respiration rate in males (> 2-fold), and a suppressed respiratory response in females when coupled with indirect elevated pCO2 exposures. Under the combined indirect+direct exposure, carbon trophic transfer efficiency from phytoplankton-to-zooplankton declined to < 50% of control populations, with a commensurate decrease in recruitment. For the first time an explicit role was demonstrated for biochemical stoichiometry in shaping copepod trophic dynamics. The altered biochemical composition of the CO2-exposed prey affected the biochemical stoichiometry of the copepods, which could have ramifications for production of higher tropic levels, notably fisheries. Our work indicates that the control of phytoplankton and the support of higher trophic levels involving copepods have clear potential to be adversely affected under future OA scenarios. PMID:27082737

Coral Energy Reserves and Calcification in a High-CO2 World at Two Temperatures

PubMed Central

Schoepf, Verena; Grottoli, Andréa G.; Warner, Mark E.; Cai, Wei-Jun; Melman, Todd F.; Hoadley, Kenneth D.; Pettay, D. Tye; Hu, Xinping; Li, Qian; Xu, Hui; Wang, Yongchen; Matsui, Yohei; Baumann, Justin H.

2013-01-01

Rising atmospheric CO2 concentrations threaten coral reefs globally by causing ocean acidification (OA) and warming. Yet, the combined effects of elevated pCO2 and temperature on coral physiology and resilience remain poorly understood. While coral calcification and energy reserves are important health indicators, no studies to date have measured energy reserve pools (i.e., lipid, protein, and carbohydrate) together with calcification under OA conditions under different temperature scenarios. Four coral species, Acropora millepora, Montipora monasteriata, Pocillopora damicornis, Turbinaria reniformis, were reared under a total of six conditions for 3.5 weeks, representing three pCO2 levels (382, 607, 741 µatm), and two temperature regimes (26.5, 29.0°C) within each pCO2 level. After one month under experimental conditions, only A. millepora decreased calcification (−53%) in response to seawater pCO2 expected by the end of this century, whereas the other three species maintained calcification rates even when both pCO2 and temperature were elevated. Coral energy reserves showed mixed responses to elevated pCO2 and temperature, and were either unaffected or displayed nonlinear responses with both the lowest and highest concentrations often observed at the mid-pCO2 level of 607 µatm. Biweekly feeding may have helped corals maintain calcification rates and energy reserves under these conditions. Temperature often modulated the response of many aspects of coral physiology to OA, and both mitigated and worsened pCO2 effects. This demonstrates for the first time that coral energy reserves are generally not metabolized to sustain calcification under OA, which has important implications for coral health and bleaching resilience in a high-CO2 world. Overall, these findings suggest that some corals could be more resistant to simultaneously warming and acidifying oceans than previously expected. PMID:24146747

Effect of elevated pCO2 on metabolic responses of porcelain crab (Petrolisthes cinctipes) Larvae exposed to subsequent salinity stress.

PubMed

Miller, Seth H; Zarate, Sonia; Smith, Edmund H; Gaylord, Brian; Hosfelt, Jessica D; Hill, Tessa M

2014-01-01

Future climate change is predicted to alter the physical characteristics of oceans and estuaries, including pH, temperature, oxygen, and salinity. Investigating how species react to the influence of such multiple stressors is crucial for assessing how future environmental change will alter marine ecosystems. The timing of multiple stressors can also be important, since in some cases stressors arise simultaneously, while in others they occur in rapid succession. In this study, we investigated the effects of elevated pCO2 on oxygen consumption by larvae of the intertidal porcelain crab Petrolisthes cinctipes when exposed to subsequent salinity stress. Such an exposure mimics how larvae under future acidified conditions will likely experience sudden runoff events such as those that occur seasonally along portions of the west coast of the U.S. and in other temperate systems, or how larvae encounter hypersaline waters when crossing density gradients via directed swimming. We raised larvae in the laboratory under ambient and predicted future pCO2 levels (385 and 1000 µatm) for 10 days, and then moved them to seawater at ambient pCO2 but with decreased, ambient, or elevated salinity, to monitor their respiration. While larvae raised under elevated pCO2 or exposed to stressful salinity conditions alone did not exhibit higher respiration rates than larvae held in ambient conditions, larvae exposed to elevated pCO2 followed by stressful salinity conditions consumed more oxygen. These results show that even when multiple stressors act sequentially rather than simultaneously, they can retain their capacity to detrimentally affect organisms.

Effect of Elevated pCO2 on Metabolic Responses of Porcelain Crab (Petrolisthes cinctipes) Larvae Exposed to Subsequent Salinity Stress

PubMed Central

Miller, Seth H.; Zarate, Sonia; Smith, Edmund H.; Gaylord, Brian; Hosfelt, Jessica D.; Hill, Tessa M.

2014-01-01

Future climate change is predicted to alter the physical characteristics of oceans and estuaries, including pH, temperature, oxygen, and salinity. Investigating how species react to the influence of such multiple stressors is crucial for assessing how future environmental change will alter marine ecosystems. The timing of multiple stressors can also be important, since in some cases stressors arise simultaneously, while in others they occur in rapid succession. In this study, we investigated the effects of elevated pCO2 on oxygen consumption by larvae of the intertidal porcelain crab Petrolisthes cinctipes when exposed to subsequent salinity stress. Such an exposure mimics how larvae under future acidified conditions will likely experience sudden runoff events such as those that occur seasonally along portions of the west coast of the U.S. and in other temperate systems, or how larvae encounter hypersaline waters when crossing density gradients via directed swimming. We raised larvae in the laboratory under ambient and predicted future pCO2 levels (385 and 1000 µatm) for 10 days, and then moved them to seawater at ambient pCO2 but with decreased, ambient, or elevated salinity, to monitor their respiration. While larvae raised under elevated pCO2 or exposed to stressful salinity conditions alone did not exhibit higher respiration rates than larvae held in ambient conditions, larvae exposed to elevated pCO2 followed by stressful salinity conditions consumed more oxygen. These results show that even when multiple stressors act sequentially rather than simultaneously, they can retain their capacity to detrimentally affect organisms. PMID:25295878

Expression of calcification and metabolism-related genes in response to elevated pCO2 and temperature in the reef-building coral Acropora millepora.

PubMed

Rocker, Melissa M; Noonan, Sam; Humphrey, Craig; Moya, Aurelie; Willis, Bette L; Bay, Line K

2015-12-01

Declining health of scleractinian corals in response to deteriorating environmental conditions is widely acknowledged, however links between physiological and functional genomic responses of corals are less well understood. Here we explore growth and the expression of 20 target genes with putative roles in metabolism and calcification in the branching coral, Acropora millepora, in two separate experiments: 1) elevated pCO2 (464, 822, 1187 and 1638 μatm) and ambient temperature (27°C), and 2) elevated pCO2 (490 and 822 μatm) and temperature (28 and 31 °C). After 14 days of exposure to elevated pCO2 and ambient temperatures, no evidence of differential expression of either calcification or metabolism genes was detected between control and elevated pCO2 treatments. After 37 days of exposure to control and elevated pCO2, Ubiquinol-Cytochrome-C Reductase Subunit 2 gene (QCR2; a gene involved in complex III of the electron chain transport within the mitochondria and critical for generation of ATP) was significantly down-regulated in the elevated pCO2 treatment in both ambient and elevated temperature treatments. Overall, the general absence of a strong response to elevated pCO2 and temperature by the other 19 targeted calcification and metabolism genes suggests that corals may not be affected by these stressors on longer time scales (37 days). These results also highlight the potential for QCR2 to act as a biomarker of coral genomic responses to changing environments. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of acute ocean acidification on spatially-diverse polar pelagic foodwebs: Insights from on-deck microcosms

NASA Astrophysics Data System (ADS)

Tarling, G. A.; Peck, V. L.; Ward, P.; Ensor, N. S.; Achterberg, E.; Tynan, E.; Poulton, A. J.; Mitchell, E.; Zubkov, M. V.

2016-05-01

The polar oceans are experiencing some of the largest levels of ocean acidification (OA) resulting from the uptake of anthropogenic carbon dioxide (CO2). Our understanding of the impacts this is having on polar marine communities is mainly derived from studies of single species in laboratory conditions, while the consequences for food web interactions remain largely unknown. This study carried out experimental manipulations of natural pelagic communities at different high latitude sites in both the northern (Nordic Seas) and southern hemispheres (Scotia and Weddell Seas). The aim of this study was to identify more generic responses and achieve greater experimental reproducibility through implementing a series of short term (4 d), multilevel (3 treatment) carbonate chemistry manipulation experiments on unfiltered natural surface-ocean communities, including grazing copepods. The experiments were successfully executed at six different sites, covering a diverse range of environmental conditions and differing plankton community compositions. The study identified the interaction between copepods and dinoflagellate cell abundance to be significantly altered by elevated levels of dissolved CO2 (pCO2), with dinoflagellates decreasing relative to ambient conditions across all six experiments. A similar pattern was not observed in any other major phytoplankton group. The patterns indicate that copepods show a stronger preference for dinoflagellates when in elevated pCO2 conditions, demonstrating that changes in food quality and altered grazing selectivity may be a major consequence of ocean acidification. The study also found that transparent exopolymeric particles (TEP) generally increased when pCO2 levels were elevated, but the response was dependent on the exact set of environmental conditions. Bacteria and nannoplankton showed a neutral response to elevated pCO2 and there was no significant relationship between changes in bacterial or nannoplankton abundance and that of TEP concentrations. Overall, the study illustrated that, although some similar responses exist, these contrasting high latitude surface ocean communities are likely to show different responses to the onset of elevated pCO2.

Effect of ocean acidification on growth and otolith condition of juvenile scup, Stenotomus chrysops.

PubMed

Perry, Dean M; Redman, Dylan H; Widman, James C; Meseck, Shannon; King, Andrew; Pereira, Jose J

2015-09-01

Increasing amounts of atmospheric carbon dioxide (CO2) from human industrial activities are causing changes in global ocean carbonate chemistry, resulting in a reduction in pH, a process termed "ocean acidification." It is important to determine which species are sensitive to elevated levels of CO2 because of potential impacts to ecosystems, marine resources, biodiversity, food webs, populations, and effects on economies. Previous studies with marine fish have documented that exposure to elevated levels of CO2 caused increased growth and larger otoliths in some species. This study was conducted to determine whether the elevated partial pressure of CO2 (pCO2) would have an effect on growth, otolith (ear bone) condition, survival, or the skeleton of juvenile scup, Stenotomus chrysops, a species that supports both important commercial and recreational fisheries. Elevated levels of pCO2 (1200-2600 μatm) had no statistically significant effect on growth, survival, or otolith condition after 8 weeks of rearing. Field data show that in Long Island Sound, where scup spawn, in situ levels of pCO2 are already at levels ranging from 689 to 1828 μatm due to primary productivity, microbial activity, and anthropogenic inputs. These results demonstrate that ocean acidification is not likely to cause adverse effects on the growth and survivability of every species of marine fish. X-ray analysis of the fish revealed a slightly higher incidence of hyperossification in the vertebrae of a few scup from the highest treatments compared to fish from the control treatments. Our results show that juvenile scup are tolerant to increases in seawater pCO2, possibly due to conditions this species encounters in their naturally variable environment and their well-developed pH control mechanisms.

Species-Specific Responses of Juvenile Rockfish to Elevated pCO2: From Behavior to Genomics

PubMed Central

Hamilton, Scott L.; Logan, Cheryl A.; Fennie, Hamilton W.; Sogard, Susan M.; Barry, James P.; Makukhov, April D.; Tobosa, Lauren R.; Boyer, Kirsten; Lovera, Christopher F.; Bernardi, Giacomo

2017-01-01

In the California Current ecosystem, global climate change is predicted to trigger large-scale changes in ocean chemistry within this century. Ocean acidification—which occurs when increased levels of atmospheric CO2 dissolve into the ocean—is one of the biggest potential threats to marine life. In a coastal upwelling system, we compared the effects of chronic exposure to low pH (elevated pCO2) at four treatment levels (i.e., pCO2 = ambient [500], moderate [750], high [1900], and extreme [2800 μatm]) on behavior, physiology, and patterns of gene expression in white muscle tissue of juvenile rockfish (genus Sebastes), integrating responses from the transcriptome to the whole organism level. Experiments were conducted simultaneously on two closely related species that both inhabit kelp forests, yet differ in early life history traits, to compare high-CO2 tolerance among species. Our findings indicate that these congeners express different sensitivities to elevated CO2 levels. Copper rockfish (S. caurinus) exhibited changes in behavioral lateralization, reduced critical swimming speed, depressed aerobic scope, changes in metabolic enzyme activity, and increases in the expression of transcription factors and regulatory genes at high pCO2 exposure. Blue rockfish (S. mystinus), in contrast, showed no significant changes in behavior, swimming physiology, or aerobic capacity, but did exhibit significant changes in the expression of muscle structural genes as a function of pCO2, indicating acclimatization potential. The capacity of long-lived, late to mature, commercially important fish to acclimatize and adapt to changing ocean chemistry over the next 50–100 years is likely dependent on species-specific physiological tolerances. PMID:28056071

Sensitivity towards elevated pCO2 in great scallop (Pecten maximus Lamarck) embryos and fed larvae

NASA Astrophysics Data System (ADS)

Andersen, Sissel; Grefsrud, Ellen S.; Harboe, Torstein

2017-02-01

The increasing amount of dissolved anthropogenic CO2 has caused a drop in pH values in the open ocean known as ocean acidification. This change in seawater carbonate chemistry has been shown to have a negative effect on a number of marine organisms. Early life stages are the most vulnerable, and especially the organisms that produce calcified structures in the phylum Mollusca. Few studies have looked at effects on scallops, and this is the first study presented including fed larvae of the great scallop (Pecten maximus) followed until day 14 post-fertilization. Fertilized eggs from unexposed parents were exposed to three levels of pCO2 using four replicate units: 465 (ambient), 768 and 1294 µatm, corresponding to pHNIST of 7.94, 7.75 (-0.19 units) and 7.54 (-0.40 units), respectively. All of the observed parameters were negatively affected by elevated pCO2: survival, larval development, shell growth and normal shell development. The latter was observed to be affected only 2 days after fertilization. Negative effects on the fed larvae at day 7 were similar to what was shown earlier for unfed P. maximus larvae. Growth rate in the group at 768 µatm seemed to decline after day 7, indicating that the ability to overcome the environmental change at moderately elevated pCO2 was lost over time. The present study shows that food availability does not decrease the sensitivity to elevated pCO2 in P. maximus larvae. Unless genetic adaptation and acclimatization counteract the negative effects of long term elevated pCO2, recruitment in populations of P. maximus will most likely be negatively affected by the projected drop of 0.06-0.32 units in pH within year 2100.

Effects of ocean acidification on calcification of symbiont-bearing reef foraminifers

NASA Astrophysics Data System (ADS)

Fujita, K.; Hikami, M.; Suzuki, A.; Kuroyanagi, A.; Sakai, K.; Kawahata, H.; Nojiri, Y.

2011-08-01

Ocean acidification (decreases in carbonate ion concentration and pH) in response to rising atmospheric pCO2 is generally expected to reduce rates of calcification by reef calcifying organisms, with potentially severe implications for coral reef ecosystems. Large, algal symbiont-bearing benthic foraminifers, which are important primary and carbonate producers in coral reefs, produce high-Mg calcite shells, whose solubility can exceed that of aragonite produced by corals, making them the "first responder" in coral reefs to the decreasing carbonate saturation state of seawater. Here we report results of culture experiments performed to assess the effects of ongoing ocean acidification on the calcification of symbiont-bearing reef foraminifers using a high-precision pCO2 control system. Living clone individuals of three foraminiferal species (Baculogypsina sphaerulata, Calcarina gaudichaudii, and Amphisorus hemprichii) were subjected to seawater at five pCO2 levels from 260 to 970 μatm. Cultured individuals were maintained for about 12 weeks in an indoor flow-through system under constant water temperature, light intensity, and photoperiod. After the experiments, the shell diameter and weight of each cultured specimen were measured. Net calcification of B. sphaerulata and C. gaudichaudii, which secrete a hyaline shell and host diatom symbionts, increased under intermediate levels of pCO2 (580 and/or 770 μatm) and decreased at a higher pCO2 level (970 μatm). Net calcification of A. hemprichii, which secretes a porcelaneous shell and hosts dinoflagellate symbionts, tended to decrease at elevated pCO2. Observed different responses between hyaline and porcelaneous species are possibly caused by the relative importance of elevated pCO2, which induces CO2 fertilization effects by algal symbionts, versus associated changes in seawater carbonate chemistry, which decreases a carbonate concentration. Our findings suggest that ongoing ocean acidification might favor symbiont-bearing reef foraminifers with hyaline shells at intermediate pCO2 levels (580 to 770 μatm) but be unfavorable to those with either hyaline or porcelaneous shells at higher pCO2 levels (near 1000 μatm).

Adaptation and acclimatization to ocean acidification in marine ectotherms: an in situ transplant experiment with polychaetes at a shallow CO2 vent system

PubMed Central

Calosi, Piero; Rastrick, Samuel P. S.; Lombardi, Chiara; de Guzman, Heidi J.; Davidson, Laura; Jahnke, Marlene; Giangrande, Adriana; Hardege, Jörg D.; Schulze, Anja; Spicer, John I.; Gambi, Maria-Cristina

2013-01-01

Metabolic rate determines the physiological and life-history performances of ectotherms. Thus, the extent to which such rates are sensitive and plastic to environmental perturbation is central to an organism's ability to function in a changing environment. Little is known of long-term metabolic plasticity and potential for metabolic adaptation in marine ectotherms exposed to elevated pCO2. Consequently, we carried out a series of in situ transplant experiments using a number of tolerant and sensitive polychaete species living around a natural CO2 vent system. Here, we show that a marine metazoan (i.e. Platynereis dumerilii) was able to adapt to chronic and elevated levels of pCO2. The vent population of P. dumerilii was physiologically and genetically different from nearby populations that experience low pCO2, as well as smaller in body size. By contrast, different populations of Amphiglena mediterranea showed marked physiological plasticity indicating that adaptation or acclimatization are both viable strategies for the successful colonization of elevated pCO2 environments. In addition, sensitive species showed either a reduced or increased metabolism when exposed acutely to elevated pCO2. Our findings may help explain, from a metabolic perspective, the occurrence of past mass extinction, as well as shed light on alternative pathways of resilience in species facing ongoing ocean acidification. PMID:23980245

Adaptation and acclimatization to ocean acidification in marine ectotherms: an in situ transplant experiment with polychaetes at a shallow CO2 vent system.

PubMed

Calosi, Piero; Rastrick, Samuel P S; Lombardi, Chiara; de Guzman, Heidi J; Davidson, Laura; Jahnke, Marlene; Giangrande, Adriana; Hardege, Jörg D; Schulze, Anja; Spicer, John I; Gambi, Maria-Cristina

2013-01-01

Metabolic rate determines the physiological and life-history performances of ectotherms. Thus, the extent to which such rates are sensitive and plastic to environmental perturbation is central to an organism's ability to function in a changing environment. Little is known of long-term metabolic plasticity and potential for metabolic adaptation in marine ectotherms exposed to elevated pCO2. Consequently, we carried out a series of in situ transplant experiments using a number of tolerant and sensitive polychaete species living around a natural CO2 vent system. Here, we show that a marine metazoan (i.e. Platynereis dumerilii) was able to adapt to chronic and elevated levels of pCO2. The vent population of P. dumerilii was physiologically and genetically different from nearby populations that experience low pCO2, as well as smaller in body size. By contrast, different populations of Amphiglena mediterranea showed marked physiological plasticity indicating that adaptation or acclimatization are both viable strategies for the successful colonization of elevated pCO2 environments. In addition, sensitive species showed either a reduced or increased metabolism when exposed acutely to elevated pCO2. Our findings may help explain, from a metabolic perspective, the occurrence of past mass extinction, as well as shed light on alternative pathways of resilience in species facing ongoing ocean acidification.

Does Long-Term Elevation of CO2 Concentration Increase Photosynthesis in Forest Floor Vegetation? (Indiana Strawberry in a Maryland Forest).

PubMed

Osborne, C. P.; Drake, B. G.; LaRoche, J.; Long, S. P.

1997-05-01

As the partial pressure of CO2 (pCO2) in the atmosphere rises, photorespiratory loss of carbon in C3 photosynthesis will diminish and the net efficiency of light-limited photosynthetic carbon uptake should rise. We tested this expectation for Indiana strawberry (Duchesnea indica) growing on a Maryland forest floor. Open-top chambers were used to elevate the pCO2 of a forest floor habitat to 67 Pa and were paired with control chambers providing an ambient pCO2 of 38 Pa. After 3.5 years, D. indica leaves grown and measured in the elevated pCO2 showed a significantly greater maximum quantum efficiency of net photosynthesis (by 22%) and a lower light compensation point (by 42%) than leaves grown and measured in the control chambers. The quantum efficiency to minimize photorespiration, measured in 1% O2, was the same for controls and plants grown at elevated pCO2. This showed that the maximum efficiency of light-energy transduction into assimilated carbon was not altered by acclimation and that the increase in light-limited photosynthesis at elevated pCO2 was simply a function of the decrease in photorespiration. Acclimation did decrease the ribulose-1,5-bisphosphate carboxylase/oxygenase and light-harvesting chlorophyll protein content of the leaf by more than 30%. These changes were associated with a decreased capacity for light-saturated, but not light-limited, photosynthesis. Even so, leaves of D. indica grown and measured at elevated pCO2 showed greater light-saturated photosynthetic rates than leaves grown and measured at the current atmospheric pCO2. In situ measurements under natural forest floor lighting showed large increases in leaf photosynthesis at elevated pCO2, relative to controls, in both summer and fall. The increase in efficiency of light-limited photosynthesis with elevated pCO2 allowed positive net photosynthetic carbon uptake on days and at locations on the forest floor that light fluxes were insufficient for positive net photosynthesis in the current atmospheric pCO2.

Foraminiferal calcification and CO2

NASA Astrophysics Data System (ADS)

Nooijer, L. D.; Toyofuku, T.; Reichart, G. J.

2017-12-01

Ongoing burning of fossil fuels increases atmospheric CO2, elevates marine dissolved CO2 and decreases pH and the saturation state with respect to calcium carbonate. Intuitively this should decrease the ability of CaCO3-producing organisms to build their skeletons and shells. Whereas on geological time scales weathering and carbonate deposition removes carbon from the geo-biosphere, on time scales up to thousands of years, carbonate precipitation increases pCO2 because of the associated shift in seawater carbon speciation. Hence reduced calcification provides a potentially important negative feedback on increased pCO2 levels. Here we show that foraminifera form their calcium carbonate by active proton pumping. This elevates the internal pH and acidifies the direct foraminiferal surrounding. This also creates a strong pCO2 gradient and facilitates the uptake of DIC in the form of carbon dioxide. This finding uncouples saturation state from calcification and predicts that the added carbon due to ocean acidification will promote calcification by these organisms. This unknown effect could add substantially to atmospheric pCO2 levels, and might need to be accounted for in future mitigation strategies.

Acclimation of bloom-forming and perennial seaweeds to elevated pCO2 conserved across levels of environmental complexity.

PubMed

Xu, Dong; Schaum, Charlotte-Elisa; Lin, Fan; Sun, Ke; Munroe, James R; Zhang, Xiao W; Fan, Xiao; Teng, Lin H; Wang, Yi T; Zhuang, Zhi M; Ye, Naihao

2017-11-01

Macroalgae contribute approximately 15% of the primary productivity in coastal marine ecosystems, fix up to 27.4 Tg of carbon per year, and provide important structural components for life in coastal waters. Despite this ecological and commercial importance, direct measurements and comparisons of the short-term responses to elevated pCO 2 in seaweeds with different life-history strategies are scarce. Here, we cultured several seaweed species (bloom forming/nonbloom forming/perennial/annual) in the laboratory, in tanks in an indoor mesocosm facility, and in coastal mesocosms under pCO 2 levels ranging from 400 to 2,000 μatm. We find that, across all scales of the experimental setup, ephemeral species of the genus Ulva increase their photosynthesis and growth rates in response to elevated pCO 2 the most, whereas longer-lived perennial species show a smaller increase or a decrease. These differences in short-term growth and photosynthesis rates are likely to give bloom-forming green seaweeds a competitive advantage in mixed communities, and our results thus suggest that coastal seaweed assemblages in eutrophic waters may undergo an initial shift toward communities dominated by bloom-forming, short-lived seaweeds. © 2017 John Wiley & Sons Ltd.

Changes in gene expression, cell physiology and toxicity of the harmful cyanobacterium Microcystis aeruginosa at elevated CO2

PubMed Central

Sandrini, Giovanni; Cunsolo, Serena; Schuurmans, J. Merijn; Matthijs, Hans C. P.; Huisman, Jef

2015-01-01

Rising CO2 concentrations may have large effects on aquatic microorganisms. In this study, we investigated how elevated pCO2 affects the harmful freshwater cyanobacterium Microcystis aeruginosa. This species is capable of producing dense blooms and hepatotoxins called microcystins. Strain PCC 7806 was cultured in chemostats that were shifted from low to high pCO2 conditions. This resulted in a transition from a C-limited to a light-limited steady state, with a ~2.7-fold increase of the cyanobacterial biomass and ~2.5-fold more microcystin per cell. Cells increased their chlorophyll a and phycocyanin content, and raised their PSI/PSII ratio at high pCO2. Surprisingly, cells had a lower dry weight and contained less carbohydrates, which might be an adaptation to improve the buoyancy of Microcystis when light becomes more limiting at high pCO2. Only 234 of the 4691 genes responded to elevated pCO2. For instance, expression of the carboxysome, RuBisCO, photosystem and C metabolism genes did not change significantly, and only a few N assimilation genes were expressed differently. The lack of large-scale changes in the transcriptome could suit a buoyant species that lives in eutrophic lakes with strong CO2 fluctuations very well. However, we found major responses in inorganic carbon uptake. At low pCO2, cells were mainly dependent on bicarbonate uptake, whereas at high pCO2 gene expression of the bicarbonate uptake systems was down-regulated and cells shifted to CO2 and low-affinity bicarbonate uptake. These results show that the need for high-affinity bicarbonate uptake systems ceases at elevated CO2. Moreover, the combination of an increased cyanobacterial abundance, improved buoyancy, and higher toxin content per cell indicates that rising atmospheric CO2 levels may increase the problems associated with the harmful cyanobacterium Microcystis in eutrophic lakes. PMID:25999931

Impact of high pCO2 on shell structure of the bivalve Cerastoderma edule.

PubMed

Milano, Stefania; Schöne, Bernd R; Wang, Schunfeng; Müller, Werner E

2016-08-01

Raised atmospheric emissions of carbon dioxide (CO2) result in an increased ocean pCO2 level and decreased carbonate saturation state. Ocean acidification potentially represents a major threat to calcifying organisms, specifically mollusks. The present study focuses on the impact of elevated pCO2 on shell microstructural and mechanical properties of the bivalve Cerastoderma edule. The mollusks were collected from the Baltic Sea and kept in flow-through systems at six different pCO2 levels from 900 μatm (control) to 24,400 μatm. Extreme pCO2 levels were used to determine the effects of potential leaks from the carbon capture and sequestration sites where CO2 is stored in sub-seabed geological formations. Two approaches were combined to determine the effects of the acidified conditions: (1) Shell microstructures and dissolution damage were analyzed using scanning electron microscopy (SEM) and (2) shell hardness was tested using nanoindentation. Microstructures of specimens reared at different pCO2 levels do not show significant changes in their size and shape. Likewise, the increase of pCO2 does not affect shell hardness. However, dissolution of ontogenetically younger portions of the shell becomes more severe with the increase of pCO2. Irrespective of pCO2, strong negative correlations exist between microstructure size and shell mechanics. An additional sample from the North Sea revealed the same microstructural-mechanical interdependency as the shells from the Baltic Sea. Our findings suggest that the skeletal structure of C. edule is not intensely influenced by pCO2 variations. Furthermore, our study indicates that naturally occurring shell mechanical property depends on the shell architecture at μm-scale. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of elevated pCO2 on reproductive properties of the benthic copepod Tigriopus japonicus and gastropod Babylonia japonica.

PubMed

Kita, Jun; Kikkawa, Takashi; Asai, Takamasa; Ishimatsu, Atsushi

2013-08-30

We investigated the effects of elevated pCO2 in seawater both on the acute mortality and the reproductive properties of the benthic copepod Tigriopus japonicus and gastropod Babylonia japonica with the purpose of accumulating basic data for assessing potential environmental impacts of sub-sea geological storage of anthropogenic CO2 in Japan. Acute tests showed that nauplii of T. japonicus have a high tolerance to elevated pCO2 environments. Full life cycle tests on T. japonicus indicated NOEC=5800μatm and LOEC=37,000μatm. Adult B. japonica showed remarkable resistance to elevated pCO2 in the acute tests. Embryonic development of B. japonica showed a NOEC=1500μatm and LOEC=5400μatm. T. japonicus showed high resistance to elevated pCO2 throughout the life cycle and B. japonica are rather sensitive during the veliger stage when they started to form their shells. Copyright © 2013 Elsevier Ltd. All rights reserved.

The Interrelationship of pCO2, Soil Moisture Content, and Biomass Fertilization Expressed in the Carbon Isotope Signature of C3 Plant Tissue

NASA Astrophysics Data System (ADS)

Schubert, B.; Jahren, A. H.

2017-12-01

Hundreds of chamber and field experiments have shown an increase in C3 plant biomass in response to elevated atmospheric carbon dioxide (pCO2); however, secondary water and nutrient deficits are thought to limit this response. Some have hypothesized that secondary limitation might be self-alleviating under elevated pCO2 as greater root biomass imparts enhanced access to water and nutrients. Here we present results of growth chamber experiments designed to test this hypothesis: we grew 206 Arabidopsis thaliana plants within 5 growth chambers, each set at a different level of pCO2: 390, 685, 1075, 1585, and 2175 ppmv. Within each growth chamber, soil moisture content (θm) was maintained across a spectrum: 1.50, 0.83, 0.44, and 0.38 g g-1. After 3 weeks of total growth, tissues were analyzed for both biomass and net carbon isotope discrimination (Δ13C) value. From these values, we calculated Δresidual, which represents the residual effect of water stress after subtraction of the effect of pCO2 due to photorespiration. Across the full range of moisture content, Δresidual displayed a significant 2.5‰ increase with increasing pCO2. This further implies a 0.1 unit increase in ci/ca, consistent with decreased water stress at elevated pCO2. The influence of CO2 fertilization on the alleviation of water stress was further evidenced in a positive correlation between percent biomass change and Δresidual, such that a doubling of plant biomass yielded a 1.85‰ increase in carbon isotope discrimination. In addition to providing new insight into water uptake in plants growing under elevated carbon dioxide, these data underscore the importance of separating the effects of increased pCO2 (via photorespiration) and altered ci/ca (via stomatal conductance) when considering changes in the Δ13C value of C3 land plants during the Anthropocene, or across any geological period that includes a marked change in global carbon cycling.

Ocean warming has a greater effect than acidification on the early life history development and swimming performance of a large circumglobal pelagic fish.

PubMed

Watson, Sue-Ann; Allan, Bridie J M; McQueen, David E; Nicol, Simon; Parsons, Darren M; Pether, Stephen M J; Pope, Stephen; Setiawan, Alvin N; Smith, Neville; Wilson, Carly; Munday, Philip L

2018-05-22

Ocean warming and acidification are serious threats to marine life; however, their individual and combined effects on large pelagic and predatory fishes are poorly understood. We determined the effects of projected future temperature and carbon dioxide (CO 2 ) levels on survival, growth, morphological development and swimming performance on the early life stages of a large circumglobal pelagic fish, the yellowtail kingfish Seriola lalandi. Eggs, larvae and juveniles were reared in cross-factored treatments of temperature (21 and 25°C) and pCO 2 (500 and 985 μatm) from fertilisation to 25 days post hatching (dph). Temperature had the greatest effect on survival, growth and development. Survivorship was lower, but growth and morphological development were faster at 25°C, with surviving fish larger and more developed at 1, 11 and 21 dph. Elevated pCO 2 affected size at 1 dph, but not at 11 or 21 dph, and did not affect survival or morphological development. Elevated temperature and pCO 2 had opposing effects on swimming performance at 21 dph. Critical swimming speed (U crit ) was increased by elevated temperature but reduced by elevated pCO 2 . Additionally, elevated temperature increased the proportion of individuals that responded to a startle stimulus, reduced latency to respond and increased maximum escape speed, potentially due to the more advanced developmental stage of juveniles at 25°C. By contrast, elevated pCO 2 reduced the distance moved and average speed in response to a startle stimulus. Our results show that higher temperature is likely to be the primary driver of global change impacts on kingfish early life history; however, elevated pCO 2 could affect critical aspects of swimming performance in this pelagic species. Our findings will help parameterise and structure fisheries population dynamics models and improve projections of impacts to large pelagic fishes under climate change scenarios to better inform adaptation and mitigation responses. © 2018 John Wiley & Sons Ltd.

Development under elevated pCO2 conditions does not affect lipid utilization and protein content in early life-history stages of the purple sea urchin, Strongylocentrotus purpuratus.

PubMed

Matson, Paul G; Yu, Pauline C; Sewell, Mary A; Hofmann, Gretchen E

2012-12-01

Ocean acidification (OA) is expected to have a major impact on marine species, particularly during early life-history stages. These effects appear to be species-specific and may include reduced survival, altered morphology, and depressed metabolism. However, less information is available regarding the bioenergetics of development under elevated CO(2) conditions. We examined the biochemical and morphological responses of Strongylocentrotus purpuratus during early development under ecologically relevant levels of pCO(2) (365, 1030, and 1450 μatm) that may occur during intense upwelling events. The principal findings of this study were (1) lipid utilization rates and protein content in S. purpuratus did not vary with pCO(2); (2) larval growth was reduced at elevated pCO(2) despite similar rates of energy utilization; and (3) relationships between egg phospholipid content and larval length were found under control but not high pCO(2) conditions. These results suggest that this species may either prioritize endogenous energy toward development and physiological function at the expense of growth, or that reduced larval length may be strictly due to higher costs of growth under OA conditions. This study highlights the need to further expand our knowledge of the physiological mechanisms involved in OA response in order to better understand how present populations may respond to global environmental change.

Effects of ocean acidification on immune responses of the Pacific oyster Crassostrea gigas.

PubMed

Wang, Qing; Cao, Ruiwen; Ning, Xuanxuan; You, Liping; Mu, Changkao; Wang, Chunlin; Wei, Lei; Cong, Ming; Wu, Huifeng; Zhao, Jianmin

2016-02-01

Ocean acidification (OA), caused by anthropogenic CO2emissions, has been proposed as one of the greatest threats in marine ecosystems. A growing body of evidence shows that ocean acidification can impact development, survival, growth and physiology of marine calcifiers. In this study, the immune responses of the Pacific oyster Crassostrea gigas were investigated after elevated pCO2 exposure for 28 days. The results demonstrated that OA caused an increase of apoptosis and reactive oxygen species (ROS) production in hemocytes. Moreover, elevated pCO2 had an inhibitory effect on some antioxidant enzyme activities and decreased the GSH level in digestive gland. However, the mRNA expression pattern of several immune related genes varied depending on the exposure time and tissues. After exposure to pCO2 at ∼2000 ppm for 28 days, the mRNA expressions of almost all tested genes were significantly suppressed in gills and stimulated in hemocytes. Above all, our study demonstrated that elevated pCO2 have a significant impact on the immune systems of the Pacific oyster, which may constitute as a potential threat to increased susceptibility of bivalves to diseases. Copyright © 2015 Elsevier Ltd. All rights reserved.

Environmental salinity modulates the effects of elevated CO2 levels on juvenile hard-shell clams, Mercenaria mercenaria.

PubMed

Dickinson, Gary H; Matoo, Omera B; Tourek, Robert T; Sokolova, Inna M; Beniash, Elia

2013-07-15

Ocean acidification due to increasing atmospheric CO2 concentrations results in a decrease in seawater pH and shifts in the carbonate chemistry that can negatively affect marine organisms. Marine bivalves such as the hard-shell clam, Mercenaria mercenaria, serve as ecosystem engineers in estuaries and coastal zones of the western Atlantic and, as for many marine calcifiers, are sensitive to the impacts of ocean acidification. In estuaries, the effects of ocean acidification can be exacerbated by low buffering capacity of brackish waters, acidic inputs from freshwaters and land, and/or the negative effects of salinity on the physiology of organisms. We determined the interactive effects of 21 weeks of exposure to different levels of CO2 (~395, 800 and 1500 μatm corresponding to pH of 8.2, 8.1 and 7.7, respectively) and salinity (32 versus 16) on biomineralization, shell properties and energy metabolism of juvenile hard-shell clams. Low salinity had profound effects on survival, energy metabolism and biomineralization of hard-shell clams and modulated their responses to elevated PCO2. Negative effects of low salinity in juvenile clams were mostly due to the strongly elevated basal energy demand, indicating energy deficiency, that led to reduced growth, elevated mortality and impaired shell maintenance (evidenced by the extensive damage to the periostracum). The effects of elevated PCO2 on physiology and biomineralization of hard-shell clams were more complex. Elevated PCO2 (~800-1500 μatm) had no significant effects on standard metabolic rates (indicative of the basal energy demand), but affected growth and shell mechanical properties in juvenile clams. Moderate hypercapnia (~800 μatm PCO2) increased shell and tissue growth and reduced mortality of juvenile clams in high salinity exposures; however, these effects were abolished under the low salinity conditions or at high PCO2 (~1500 μatm). Mechanical properties of the shell (measured as microhardness and fracture toughness of the shells) were negatively affected by elevated CO2 alone or in combination with low salinity, which may have important implications for protection against predators or environmental stressors. Our data indicate that environmental salinity can strongly modulate responses to ocean acidification in hard-shell clams and thus should be taken into account when predicting the effects of ocean acidification on estuarine bivalves.

Ocean Acidification Differentially Affects the Photosynthesis of Key New England Macrophytes

NASA Astrophysics Data System (ADS)

Fachon, E.; Ets-Hokin, J. M.; Donham, E. M.; Price, N.

2016-02-01

While the influence of anthropogenic CO2 emissions on seawater chemistry is detrimental to calcification among CaCO3 reliant organisms such as commercially important shellfish species, non-calcareous macrophytes like seagrasses and seaweeds can experience enhanced growth under elevated pCO2 conditions and may be a substantial, if ephemeral, CO2 sink. Most marine macrophytes rely on enzyme conversion of HCO3- to supply the inorganic carbon necessary for photosynthesis; the ability to down-regulate this energetically expensive carbon acquisition under high pCO2 conditions could determine future species success. We exposed four commercially and ecologically relevant New England macrophytes (Saccharina latissima, Fucus vesiculosus, Ulva lactuca, and Zostera marina) to pre-industrial (280 uatm), present (400 and 520 utam - recorded in Casco Bay) and future (640, 880 and 1120 uatm - as predicted by the IPCC) pCO2 levels in 1.5 hr long respirometry assays after 72 hrs acclimation. CO2 consumption, photosynthetic quotient (Q = CO2 consumed:O2 evolved), and change in carbonate saturation state (Ωcalcite) were calculated for each sample using differences in initial and final carbonate chemistry and dissolved oxygen concentrations. All species experienced increases in rate of CO2 uptake and Q under elevated pCO2 treatments, but response level differed across species. Saccharina latissima had the greatest relative effect on all parameters measured, consuming 4 times more carbon at high pCO2 levels than the lowest performing species. While all macrophytes were able to raise Ωcalcite, the magnitude of change decreased at higher pCO2 levels, suggesting a limitation to the degree to which photosynthesis can locally raise calcification potential for sensitive native or farmed populations of shellfish in the future. The varied responses observed across species have implications for future community structures and for phytoremediation efforts.

The combined effects of temperature and CO2 lead to altered gene expression in Acropora aspera

NASA Astrophysics Data System (ADS)

Ogawa, D.; Bobeszko, T.; Ainsworth, T.; Leggat, W.

2013-12-01

This study explored the interactive effects of near-term CO2 increases (40-90 ppm above current ambient) during a simulated bleaching event (34 °C for 5 d) of Acropora aspera by linking physiology to expression patterns of genes involved in carbon metabolism. Symbiodinium photosynthetic efficiency ( F v / F m ) was significantly depressed by the bleaching event, while elevated pressure of CO2 (pCO2) slightly mitigated the effects of increased temperature on F v / F m during the final 4 d of the recovery period, however, did not affect the loss of symbionts. Elevated pCO2 alone had no effect on F v / F m or symbiont density. Expression of targeted Symbiodinium genes involved in carbon metabolism and heat stress response was not significantly altered by either increased temperature and/or CO2. Of the selected host genes, two carbonic anhydrase isoforms (coCA2 and coCA3) exhibited the largest changes, most notably in crossed bleaching and elevated pCO2 treatments. CA2 was significantly down-regulated on day 14 in all treatments, with the greatest decrease in the crossed treatment (relative expression compared to control = 0.16; p < 0.05); CA3 showed a similar trend, with expression levels 0.20-fold of controls on day 14 ( p < 0.05) in the elevated temperature/pCO2 treatment. The synergistic effects of ocean acidification and bleaching were evident during this study and demonstrate that increased pCO2 in surface waters will impact corals much sooner than many studies utilising end-of-century pCO2 concentrations would indicate.

Combined effects of CO2 and light on the N2-fixing cyanobacterium Trichodesmium IMS101: a mechanistic view.

PubMed

Levitan, Orly; Kranz, Sven A; Spungin, Dina; Prásil, Ondrej; Rost, Björn; Berman-Frank, Ilana

2010-09-01

The marine diazotrophic cyanobacterium Trichodesmium responds to elevated atmospheric CO(2) partial pressure (pCO(2)) with higher N(2) fixation and growth rates. To unveil the underlying mechanisms, we examined the combined influence of pCO(2) (150 and 900 microatm) and light (50 and 200 micromol photons m(-2) s(-1)) on Trichodesmium IMS101. We expand on a complementary study that demonstrated that while elevated pCO(2) enhanced N(2) fixation and growth, oxygen evolution and carbon fixation increased mainly as a response to high light. Here, we investigated changes in the photosynthetic fluorescence parameters of photosystem II, in ratios of the photosynthetic units (photosystem I:photosystem II), and in the pool sizes of key proteins involved in the fixation of carbon and nitrogen as well as their subsequent assimilation. We show that the combined elevation in pCO(2) and light controlled the operation of the CO(2)-concentrating mechanism and enhanced protein activity without increasing their pool size. Moreover, elevated pCO(2) and high light decreased the amounts of several key proteins (NifH, PsbA, and PsaC), while amounts of AtpB and RbcL did not significantly change. Reduced investment in protein biosynthesis, without notably changing photosynthetic fluxes, could free up energy that can be reallocated to increase N(2) fixation and growth at elevated pCO(2) and light. We suggest that changes in the redox state of the photosynthetic electron transport chain and posttranslational regulation of key proteins mediate the high flexibility in resources and energy allocation in Trichodesmium. This strategy should enable Trichodesmium to flourish in future surface oceans characterized by elevated pCO(2), higher temperatures, and high light.

Warming and Acidification Induced Mass Mortality of a Coastal Keystone predator

NASA Astrophysics Data System (ADS)

Melzner, F.; Findeisen, U.

2016-02-01

The Baltic Sea is characterized by low salinity and pronounced fluctuations in pCO2. On-line monitoring of pCO2 in 2014 in Kiel Fjord demonstrated occurrence of peak values of >2,000 µatm in summer and autumn and average values >750 µatm. We assessed the impacts of elevated temperature (ambient temperature, ambient +3°C) and pCO2 (500, 1,500, 2,400 µatm) on the keystone species Asterias rubens in a fully crossed long - term experiment (N=5 replicate tanks each, 1 year duration). During spring and early summer (February - June), high temperature animals ingested significantly more food and spawned significantly earlier (April 30th) than ambient acclimated animals (May 23rd). Elevated pCO2 led to comparatively minor reductions in food intake and scope for growth during that period. During summer (June - August), elevated temperature >25°C caused negative energy budgets and >95% mortality in the warm acclimated groups, while mortality was low in the ambient temperature groups. Our results indicate that A. rubens may benefit from increased temperature during colder months, yet dramatically suffer during summer heat waves in warm years. Meaningful experimental approaches to assess species vulnerability to climate change need to encompass all seasons and realistic abiotic stressor levels.

Physiological response of the cold-water coral Desmophyllum dianthus to thermal stress and ocean acidification.

PubMed

Gori, Andrea; Ferrier-Pagès, Christine; Hennige, Sebastian J; Murray, Fiona; Rottier, Cécile; Wicks, Laura C; Roberts, J Murray

2016-01-01

Rising temperatures and ocean acidification driven by anthropogenic carbon emissions threaten both tropical and temperate corals. However, the synergistic effect of these stressors on coral physiology is still poorly understood, in particular for cold-water corals. This study assessed changes in key physiological parameters (calcification, respiration and ammonium excretion) of the widespread cold-water coral Desmophyllum dianthus maintained for ∼8 months at two temperatures (ambient 12 °C and elevated 15 °C) and two pCO2 conditions (ambient 390 ppm and elevated 750 ppm). At ambient temperatures no change in instantaneous calcification, respiration or ammonium excretion rates was observed at either pCO2 levels. Conversely, elevated temperature (15 °C) significantly reduced calcification rates, and combined elevated temperature and pCO2 significantly reduced respiration rates. Changes in the ratio of respired oxygen to excreted nitrogen (O:N), which provides information on the main sources of energy being metabolized, indicated a shift from mixed use of protein and carbohydrate/lipid as metabolic substrates under control conditions, to less efficient protein-dominated catabolism under both stressors. Overall, this study shows that the physiology of D. dianthus is more sensitive to thermal than pCO2 stress, and that the predicted combination of rising temperatures and ocean acidification in the coming decades may severely impact this cold-water coral species.

The influence of food supply on the response of Olympia oyster larvae to ocean acidification

NASA Astrophysics Data System (ADS)

Hettinger, A.; Sanford, E.; Hill, T. M.; Hosfelt, J. D.; Russell, A. D.; Gaylord, B.

2013-10-01

Increases in atmospheric carbon dioxide drive accompanying changes in the marine carbonate system as carbon dioxide (CO2) enters seawater and alters ocean pH (termed "ocean acidification"). However, such changes do not occur in isolation, and other environmental factors have the potential to modulate the consequences of altered ocean chemistry. Given that physiological mechanisms used by organisms to confront acidification can be energetically costly, we explored the potential for food supply to influence the response of Olympia oyster (Ostrea lurida) larvae to ocean acidification. In laboratory experiments, we reared oyster larvae under a factorial combination of pCO2 and food level. Elevated pCO2 had negative effects on larval growth, total dry weight, and metamorphic success, but high food availability partially offset these influences. The combination of elevated pCO2 and low food availability led to the greatest reduction in larval performance. However, the effects of food and pCO2 interacted additively rather than synergistically, indicating that they operated independently. Despite the potential for abundant resources to counteract the consequences of ocean acidification, impacts were never completely negated, suggesting that even under conditions of enhanced primary production and elevated food availability, impacts of ocean acidification may still accrue in some consumers.

Influence of elevated temperature, pCO2, and nutrients on larva-biofilm interaction: Elucidation with acorn barnacle, Balanus amphitrite Darwin (Cirripedia: Thoracica)

NASA Astrophysics Data System (ADS)

Baragi, Lalita V.; Anil, Arga Chandrashekar

2017-02-01

Selection of optimal habitat by larvae of sessile organism is influenced by cues offered by the biofilm. Ocean warming and acidification are likely to enforce changes in the biofilm community and inturn influence the settlement process. Hence, we evaluated the influence of biofilm (multispecies and unialgal) and diet-mediated changes on the settlement of Balanus amphitrite cyprids (presettlement non-feeding larval stage) under different combinations of temperature (28, 30, 32 and 34 °C), pCO2 (400, 750 and 1500 μatm) and nutrient (unenriched and f/2 enriched). Nutrient enrichment enhanced the diatom and bacterial abundance at ambient temperature (30 °C) and pCO2 (400 μatm), which inturn increased larval settlement. Elevated pCO2 (750 and 1500 μatm) had no direct effect but a variable cascading effect on the settlement via biofilm-mediated changes was observed, depending on the type of biofilm. In contrast, elevated temperature (32 and 34 °C), either individually or in combination with elevated pCO2 had direct negative effect on settlement. However, biofilm-mediated changes compensated this negative effect. The larval settlement was also influenced by changes in the larval diet. Under elevated temperature and pCO2, cyprids raised with a feed (Chaetoceros calcitrans) from ambient temperature and pCO2 were of poor quality (lower RNA:DNA ratio, lower protein synthetic capacity) and yielded lower settlement. However, cyprids raised with a feed from elevated temperature and pCO2 were of better quality (higher RNA:DNA ratio, higher protein synthetic capacity) and yielded higher settlement. Overall, the observations from the present study provide insights into the significance of biotic interactions on the coastal biofouling communities under future climatic scenario and emphasise the need for future experiments on these aspects.

Antimüllerian hormone levels are independently related to ovarian hyperandrogenism and polycystic ovaries.

PubMed

Rosenfield, Robert L; Wroblewski, Kristen; Padmanabhan, Vasantha; Littlejohn, Elizabeth; Mortensen, Monica; Ehrmann, David A

2012-07-01

To determine the relationship of antimüllerian hormone (AMH) levels to polycystic ovaries and ovarian androgenic function. Prospective case-control study. General clinical research center. Eumenorrheic asymptomatic volunteers without (V-NO; n = 19; reference population) or with (V-PCO; n = 28) a polycystic ovary and hyperandrogenemic anovulatory subjects grouped according to ovarian function into typical PCOS (PCOS-T; n = 37) and atypical PCOS (PCOS-A; n = 18). Pelvic ultrasonography, short dexamethasone androgen-suppression test (SDAST), and GnRH agonist (GnRHag) test. Baseline AMH levels were related to polycystic ovary status, testosterone response to SDAST, and 17-hydroxyprogesterone response to GnRHag test. AMH levels correlated with SDAST and GnRHag test outcomes. AMH was elevated (>6.2 ng/mL) in 32% of V-PCO versus 5% V-NO. The 21% of V-PCO who met Rotterdam PCOS criteria all had functional ovarian hyperandrogenism, but AMH levels were similar to nonhyperandrogenic V-PCO. AMH >10.7 ng/mL discriminated V-PCO from PCOS with 96% specificity and 41% sensitivity for PCOS-T, and insignificantly for PCOS-A. AMH levels are independently related to ovarian androgenic function and polycystic ovaries. Very high AMH levels are specific but insensitive for PCOS. In the absence of hyperandrogenism, moderate AMH elevation in women with normal-variant polycystic ovaries seems to indicate an enlarged oocyte pool. Copyright © 2012 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Antimüllerian hormone levels are independently related to ovarian hyperandrogenism and polycystic ovaries

PubMed Central

Rosenfield, Robert L.; Wroblewski, Kristen; Padmanabhan, Vasantha; Littlejohn, Elizabeth; Mortensen, Monica; Ehrmann, David A.

2013-01-01

Objective To determine the relationship of antimüllerian hormone (AMH) levels to polycystic ovaries and ovarian androgenic function. Design Prospective case-control study. Setting General clinical research center. Participant(s) Eumenorrheic asymptomatic volunteers without (V-NO; n = 19; reference population) or with (V-PCO; n = 28) a polycystic ovary and hyperandrogenemic anovulatory subjects grouped according to ovarian function into typical PCOS (PCOS-T; n = 37) and atypical PCOS (PCOS-A; n = 18). Intervention(s) Pelvic ultrasonography, short dexamethasone androgen-suppression test (SDAST), and GnRH agonist (GnRHag) test. Main Outcome Measure(s) Baseline AMH levels were related to polycystic ovary status, testosterone response to SDAST, and 17-hydroxyprogesterone response to GnRHag test. Result(s) AMH levels correlated with SDAST and GnRHag test outcomes. AMH was elevated (>6.2 ng/mL) in 32% of V-PCO versus 5% V-NO. The 21% of V-PCO who met Rotterdam PCOS criteria all had functional ovarian hyperandrogenism, but AMH levels were similar to nonhyperandrogenic V-PCO. AMH >10.7 ng/mL discriminated V-PCO from PCOS with 96% specificity and 41% sensitivity for PCOS-T, and insignificantly for PCOS-A. Conclusion(s) AMH levels are independently related to ovarian androgenic function and polycystic ovaries. Very high AMH levels are specific but insensitive for PCOS. In the absence of hyperandrogenism, moderate AMH elevation in women with normal-variant polycystic ovaries seems to indicate an enlarged oocyte pool. PMID:22541936

Global distortion of GPS networks associated with satellite antenna model errors

NASA Astrophysics Data System (ADS)

Cardellach, E.; Elósegui, P.; Davis, J. L.

2007-07-01

Recent studies of the GPS satellite phase center offsets (PCOs) suggest that these have been in error by ˜1 m. Previous studies had shown that PCO errors are absorbed mainly by parameters representing satellite clock and the radial components of site position. On the basis of the assumption that the radial errors are equal, PCO errors will therefore introduce an error in network scale. However, PCO errors also introduce distortions, or apparent deformations, within the network, primarily in the radial (vertical) component of site position that cannot be corrected via a Helmert transformation. Using numerical simulations to quantify the effects of PCO errors, we found that these PCO errors lead to a vertical network distortion of 6-12 mm per meter of PCO error. The network distortion depends on the minimum elevation angle used in the analysis of the GPS phase observables, becoming larger as the minimum elevation angle increases. The steady evolution of the GPS constellation as new satellites are launched, age, and are decommissioned, leads to the effects of PCO errors varying with time that introduce an apparent global-scale rate change. We demonstrate here that current estimates for PCO errors result in a geographically variable error in the vertical rate at the 1-2 mm yr-1 level, which will impact high-precision crustal deformation studies.

Elevated pCO2 affects tissue biomass composition, but not calcification, in a reef coral under two light regimes

PubMed Central

Mason, R. A. B.; Ellis, W. R.; Cunning, R.; Gates, R. D.

2017-01-01

Ocean acidification (OA) is predicted to reduce reef coral calcification rates and threaten the long-term growth of coral reefs under climate change. Reduced coral growth at elevated pCO2 may be buffered by sufficiently high irradiances; however, the interactive effects of OA and irradiance on other fundamental aspects of coral physiology, such as the composition and energetics of coral biomass, remain largely unexplored. This study tested the effects of two light treatments (7.5 versus 15.7 mol photons m−2 d−1) at ambient or elevated pCO2 (435 versus 957 µatm) on calcification, photopigment and symbiont densities, biomass reserves (lipids, carbohydrates, proteins), and biomass energy content (kJ) of the reef coral Pocillopora acuta from Kāne‘ohe Bay, Hawai‘i. While pCO2 and light had no effect on either area- or biomass-normalized calcification, tissue lipids gdw−1 and kJ gdw−1 were reduced 15% and 14% at high pCO2, and carbohydrate content increased 15% under high light. The combination of high light and high pCO2 reduced protein biomass (per unit area) by approximately 20%. Thus, under ecologically relevant irradiances, P. acuta in Kāne‘ohe Bay does not exhibit OA-driven reductions in calcification reported for other corals; however, reductions in tissue lipids, energy content and protein biomass suggest OA induced an energetic deficit and compensatory catabolism of tissue biomass. The null effects of OA on calcification at two irradiances support a growing body of work concluding some reef corals may be able to employ compensatory physiological mechanisms that maintain present-day levels of calcification under OA. However, negative effects of OA on P. acuta biomass composition and energy content may impact the long-term performance and scope for growth of this species in a high pCO2 world. PMID:29291059

Elevated pCO2 enhances bacterioplankton removal of organic carbon

PubMed Central

James, Anna K.; Passow, Uta; Brzezinski, Mark A.; Parsons, Rachel J.; Trapani, Jennifer N.; Carlson, Craig A.

2017-01-01

Factors that affect the removal of organic carbon by heterotrophic bacterioplankton can impact the rate and magnitude of organic carbon loss in the ocean through the conversion of a portion of consumed organic carbon to CO2. Through enhanced rates of consumption, surface bacterioplankton communities can also reduce the amount of dissolved organic carbon (DOC) available for export from the surface ocean. The present study investigated the direct effects of elevated pCO2 on bacterioplankton removal of several forms of DOC ranging from glucose to complex phytoplankton exudate and lysate, and naturally occurring DOC. Elevated pCO2 (1000–1500 ppm) enhanced both the rate and magnitude of organic carbon removal by bacterioplankton communities compared to low (pre-industrial and ambient) pCO2 (250 –~400 ppm). The increased removal was largely due to enhanced respiration, rather than enhanced production of bacterioplankton biomass. The results suggest that elevated pCO2 can increase DOC consumption and decrease bacterioplankton growth efficiency, ultimately decreasing the amount of DOC available for vertical export and increasing the production of CO2 in the surface ocean. PMID:28257422

Elevated lactate during psychogenic hyperventilation.

PubMed

ter Avest, E; Patist, F M; Ter Maaten, J C; Nijsten, M W N

2011-04-01

Elevated arterial lactate levels are closely related to morbidity and mortality in various patient categories. In the present retrospective study, the relation between arterial lactate, partial pressure of carbon dioxide (Pco(2)) and pH was systematically investigated in patients who visited the emergency department (ED) with psychogenic hyperventilation. Over a 5-month period, all the patients who visited the ED of a university hospital with presumed psychogenic hyperventilation were evaluated. Psychogenic hyperventilation was presumed to be present when an increased respiratory rate (>20 min) was documented at or before the ED visit and when somatic causes explaining the hyperventilation were absent. Arterial blood gas and lactate levels (reference values 0.5-1.5 mmol/l) were immediately measured by a point-of-care analyser that was managed and calibrated by the central laboratory. During the study period, 46 patients were diagnosed as having psychogenic hyperventilation. The median (range) Pco(2) for this group was 4.3 (2.0-5.5) kPa, the pH was 7.47 (7.40-7.68) and the lactate level was 1.2 (0.5-4.4) mmol/l. 14 participants (30%) had a lactate level above the reference value of 1.5 mmol/l. Pco(2) was the most important predictor of lactate in multivariate analysis. None of the participants underwent any medical treatment other than observation at the ED or had been hospitalised after their ED visit. In patients with psychogenic hyperventilation, lactate levels are frequently elevated. Whereas high lactates are usually associated with acidosis and an increased risk of poor outcome, in patients with psychogenic hyperventilation, high lactates are associated with hypocapnia and alkalosis. In this context, elevated arterial lactate levels should not be regarded as an adverse sign.

Responses of two scleractinian corals to cobalt pollution and ocean acidification.

PubMed

Biscéré, Tom; Rodolfo-Metalpa, Riccardo; Lorrain, Anne; Chauvaud, Laurent; Thébault, Julien; Clavier, Jacques; Houlbrèque, Fanny

2015-01-01

The effects of ocean acidification alone or in combination with warming on coral metabolism have been extensively investigated, whereas none of these studies consider that most coral reefs near shore are already impacted by other natural anthropogenic inputs such as metal pollution. It is likely that projected ocean acidification levels will aggravate coral reef health. We first investigated how ocean acidification interacts with one near shore locally abundant metal on the physiology of two major reef-building corals: Stylophora pistillata and Acropora muricata. Two pH levels (pHT 8.02; pCO2 366 μatm and pHT 7.75; pCO2 1140 μatm) and two cobalt concentrations (natural, 0.03 μg L-1 and polluted, 0.2 μg L-1) were tested during five weeks in aquaria. We found that, for both species, cobalt input decreased significantly their growth rates by 28% while it stimulated their photosystem II, with higher values of rETRmax (relative Electron Transport Rate). Elevated pCO2 levels acted differently on the coral rETRmax values and did not affect their growth rates. No consistent interaction was found between pCO2 levels and cobalt concentrations. We also measured in situ the effect of higher cobalt concentrations (1.06 ± 0.16 μg L-1) on A. muricata using benthic chamber experiments. At this elevated concentration, cobalt decreased simultaneously coral growth and photosynthetic rates, indicating that the toxic threshold for this pollutant has been reached for both host cells and zooxanthellae. Our results from both aquaria and in situ experiments, suggest that these coral species are not particularly sensitive to high pCO2 conditions but they are to ecologically relevant cobalt concentrations. Our study reveals that some reefs may be yet subjected to deleterious pollution levels, and even if no interaction between pCO2 levels and cobalt concentration has been found, it is likely that coral metabolism will be weakened if they are subjected to additional threats such as temperature increase, other heavy metals, and eutrophication.

Responses of Two Scleractinian Corals to Cobalt Pollution and Ocean Acidification

PubMed Central

Biscéré, Tom; Rodolfo-Metalpa, Riccardo; Lorrain, Anne; Chauvaud, Laurent; Thébault, Julien; Clavier, Jacques; Houlbrèque, Fanny

2015-01-01

The effects of ocean acidification alone or in combination with warming on coral metabolism have been extensively investigated, whereas none of these studies consider that most coral reefs near shore are already impacted by other natural anthropogenic inputs such as metal pollution. It is likely that projected ocean acidification levels will aggravate coral reef health. We first investigated how ocean acidification interacts with one near shore locally abundant metal on the physiology of two major reef-building corals: Stylophora pistillata and Acropora muricata. Two pH levels (pHT 8.02; pCO2 366 μatm and pHT 7.75; pCO2 1140 μatm) and two cobalt concentrations (natural, 0.03 μg L-1 and polluted, 0.2 μg L-1) were tested during five weeks in aquaria. We found that, for both species, cobalt input decreased significantly their growth rates by 28% while it stimulated their photosystem II, with higher values of rETRmax (relative Electron Transport Rate). Elevated pCO2 levels acted differently on the coral rETRmax values and did not affect their growth rates. No consistent interaction was found between pCO2 levels and cobalt concentrations. We also measured in situ the effect of higher cobalt concentrations (1.06 ± 0.16 μg L-1) on A. muricata using benthic chamber experiments. At this elevated concentration, cobalt decreased simultaneously coral growth and photosynthetic rates, indicating that the toxic threshold for this pollutant has been reached for both host cells and zooxanthellae. Our results from both aquaria and in situ experiments, suggest that these coral species are not particularly sensitive to high pCO2 conditions but they are to ecologically relevant cobalt concentrations. Our study reveals that some reefs may be yet subjected to deleterious pollution levels, and even if no interaction between pCO2 levels and cobalt concentration has been found, it is likely that coral metabolism will be weakened if they are subjected to additional threats such as temperature increase, other heavy metals, and eutrophication. PMID:25849317

Metabolic shifts in the Antarctic fish Notothenia rossii in response to rising temperature and PCO2

PubMed Central

2012-01-01

Introduction Ongoing ocean warming and acidification increasingly affect marine ecosystems, in particular around the Antarctic Peninsula. Yet little is known about the capability of Antarctic notothenioid fish to cope with rising temperature in acidifying seawater. While the whole animal level is expected to be more sensitive towards hypercapnia and temperature, the basis of thermal tolerance is set at the cellular level, with a putative key role for mitochondria. This study therefore investigates the physiological responses of the Antarctic Notothenia rossii after long-term acclimation to increased temperatures (7°C) and elevated PCO2 (0.2 kPa CO2) at different levels of physiological organisation. Results For an integrated picture, we analysed the acclimation capacities of N. rossii by measuring routine metabolic rate (RMR), mitochondrial capacities (state III respiration) as well as intra- and extracellular acid–base status during acute thermal challenges and after long-term acclimation to changing temperature and hypercapnia. RMR was partially compensated during warm- acclimation (decreased below the rate observed after acute warming), while elevated PCO2 had no effect on cold or warm acclimated RMR. Mitochondrial state III respiration was unaffected by temperature acclimation but depressed in cold and warm hypercapnia-acclimated fish. In both cold- and warm-exposed N. rossii, hypercapnia acclimation resulted in a shift of extracellular pH (pHe) towards more alkaline values. A similar overcompensation was visible in muscle intracellular pH (pHi). pHi in liver displayed a slight acidosis after warm normo- or hypercapnia acclimation, nevertheless, long-term exposure to higher PCO2 was compensated for by intracellular bicarbonate accumulation. Conclusion The partial warm compensation in whole animal metabolic rate indicates beginning limitations in tissue oxygen supply after warm-acclimation of N. rossii. Compensatory mechanisms of the reduced mitochondrial capacities under chronic hypercapnia may include a new metabolic equilibrium to meet the elevated energy demand for acid–base regulation. New set points of acid–base regulation under hypercapnia, visible at the systemic and intracellular level, indicate that N. rossii can at least in part acclimate to ocean warming and acidification. It remains open whether the reduced capacities of mitochondrial energy metabolism are adaptive or would impair population fitness over longer timescales under chronically elevated temperature and PCO2. PMID:23075125

The influence of abrupt increases in seawater pCO2 on plankton productivity in the subtropical North Pacific Ocean

PubMed Central

Böttjer, Daniela; Letelier, Ricardo M.; Church, Matthew J.

2018-01-01

We conducted a series of experiments to examine short-term (2–5 days) effects of abrupt increases in the partial pressure of carbon dioxide (pCO2) in seawater on rates of primary and bacterial production at Station ALOHA (22°45’ N, 158° W) in the North Pacific Subtropical Gyre (NPSG). The majority of experiments (8 of 10 total) displayed no response in rates of primary production (measured by 14C-bicarbonate assimilation; 14C-PP) under elevated pCO2 (~1100 μatm) compared to ambient pCO2 (~387 μatm). In 2 of 10 experiments, rates of 14C-PP decreased significantly (~43%) under elevated pCO2 treatments relative to controls. Similarly, no significant differences between treatments were observed in 6 of 7 experiments where bacterial production was measured via incorporation of 3H-leucine (3H-Leu), while in 1 experiment, rates of 3H-Leu incorporation measured in the dark (3H-LeuDark) increased more than 2-fold under high pCO2 conditions. We also examined photoperiod-length, depth-dependent (0–125 m) responses in rates of 14C-PP and 3H-Leu incorporation to abrupt pCO2 increases (to ~750 μatm). In the majority of these depth-resolved experiments (4 of 5 total), rates of 14C-PP demonstrated no consistent response to elevated pCO2. In 2 of 5 depth-resolved experiments, rates of 3H-LeuDark incorporation were lower (10% to 15%) under elevated pCO2 compared to controls. Our results revealed that rates of 14C-PP and bacterial production in this persistently oligotrophic habitat generally demonstrated no or weak responses to abrupt changes in pCO2. We postulate that any effects caused by changes in pCO2 may be masked or outweighed by the role that nutrient availability and temperature play in controlling metabolism in this ecosystem. PMID:29694353

Elevated temperature drives kelp microbiome dysbiosis, while elevated carbon dioxide induces water microbiome disruption

PubMed Central

Morris, Megan M.; Brown, Matt; Doane, Michael; Edwards, Matthew S.; Michael, Todd P.; Dinsdale, Elizabeth A.

2018-01-01

Global climate change includes rising temperatures and increased pCO2 concentrations in the ocean, with potential deleterious impacts on marine organisms. In this case study we conducted a four-week climate change incubation experiment, and tested the independent and combined effects of increased temperature and partial pressure of carbon dioxide (pCO2), on the microbiomes of a foundation species, the giant kelp Macrocystis pyrifera, and the surrounding water column. The water and kelp microbiome responded differently to each of the climate stressors. In the water microbiome, each condition caused an increase in a distinct microbial order, whereas the kelp microbiome exhibited a reduction in the dominant kelp-associated order, Alteromondales. The water column microbiomes were most disrupted by elevated pCO2, with a 7.3 fold increase in Rhizobiales. The kelp microbiome was most influenced by elevated temperature and elevated temperature in combination with elevated pCO2. Kelp growth was negatively associated with elevated temperature, and the kelp microbiome showed a 5.3 fold increase Flavobacteriales and a 2.2 fold increase alginate degrading enzymes and sulfated polysaccharides. In contrast, kelp growth was positively associated with the combination of high temperature and high pCO2 ‘future conditions’, with a 12.5 fold increase in Planctomycetales and 4.8 fold increase in Rhodobacteriales. Therefore, the water and kelp microbiomes acted as distinct communities, where the kelp was stabilizing the microbiome under changing pCO2 conditions, but lost control at high temperature. Under future conditions, a new equilibrium between the kelp and the microbiome was potentially reached, where the kelp grew rapidly and the commensal microbes responded to an increase in mucus production. PMID:29474389

Antarctic emerald rockcod have the capacity to compensate for warming when uncoupled from CO2 -acidification.

PubMed

Davis, Brittany E; Flynn, Erin E; Miller, Nathan A; Nelson, Frederick A; Fangue, Nann A; Todgham, Anne E

2018-02-01

Increases in atmospheric CO 2 levels and associated ocean changes are expected to have dramatic impacts on marine ecosystems. Although the Southern Ocean is experiencing some of the fastest rates of change, few studies have explored how Antarctic fishes may be affected by co-occurring ocean changes, and even fewer have examined early life stages. To date, no studies have characterized potential trade-offs in physiology and behavior in response to projected multiple climate change stressors (ocean acidification and warming) on Antarctic fishes. We exposed juvenile emerald rockcod Trematomus bernacchii to three PCO 2 treatments (~450, ~850, and ~1,200 μatm PCO 2 ) at two temperatures (-1 or 2°C). After 2, 7, 14, and 28 days, metrics of physiological performance including cardiorespiratory function (heart rate [f H ] and ventilation rate [f V ]), metabolic rate (M˙O2), and cellular enzyme activity were measured. Behavioral responses, including scototaxis, activity, exploration, and escape response were assessed after 7 and 14 days. Elevated PCO 2 independently had little impact on either physiology or behavior in juvenile rockcod, whereas warming resulted in significant changes across acclimation time. After 14 days, f H , f V and M˙O2 significantly increased with warming, but not with elevated PCO 2 . Increased physiological costs were accompanied by behavioral alterations including increased dark zone preference up to 14%, reduced activity by 12%, as well as reduced escape time suggesting potential trade-offs in energetics. After 28 days, juvenile rockcod demonstrated a degree of temperature compensation as f V , M˙O2, and cellular metabolism significantly decreased following the peak at 14 days; however, temperature compensation was only evident in the absence of elevated PCO 2 . Sustained increases in f V and M˙O2 after 28 days exposure to elevated PCO 2 indicate additive (f V ) and synergistic (M˙O2) interactions occurred in combination with warming. Stressor-induced energetic trade-offs in physiology and behavior may be an important mechanism leading to vulnerability of Antarctic fishes to future ocean change. © 2017 John Wiley & Sons Ltd.

Alteration of Oceanic Nitrification Under Elevated Carbon Dioxide Concentrations

NASA Astrophysics Data System (ADS)

Beman, J.; Chow, C. E.; Popp, B. N.; Fuhrman, J. A.; Feng, Y.; Hutchins, D. A.

2008-12-01

Atmospheric carbon dioxide (CO2) concentrations are increasing exponentially and expected to double by the year 2100. Dissolution of excess CO2 in the upper ocean reduces pH, alters carbonate chemistry, and also represents a potential resource for autotrophic organisms that convert inorganic carbon into biomass--including a broad spectrum of marine microbes. These bacteria and archaea drive global biogeochemical cycles of carbon and nitrogen and constitute the vast majority of biomass in the sea, yet their responses to reduced pH and increased pCO2 remain largely undocumented. Here we show that elevated pCO2 may sharply reduce nitrification rates and populations of nitrifying microorganisms in the ocean. Multiple experiments were performed in the Sargasso Sea and the Southern California Bight under glacial maximum (193 ppm), present day (390 ppm), and projected (750 ppm) pCO2 concentrations, over time scales from hours to multiple days, and at depths of 45 m to 240 m. Measurement of nitrification rates using isotopically-labeled nitrogen showed 2-5 fold reduction under elevated pCO2--as well as an increase under glacial maximum pCO2. Marine Crenarchaeota are likely involved in nitrification as ammonia-oxidizing archaea (AOA) and are among the most abundant microbial groups in the ocean, yet this group decreased by 40-80% under increased pCO2, based on quantification of both 16S rRNA and ammonia monooxygenase (amoA) gene copies. Crenarchaeota also steadily declined over the course of multiple days under elevated pCO2, whereas ammonia-oxidizing (AOB) and nitrite-oxidizing bacteria (NOB) were more variable in their responses or were not detected. These findings suggest that projected increases in pCO2 and subsequent decreases in pH may strongly influence marine biogeochemistry and microbial community structure in the sea.

An investigation of the calcification response of the scleractinian coral Astrangia poculata to elevated pCO2 and the effects of nutrients, zooxanthellae and gender

NASA Astrophysics Data System (ADS)

Holcomb, M.; Cohen, A. L.; McCorkle, D. C.

2012-01-01

The effects of nutrients and pCO2 on zooxanthellate and azooxanthellate colonies of the temperate scleractinian coral Astrangia poculata (Ellis and Solander, 1786) were investigated at two different temperatures (16 °C and 24 °C). Corals exposed to elevated pCO2 tended to have lower relative calcification rates, as estimated from changes in buoyant weights. Experimental nutrient enrichments had no significant effect nor did there appear to be any interaction between pCO2 and nutrients. Elevated pCO2 appeared to have a similar effect on coral calcification whether zooxanthellae were present or absent at 16 °C. However, at 24 °C, the interpretation of the results is complicated by a significant interaction between gender and pCO2 for spawning corals. At 16 °C, gamete release was not observed, and no gender differences in calcification rates were observed - female and male corals showed similar reductions in calcification rates in response to elevated CO2 (15% and 19% respectively). Corals grown at 24 °C spawned repeatedly and male and female corals exhibited two different growth rate patterns - female corals grown at 24 °C and exposed to CO2 had calcification rates 39% lower than females grown at ambient CO2, while males showed a non-significant decline of 5% under elevated CO2. The increased sensitivity of females to elevated pCO2 may reflect a greater investment of energy in reproduction (egg production) relative to males (sperm production). These results suggest that both gender and spawning are important factors in determining the sensitivity of corals to ocean acidification, and considering these factors in future research may be critical to predicting how the population structures of marine calcifiers will change in response to ocean acidification.

Effects of elevated seawater pCO2 on gene expression patterns in the gills of the green crab, Carcinus maenas

PubMed Central

2011-01-01

Background The green crab Carcinus maenas is known for its high acclimation potential to varying environmental abiotic conditions. A high ability for ion and acid-base regulation is mainly based on an efficient regulation apparatus located in gill epithelia. However, at present it is neither known which ion transport proteins play a key role in the acid-base compensation response nor how gill epithelia respond to elevated seawater pCO2 as predicted for the future. In order to promote our understanding of the responses of green crab acid-base regulatory epithelia to high pCO2, Baltic Sea green crabs were exposed to a pCO2 of 400 Pa. Gills were screened for differentially expressed gene transcripts using a 4,462-feature microarray and quantitative real-time PCR. Results Crabs responded mainly through fine scale adjustment of gene expression to elevated pCO2. However, 2% of all investigated transcripts were significantly regulated 1.3 to 2.2-fold upon one-week exposure to CO2 stress. Most of the genes known to code for proteins involved in osmo- and acid-base regulation, as well as cellular stress response, were were not impacted by elevated pCO2. However, after one week of exposure, significant changes were detected in a calcium-activated chloride channel, a hyperpolarization activated nucleotide-gated potassium channel, a tetraspanin, and an integrin. Furthermore, a putative syntaxin-binding protein, a protein of the transmembrane 9 superfamily, and a Cl-/HCO3- exchanger of the SLC 4 family were differentially regulated. These genes were also affected in a previously published hypoosmotic acclimation response study. Conclusions The moderate, but specific response of C. maenas gill gene expression indicates that (1) seawater acidification does not act as a strong stressor on the cellular level in gill epithelia; (2) the response to hypercapnia is to some degree comparable to a hypoosmotic acclimation response; (3) the specialization of each of the posterior gill arches might go beyond what has been demonstrated up to date; and (4) a re-configuration of gill epithelia might occur in response to hypercapnia. PMID:21978240

Global Distortion of GPS Networks Associated with Satellite Antenna Model Errors

NASA Technical Reports Server (NTRS)

Cardellach, E.; Elosequi, P.; Davis, J. L.

2007-01-01

Recent studies of the GPS satellite phase center offsets (PCOs) suggest that these have been in error by approx.1 m. Previous studies had shown that PCO errors are absorbed mainly by parameters representing satellite clock and the radial components of site position. On the basis of the assumption that the radial errors are equal, PCO errors will therefore introduce an error in network scale. However, PCO errors also introduce distortions, or apparent deformations, within the network, primarily in the radial (vertical) component of site position that cannot be corrected via a Helmert transformation. Using numerical simulations to quantify the effects of PC0 errors, we found that these PCO errors lead to a vertical network distortion of 6-12 mm per meter of PCO error. The network distortion depends on the minimum elevation angle used in the analysis of the GPS phase observables, becoming larger as the minimum elevation angle increases. The steady evolution of the GPS constellation as new satellites are launched, age, and are decommissioned, leads to the effects of PCO errors varying with time that introduce an apparent global-scale rate change. We demonstrate here that current estimates for PCO errors result in a geographically variable error in the vertical rate at the 1-2 mm/yr level, which will impact high-precision crustal deformation studies.

Response of the Arctic pteropod Limacina helicina to projected future environmental conditions.

PubMed

Comeau, Steeve; Jeffree, Ross; Teyssié, Jean-Louis; Gattuso, Jean-Pierre

2010-06-29

Thecosome pteropods (pelagic mollusks) can play a key role in the food web of various marine ecosystems. They are a food source for zooplankton or higher predators such as fishes, whales and birds that is particularly important in high latitude areas. Since they harbor a highly soluble aragonitic shell, they could be very sensitive to ocean acidification driven by the increase of anthropogenic CO(2) emissions. The effect of changes in the seawater chemistry was investigated on Limacina helicina, a key species of Arctic pelagic ecosystems. Individuals were kept in the laboratory under controlled pCO(2) levels of 280, 380, 550, 760 and 1020 microatm and at control (0 degrees C) and elevated (4 degrees C) temperatures. The respiration rate was unaffected by pCO(2) at control temperature, but significantly increased as a function of the pCO(2) level at elevated temperature. pCO(2) had no effect on the gut clearance rate at either temperature. Precipitation of CaCO(3), measured as the incorporation of (45)Ca, significantly declined as a function of pCO(2) at both temperatures. The decrease in calcium carbonate precipitation was highly correlated to the aragonite saturation state. Even though this study demonstrates that pteropods are able to precipitate calcium carbonate at low aragonite saturation state, the results support the current concern for the future of Arctic pteropods, as the production of their shell appears to be very sensitive to decreased pH. A decline of pteropod populations would likely cause dramatic changes to various pelagic ecosystems.

Response of the Arctic Pteropod Limacina helicina to Projected Future Environmental Conditions

PubMed Central

Comeau, Steeve; Jeffree, Ross; Teyssié, Jean-Louis; Gattuso, Jean-Pierre

2010-01-01

Thecosome pteropods (pelagic mollusks) can play a key role in the food web of various marine ecosystems. They are a food source for zooplankton or higher predators such as fishes, whales and birds that is particularly important in high latitude areas. Since they harbor a highly soluble aragonitic shell, they could be very sensitive to ocean acidification driven by the increase of anthropogenic CO2 emissions. The effect of changes in the seawater chemistry was investigated on Limacina helicina, a key species of Arctic pelagic ecosystems. Individuals were kept in the laboratory under controlled pCO2 levels of 280, 380, 550, 760 and 1020 µatm and at control (0°C) and elevated (4°C) temperatures. The respiration rate was unaffected by pCO2 at control temperature, but significantly increased as a function of the pCO2 level at elevated temperature. pCO2 had no effect on the gut clearance rate at either temperature. Precipitation of CaCO3, measured as the incorporation of 45Ca, significantly declined as a function of pCO2 at both temperatures. The decrease in calcium carbonate precipitation was highly correlated to the aragonite saturation state. Even though this study demonstrates that pteropods are able to precipitate calcium carbonate at low aragonite saturation state, the results support the current concern for the future of Arctic pteropods, as the production of their shell appears to be very sensitive to decreased pH. A decline of pteropod populations would likely cause dramatic changes to various pelagic ecosystems. PMID:20613868

Mesozooplankton community development at elevated CO2 concentrations: results from a mesocosm experiment in an Arctic fjord

NASA Astrophysics Data System (ADS)

Niehoff, B.; Schmithüsen, T.; Knüppel, N.; Daase, M.; Czerny, J.; Boxhammer, T.

2013-03-01

The increasing CO2 concentration in the atmosphere caused by burning fossil fuels leads to increasing pCO2 and decreasing pH in the world ocean. These changes may have severe consequences for marine biota, especially in cold-water ecosystems due to higher solubility of CO2. However, studies on the response of mesozooplankton communities to elevated CO2 are still lacking. In order to test whether abundance and taxonomic composition change with pCO2, we have sampled nine mesocosms, which were deployed in Kongsfjorden, an Arctic fjord at Svalbard, and were adjusted to eight CO2 concentrations, initially ranging from 185 μatm to 1420 μatm. Vertical net hauls were taken weekly over about one month with an Apstein net (55 μm mesh size) in all mesocosms and the surrounding fjord. In addition, sediment trap samples, taken every second day in the mesocosms, were analysed to account for losses due to vertical migration and mortality. The taxonomic analysis revealed that meroplanktonic larvae (Cirripedia, Polychaeta, Bivalvia, Gastropoda, and Decapoda) dominated in the mesocosms while copepods (Calanus spp., Oithona similis, Acartia longiremis and Microsetella norvegica) were found in lower abundances. In the fjord copepods prevailed for most of our study. With time, abundance and taxonomic composition developed similarly in all mesocosms and the pCO2 had no significant effect on the overall community structure. Also, we did not find significant relationships between the pCO2 level and the abundance of single taxa. Changes in heterogeneous communities are, however, difficult to detect, and the exposure to elevated pCO2 was relatively short. We therefore suggest that future mesocosm experiments should be run for longer periods.

Experimental assessment of diazotroph responses to elevated seawater pCO2 in the North Pacific Subtropical Gyre

NASA Astrophysics Data System (ADS)

Böttjer, Daniela; Karl, David M.; Letelier, Ricardo M.; Viviani, Donn A.; Church, Matthew J.

2014-06-01

We examined short-term (24-72 h) responses of naturally occurring marine N2 fixing microorganisms (termed diazotrophs) to abrupt increases in the partial pressure of carbon dioxide (pCO2) in seawater during nine incubation experiments conducted between May 2010 and September 2012 at Station ALOHA (A Long-term Oligotrophic Habitat Assessment) (22°45'N, 158°W) in the North Pacific Subtropical Gyre (NPSG). Rates of N2 fixation, nitrogenase (nifH) gene abundances and transcripts of six major groups of cyanobacterial diazotrophs (including both unicellular and filamentous phylotypes), and rates of primary productivity (as measured by 14C-bicarbonate assimilation into plankton biomass) were determined under contemporary (~390 ppm) and elevated pCO2 conditions (~1100 ppm). Quantitative polymerase chain reaction (QPCR) amplification of planktonic nifH genes revealed that unicellular cyanobacteria phylotypes dominated gene abundances during these experiments. In the majority of experiments (seven out of nine), elevated pCO2 did not significantly influence rates of dinitrogen (N2) fixation or primary productivity (two-way analysis of variance (ANOVA), P > 0.05). During two experiments, rates of N2 fixation and primary productivity were significantly lower (by 79 to 82% and 52 to 72%, respectively) in the elevated pCO2 treatments relative to the ambient controls (two-way ANOVA, P < 0.05). QPCR amplification of nifH genes and gene transcripts revealed that diazotroph abundances and nifH gene expression were largely unchanged by the perturbation of the seawater pCO2. Our results suggest that naturally occurring N2 fixing plankton assemblages in the NPSG are relatively resilient to large, short-term increases in pCO2.

Stimulated Bacterial Growth under Elevated pCO2: Results from an Off-Shore Mesocosm Study

PubMed Central

Endres, Sonja; Galgani, Luisa; Riebesell, Ulf; Schulz, Kai-Georg; Engel, Anja

2014-01-01

Marine bacteria are the main consumers of freshly produced organic matter. Many enzymatic processes involved in the bacterial digestion of organic compounds were shown to be pH sensitive in previous studies. Due to the continuous rise in atmospheric CO2 concentration, seawater pH is presently decreasing at a rate unprecedented during the last 300 million years but the consequences for microbial physiology, organic matter cycling and marine biogeochemistry are still unresolved. We studied the effects of elevated seawater pCO2 on a natural plankton community during a large-scale mesocosm study in a Norwegian fjord. Nine Kiel Off-Shore Mesocosms for Future Ocean Simulations (KOSMOS) were adjusted to different pCO2 levels ranging initially from ca. 280 to 3000 µatm and sampled every second day for 34 days. The first phytoplankton bloom developed around day 5. On day 14, inorganic nutrients were added to the enclosed, nutrient-poor waters to stimulate a second phytoplankton bloom, which occurred around day 20. Our results indicate that marine bacteria benefit directly and indirectly from decreasing seawater pH. During the first phytoplankton bloom, 5–10% more transparent exopolymer particles were formed in the high pCO2 mesocosms. Simultaneously, the efficiency of the protein-degrading enzyme leucine aminopeptidase increased with decreasing pH resulting in up to three times higher values in the highest pCO2/lowest pH mesocosm compared to the controls. In general, total and cell-specific aminopeptidase activities were elevated under low pH conditions. The combination of enhanced enzymatic hydrolysis of organic matter and increased availability of gel particles as substrate supported up to 28% higher bacterial abundance in the high pCO2 treatments. We conclude that ocean acidification has the potential to stimulate the bacterial community and facilitate the microbial recycling of freshly produced organic matter, thus strengthening the role of the microbial loop in the surface ocean. PMID:24941307

Prediction of atmospheric δ 13CO 2 using fossil plant tissues

DOE Office of Scientific and Technical Information (OSTI.GOV)

A. Hope Jahren; Arens, Nan Crystal; Harbeson, Stephanie A.

2008-06-30

To summarize the content: we presented the results of laboratory experiments designed to quantify the relationship between plant tissue δ 13C and δ 13CO 2 values under varying environmental conditions, including differential pCO 2 ranging from 1 to 3 times today’s levels. As predicted, plants grown under elevated pCO2 showed increased average biomass compared to controls grown at the same temperature. Across a very large range in δ 13Ca (≈ 24 ‰) and pCO 2 (≈ 740 ppmv) we observed a consistent correlation between δ13Ca and δ 13Cp (p<0.001). We show an average isotopic depletion of -25.4 ‰ for above-groundmore » tissue and -23.2 ‰ for below-ground tissue of Raphanus sativus L. relative to the composition of the atmosphere under which it formed. For both above- and below-ground tissue, grown at both ~23 °C and ~29 °C, correlation was strong and significant (r2 ≥ 0.98, p<0.001); variation in pCO 2 level had little or no effect on this relationship.« less

The Eocene Arctic Azolla bloom: environmental conditions, productivity and carbon drawdown.

PubMed

Speelman, E N; Van Kempen, M M L; Barke, J; Brinkhuis, H; Reichart, G J; Smolders, A J P; Roelofs, J G M; Sangiorgi, F; de Leeuw, J W; Lotter, A F; Sinninghe Damsté, J S

2009-03-01

Enormous quantities of the free-floating freshwater fern Azolla grew and reproduced in situ in the Arctic Ocean during the middle Eocene, as was demonstrated by microscopic analysis of microlaminated sediments recovered from the Lomonosov Ridge during Integrated Ocean Drilling Program (IODP) Expedition 302. The timing of the Azolla phase (approximately 48.5 Ma) coincides with the earliest signs of onset of the transition from a greenhouse towards the modern icehouse Earth. The sustained growth of Azolla, currently ranking among the fastest growing plants on Earth, in a major anoxic oceanic basin may have contributed to decreasing atmospheric pCO2 levels via burial of Azolla-derived organic matter. The consequences of these enormous Azolla blooms for regional and global nutrient and carbon cycles are still largely unknown. Cultivation experiments have been set up to investigate the influence of elevated pCO2 on Azolla growth, showing a marked increase in Azolla productivity under elevated (760 and 1910 ppm) pCO2 conditions. The combined results of organic carbon, sulphur, nitrogen content and 15N and 13C measurements of sediments from the Azolla interval illustrate the potential contribution of nitrogen fixation in a euxinic stratified Eocene Arctic. Flux calculations were used to quantitatively reconstruct the potential storage of carbon (0.9-3.5 10(18) gC) in the Arctic during the Azolla interval. It is estimated that storing 0.9 10(18) to 3.5 10(18) g carbon would result in a 55 to 470 ppm drawdown of pCO2 under Eocene conditions, indicating that the Arctic Azolla blooms may have had a significant effect on global atmospheric pCO2 levels through enhanced burial of organic matter.

Prolonged exposure to elevated CO(2) promotes growth of the algal symbiont Symbiodinium muscatinei in the intertidal sea anemone Anthopleura elegantissima.

PubMed

Towanda, Trisha; Thuesen, Erik V

2012-07-15

Some photosynthetic organisms benefit from elevated levels of carbon dioxide, but studies on the effects of elevated PCO(2) on the algal symbionts of animals are very few. This study investigated the impact of hypercapnia on a photosynthetic symbiosis between the anemone Anthopleura elegantissima and its zooxanthella Symbiodinium muscatinei. Anemones were maintained in the laboratory for 1 week at 37 Pa PCO(2) and pH 8.1. Clonal pairs were then divided into two groups and maintained for 6 weeks under conditions naturally experienced in their intertidal environment, 45 Pa PCO(2), pH 8.1 and 231 Pa PCO(2), pH 7.3. Respiration and photosynthesis were measured after the 1-week acclimation period and after 6 weeks in experimental conditions. Density of zooxanthellal cells, zooxanthellal cell size, mitotic index and chlorophyll content were compared between non-clonemate anemones after the 1-week acclimation period and clonal anemones at the end of the experiment. Anemones thrived in hypercapnia. After 6 weeks, A. elegantissima exhibited higher rates of photosynthesis at 45 Pa (4.2 µmol O(2) g(-1) h(-1)) and 231 Pa (3.30 µmol O(2) g(-1) h(-1)) than at the initial 37 Pa (1.53 µmol O(2) g(-1) h(-1)). Likewise, anemones at 231 Pa received more of their respiratory carbon from zooxanthellae (CZAR  = 78.2%) than those at 37 Pa (CZAR  = 66.6%) but less than anemones at 45 Pa (CZAR  = 137.3%). The mitotic index of zooxanthellae was significantly greater in the hypercapnic anemones than in anemones at lower PCO(2). Excess zooxanthellae were expelled by their hosts, and cell densities, cell diameters and chlorophyll contents were not significantly different between the groups. The response of A. elegantissima to hypercapnic acidification reveals the potential adaptation of an intertidal, photosynthetic symbiosis for high PCO(2).

Prolonged exposure to elevated CO2 promotes growth of the algal symbiont Symbiodinium muscatinei in the intertidal sea anemone Anthopleura elegantissima

PubMed Central

Towanda, Trisha; Thuesen, Erik V.

2012-01-01

Summary Some photosynthetic organisms benefit from elevated levels of carbon dioxide, but studies on the effects of elevated PCO2 on the algal symbionts of animals are very few. This study investigated the impact of hypercapnia on a photosynthetic symbiosis between the anemone Anthopleura elegantissima and its zooxanthella Symbiodinium muscatinei. Anemones were maintained in the laboratory for 1 week at 37 Pa PCO2 and pH 8.1. Clonal pairs were then divided into two groups and maintained for 6 weeks under conditions naturally experienced in their intertidal environment, 45 Pa PCO2, pH 8.1 and 231 Pa PCO2, pH 7.3. Respiration and photosynthesis were measured after the 1-week acclimation period and after 6 weeks in experimental conditions. Density of zooxanthellal cells, zooxanthellal cell size, mitotic index and chlorophyll content were compared between non-clonemate anemones after the 1-week acclimation period and clonal anemones at the end of the experiment. Anemones thrived in hypercapnia. After 6 weeks, A. elegantissima exhibited higher rates of photosynthesis at 45 Pa (4.2 µmol O2 g−1 h−1) and 231 Pa (3.30 µmol O2 g−1 h−1) than at the initial 37 Pa (1.53 µmol O2 g−1 h−1). Likewise, anemones at 231 Pa received more of their respiratory carbon from zooxanthellae (CZAR  = 78.2%) than those at 37 Pa (CZAR  = 66.6%) but less than anemones at 45 Pa (CZAR  = 137.3%). The mitotic index of zooxanthellae was significantly greater in the hypercapnic anemones than in anemones at lower PCO2. Excess zooxanthellae were expelled by their hosts, and cell densities, cell diameters and chlorophyll contents were not significantly different between the groups. The response of A. elegantissima to hypercapnic acidification reveals the potential adaptation of an intertidal, photosynthetic symbiosis for high PCO2. PMID:23213455

Effects of ocean acidification on calcification of symbiont-bearing reef foraminifers

NASA Astrophysics Data System (ADS)

Fujita, K.; Hikami, M.; Suzuki, A.; Kuroyanagi, A.; Kawahata, H.

2011-02-01

Ocean acidification (decreases in carbonate ion concentration and pH) in response to rising atmospheric pCO2 is generally expected to reduce rates of calcification by reef calcifying organisms, with potentially severe implications for coral reef ecosystems. Large, algal symbiont-bearing benthic foraminifers, which are important primary and carbonate producers in coral reefs, produce high-Mg calcite shells, whose solubility can exceed that of aragonite produced by corals, making them the "first responder" in coral reefs to the decreasing carbonate saturation state of seawater. Here we report results of culture experiments performed to assess the effects of ongoing ocean acidification on the calcification of symbiont-bearing reef foraminifers using a high-precision pCO2 control system. Living clone individuals of three foraminiferal species (Baculogypsina sphaerulata, Calcarina gaudichaudii, and Amphisorus hemprichii) were subjected to seawater at five pCO2 levels from 260 to 970 μatm. Cultured individuals were maintained for about 12 weeks in an indoor flow-through system under constant water temperature, light intensity, and photoperiod. After the experiments, the shell diameter and weight of each cultured specimen were measured. Net calcification of Baculogypsina and Calcarina, which secrete a hyaline shell and host diatom symbionts, increased under intermediate levels of pCO2 (580 and/or 770 μatm) and decreased at a higher pCO2 level (970 μatm). Net calcification of Amphisorus, which secretes a porcelaneous shell and hosts dinoflagellate symbionts, tended to decrease at elevated pCO2. These different responses among the three species are possibly due to differences in calcification mechanisms (in particular, the specific carbonate species used for calcification) between hyaline and porcelaneous taxa, and to links between calcification by the foraminiferal hosts and photosynthesis by the algal endosymbionts. Our findings suggest that ongoing ocean acidification might favor symbiont-bearing reef foraminifers with hyaline shells at intermediate pCO2 levels (580 to 770 μatm) but be unfavorable to those with either hyaline or porcelaneous shells at higher pCO2 levels (near 1000 μatm).

Enhancement of High-Density Lipoprotein Cholesterol Functions by Encapsulation of Policosanol Exerts Anti-Senescence and Tissue Regeneration Effects Via Improvement of Anti-Glycation, Anti-Apoptosis, and Cholesteryl Ester Transfer Inhibition.

PubMed

Lim, So-Mang; Yoo, Jeong-Ah; Lee, Eun-Young; Cho, Kyung-Hyun

2016-02-01

Consumption of policosanol (PCO), a refined mixture of sugar cane wax alcohols, can elevate serum levels of high-density lipoprotein cholesterol (HDL-C), although the molecular mechanism is still unknown. To investigate the mechanism of action responsible for the anti-senescence effects of PCO on lipoprotein metabolism and HDL functionality, we synthesized reconstituted HDL (rHDL) containing PCO. Encapsulation of PCO by rHDL (PCO-rHDL) enhanced anti-oxidant activity against cupric ion-mediated low-density lipoprotein (LDL) oxidation. PCO-rHDL (final concentration, 9 μM PCO) showed more potent anti-oxidant activity than vitamin C treatment (final concentration, 100 μM). PCO-rHDL inhibited fructose-mediated glycation, which is a major pathological mechanism of diabetic complications, in a dose-dependent manner. PCO also showed cytoprotective effects in monocytes and macrophages with less triggering of apoptotic processes and reactive oxygen species (ROS) production in the presence of hydrogen peroxide (H2O2). PCO-rHDL strongly inhibited uptake of acetylated LDL into macrophages, which is an initial atherosclerotic process. Surprisingly, PCO-rHDL inhibited human serum cholesteryl ester transfer protein (CETP) activity by up to 47% (final concentration, 10 μM PCO). Subcutaneous injection of PCO-rHDL dose-dependently enhanced tissue regeneration activity by 2.4-fold and 3.6-fold compared to that of the phosphate-buffered saline (PBS) control. In conclusion, PCO in HDL showed potent anti-oxidant, anti-glycation, and CETP inhibitory activities along with tissue regenerative activity, especially upon incorporation into HDL. These results suggest that PCO can enhance functionality of HDL in serum to exert anti-senescence and longevity effects.

Increased temperature mitigates the effects of ocean acidification on the calcification of juvenile Pocillopora damicornis, but at a cost

NASA Astrophysics Data System (ADS)

Jiang, Lei; Zhang, Fang; Guo, Ming-Lan; Guo, Ya-Juan; Zhang, Yu-Yang; Zhou, Guo-Wei; Cai, Lin; Lian, Jian-Sheng; Qian, Pei-Yuan; Huang, Hui

2018-03-01

This study tested the interactive effects of increased seawater temperature and CO2 partial pressure ( pCO2) on the photochemistry, bleaching, and early growth of the reef coral Pocillopora damicornis. New recruits were maintained at ambient or high temperature (29 or 30.8 °C) and pCO2 ( 500 and 1100 μatm) in a full-factorial experiment for 3 weeks. Neither a sharp decline in photochemical efficiency (Fv/Fm) nor evident bleaching was observed at high temperature and/or high pCO2. Furthermore, elevated temperature greatly promoted lateral growth and calcification, while polyp budding exhibited temperature-dependent responses to pCO2. High pCO2 depressed calcification by 28% at ambient temperature, but did not impact calcification at 30.8 °C. Interestingly, elevated temperature in concert with high pCO2 significantly retarded the budding process. These results suggest that increased temperature can mitigate the adverse effects of acidification on the calcification of juvenile P. damicornis, but at a substantial cost to asexual budding.

The O2, pH and Ca2+ Microenvironment of Benthic Foraminifera in a High CO2 World

PubMed Central

Glas, Martin S.; Fabricius, Katharina E.; de Beer, Dirk; Uthicke, Sven

2012-01-01

Ocean acidification (OA) can have adverse effects on marine calcifiers. Yet, phototrophic marine calcifiers elevate their external oxygen and pH microenvironment in daylight, through the uptake of dissolved inorganic carbon (DIC) by photosynthesis. We studied to which extent pH elevation within their microenvironments in daylight can counteract ambient seawater pH reductions, i.e. OA conditions. We measured the O2 and pH microenvironment of four photosymbiotic and two symbiont-free benthic tropical foraminiferal species at three different OA treatments (∼432, 1141 and 2151 µatm pCO2). The O2 concentration difference between the seawater and the test surface (ΔO2) was taken as a measure for the photosynthetic rate. Our results showed that O2 and pH levels were significantly higher on photosymbiotic foraminiferal surfaces in light than in dark conditions, and than on surfaces of symbiont-free foraminifera. Rates of photosynthesis at saturated light conditions did not change significantly between OA treatments (except in individuals that exhibited symbiont loss, i.e. bleaching, at elevated pCO2). The pH at the cell surface decreased during incubations at elevated pCO2, also during light incubations. Photosynthesis increased the surface pH but this increase was insufficient to compensate for ambient seawater pH decreases. We thus conclude that photosynthesis does only partly protect symbiont bearing foraminifera against OA. PMID:23166810

Intra-population variability of ocean acidification impacts on the physiology of Baltic blue mussels (Mytilus edulis): integrating tissue and organism response.

PubMed

Stapp, L S; Thomsen, J; Schade, H; Bock, C; Melzner, F; Pörtner, H O; Lannig, G

2017-05-01

Increased maintenance costs at cellular, and consequently organism level, are thought to be involved in shaping the sensitivity of marine calcifiers to ocean acidification (OA). Yet, knowledge of the capacity of marine calcifiers to undergo metabolic adaptation is sparse. In Kiel Fjord, blue mussels thrive despite periodically high seawater PCO 2 , making this population interesting for studying metabolic adaptation under OA. Consequently, we conducted a multi-generation experiment and compared physiological responses of F1 mussels from 'tolerant' and 'sensitive' families exposed to OA for 1 year. Family classifications were based on larval survival; tolerant families settled at all PCO 2 levels (700, 1120, 2400 µatm) while sensitive families did not settle at the highest PCO 2 (≥99.8% mortality). We found similar filtration rates between family types at the control and intermediate PCO 2 level. However, at 2400 µatm, filtration and metabolic scope of gill tissue decreased in tolerant families, indicating functional limitations at the tissue level. Routine metabolic rates (RMR) and summed tissue respiration (gill and outer mantle tissue) of tolerant families were increased at intermediate PCO 2 , indicating elevated cellular homeostatic costs in various tissues. By contrast, OA did not affect tissue and routine metabolism of sensitive families. However, tolerant mussels were characterised by lower RMR at control PCO 2 than sensitive families, which had variable RMR. This might provide the energetic scope to cover increased energetic demands under OA, highlighting the importance of analysing intra-population variability. The mechanisms shaping such difference in RMR and scope, and thus species' adaptation potential, remain to be identified.

Response of the calcifying coccolithophore Emiliania huxleyi to low pH/high pCO2: from physiology to molecular level.

PubMed

Richier, Sophie; Fiorini, Sarah; Kerros, Marie-Emmanuelle; von Dassow, Peter; Gattuso, Jean-Pierre

2011-01-01

The emergence of ocean acidification as a significant threat to calcifying organisms in marine ecosystems creates a pressing need to understand the physiological and molecular mechanisms by which calcification is affected by environmental parameters. We report here, for the first time, changes in gene expression induced by variations in pH/pCO 2 in the widespread and abundant coccolithophore Emiliania huxleyi . Batch cultures were subjected to increased partial pressure of CO 2 (pCO 2 ; i.e. decreased pH), and the changes in expression of four functional gene classes directly or indirectly related to calcification were investigated. Increased pCO 2 did not affect the calcification rate and only carbonic anhydrase transcripts exhibited a significant down-regulation. Our observation that elevated pCO 2 induces only limited changes in the transcription of several transporters of calcium and bicarbonate gives new significant elements to understand cellular mechanisms underlying the early response of E. huxleyi to CO 2 -driven ocean acidification.

Effects of ocean acidification increase embryonic sensitivity to thermal extremes in Atlantic cod, Gadus morhua.

PubMed

Dahlke, Flemming T; Leo, Elettra; Mark, Felix C; Pörtner, Hans-Otto; Bickmeyer, Ulf; Frickenhaus, Stephan; Storch, Daniela

2017-04-01

Thermal tolerance windows serve as a powerful tool for estimating the vulnerability of marine species and their life stages to increasing temperature means and extremes. However, it remains uncertain to which extent additional drivers, such as ocean acidification, modify organismal responses to temperature. This study investigated the effects of CO 2 -driven ocean acidification on embryonic thermal sensitivity and performance in Atlantic cod, Gadus morhua, from the Kattegat. Fertilized eggs were exposed to factorial combinations of two PCO 2 conditions (400 μatm vs. 1100 μatm) and five temperature treatments (0, 3, 6, 9 and 12 °C), which allow identifying both lower and upper thermal tolerance thresholds. We quantified hatching success, oxygen consumption (MO 2 ) and mitochondrial functioning of embryos as well as larval morphometrics at hatch and the abundance of acid-base-relevant ionocytes on the yolk sac epithelium of newly hatched larvae. Hatching success was high under ambient spawning conditions (3-6 °C), but decreased towards both cold and warm temperature extremes. Elevated PCO 2 caused a significant decrease in hatching success, particularly at cold (3 and 0 °C) and warm (12 °C) temperatures. Warming imposed limitations to MO 2 and mitochondrial capacities. Elevated PCO 2 stimulated MO 2 at cold and intermediate temperatures, but exacerbated warming-induced constraints on MO 2 , indicating a synergistic interaction with temperature. Mitochondrial functioning was not affected by PCO 2 . Increased MO 2 in response to elevated PCO 2 was paralleled by reduced larval size at hatch. Finally, ionocyte abundance decreased with increasing temperature, but did not differ between PCO 2 treatments. Our results demonstrate increased thermal sensitivity of cod embryos under future PCO 2 conditions and suggest that acclimation to elevated PCO 2 requires reallocation of limited resources at the expense of embryonic growth. We conclude that ocean acidification constrains the thermal performance window of embryos, which has important implication for the susceptibility of cod to projected climate change. © 2016 John Wiley & Sons Ltd.

Carbon dioxide concentration in caves and soils in an alpine setting: implications for speleothem fabrics and their palaeoclimate significance

NASA Astrophysics Data System (ADS)

Borsato, Andrea; Frisia, Silvia; Miorandi, Renza

2015-04-01

Carbon dioxide concentration in soils controls carbonate dissolution, soil CO2 efflux to the atmosphere, and CO2 transfer to the subsurface that lead, ultimately, to speleothem precipitation. Systematic studies on CO2 concentration variability in soil and caves at regional scale are, however, few. Here, the systematic investigation of CO2 concentration in caves and soils in a temperate, Alpine region along a 2,100 m altitudinal range transect, which corresponds to a mean annual temperature (MAT) range of 12°C is presented. Soil pCO2 is controlled by the elevation and MAT and exhibits strong seasonality, which follows surface air temperature with a delay of about a month. The aquifer pCO2, by contrast, is fairly constant throughout the year, and it is primarily influenced by summer soil pCO2. Cave CO2 concentration is a balance between the CO2 influx and CO2 efflux, where the efflux is controlled by the cave ventilation, which is responsible for low pCO2 values recorded in most of the caves with respect to soil levels. Carbon dioxide in the innermost part of the studied caves exhibits a clear seasonal pattern. Thermal convection is the most common mechanism causing higher ventilation and low cave air pCO2 levels during the winter season: this promotes CO2 degassing and higher supersaturation in the drip water and, eventually, higher speleothem growth rates during winter. The combined influence of three parameters - dripwater pCO2, dripwater Ca content, and cave air pCO2 - all related to the infiltration elevation and MAT directly controls calcite supersaturation in dripwater. Four different altitudinal belts are then defined, which reflect temperature-dependent saturation state of dripwaters. These belts broadly correspond to vegetation zones: the lower montane (100 to 800 m asl), the upper montane (800 to 1600 m asl), the subalpine (1600 to 2200 m asl) and the Alpine (above 2200 m asl). Each altitudinal belt is characterised by different calcite fabrics, which can shift upward/downward in elevation as a response to temperature increase/decrease through time. In the lower and upper montane zones the columnar types (compact, open, fascicular optic) are the most common fabrics, with the microcrystalline type most typical of the upper montane zone. The dendritic fabric becomes predominant in the higher upper montane and lower subalpine zones. The higher subalpine to lower alpine zones the only speleothem actually forming is moonmilk. Eventually, the occurrence of "altitudinal" fabrics within the vertical growth axis of a stalagmite is indicative of changes in the MAT through time Therefore, fabric changes in fossil speleothems in temperate climate settings can be potentially used to reconstruct regional MAT changes in the past.

CO32- concentration and pCO2 thresholds for calcification and dissolution on the Molokai reef flat, Hawaii

USGS Publications Warehouse

Yates, K.K.; Halley, R.B.

2006-01-01

The severity of the impact of elevated atmospheric pCO2 to coral reef ecosystems depends, in part, on how sea-water pCO2 affects the balance between calcification and dissolution of carbonate sediments. Presently, there are insufficient published data that relate concentrations of pCO 2 and CO32- to in situ rates of reef calcification in natural settings to accurately predict the impact of elevated atmospheric pCO2 on calcification and dissolution processes. Rates of net calcification and dissolution, CO32- concentrations, and pCO2 were measured, in situ, on patch reefs, bare sand, and coral rubble on the Molokai reef flat in Hawaii. Rates of calcification ranged from 0.03 to 2.30 mmol CaCO3 m-2 h-1 and dissolution ranged from -0.05 to -3.3 mmol CaCO3 m-2 h-1. Calcification and dissolution varied diurnally with net calcification primarily occurring during the day and net dissolution occurring at night. These data were used to calculate threshold values for pCO2 and CO32- at which rates of calcification and dissolution are equivalent. Results indicate that calcification and dissolution are linearly correlated with both CO32- and pCO2. Threshold pCO2 and CO32- values for individual substrate types showed considerable variation. The average pCO2 threshold value for all substrate types was 654??195 ??atm and ranged from 467 to 1003 ??atm. The average CO32- threshold value was 152??24 ??mol kg-1, ranging from 113 to 184 ??mol kg-1. Ambient seawater measurements of pCO2 and CO32- indicate that CO32- and pCO2 threshold values for all substrate types were both exceeded, simultaneously, 13% of the time at present day atmospheric pCO2 concentrations. It is predicted that atmospheric pCO2 will exceed the average pCO2 threshold value for calcification and dissolution on the Molokai reef flat by the year 2100.

Polycystic Ovary-Like Abnormalities (PCO-L) in women with functional hypothalamic amenorrhea.

PubMed

Robin, G; Gallo, C; Catteau-Jonard, S; Lefebvre-Maunoury, C; Pigny, P; Duhamel, A; Dewailly, D

2012-11-01

In the general population, about 30% of asymptomatic women have polycystic ovary-like abnormalities (PCO-L), i.e. polycystic ovarian morphology (PCOM) at ultrasound and/or increased anti-Müllerian hormone (AMH) serum level. PCOM has also been reported in 30-50% of women with functional hypothalamic amenorrhea (FHA). The aim of this study was to verify whether both PCOM and excessive AMH level indicate PCO-L in FHA and to elucidate its significance. We conducted a retrospective analysis using a database and comparison with a control population. Subjects received ambulatory care in an academic hospital. Fifty-eight patients with FHA were compared to 217 control women with nonendocrine infertility and body mass index of less than 25 kg/m(2). There were no interventions. We measured serum testosterone, androstenedione, FSH, LH, AMH, and ovarian area values. The antral follicle count (AFC) was used as a binary variable (i.e. negative or positive) because of the evolution of its sensitivity over the time of this study. The ability of these variables (except AFC) to detect PCO-L in both populations was tested by cluster analysis. One cluster (cluster 2) suggesting PCO-L was detected in the control population (n = 52; 24%), whereas two such clusters were observed in the FHA population (n = 22 and n = 6; 38 and 10%; clusters 2 and 3, respectively). Cluster 2 in FHA had similar features of PCO-L as cluster 2 in controls, with higher prevalence of positive AFC (70%) and PCOM (70%), higher values of ovarian area and higher serum AMH (P < 0.0001 for all), and testosterone levels (P < 0.01) than in cluster 1. Cluster 3 in FHA was peculiar, with frankly elevated AMH levels. In the whole population (controls + FHA), PCO-L was significantly associated with lower FSH values (P < 0.0001). PCO-L in FHA is a frequent and usually incidental finding of unclear significance, as in controls. The association of PCO-L with hypothalamic amenorrhea should not lead to a mistaken diagnosis of PCOS.

Elevated carbon dioxide alters the plasma composition and behaviour of a shark

PubMed Central

Green, Leon; Jutfelt, Fredrik

2014-01-01

Increased carbon emissions from fossil fuels are increasing the pCO2 of the ocean surface waters in a process called ocean acidification. Elevated water pCO2 can induce physiological and behavioural effects in teleost fishes, although there appear to be large differences in sensitivity between species. There is currently no information available on the possible responses to future ocean acidification in elasmobranch fishes. We exposed small-spotted catsharks (Scyliorhinus canicula) to either control conditions or a year 2100 scenario of 990 μatm pCO2 for four weeks. We did not detect treatment effects on growth, resting metabolic rate, aerobic scope, skin denticle ultrastructure or skin denticle morphology. However, we found that the elevated pCO2 group buffered internal acidosis via accumulation with an associated increase in Na+, indicating that the blood chemistry remained altered despite the long acclimation period. The elevated pCO2 group also exhibited a shift in their nocturnal swimming pattern from a pattern of many starts and stops to more continuous swimming. Although CO2-exposed teleost fishes can display reduced behavioural asymmetry (lateralization), the CO2-exposed sharks showed increased lateralization. These behavioural effects may suggest that elasmobranch neurophysiology is affected by CO2, as in some teleosts, or that the sharks detect CO2 as a constant stressor, which leads to altered behaviour. The potential direct effects of ocean acidification should henceforth be considered when assessing future anthropogenic effects on sharks. PMID:25232027

Climate, pCO2 and terrestrial carbon cycle linkages during late Palaeozoic glacial-interglacial cycles

NASA Astrophysics Data System (ADS)

Montañez, Isabel P.; McElwain, Jennifer C.; Poulsen, Christopher J.; White, Joseph D.; Dimichele, William A.; Wilson, Jonathan P.; Griggs, Galen; Hren, Michael T.

2016-11-01

Earth's last icehouse, 300 million years ago, is considered the longest-lived and most acute of the past half-billion years, characterized by expansive continental ice sheets and possibly tropical low-elevation glaciation. This atypical climate has long been attributed to anomalous radiative forcing promoted by a 3% lower incident solar luminosity and sustained low atmospheric pCO2 (<=300 ppm). Climate models, however, indicate a CO2 sensitivity of ice-sheet distribution and sea-level response that questions this long-standing climate paradigm by revealing major discrepancy between hypothesized ice distribution, pCO2, and geologic records of glacioeustasy. Here we present a high-resolution record of atmospheric pCO2 for 16 million years of the late Palaeozoic, developed using soil carbonate-based and fossil leaf-based proxies, that resolves the climate conundrum. Palaeo-fluctuations on the 105-yr scale occur within the CO2 range predicted for anthropogenic change and co-vary with substantial change in sea level and ice volume. We further document coincidence between pCO2 changes and repeated restructuring of Euramerican tropical forests that, in conjunction with modelled vegetation shifts, indicate a more dynamic carbon sequestration history than previously considered and a major role for terrestrial vegetation-CO2 feedbacks in driving eccentricity-scale climate cycles of the late Palaeozoic icehouse.

The response of Antarctic sea ice algae to changes in pH and CO2.

PubMed

McMinn, Andrew; Müller, Marius N; Martin, Andrew; Ryan, Ken G

2014-01-01

Ocean acidification substantially alters ocean carbon chemistry and hence pH but the effects on sea ice formation and the CO2 concentration in the enclosed brine channels are unknown. Microbial communities inhabiting sea ice ecosystems currently contribute 10-50% of the annual primary production of polar seas, supporting overwintering zooplankton species, especially Antarctic krill, and seeding spring phytoplankton blooms. Ocean acidification is occurring in all surface waters but the strongest effects will be experienced in polar ecosystems with significant effects on all trophic levels. Brine algae collected from McMurdo Sound (Antarctica) sea ice was incubated in situ under various carbonate chemistry conditions. The carbon chemistry was manipulated with acid, bicarbonate and bases to produce a pCO2 and pH range from 238 to 6066 µatm and 7.19 to 8.66, respectively. Elevated pCO2 positively affected the growth rate of the brine algal community, dominated by the unique ice dinoflagellate, Polarella glacialis. Growth rates were significantly reduced when pH dropped below 7.6. However, when the pH was held constant and the pCO2 increased, growth rates of the brine algae increased by more than 20% and showed no decline at pCO2 values more than five times current ambient levels. We suggest that projected increases in seawater pCO2, associated with OA, will not adversely impact brine algal communities.

Adjustments of molecular key components of branchial ion and pH regulation in Atlantic cod (Gadus morhua) in response to ocean acidification and warming.

PubMed

Michael, Katharina; Kreiss, Cornelia M; Hu, Marian Y; Koschnick, Nils; Bickmeyer, Ulf; Dupont, Sam; Pörtner, Hans-O; Lucassen, Magnus

2016-03-01

Marine teleost fish sustain compensation of extracellular pH after exposure to hypercapnia by means of efficient ion and acid-base regulation. Elevated rates of ion and acid-base regulation under hypercapnia may be stimulated further by elevated temperature. Here, we characterized the regulation of transepithelial ion transporters (NKCC1, NBC1, SLC26A6, NHE1 and 2) and ATPases (Na(+)/K(+) ATPase and V-type H(+) ATPase) in gills of Atlantic cod (Gadus morhua) after 4 weeks of exposure to ambient and future PCO2 levels (550 μatm, 1200 μatm, 2200 μatm) at optimum (10 °C) and summer maximum temperature (18 °C), respectively. Gene expression of most branchial ion transporters revealed temperature- and dose-dependent responses to elevated PCO2. Transcriptional regulation resulted in stable protein expression at 10 °C, whereas expression of most transport proteins increased at medium PCO2 and 18 °C. mRNA and protein expression of distinct ion transport proteins were closely co-regulated, substantiating cellular functional relationships. Na(+)/K(+) ATPase capacities were PCO2 independent, but increased with acclimation temperature, whereas H(+) ATPase capacities were thermally compensated but decreased at medium PCO2 and 10 °C. When functional capacities of branchial ATPases were compared with mitochondrial F1Fo ATP-synthase strong correlations of F1Fo ATP-synthase and ATPase capacities generally indicate close coordination of branchial aerobic ATP demand and supply. Our data indicate physiological plasticity in the gills of cod to adjust to a warming, acidifying ocean within limits. In light of the interacting and non-linear, dose-dependent effects of both climate factors the role of these mechanisms in shaping resilience under climate change remains to be explored. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

A Comparison of Coral and Mollusk Calcification Strategies Under Future Ocean Acidification Scenarios

NASA Astrophysics Data System (ADS)

Cameron, L.; Reymond, C.; Westfield, I. T.; Mueller-Lundin, F.; Fink, A.; Hardenberg, S.; Westphal, H.; de Beer, D.; Ries, J. B.

2016-12-01

Here, we contrast the calcification dynamics of the coral Stylophora pistillata and the scallop Pecten maximus under future ocean acidification scenarios. Specimens were cultured in fully crossed pCO2 (400, 1000, 3000 matm) and temperature (28, 31 °C for corals; 9, 12 °C for scallops) treatments. Net calcification rates were determined from changes in the organisms' buoyant weights between the beginning and end of the experiment. After one month of exposure, proton-sensitive microelectrodes were used to measure pH at the calcification site of both corals and scallops. Net calcification rates of S. pistillata increased linearly with increasing pCO2 at 28 °C, but were near zero in all pCO2 treatments at 31 °C. Under each pCO2 treatment, net calcification rates of S. pistillata were significantly greater at 28 °C than at 31 °C. Net calcification rates of P. maximus decreased linearly with increasing pCO2 at 12 °C, but showed no significant trend with pCO2 at 9 °C. Net calcification rates of P. maximus under each pCO2 were significantly greater at 12 °C than at 9 °C. Microelectrode measurements revealed that regulation of calcification site pH differed substantially between the investigated coral and scallop. The coral exhibited calcifying fluid pH that was elevated relative to seawater pH by 0.3 - 0.5 units under all pCO2 conditions at 28 °C, and by 0.1 - 0.3 under all pCO2 conditions at 31 °C. In contrast, the scallop exhibited extrapallial fluid pH fixed at 7.8 - 8.2 pH units under 400 and 1000 matm pCO2 at both 9 and 12 °C. At 3000 matm pCO2, extrapallial fluid pH decreased to between 7.1 and 7.3 under both temperatures. These results suggest that the investigated coral calcifies more quickly under higher pCO2 by elevating pH of its calcifying fluid, thereby converting the increased DIC to carbonate ions for calcification. However, this ability appears to be impaired under substantially elevated temperatures (31 °C), resulting in conditions unfavorable for calcification. The scallop, in contrast, maintained its extrapallial fluid pH at a relatively constant seawater pH (7.8 - 8.2) under both 400 and 1000 matm pCO2, maintaining conditions favorable for calcification. At 3000 matm pCO2, the scallop appears to lose control of its extrapallial fluid pH, resulting in a substantial pH decline that is unsupportive of calcification.

Lethal and sublethal responses of native mussels (Unionidae: Lampsilis siliquoidea and L. higginsii) to elevated carbon dioxide

USGS Publications Warehouse

Waller, Diane L.; Bartsch, Michelle; Bartsch, Lynn; Jackson, Craig

2018-01-01

Levels of carbon dioxide (CO2) that have been proposed for aquatic invasive species (AIS) control [24 000 – 96 000 µatm partial pressure CO2 (PCO2); 1 atm = 101.325 kPa] were tested on juvenile mussels, the Fatmucket (Lampsilis siliquoidea) and the U.S. federally endangered Higgins Eye (L. higginsii). A suite of responses (survival, growth, behavior, and gene expression) were measured after 28-d exposure and 14-d postexposure to CO2. The 28-d LC20 (lethal concentration to 20%) was lower for L. higginsii (31 800 µatm PCO2, 95% confidence interval (CI) 15 000 – 42 800 µatm) than for L. siliquoidea (58 200 µatm PCO2, 95% CI 45 200 – 68 100 µatm). Treatment-related reductions occurred in all measures of growth and condition. Expression of chitin synthase, key for shell formation, was down-regulated at 28-d exposure. Carbon dioxide caused narcotization and unburial of mussels, behaviors that could increase mortality by predation and displacement. We conclude that survival and growth of juvenile mussels could be reduced by continuous exposure to elevated CO2, but recovery may be possible in shorter duration exposure.

Effects of Tidally Driven Variation on the Response of Coralline Algae to Ocean Acidification

NASA Astrophysics Data System (ADS)

Ets-Hokin, J. M.; Fachon, E.; Donham, E. M.; Price, N.

2016-02-01

As atmospheric CO2 levels continue to rise, our oceans are becoming more acidic, making it difficult for calcareous organisms like coralline algae to calcify. Coralline algae are early colonizers after disturbances and foundational species that initiate succession by inducing larval settlement of many invertebrate species. However, coralline algae tend to be more susceptible to experimentally elevated pCO2 than other calcifiers, likely due to the higher magnesium content in their calcite skeleton, which can render them more soluble. Magnesium content varies between individuals and is context dependent, thus could be a mechanism of acclimation for algae recruiting to harsh environments. To test this hypothesis, we collected Corallina officinalis from tide pools that experience extreme daily variation and from a well-flushed site that experiences lower daily variation in seawater pH. Samples were placed for 22 days in 1L microcosms bubbled with air enriched with pCO2, with values ranging from preindustrial lows (280 uatm) to predicted highs over the next century (1120 uatm) over 6 treatment levels. C. officinalis collected in the isolated tide pools showed decreased growth ( 50%) both in net calcification (measured via buoyant weight method) and linear extension (visualized with fluorescent stain) in low and high pCO2 levels, with growth peaking at an optimal pCO2 value of approximatly 300 uatm similar to present-day conditions. In contrast C. officinalis collected from the flushed site had no response to pCO2 treatments but had significantly lower growth overall. Tide pool two showed higher inclusion of magnesium in its carbonate skeleton which could explain its more pronounced response to the pCO2 treatments. While living in harsh environments can acclimate coralline algae to high pCO2, overall growth rates are substantially lower and will likely be insufficient to alleviate effects of ocean acidification.

pCO2 Effects on Species Composition and Growth of an Estuarine Phytoplankton Community

NASA Astrophysics Data System (ADS)

Grear, J. S.; Rynearson, T. A.; Montalbano, A. L.; Govenar, B. W.; Menden-Deuer, S.

2016-02-01

Ocean and coastal waters are experiencing changes in carbonate chemistry, including pH, in response to increasing atmospheric CO2 concentration and the microbial degradation of organic matter associated with nutrient enrichment. The effects of this change on plankton communities have important implications for food webs and biogeochemical cycling. However, conflicting results have emerged regarding responses of phytoplankton species and communities to experimental CO2 enrichment. We performed winter "ecostat" incubations of natural plankton communities from lower Narragansett Bay at ambient bay temperatures (5-13 C), light, and nutrients under three levels of CO2 enrichment simulating past, present and future conditions (mean pCO2 levels were 224, 361, and 724 uatm). Major increases in relative diatom abundance occurred during the experiment but were similar across pCO2 treatments. At the end of the experiment, 24-hr growth responses to pCO2 varied as a function of cell size. The smallest size fraction (<5 µm) grew faster at the elevated pCO2 level. In contrast, the 5-20 µm size fraction grew fastest in the Present treatment and there were no significant differences in growth rate among treatments in the > 20 µm size fraction. Cell size distribution shifted toward smaller cells in both the Past and Future treatments but remained unchanged in the Present treatment. These non-monotonic effects of increasing pCO2 may be related to opposing physiological effects of high CO2 vs low pH both within and among species. Interaction of these effects with other factors (e.g., nutrients, light, temperature, grazing, initial species composition) may explain variability among published studies. The absence of clear treatment-specific effects at the community level suggest that extrapolation of species-specific responses would produce misleading predictions of ocean acidification impacts on plankton production.

Elevated carbon dioxide alters the plasma composition and behaviour of a shark.

PubMed

Green, Leon; Jutfelt, Fredrik

2014-09-01

Increased carbon emissions from fossil fuels are increasing the pCO2 of the ocean surface waters in a process called ocean acidification. Elevated water pCO2 can induce physiological and behavioural effects in teleost fishes, although there appear to be large differences in sensitivity between species. There is currently no information available on the possible responses to future ocean acidification in elasmobranch fishes. We exposed small-spotted catsharks (Scyliorhinus canicula) to either control conditions or a year 2100 scenario of 990 μatm pCO2 for four weeks. We did not detect treatment effects on growth, resting metabolic rate, aerobic scope, skin denticle ultrastructure or skin denticle morphology. However, we found that the elevated pCO2 group buffered internal acidosis via [Formula: see text] accumulation with an associated increase in Na(+), indicating that the blood chemistry remained altered despite the long acclimation period. The elevated pCO2 group also exhibited a shift in their nocturnal swimming pattern from a pattern of many starts and stops to more continuous swimming. Although CO2-exposed teleost fishes can display reduced behavioural asymmetry (lateralization), the CO2-exposed sharks showed increased lateralization. These behavioural effects may suggest that elasmobranch neurophysiology is affected by CO2, as in some teleosts, or that the sharks detect CO2 as a constant stressor, which leads to altered behaviour. The potential direct effects of ocean acidification should henceforth be considered when assessing future anthropogenic effects on sharks. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

pCO2 effects on species composition and growth of an estuarine phytoplankton community

NASA Astrophysics Data System (ADS)

Grear, Jason S.; Rynearson, Tatiana A.; Montalbano, Amanda L.; Govenar, Breea; Menden-Deuer, Susanne

2017-05-01

The effects of ongoing changes in ocean carbonate chemistry on plankton ecology have important implications for food webs and biogeochemical cycling. However, conflicting results have emerged regarding species-specific responses to pCO2 enrichment and thus community responses have been difficult to predict. To assess community level effects (e.g., production) of altered carbonate chemistry, studies are needed that capitalize on the benefits of controlled experiments but also retain features of intact ecosystems that may exacerbate or ameliorate the effects observed in single-species or single cohort experiments. We performed incubations of natural plankton communities from Narragansett Bay, RI, USA in winter at ambient bay temperatures (5-13 °C), light and nutrient concentrations. Three levels of controlled and constant CO2 concentrations were imposed, simulating past, present and future conditions at mean pCO2 levels of 224, 361, and 724 μatm respectively. Samples for carbonate analysis, chlorophyll a, plankton size-abundance, and plankton species composition were collected daily and phytoplankton growth rates in three different size fractions (<5, 5-20, and >20 μm) were measured at the end of the 7-day incubation period. Community composition changed during the incubation period with major increases in relative diatom abundance, which were similar across pCO2 treatments. At the end of the experiment, 24-hr growth responses to pCO2 levels varied as a function of cell size. The smallest size fraction (<5 μm) grew faster at the elevated pCO2 level. In contrast, the 5-20 μm size fraction grew fastest in the Present treatment and there were no significant differences in growth rate among treatments in the >20 μm size fraction. Cell size distribution shifted toward smaller cells in both the Past and Future treatments but remained unchanged in the Present treatment. Similarity in Past and Future treatments for cell size distribution and growth rate (5-20 μm size fraction) illustrate non-monotonic effects of altered pCO2 on ecological indicators and may be related to opposing physiological effects of high CO2 and low pH both within and among species. Interaction of these effects with other factors (e.g., nutrients, light, temperature, grazing, initial species composition) may explain variability among published studies. The absence of clear treatment-specific effects at the community level suggests that extrapolation of species-specific responses or experiments with only present day and future pCO2 treatments levels could produce misleading predictions of ocean acidification impacts on plankton production.

Predation of freshwater fish in environments with elevated carbon dioxide

USGS Publications Warehouse

Midway, Stephen R.; Hasler, Caleb T.; Wagner, Tyler; Suski, Cory D.

2017-01-01

Carbon dioxide (CO2) in fresh-water environments is poorly understood, yet in marine environments CO2 can affect fish behaviour, including predator–prey relationships. To examine changes in predator success in elevated CO2, we experimented with predatory Micropterus salmoides and Pimephales promelas prey. We used a two-factor fully crossed experimental design; one factor was 4-day (acclimation) CO2 concentration and the second factor CO2 concentration during 20-min predation experiments. Both factors had three treatment levels, including ambient partial pressure of CO2(pCO2; 0–1000 μatm), low pCO2 (4000–5000 μatm) and high pCO2 (8000–10 000 μatm). Micropterus salmoides was exposed to both factors, whereas P. promelas was not exposed to the acclimation factor. In total, 83 of the 96 P. promelas were consumed (n = 96 trials) and we saw no discernible effect of CO2 on predator success or time to predation. Failed strikes and time between failed strikes were too infrequent to model. Compared with marine systems, our findings are unique in that we not only saw no changes in prey capture success with increasing CO2, but we also used CO2 treatments that were substantially higher than those in past experiments. Our work demonstrated a pronounced resiliency of freshwater predators to elevated CO2 exposure, and a starting point for future work in this area.

Ocean warming and acidification modulate energy budget and gill ion regulatory mechanisms in Atlantic cod (Gadus morhua).

PubMed

Kreiss, C M; Michael, K; Lucassen, M; Jutfelt, F; Motyka, R; Dupont, S; Pörtner, H-O

2015-10-01

Ocean warming and acidification are threatening marine ecosystems. In marine animals, acidification is thought to enhance ion regulatory costs and thereby baseline energy demand, while elevated temperature also increases baseline metabolic rate. Here we investigated standard metabolic rates (SMR) and plasma parameters of Atlantic cod (Gadus morhua) after 3-4 weeks of exposure to ambient and future PCO2 levels (550, 1200 and 2200 µatm) and at two temperatures (10, 18 °C). In vivo branchial ion regulatory costs were studied in isolated, perfused gill preparations. Animals reared at 18 °C responded to increasing CO2 by elevating SMR, in contrast to specimens at 10 °C. Isolated gills at 10 °C and elevated PCO2 (≥1200 µatm) displayed increased soft tissue mass, in parallel to increased gill oxygen demand, indicating an increased fraction of gill in whole animal energy budget. Altered gill size was not found at 18 °C, where a shift in the use of ion regulation mechanisms occurred towards enhanced Na(+)/H(+)-exchange and HCO3 (-) transport at high PCO2 (2200 µatm), paralleled by higher Na(+)/K(+)-ATPase activities. This shift did not affect total gill energy consumption leaving whole animal energy budget unaffected. Higher Na(+)/K(+)-ATPase activities in the warmth might have compensated for enhanced branchial permeability and led to reduced plasma Na(+) and/or Cl(-) concentrations and slightly lowered osmolalities seen at 18 °C and 550 or 2200 µatm PCO2 in vivo. Overall, the gill as a key ion regulation organ seems to be highly effective in supporting the resilience of cod to effects of ocean warming and acidification.

The influence of food supply on the response of Olympia oyster larvae to ocean acidification

NASA Astrophysics Data System (ADS)

Hettinger, A.; Sanford, E.; Hill, T. M.; Hosfelt, J. D.; Russell, A. D.; Gaylord, B.

2013-03-01

Increases in atmospheric carbon dioxide drive accompanying changes in the marine carbonate system as carbon dioxide (CO2) enters seawater and alters its pH (termed "ocean acidification"). However, such changes do not occur in isolation, and other environmental factors have the potential to modulate the consequences of altered ocean chemistry. Given that physiological mechanisms used by organisms to confront acidification can be energetically costly, we explored the potential for food supply to influence the response of Olympia oyster (Ostrea lurida) larvae to ocean acidification. In laboratory experiments, we reared oyster larvae under a factorial combination of pCO2 and food level. High food availability offset the negative consequences of elevated pCO2 on larval shell growth and total dry weight. Low food availability, in contrast, exacerbated these impacts. In both cases, effects of food and pCO2 interacted additively rather than synergistically, indicating that they operated independently. Despite the potential for abundant resources to counteract the consequences of ocean acidification, impacts were never completely negated, suggesting that even under conditions of enhanced primary production and elevated food availability, impacts of ocean acidification may still accrue in some consumers.

Colony-specific calcification and mortality under ocean acidification in the branching coral Montipora digitata.

PubMed

Kavousi, Javid; Tanaka, Yasuaki; Nishida, Kozue; Suzuki, Atsushi; Nojiri, Yukihiro; Nakamura, Takashi

2016-08-01

Ocean acidification (OA) threatens calcifying marine organisms including reef-building corals. In this study, we examined the OA responses of individual colonies of the branching scleractinian coral Montipora digitata. We exposed nubbins of unique colonies (n = 15) to ambient or elevated pCO2 under natural light and temperature regimes for 110 days. Although elevated pCO2 exposure on average reduced calcification, individual colonies showed unique responses ranging from declines in positive calcification to negative calcification (decalcification) to no change. Similarly, mortality was greater on average in elevated pCO2, but also showed colony-specific patterns. High variation in colony responses suggests the possibility that ongoing OA may lead to natural selection of OA-tolerant colonies within a coral population. Copyright © 2016 Elsevier Ltd. All rights reserved.

Does elevated pCO2 affect reef octocorals?

PubMed

Gabay, Yasmin; Benayahu, Yehuda; Fine, Maoz

2013-03-01

Increasing anthropogenic pCO2 alters seawater chemistry, with potentially severe consequences for coral reef growth and health. Octocorals are the second most important faunistic component in many reefs, often occupying 50% or more of the available substrate. Three species of octocorals from two families were studied in Eilat (Gulf of Aqaba), comprising the zooxanthellate Ovabunda macrospiculata and Heteroxenia fuscescens (family Xeniidae), and Sarcophyton sp. (family Alcyoniidae). They were maintained under normal (8.2) and reduced (7.6 and 7.3) pH conditions for up to 5 months. Their biolological features, including protein concentration, polyp weight, density of zooxanthellae, and their chlorophyll concentration per cell, as well as polyp pulsation rate, were examined under conditions more acidic than normal, in order to test the hypothesis that rising pCO2 would affect octocorals. The results indicate no statistically significant difference between the octocorals exposed to reduced pH values compared to the control. It is therefore suggested that the octocorals' tissue may act as a protective barrier against adverse pH conditions, thus maintaining them unharmed at high levels of pCO2.

In situ developmental responses of tropical sea urchin larvae to ocean acidification conditions at naturally elevated pCO2 vent sites.

PubMed

Lamare, Miles D; Liddy, Michelle; Uthicke, Sven

2016-11-30

Laboratory experiments suggest that calcifying developmental stages of marine invertebrates may be the most ocean acidification (OA)-sensitive life-history stage and represent a life-history bottleneck. To better extrapolate laboratory findings to future OA conditions, developmental responses in sea urchin embryos/larvae were compared under ecologically relevant in situ exposures on vent-elevated pCO 2 and ambient pCO 2 coral reefs in Papua New Guinea. Echinometra embryos/larvae were reared in meshed chambers moored in arrays on either venting reefs or adjacent non-vent reefs. After 24 and 48 h, larval development and morphology were quantified. Compared with controls (mean pH (T) = 7.89-7.92), larvae developing in elevated pCO 2 vent conditions (pH (T) = 7.50-7.72) displayed a significant reduction in size and increased abnormality, with a significant correlation of seawater pH with both larval size and larval asymmetry across all experiments. Reciprocal transplants (embryos from vent adults transplanted to control conditions, and vice versa) were also undertaken to identify if adult acclimatization can translate resilience to offspring (i.e. transgenerational processes). Embryos originating from vent adults were, however, no more tolerant to reduced pH. Sea temperature and chlorophyll-a concentrations (i.e. larval nutrition) did not contribute to difference in larval size, but abnormality was correlated with chlorophyll levels. This study is the first to examine the response of marine larvae to OA scenarios in the natural environment where, importantly, we found that stunted and abnormal development observed in situ are consistent with laboratory observations reported in sea urchins, in both the direction and magnitude of the response. © 2016 The Author(s).

In situ developmental responses of tropical sea urchin larvae to ocean acidification conditions at naturally elevated pCO2 vent sites

PubMed Central

Liddy, Michelle; Uthicke, Sven

2016-01-01

Laboratory experiments suggest that calcifying developmental stages of marine invertebrates may be the most ocean acidification (OA)-sensitive life-history stage and represent a life-history bottleneck. To better extrapolate laboratory findings to future OA conditions, developmental responses in sea urchin embryos/larvae were compared under ecologically relevant in situ exposures on vent-elevated pCO2 and ambient pCO2 coral reefs in Papua New Guinea. Echinometra embryos/larvae were reared in meshed chambers moored in arrays on either venting reefs or adjacent non-vent reefs. After 24 and 48 h, larval development and morphology were quantified. Compared with controls (mean pH(T) = 7.89–7.92), larvae developing in elevated pCO2 vent conditions (pH(T) = 7.50–7.72) displayed a significant reduction in size and increased abnormality, with a significant correlation of seawater pH with both larval size and larval asymmetry across all experiments. Reciprocal transplants (embryos from vent adults transplanted to control conditions, and vice versa) were also undertaken to identify if adult acclimatization can translate resilience to offspring (i.e. transgenerational processes). Embryos originating from vent adults were, however, no more tolerant to reduced pH. Sea temperature and chlorophyll-a concentrations (i.e. larval nutrition) did not contribute to difference in larval size, but abnormality was correlated with chlorophyll levels. This study is the first to examine the response of marine larvae to OA scenarios in the natural environment where, importantly, we found that stunted and abnormal development observed in situ are consistent with laboratory observations reported in sea urchins, in both the direction and magnitude of the response. PMID:27903867

Ocean acidification causes structural deformities in juvenile coral skeletons.

PubMed

Foster, Taryn; Falter, James L; McCulloch, Malcolm T; Clode, Peta L

2016-02-01

Rising atmospheric CO2 is causing the oceans to both warm and acidify, which could reduce the calcification rates of corals globally. Successful coral recruitment and high rates of juvenile calcification are critical to the replenishment and ultimate viability of coral reef ecosystems. Although elevated Pco2 (partial pressure of CO2) has been shown to reduce the skeletal weight of coral recruits, the structural changes caused by acidification during initial skeletal deposition are unknown. We show, using high-resolution three-dimensional x-ray microscopy, that ocean acidification (Pco2 ~900 μatm, pH ~7.7) not only causes reduced overall mineral deposition but also a deformed and porous skeletal structure in newly settled coral recruits. In contrast, elevated temperature (+3°C) had little effect on skeletal formation except to partially mitigate the effects of elevated Pco2. The striking structural deformities we observed show that new recruits are at significant risk, being unable to effectively build their skeletons in the Pco2 conditions predicted to occur for open ocean surface waters under a "business-as-usual" emissions scenario [RCP (representative concentration pathway) 8.5] by the year 2100.

Ocean acidification causes structural deformities in juvenile coral skeletons

PubMed Central

Foster, Taryn; Falter, James L.; McCulloch, Malcolm T.; Clode, Peta L.

2016-01-01

Rising atmospheric CO2 is causing the oceans to both warm and acidify, which could reduce the calcification rates of corals globally. Successful coral recruitment and high rates of juvenile calcification are critical to the replenishment and ultimate viability of coral reef ecosystems. Although elevated Pco2 (partial pressure of CO2) has been shown to reduce the skeletal weight of coral recruits, the structural changes caused by acidification during initial skeletal deposition are unknown. We show, using high-resolution three-dimensional x-ray microscopy, that ocean acidification (Pco2 ~900 μatm, pH ~7.7) not only causes reduced overall mineral deposition but also a deformed and porous skeletal structure in newly settled coral recruits. In contrast, elevated temperature (+3°C) had little effect on skeletal formation except to partially mitigate the effects of elevated Pco2. The striking structural deformities we observed show that new recruits are at significant risk, being unable to effectively build their skeletons in the Pco2 conditions predicted to occur for open ocean surface waters under a “business-as-usual” emissions scenario [RCP (representative concentration pathway) 8.5] by the year 2100. PMID:26989776

Relationship between respiratory failure and plasma noradrenaline levels in amyotrophic lateral sclerosis.

PubMed

Yamashita, A; Koike, Y; Takahashi, A; Hirayama, M; Murakami, N; Sobue, G

1997-08-01

We evaluated plasma noradrenaline (NA) levels at test and during head-up tilt test in 20 patients with sporadic amyotrophic lateral sclerosis (ALS). Their fasting plasma NA levels ranged from 195 to 4227 pg/ml. The average plasma NA level was 483 pg/ml in five ambulatory patients, 341 in two wheelchair-bound patients, 1264 in 11 bedridden patients, and 208 in two respirator-dependent patients whose disability grading was the worst among the four groups. Arterial carbon dioxide (PCO2) was evaluated as a measure of respiratory function. The coefficient of correlation between PCO2 and plasma NA was r = 0.654 (p < 0.01). Either respiratory failure or lower motor neuron dysfunction may relate to the elevation of plasma NA levels. In the two bedridden patients, plasma NA levels and heart rate at rest increased significantly as the disease progressed. Cardiovascular responses to head-up tilting were normal. These data suggest that the elevation of plasma NA levels may be related to progression of respiratory failure and lower motor neuron dysfunction. In conclusion, sympathetic hyperactivity in ALS is considered to be not primary, but secondary to somatic motor disabilities and respiratory failure.

Improving the Ginkgo CO2 barometer: Implications for the early Cenozoic atmosphere

NASA Astrophysics Data System (ADS)

Barclay, Richard S.; Wing, Scott L.

2016-04-01

Stomatal properties of fossil Ginkgo have been used widely to infer the atmospheric concentration of CO2 in the geological past (paleo-pCO2). Many of these estimates of paleo-pCO2 have relied on the inverse correlation between pCO2 and stomatal index (SI - the proportion of epidermal cells that are stomata) observed in recent Ginkgo biloba, and therefore depend on the accuracy of this relationship. The SI - pCO2 relationship in G. biloba has not been well documented, however. Here we present new measurements of SI for leaves of G. biloba that grew under pCO2 from 290 to 430 ppm. We prepared and imaged all specimens using a consistent procedure and photo-documented each count. As in prior studies, we found a significant inverse relationship between SI and pCO2, however, the relationship is more linear, has a shallower slope, and a lower correlation coefficient than previously reported. We examined leaves of G. biloba grown under pCO2 of 1500 ppm, but found they had highly variable SI and a large proportion of malformed stomata. We also measured stomatal dimensions, stomatal density, and the carbon isotope composition of G. biloba leaves in order to test a mechanistic model for inferring pCO2. This model overestimated observed pCO2, performing less well than the SI method between 290 and 430 ppm. We used our revised SI-pCO2 response curve, and new observations of selected fossils, to estimate late Cretaceous and Cenozoic pCO2 from fossil Ginkgo adiantoides. All but one of the new estimates is below 800 ppm, and together they show little long-term change in pCO2 or relation to global temperature. The low Paleogene pCO2 levels indicated by the Ginkgo SI proxy are not consistent with the high pCO2 inferred by some climate and carbon cycle models. We cannot currently resolve the discrepancy, but greater agreement between proxy data and models may come from a better understanding of the stomatal response of G. biloba to elevated pCO2, better counts and measurements of fossil Ginkgo, or models that can simulate greenhouse climates at lower pCO2.

Effect of acidity and elevated PCO2 on acid. Neutralization within pulsed limestone bed reactors receiving coal mine drainage

USGS Publications Warehouse

Watten, B.J.; Sibrell, P.L.; Schwartz, M.F.

2004-01-01

Limestone has potential for reducing reagent costs and sludge volume associated with the treatment of acid mine drainage (AMD), but its use has been restricted by slow dissolution rates and sensitivity to scale forming reactions that retard transport of H+ at the solid-liquid interface. We evaluated a pulsed limestone bed (PLB) remediation process designed to circumvent these problems through use of intermittently fluidized beds of granular limestone and elevated carbon dioxide pressure. PLB limestone dissolution (LD, mg/L), and effluent alkalinity (Alk, mg/L) were correlated with reactor pressure (PCO2, kPa), influent acidity (Acy, mg/L) and reactor bed height (H, cm) using a prototype capable of processing 10 L/min. The PLB process effectively neutralized sulfuric acid acidity over the range of 6-1033 mg/L (as CaCO3) while generating high concentrations of alkalinity (36-1086 mg/L) despite a hydraulic residence time of just 4.2-5.0 min. Alk and LD (mg/L CaCO3) rose with increases in influent acidity and PCO2 (p < 0.001) according to the models: Alk = 58 + 38.4 (PCO2)0.5 + 0.080 (Acy) - 0.0059(PCO2) 0.5 (Acy); LD = 55 + 38.3 (PCO2)0.5 + 1.08 (Acy) - 0.0059 (PCO2)0.5 (Acy). Alkalinity decreased at an increasing rate with reductions in H over the range of 27.3-77.5 cm (p < 0.001). Carbon dioxide requirements (Q(avg)CO2, L/min) increased with PCO2 (p < 0.001) following the model Q(avg)CO2 = 0.858 (PCO2)0.620, resulting in a greater degree of pH buffering (depression) within the reactors, a rise in limestone solubility and an increase in limestone dissolution related to carbonic acid attack. Corresponding elevated concentrations of effluent alkalinity allow for sidestream treatment with blending. Numerical modeling demonstrated that carbon dioxide requirements are reduced as influent acidity rises and when carbon dioxide is recovered from system effluent and recycled. Field trials demonstrated that the PLB process is capable of raising the pH of AMD above that required for hydrolysis and precipitation of Fe3+ and Al 3+ but not Fe2+ and Mn2+.

The Effects of Acidic and Hypoxic Conditions on the Estuarine ...

EPA Pesticide Factsheets

The interactive and combined effects of coastal acidification and hypoxia on estuarine species is an increasing concern as these stressors change concomitantly. There is a need to understand how these environmental factors interact, as well as their effect on estuarine organisms. A method was developed for this research whereby four exposure treatments were created simultaneously: ambient, elevated pCO2, (~1300µatm, IPCC RCP 8.5 scenario), hypoxic (low dissolved oxygen, ~2 mg/L), and combined elevated pCO2 with low dissolved oxygen. An exposure with variant water quality parameters allows for the comparative study of organismal survival response to acidified and hypoxic conditions. The goal of this research is to determine acute species sensitivity, which is determined by survivability, to the combined effects of elevated pCO2 and hypoxia over a 5 day period, as well as possible differences in sensitivity between life-stages. Preliminary research on sheepshead minnow and mysid shrimp, indicates that mysid shrimp were tolerant of both elevated pCO2 and low DO exposure regardless of life-stage, whereas sheepshead minnows were more sensitive to the combined effects of acidification and hypoxia. This work is part of the first phase of the NECAH project, which is identifying species that are sensitive to the combined effects of acidification and hypoxia. The project describes the initial work on the first 2 species selected for testing and the final product will be

Impact of long-term moderate hypercapnia and elevated temperature on the energy budget of isolated gills of Atlantic cod (Gadus morhua).

PubMed

Kreiss, Cornelia M; Michael, Katharina; Bock, Christian; Lucassen, Magnus; Pörtner, Hans-O

2015-04-01

Effects of severe hypercapnia have been extensively studied in marine fishes, while knowledge on the impacts of moderately elevated CO2 levels and their combination with warming is scarce. Here we investigate ion regulation mechanisms and energy budget in gills from Atlantic cod acclimated long-term to elevated PCO2 levels (2500 μatm) and temperature (18°C). Isolated perfused gill preparations were established to determine gill thermal plasticity during acute exposures (10-22°C) and in vivo costs of Na(+)/K(+)-ATPase activity, protein and RNA synthesis. Maximum enzyme capacities of F1Fo-ATPase, H(+)-ATPase and Na(+)/K(+)-ATPase were measured in vitro in crude gill homogenates. After whole animal acclimation to elevated PCO2 and/or warming, branchial oxygen consumption responded more strongly to acute temperature change. The fractions of gill respiration allocated to protein and RNA synthesis remained unchanged. In gills of fish CO2-exposed at both temperatures, energy turnover associated with Na(+)/K(+)-ATPase activity was reduced by 30% below rates of control fish. This contrasted in vitro capacities of Na(+)/K(+)-ATPase, which remained unchanged under elevated CO2 at 10°C, and earlier studies which had found a strong upregulation under severe hypercapnia. F1Fo-ATPase capacities increased in hypercapnic gills at both temperatures, whereas Na(+)/K(+)ATPase and H(+)-ATPase capacities only increased in response to elevated CO2 and warming indicating the absence of thermal compensation under CO2. We conclude that in vivo ion regulatory energy demand is lowered under moderately elevated CO2 levels despite the stronger thermal response of total gill respiration and the upregulation of F1Fo-ATPase. This effect is maintained at elevated temperature. Copyright © 2014 Elsevier Inc. All rights reserved.

Is the response of coral calcification to seawater acidification related to nutrient loading?

NASA Astrophysics Data System (ADS)

Chauvin, Anne; Denis, Vianney; Cuet, Pascale

2011-12-01

The effect of decreasing aragonite saturation state (ΩArag) of seawater (elevated pCO2) on calcification rates of Acropora muricata was studied using nubbins prepared from parent colonies located at two sites of La Saline reef (La Réunion Island, western Indian Ocean): a back-reef site (BR) affected by nutrient-enriched groundwater discharge (mainly nitrate), and a reef flat site (RF) with low terrigenous inputs. Protein and chlorophyll a content of the nubbins, as well as zooxanthellae abundance, were lower at RF than BR. Nubbins were incubated at ~27°C over 2 h under sunlight, in filtered seawater manipulated to get differing initial pCO2 (1,440-340 μatm), ΩArag (1.4-4.0), and dissolved inorganic carbon (DIC) concentrations (2,100-1,850 μmol kg-1). Increasing DIC concentrations at constant total alkalinity (AT) resulted in a decrease in ΩArag and an increase in pCO2. AT at the beginning of the incubations was kept at a natural level of 2,193 ± 6 μmol kg-1 (mean ± SD). Net photosynthesis (NP) and calcification were calculated from changes in pH and AT during the incubations. Calcification decrease in response to doubling pCO2 relative to preindustrial level was 22% for RF nubbins. When normalized to surface area of the nubbins, (1) NP and calcification were higher at BR than RF, (2) NP increased in high pCO2 treatments at BR compared to low pCO2 treatments, and (3) calcification was not related to ΩArag at BR. When normalized to NP, calcification was linearly related to ΩArag at both sites, and the slopes of the relationships were not significantly different. The increase in NP at BR in the high pCO2 treatments may have increased calcification and thus masked the negative effect of low ΩArag on calcification. Removing the effect of NP variations at BR showed that calcification declined in a similar manner with decreased ΩArag (increased pCO2) whatever the nutrient loading.

ELEVATED CARBON DIOXIDE DIFFERENTIALLY ALTERS THE PHOTOPHYSIOLOGY OF THALASSIOSIRA PSEUDONANA (BACILLARIOPHYCEAE) AND EMILIANIA HUXLEYI (HAPTOPHYTA)(1).

PubMed

McCarthy, Avery; Rogers, Susan P; Duffy, Stephen J; Campbell, Douglas A

2012-06-01

Increasing anthropogenic carbon dioxide is causing changes to ocean chemistry, which will continue in a predictable manner. Dissolution of additional atmospheric carbon dioxide leads to increased concentrations of dissolved carbon dioxide and bicarbonate and decreased pH in ocean water. The concomitant effects on phytoplankton ecophysiology, leading potentially to changes in community structure, are now a focus of concern. Therefore, we grew the coccolithophore Emiliania huxleyi (Lohmann) W. W. Hay et H. Mohler and the diatom strains Thalassiosira pseudonana (Hust.) Hasle et Heimdal CCMP 1014 and T. pseudonana CCMP 1335 under low light in turbidostat photobioreactors bubbled with air containing 390 ppmv or 750 ppmv CO2 . Increased pCO2 led to increased growth rates in all three strains. In addition, protein levels of RUBISCO increased in the coastal strains of both species, showing a larger capacity for CO2 assimilation at 750 ppmv CO2 . With increased pCO2 , both T. pseudonana strains displayed an increased susceptibility to PSII photoinactivation and, to compensate, an augmented capacity for PSII repair. Consequently, the cost of maintaining PSII function for the diatoms increased at increased pCO2 . In E. huxleyi, PSII photoinactivation and the counter-acting repair, while both intrinsically larger than in T. pseudonana, did not change between the current and high-pCO2 treatments. The content of the photosynthetic electron transport intermediary cytochrome b6/f complex increased significantly in the diatoms under elevated pCO2 , suggesting changes in electron transport function. © 2012 Phycological Society of America.

Elevated seawater temperature, not pCO2, negatively affects post-spawning adult mussels (Mytilus edulis) under food limitation.

PubMed

Clements, Jeff C; Hicks, Carla; Tremblay, Réjan; Comeau, Luc A

2018-01-01

Pre-spawning blue mussels ( Mytilus edulis ) appear sensitive to elevated temperature and robust to elevated p CO 2 ; however, the effects of these stressors soon after investing energy into spawning remain unknown. Furthermore, while studies suggest that elevated p CO 2 affects the byssal attachment strength of Mytilus trossulus from southern latitudes, p CO 2 and temperature impacts on the byssus strength of other species at higher latitudes remain undocumented. In a 90 day laboratory experiment, we exposed post-spawning adult blue mussels ( M. edulis ) from Atlantic Canada to three p CO 2 levels ( p CO 2 ~625, 1295 and 2440 μatm) at two different temperatures (16°C and 22°C) and assessed energetic reserves on Day 90, byssal attachment strength on Days 30 and 60, and condition index and mortality on Days 30, 60 and 90. Results indicated that glycogen content was negatively affected under elevated temperature, but protein, lipid, and overall energy content were unaffected. Reduced glycogen content under elevated temperature was associated with reduced condition index, reduced byssal thread attachment strength, and increased mortality; elevated p CO 2 had no effects. Overall, these results suggest that the glycogen reserves of post-spawning adult M. edulis are sensitive to elevated temperature, and can result in reduced health and byssal attachment strength, leading to increased mortality. These results are similar to those reported for pre-spawning mussels and suggest that post-spawning blue mussels are tolerant to elevated p CO 2 and sensitive to elevated temperature. In contrast to previous studies, however, elevated pCO 2 did not affect byssus strength, suggesting that negative effects of elevated p CO 2 on byssus strength are not universal.

Late-Quaternary variation in C3 and C4 grass abundance in southeastern Australia as inferred from δ13C analysis: Assessing the roles of climate, pCO2, and fire

NASA Astrophysics Data System (ADS)

Nelson, David M.; Urban, Michael A.; Kershaw, A. Peter; Hu, Feng Sheng

2016-05-01

Climate, atmospheric pCO2, and fire all may exert major influences on the relative abundance of C3 and C4 grasses in the present-day vegetation. However, the relative role of these factors in driving variation in C3 and C4 grass abundances in the paleorecord is uncertain, and C4 abundance is often interpreted narrowly as a proxy indicator of aridity or pCO2. We measured δ13C values of individual grains of grass (Poaceae) pollen in the sediments of two sites in southeastern Australia to assess changes in the proportions of C3 and C4 grasses during the past 25,000 years. These data were compared with shifts in pCO2, temperature, moisture balance, and fire to assess how these factors were related to long-term variation of C4 grass abundance during the late Quaternary. At Caledonia Fen, a high-elevation site in the Snowy Mountains, C4 grass abundance decreased from an average of 66% during the glacial period to 11% during the Holocene, primarily in response to increased pCO2 and temperature. In contrast, this pattern did not exist in low-elevation savannah woodlands around Tower Hill Northwest Crater, where C4 grass abundance instead varied in response to shifts in regional aridity. Fire did not appear to have strongly influenced the proportions of C3 and C4 grasses on the landscape at millennial timescales at either site. These patterns are similar to those of a recent study in East Africa, suggesting that elevation-related climatic differences influence how the abundance of C3 and C4 grasses responds to shifts in climate and pCO2. These results caution against using C4 plant abundance as a proxy indicator of either climate or pCO2 without an adequate understanding of key controlling factors.

Living in warmer, more acidic oceans retards physiological recovery from tidal emersion in the velvet swimming crab, Necora puber.

PubMed

Rastrick, S P S; Calosi, P; Calder-Potts, R; Foggo, A; Nightingale, G; Widdicombe, S; Spicer, J I

2014-07-15

The distribution patterns of many species in the intertidal zone are partly determined by their ability to survive and recover from tidal emersion. During emersion, most crustaceans experience gill collapse, impairing gas exchange. Such collapse generates a state of hypoxemia and a hypercapnia-induced respiratory acidosis, leading to hyperlactaemia and metabolic acidosis. However, how such physiological responses to emersion are modified by prior exposure to elevated CO2 and temperature combinations, indicative of future climate change scenarios, is not known. We therefore investigated key physiological responses of velvet swimming crabs, Necora puber, kept for 14 days at one of four pCO2/temperature treatments (400 μatm/10°C, 1000 μatm/10°C, 400 μatm/15°C or 1000 μatm/15°C) to experimental emersion and recovery. Pre-exposure to elevated pCO2 and temperature increased pre-emersion bicarbonate ion concentrations [HCO3(-)], increasing resistance to short periods of emersion (90 min). However, there was still a significant acidosis following 180 min emersion in all treatments. The recovery of extracellular acid-base via the removal of extracellular pCO2 and lactate after emersion was significantly retarded by exposure to both elevated temperature and pCO2. If elevated environmental pCO2 and temperature lead to slower recovery after emersion, then some predominantly subtidal species that also inhabit the low to mid shore, such as N. puber, may have a reduced physiological capacity to retain their presence in the low intertidal zone, ultimately affecting their bathymetric range of distribution, as well as the structure and diversity of intertidal assemblages. © 2014. Published by The Company of Biologists Ltd.

Low Hesperian PCO2 constrained from in situ mineralogical analysis at Gale Crater, Mars

NASA Astrophysics Data System (ADS)

Bristow, Thomas F.; Haberle, Robert M.; Blake, David F.; Des Marais, David J.; Eigenbrode, Jennifer L.; Fairén, Alberto G.; Grotzinger, John P.; Stack, Kathryn M.; Mischna, Michael A.; Rampe, Elizabeth B.; Siebach, Kirsten L.; Sutter, Brad; Vaniman, David T.; Vasavada, Ashwin R.

2017-02-01

Carbon dioxide is an essential atmospheric component in martian climate models that attempt to reconcile a faint young sun with planetwide evidence of liquid water in the Noachian and Early Hesperian. In this study, we use mineral and contextual sedimentary environmental data measured by the Mars Science Laboratory (MSL) Rover Curiosity to estimate the atmospheric partial pressure of CO2 (PCO2) coinciding with a long-lived lake system in Gale Crater at ˜3.5 Ga. A reaction-transport model that simulates mineralogy observed within the Sheepbed member at Yellowknife Bay (YKB), by coupling mineral equilibria with carbonate precipitation kinetics and rates of sedimentation, indicates atmospheric PCO2 levels in the 10s mbar range. At such low PCO2 levels, existing climate models are unable to warm Hesperian Mars anywhere near the freezing point of water, and other gases are required to raise atmospheric pressure to prevent lake waters from being lost to the atmosphere. Thus, either lacustrine features of Gale formed in a cold environment by a mechanism yet to be determined, or the climate models still lack an essential component that would serve to elevate surface temperatures, at least locally, on Hesperian Mars. Our results also impose restrictions on the potential role of atmospheric CO2 in inferred warmer conditions and valley network formation of the late Noachian.

A hypothesis linking sub-optimal seawater pCO2 conditions for cnidarian-Symbiodinium symbioses with the exceedence of the interglacial threshold (> 260 ppmv)

NASA Astrophysics Data System (ADS)

Wooldridge, S. A.

2011-11-01

Most scleractinian corals and many other cnidarians host intracellular photosynthetic dinoflagellate symbionts ("zooxanthellae"). The zooxanthellae contribute to host metabolism and skeletogenesis to such an extent that this symbiosis is well recognised for its contribution in creating the coral reef ecosystem. The stable functioning of cnidarian symbioses is however dependent upon the host's ability to maintain demographic control of its algal partner. In this review, I explain how the modern envelope of seawater conditions found within many coral reef ecosystems (characterised by elevated temperatures, rising pCO2, and enriched nutrient levels) are antagonistic toward the dominant host processes that restrict excessive symbiont proliferation. Moreover, I outline a new hypothesis and initial evidence base, which support the suggestion that the additional "excess" zooxanthellae fraction permitted by seawater pCO2 levels beyond 260 ppmv significantly increases the propensity for symbiosis breakdown ("bleaching") in response to temperature and irradiance extremes. The relevance of this biological threshold is discussed in terms of historical reef extinction events, glacial-interglacial climate cycles and the modern decline of coral reef ecosystems.

A hypothesis linking sub-optimal seawater pCO2 conditions for cnidarian-Symbiodinium symbioses with the exceedence of the interglacial threshold (>260 ppmv)

NASA Astrophysics Data System (ADS)

Wooldridge, S. A.

2012-05-01

Most scleractinian corals and many other cnidarians host intracellular photosynthetic dinoflagellate symbionts ("zooxanthellae"). The zooxanthellae contribute to host metabolism and skeletogenesis to such an extent that this symbiosis is well recognised for its contribution in creating the coral reef ecosystem. The stable functioning of cnidarian symbioses is however dependent upon the host's ability to maintain demographic control of its algal partner. In this review, I explain how the modern envelope of seawater conditions found within many coral reef ecosystems (characterised by elevated temperatures, rising pCO2, and enriched nutrient levels) are antagonistic toward the dominant host processes that restrict excessive symbiont proliferation. Moreover, I outline a new hypothesis and initial evidence base, which support the suggestion that the additional "excess" zooxanthellae fraction permitted by seawater pCO2 levels beyond 260 ppmv significantly increases the propensity for symbiosis breakdown ("bleaching") in response to temperature and irradiance extremes. The relevance of this biological threshold is discussed in terms of historical reef extinction events, glacial-interglacial climate cycles and the modern decline of coral reef ecosystems.

Interactive effects of ocean acidification and warming on coral reef associated epilithic algal communities under past, present-day and future ocean conditions

NASA Astrophysics Data System (ADS)

Vogel, N.; Cantin, N. E.; Strahl, J.; Kaniewska, P.; Bay, L.; Wild, C.; Uthicke, S.

2016-06-01

Epilithic algal communities play critical ecological roles on coral reefs, but their response to individual and interactive effects of ocean warming (OW) and ocean acidification (OA) is still largely unknown. We investigated growth, photosynthesis and calcification of early epilithic algal community assemblages exposed for 6 months to four temperature profiles (-1.1, ±0.0, +0.9, +1.6 °C) that were crossed with four carbon dioxide partial pressure (pCO2) levels (360, 440, 650, 940 µatm), under flow-through conditions and natural light regimes. Additionally, we compared the cover of heavily calcified crustose coralline algae (CCA) and lightly calcified red algae of the genus Peyssonnelia among treatments. Increase in cover of epilithic communities showed optima under moderately elevated temperatures and present pCO2, while cover strongly decreased under high temperatures and high-pCO2 conditions, particularly due to decreasing cover of CCA. Similarly, community calcification rates were strongly decreased at high pCO2 under both measured temperatures. While final cover of CCA decreased under high temperature and pCO2 (additive negative effects), cover of Peyssonnelia spp. increased at high compared to annual average and moderately elevated temperatures. Thus, cover of Peyssonnelia spp. increased in treatment combinations with less CCA, which was supported by a significant negative correlation between organism groups. The different susceptibility to stressors most likely derived from a different calcification intensity and/or mineral. Notably, growth of the epilithic communities and final cover of CCA were strongly decreased under reduced-pCO2 conditions compared to the present. Thus, CCA may have acclimatized from past to present-day pCO2 conditions, and changes in carbonate chemistry, regardless in which direction, negatively affect them. However, if epilithic organisms cannot further acclimatize to OW and OA, the interacting effects of both factors may change epilithic communities in the future, thereby likely leading to reduced reef stability and recovery.

pCO2 and pH regulation of cerebral blood flow

PubMed Central

Yoon, SeongHun; Zuccarello, Mario; Rapoport, Robert M.

2012-01-01

CO2 serves as one of the fundamental regulators of cerebral blood flow (CBF). It is widely considered that this regulation occurs through pCO2-driven changes in pH of the cerebral spinal fluid (CSF), with elevated and lowered pH causing direct relaxation and contraction of the smooth muscle, respectively. However, some findings also suggest that pCO2 acts independently of and/or in conjunction with altered pH. This action may be due to a direct effect of CSF pCO2 on the smooth muscle as well as on the endothelium, nerves, and astrocytes. Findings may also point to an action of arterial pCO2 on the endothelium to regulate smooth muscle contractility. Thus, the effects of pH and pCO2 may be influenced by the absence/presence of different cell types in the various experimental preparations. Results may also be influenced by experimental parameters including myogenic tone as well as solutions containing significantly altered HCO3− concentrations, i.e., solutions routinely employed to differentiate the effects of pH from pCO2. In sum, it appears that pCO2, independently and in conjunction with pH, may regulate CBF. PMID:23049512

Effect of ocean acidification on otolith development in larvae of a tropical marine fish

NASA Astrophysics Data System (ADS)

Munday, P. L.; Hernaman, V.; Dixson, D. L.; Thorrold, S. R.

2011-03-01

Calcification in many invertebrate species is predicted to decline due to ocean acidification. The potential effects of elevated pCO2 and reduced carbonate saturation state on other species, such as fish, are less well understood. Fish otoliths (earbones) are composed of aragonite, and thus, might be susceptible to either the reduced availability of carbonate ions in seawater at low pH, or to changes in extracellular concentrations of bicarbonate and carbonate ions caused by acid-base regulation in fish exposed to high pCO2. We reared larvae of the clownfish Amphiprion percula from hatching to settlement at three pHNBS and pCO2 levels (control: pH 8.15 and 404 μatm CO2; intermediate: pH 7.8 and 1050 μatm CO2; extreme: pH 7.6 and 1721 μatm CO2) to test the possible effects of ocean acidification on otolith development. There was no effect of the intermediate treatment (pH 7.8 and 1050 μatm CO2) on otolith size, shape, symmetry between left and right otoliths, or otolith elemental chemistry, compared with controls. However, in the more extreme treatment (pH 7.6 and 1721 μatm CO2) otolith area and maximum length were larger than controls, although no other traits were affected. Our results support the hypothesis that pH regulation in the otolith endolymph of fish exposed to elevated pCO2 can lead to increased precipitation of CaCO3 in otoliths of larval fish, as proposed by an earlier study, however, our results also show that sensitivity varies considerably among species. Importantly, our results suggest that otolith development in clownfishes is robust to even the more pessimistic changes in ocean chemistry predicted to occur by 2100.

Ocean acidification effects in the early life-stages of summer flounder, Paralichthys dentatus

NASA Astrophysics Data System (ADS)

Chambers, R. C.; Candelmo, A. C.; Habeck, E. A.; Poach, M. E.; Wieczorek, D.; Cooper, K. R.; Greenfield, C. E.; Phelan, B. A.

2013-08-01

The limited available evidence about effects of high CO2 and acidification of our oceans on fish suggests that effects will differ across fish species, be subtle, and interact with other stressors. An experimental framework was implemented that includes the use of (1) multiple marine fish species of relevance to the northeastern USA that differ in their ecologies including spawning season and habitat; (2) a wide yet realistic range of environmental conditions (i.e., concurrent manipulation of CO2 levels and water temperatures), and (3) a diverse set of response variables related to fish sensitivity to elevated CO2 levels, water temperatures, and their interactions. This report is on an array of early life-history responses of summer flounder (Paralichthys dentatus), an ecologically and economically important flatfish of this region, to a wide range of pH and CO2 levels. Survival of summer flounder embryos was reduced by 50% below local ambient conditions (7.8 pH, 775 ppm pCO2) when maintained at the intermediate conditions (7.4 pH, 1860 ppm pCO2), and by 75% below local ambient when maintained at the most acidic conditions tested (7.1 pH, 4715 ppm pCO2). This pattern of reduced survival of embryos at higher CO2 levels was consistent among three females used as sources of embryos. Sizes and shapes of larvae were altered by elevated CO2 levels with longer larvae in more acidic waters. This pattern of longer larvae was evident at hatching (although longer hatchlings had less energy reserves) to midway through the larval period. Larvae from the most acidic conditions initiated metamorphosis at earlier ages and smaller sizes than those from more moderate and ambient conditions. Tissue damage was evident in older larvae (age 14 to 28 d post-hatching) from both elevated CO2 levels. Damage included liver sinusoid dilation, focal hyperplasia on the epithelium, separation of the trunk muscle bundles, and dilation of the liver sinusoids and central veins. Cranial-facial features were affected by CO2 levels that changed with ages of larvae. Skeletal elements of larvae from ambient CO2 environments were comparable or smaller than those from elevated CO2 environments when younger (14 d and 21 d post-hatching) but larger at older ages (28 d). The degree of impairment in the early life-stages of summer flounder due to elevated CO2 levels suggests that this species will be challenged by ocean acidification in the near future. Further experimental comparative studies on marine fish are warranted in order to identify the species, life-stages, ecologies, and responses that are most sensitive to increased levels of CO2 and acidity in near-future ocean waters, and a strategy is proposed for achieving these goals.

Ocean acidification accelerates reef bioerosion.

PubMed

Wisshak, Max; Schönberg, Christine H L; Form, Armin; Freiwald, André

2012-01-01

In the recent discussion how biotic systems may react to ocean acidification caused by the rapid rise in carbon dioxide partial pressure (pCO(2)) in the marine realm, substantial research is devoted to calcifiers such as stony corals. The antagonistic process - biologically induced carbonate dissolution via bioerosion - has largely been neglected. Unlike skeletal growth, we expect bioerosion by chemical means to be facilitated in a high-CO(2) world. This study focuses on one of the most detrimental bioeroders, the sponge Cliona orientalis, which attacks and kills live corals on Australia's Great Barrier Reef. Experimental exposure to lowered and elevated levels of pCO(2) confirms a significant enforcement of the sponges' bioerosion capacity with increasing pCO(2) under more acidic conditions. Considering the substantial contribution of sponges to carbonate bioerosion, this finding implies that tropical reef ecosystems are facing the combined effects of weakened coral calcification and accelerated bioerosion, resulting in critical pressure on the dynamic balance between biogenic carbonate build-up and degradation.

Contaminant desorption during long-term leaching of hydroxide-weathered Hanford sediments.

PubMed

Thompson, Aaron; Steefel, Carl I; Perdrial, Nicolas; Chorover, Ion

2010-03-15

Mineral sorption/coprecipitation is thought to be a principal sequestration mechanism for radioactive (90)Sr and (137)Cs in sediments impacted by hyperalkaline, high-level radioactive waste (HLRW) at the DOE's Hanford site. However, the long-term persistence of neo-formed, contaminant bearing phases after removal of the HLRW source is unknown. We subjected pristine Hanford sediments to hyperalkaline Na-AI-NO(3)-OH solutions containing Sr, Cs, and I at 10(-5), 10(-5), and 10(-7) molal, respectively, for 182 days with either <10 ppmv or 385 ppmv pCO(2). This resulted in the formation of feldspathoid minerals. We leached these weathered sediments with dilute, neutral-pH solutions. After 500 pore volumes (PVs), effluent Sr, Cs, NO(3), Al, Si, and pH reached a steady-state with concentrations elevated above those of feedwater. Reactive transport modeling suggests that even after 500 PV, Cs desorption can be explained by ion exchange reactions, whereas Sr desorption is best described by dissolution of Sr-substituted, neo-formed minerals. While, pCO(2) had no effect on Sr or Cs sorption, sediments weathered at <10 ppmv pCO(2) did desorb more Sr (66% vs 28%) and Cs (13% vs 8%) during leaching than those weathered at 385 ppmv pCO(2). Thus, the dissolution of neo-formed aluminosilicates may represent a long-term, low-level supply of (90)Sr at the Hanford site.

Ocean acidification weakens the immune response of blood clam through hampering the NF-kappa β and toll-like receptor pathways.

PubMed

Liu, Saixi; Shi, Wei; Guo, Cheng; Zhao, Xinguo; Han, Yu; Peng, Chao; Chai, Xueliang; Liu, Guangxu

2016-07-01

The impact of pCO2 driven ocean acidification on marine bivalve immunity remains poorly understood. To date, this impact has only been investigated in a few bivalve species and the underlying molecular mechanism remains unknown. In the present study, the effects of the realistic future ocean pCO2 levels (pH at 8.1, 7.8, and 7.4) on the total number of haemocyte cells (THC), phagocytosis status, blood cell types composition, and expression levels of twelve genes from the NF-kappa β signaling and toll-like receptor pathways of a typical bottom burrowing bivalve, blood clam (Tegillarca granosa), were investigated. The results obtained showed that while both THC number and phagocytosis frequency were significantly reduced, the percentage of red and basophil granulocytes were significantly decreased and increased, respectively, upon exposure to elevated pCO2. In addition, exposure to pCO2 acidified seawater generally led to a significant down-regulation in the inducer and key response genes of NF-kappa β signaling and toll-like receptor pathways. The results of the present study revealed that ocean acidification may hamper immune responses of the bivalve T. granosa which subsequently render individuals more susceptible to pathogens attacks such as those from virus and bacteria. Copyright © 2016 Elsevier Ltd. All rights reserved.

Clinical and biochemical characteristics of polycystic ovary syndrome in Korean women.

PubMed

Chae, Soo Jin; Kim, Jin Ju; Choi, Young Min; Hwang, Kyu Ri; Jee, Byung Chul; Ku, Seung Yup; Suh, Chang Suk; Kim, Seok Hyun; Kim, Jung Gu; Moon, Shin Yong

2008-08-01

We investigated the differences in anthropometrical, hormonal and insulin resistance parameters according to the subtype of polycystic ovary syndrome (PCOS) in Korean women. We recruited 166 women with PCOS and retrospectively recruited 277 controls. PCOS was diagnosed by irregular menstruation (IM), polycystic ovary (PCO) and hyperandrogenism (HA). Subjects were divided into four subgroups: the IM/HA/PCO group (n = 87, 52.4%), the IM/PCO group (n = 52, 31.3%), the IM/HA group (n = 23, 13.9%) and the HA/PCO group (n = 4, 2.4%). Clinical and biochemical variables were compared among the PCOS subgroups. The IM/HA/PCO and IM/HA groups showed higher body mass index (P < 0.001) and waist-to-hip ratio (P < 0.001) than the IM/PCO group. The IM/HA group had higher triglyceride levels than the other groups (P < 0.001). Higher fasting insulin (P < 0.001) and postprandial 2 h insulin (P < 0.01) were noted in the IM/HA/PCO group and the IM/HA group, compared with the IM/PCO group. Women with PCOS showed lower sex hormone-binding globulin (P < 0.001) and higher systolic blood pressure (BP) (P = 0.004), diastolic BP (P = 0.001), fasting insulin (P < 0.001), postprandial 2 h insulin (P < 0.001), homeostatic model for insulin resistance (P < 0.001) and clinical and biochemical parameters of metabolic syndrome (P < 0.05) compared with subjects without PCOS. Women with PCOS without HA are common in Korea and are less likely to have metabolic dysfunction, insulin resistance and elevated BP. PCOS without HA may be a mild phenotype of PCOS. Therefore, women with PCOS in Korea could have a reduced likelihood of having metabolic syndrome compared with women of other ethnicities.

Effects of ocean acidification driven by elevated CO2 on larval shell growth and abnormal rates of the venerid clam, Mactra veneriformis

NASA Astrophysics Data System (ADS)

Kim, Jee-Hoon; Yu, Ok Hwan; Yang, Eun Jin; Kang, Sung-Ho; Kim, Won; Choy, Eun Jung

2016-11-01

The venerid clam ( Mactra veneriformis Reeve 1854) is one of the main cultured bivalve species in intertidal and shallow subtidal ecosystems along the west coast of Korea. To understand the effects of ocean acidification on the early life stages of Korean clams, we investigated shell growth and abnormality rates and types in the D-shaped, umbonate veliger, and pediveliger stages of the venerid clam M. veneriformis during exposure to elevated seawater pCO2. In particular, we examined abnormal types of larval shell morphology categorized as shell deformations, shell distortions, and shell fissures. Specimens were incubated in seawater equilibrated with bubbled CO2-enriched air at (400±25)×10-6 (ambient control), (800±25)×10-6 (high pCO2), or (1 200±28)×10-6 (extremely high pCO2), the atmospheric CO2 concentrations predicted for the years 2014, 2084, and 2154 (70-year intervals; two human generations), respectively, in the Representative Concentration Pathway (RCP) 8.5 scenario. The mean shell lengths of larvae were significantly decreased in the high and extremely high pCO2 groups compared with the ambient control groups. Furthermore, under high and extremely high pCO2 conditions, the cultures exhibited significantly increased abundances of abnormal larvae and increased severity of abnormalities compared with the ambient control. In the umbonate veliger stage of the experimental larvae, the most common abnormalities were shell deformations, distortions, and fissures; on the other hand, convex hinges and mantle protuberances were absent. These results suggest that elevated CO2 exerts an additional burden on the health of M. veneriformis larvae by impairing early development.

Simulated leakage of high pCO2 water negatively impacts bivalve dominated infaunal communities from the Western Baltic Sea

NASA Astrophysics Data System (ADS)

Schade, Hanna; Mevenkamp, Lisa; Guilini, Katja; Meyer, Stefanie; Gorb, Stanislav N.; Abele, Doris; Vanreusel, Ann; Melzner, Frank

2016-08-01

Carbon capture and storage is promoted as a mitigation method counteracting the increase of atmospheric CO2 levels. However, at this stage, environmental consequences of potential CO2 leakage from sub-seabed storage sites are still largely unknown. In a 3-month-long mesocosm experiment, this study assessed the impact of elevated pCO2 levels (1,500 to 24,400 μatm) on Cerastoderma edule dominated benthic communities from the Baltic Sea. Mortality of C. edule was significantly increased in the highest treatment (24,400 μatm) and exceeded 50%. Furthermore, mortality of small size classes (0-1 cm) was significantly increased in treatment levels ≥6,600 μatm. First signs of external shell dissolution became visible at ≥1,500 μatm, holes were observed at >6,600 μatm. C. edule body condition decreased significantly at all treatment levels (1,500-24,400 μatm). Dominant meiofauna taxa remained unaffected in abundance. Densities of calcifying meiofauna taxa (i.e. Gastropoda and Ostracoda) decreased in high CO2 treatments (>6,600 μatm), while the non - calcifying Gastrotricha significantly increased in abundance at 24,400 μatm. In addition, microbial community composition was altered at the highest pCO2 level. We conclude that strong CO2 leakage can alter benthic infauna community composition at multiple trophic levels, likely due to high mortality of the dominant macrofauna species C. edule.

Simulated leakage of high pCO2 water negatively impacts bivalve dominated infaunal communities from the Western Baltic Sea.

PubMed

Schade, Hanna; Mevenkamp, Lisa; Guilini, Katja; Meyer, Stefanie; Gorb, Stanislav N; Abele, Doris; Vanreusel, Ann; Melzner, Frank

2016-08-19

Carbon capture and storage is promoted as a mitigation method counteracting the increase of atmospheric CO2 levels. However, at this stage, environmental consequences of potential CO2 leakage from sub-seabed storage sites are still largely unknown. In a 3-month-long mesocosm experiment, this study assessed the impact of elevated pCO2 levels (1,500 to 24,400 μatm) on Cerastoderma edule dominated benthic communities from the Baltic Sea. Mortality of C. edule was significantly increased in the highest treatment (24,400 μatm) and exceeded 50%. Furthermore, mortality of small size classes (0-1 cm) was significantly increased in treatment levels ≥6,600 μatm. First signs of external shell dissolution became visible at ≥1,500 μatm, holes were observed at >6,600 μatm. C. edule body condition decreased significantly at all treatment levels (1,500-24,400 μatm). Dominant meiofauna taxa remained unaffected in abundance. Densities of calcifying meiofauna taxa (i.e. Gastropoda and Ostracoda) decreased in high CO2 treatments (>6,600 μatm), while the non - calcifying Gastrotricha significantly increased in abundance at 24,400 μatm. In addition, microbial community composition was altered at the highest pCO2 level. We conclude that strong CO2 leakage can alter benthic infauna community composition at multiple trophic levels, likely due to high mortality of the dominant macrofauna species C. edule.

Effect of CO2-induced seawater acidification on growth, photosynthesis and inorganic carbon acquisition of the harmful bloom-forming marine microalga, Karenia mikimotoi.

PubMed

Hu, Shunxin; Zhou, Bin; Wang, You; Wang, Ying; Zhang, Xinxin; Zhao, Yan; Zhao, Xinyu; Tang, Xuexi

2017-01-01

Karenia mikimotoi is a widespread, toxic and non-calcifying dinoflagellate, which can release and produce ichthyotoxins and hemolytic toxins affecting the food web within the area of its bloom. Shifts in the physiological characteristics of K. mikimotoi due to CO2-induced seawater acidification could alter the occurrence, severity and impacts of harmful algal blooms (HABs). Here, we investigated the effects of elevated pCO2 on the physiology of K. mikimotoi. Using semi-continuous cultures under controlled laboratory conditions, growth, photosynthesis and inorganic carbon acquisition were determined over 4-6 week incubations at ambient (390ppmv) and elevated pCO2 levels (1000 ppmv and 2000 ppmv). pH-drift and inhibitor-experiments suggested that K. mikimotoi was capable of acquiring HCO3-, and that the utilization of HCO3- was predominantly mediated by anion-exchange proteins, but that HCO3- dehydration catalyzed by external carbonic anhydrase (CAext) only played a minor role in K. mikimotoi. Even though down-regulated CO2 concentrating mechanisms (CCMs) and enhanced gross photosynthetic O2 evolution were observed under 1000 ppmv CO2 conditions, the saved energy did not stimulate growth of K. mikimotoi under 1000 ppmv CO2, probably due to the increased dark respiration. However, significantly higher growth and photosynthesis [in terms of photosynthetic oxygen evolution, effective quantum Yield (Yield), photosynthetic efficiency (α), light saturation point (Ek) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity] were observed under 2000 ppmv CO2 conditions. Furthermore, elevated pCO2 increased the photo-inhibition rate of photosystem II (β) and non-photochemical quenching (NPQ) at high light. We suggest that the energy saved through the down-regulation of CCMs might lead to the additional light stress and photo-damage. Therefore, the response of this species to elevated CO2 conditions will be determined by more than regulation and efficiency of CCMs.

Altered carbon cycling and coupled changes in Early Cretaceous weathering patterns: Evidence from integrated carbon isotope and sandstone records of the western Tethys

NASA Astrophysics Data System (ADS)

Wortmann, Ulrich Georg; Herrle, Jens Olaf; Weissert, Helmut

2004-03-01

In this study we investigate if a major perturbation of the Early Cretaceous carbon cycle was accompanied by altered weathering and erosion rates. The large Aptian carbon isotope anomaly records the response of the biosphere to widespread volcanic activity and probably resulting changes in atmospheric pCO2 levels. Elevated pCO2 levels should also result in an accelerated hydrological cycle and increased silicate weathering, creating a negative feedback loop removing CO2 from the atmosphere. We propose to interpret the widespread occurrence of quartz sandstones in the Tethys-Atlantic seaway as a result of altered weathering and erosion rates in the wake of the Aptian carbon cycle excursion. We challenge the traditional notion that these are 'flysch' deposits associated with Early Cretaceous orogenic movements in the western Tethys. We propose that these sandstones were most likely part of a large conveyor belt system, acting along the Iberian and European margin of the Tethys seaway. Using chemostratigraphic correlations, we show that the activity of this system was only short-lived and coeval with changes in coastal ecology and the Aptian carbon cycle perturbations. We tentatively relate the existence of this system to a transient climate regime, characterized by fluctuating pCO2 levels.

Carbon and oxygen stable isotopes in large herbivore tooth enamel illustrate a mid-Miocene precipitation increase in the interior Pacific Northwest

NASA Astrophysics Data System (ADS)

Drewicz, A.; Kohn, M. J.

2017-12-01

The mid-Miocene Climatic Optimum (MMCO; 13.75-16.9 Ma), represents the warmest period in Earth's history during the last 35 Ma, and is distinguished by low ice volume and high ocean water temperatures. The MMCO has been associated with high atmospheric CO2 (pCO2) similar to levels anticipated in the next century. Thus, understanding MMCO climate may help enlighten predictions of future climate change. Here, using new stable oxygen and carbon isotopes of fossil ungulate tooth enamel from before, during, and after the MMCO, we show that high pCO2 corresponds with warm-wet conditions, whereas low pCO2 corresponds with cool-dry conditions. We specifically show that mean annual precipitation (MAP), as inferred from tooth enamel δ13C values and corrected for atmospheric δ13C values (Δ13C), increased with increasing pCO2. Values of Δ13C > 19.5 ‰ in the lower John Day ( 27 Ma) and Mascall ( 15.3 Ma) localities imply relatively high mean annual precipitation (MAP = 550-850 mm/yr). Values of Δ 13C < 18.5 ‰ at 18 Ma and at four levels between 15 and 3 Ma imply low MAP (≤250 mm/yr), similar to modern climate. High MAP values generally correlate with high pCO2 levels, as inferred from marine records, implicating pCO2 as a principal driver of MAP in the Pacific Northwest. A climate oscillation model best explains our δ 13C data, such that warm-wet conditions during high pCO2 events alternated with cool-dry conditions during low pCO2 events on timescales of 100 kyr. The MMCO may have been more dynamic than originally considered, with wet-warm and cool-dry cycles reflecting Milankovitch cycles. High δ18O values in specimens from the John Day (21.8±0.6 ‰ V-SMOW) and Mascall (21.3±0.5 ‰) Formations may reflect lower elevations for the upwind Cascade Range prior to 7 Ma, or its proximity to the coast compared to more inland sites (δ18O = 17.7±0.9 to 19.6±1.1 ‰). Unusually high δ18O values of Dromomeryx sp. from Red Basin (27.4±0.6 ‰) most likely reflect drought tolerance. Climate models predict that as global atmospheric CO2 levels continue to increase, the Pacific Northwest will become wetter and warmer. Data collected in this study are from time periods geologically close to our own, and corroborate thes

Primary producers may ameliorate impacts of daytime CO2 addition in a coastal marine ecosystem

PubMed Central

Silbiger, Nyssa J.; Bernatchez, Genevieve; Sorte, Cascade J.B.

2018-01-01

Predicting the impacts of ocean acidification in coastal habitats is complicated by bio-physical feedbacks between organisms and carbonate chemistry. Daily changes in pH and other carbonate parameters in coastal ecosystems, associated with processes such as photosynthesis and respiration, often greatly exceed global mean predicted changes over the next century. We assessed the strength of these feedbacks under projected elevated CO2 levels by conducting a field experiment in 10 macrophyte-dominated tide pools on the coast of California, USA. We evaluated changes in carbonate parameters over time and found that under ambient conditions, daytime changes in pH, pCO2, net ecosystem calcification (NEC), and O2 concentrations were strongly related to rates of net community production (NCP). CO2 was added to pools during daytime low tides, which should have reduced pH and enhanced pCO2. However, photosynthesis rapidly reduced pCO2 and increased pH, so effects of CO2 addition were not apparent unless we accounted for seaweed and surfgrass abundances. In the absence of macrophytes, CO2 addition caused pH to decline by ∼0.6 units and pCO2 to increase by ∼487 µatm over 6 hr during the daytime low tide. As macrophyte abundances increased, the impacts of CO2 addition declined because more CO2 was absorbed due to photosynthesis. Effects of CO2addition were, therefore, modified by feedbacks between NCP, pH, pCO2, and NEC. Our results underscore the potential importance of coastal macrophytes in ameliorating impacts of ocean acidification. PMID:29761055

Host-associated coral reef microbes respond to the cumulative pressures of ocean warming and ocean acidification.

PubMed

Webster, N S; Negri, A P; Botté, E S; Laffy, P W; Flores, F; Noonan, S; Schmidt, C; Uthicke, S

2016-01-13

Key calcifying reef taxa are currently threatened by thermal stress associated with elevated sea surface temperatures (SST) and reduced calcification linked to ocean acidification (OA). Here we undertook an 8 week experimental exposure to near-future climate change conditions and explored the microbiome response of the corals Acropora millepora and Seriatopora hystrix, the crustose coralline algae Hydrolithon onkodes, the foraminifera Marginopora vertebralis and Heterostegina depressa and the sea urchin Echinometra sp. Microbial communities of all taxa were tolerant of elevated pCO2/reduced pH, exhibiting stable microbial communities between pH 8.1 (pCO2 479-499 μatm) and pH 7.9 (pCO2 738-835 μatm). In contrast, microbial communities of the CCA and foraminifera were sensitive to elevated seawater temperature, with a significant microbial shift involving loss of specific taxa and appearance of novel microbial groups occurring between 28 and 31 °C. An interactive effect between stressors was also identified, with distinct communities developing under different pCO2 conditions only evident at 31 °C. Microbiome analysis of key calcifying coral reef species under near-future climate conditions highlights the importance of assessing impacts from both increased SST and OA, as combinations of these global stressors can amplify microbial shifts which may have concomitant impacts for coral reef structure and function.

The Effects of Elevated pCO2, Hypoxia and Temperature on Larval Sheepshead minnow, Cyprinodon variegatus: How much stress is too much?

EPA Science Inventory

Estuarine fish are acclimated to living in an environment with rapid and frequent changes in temperature, salinity, pH, and dissolved oxygen (DO) levels; the physiology of these organisms is well suited to cope with extreme thermal, hypercapnic, and hypoxic stress. While the adve...

Marine CDOM accumulation during a coastal Arctic mesocosm experiment: No response to elevated pCO2 levels

NASA Astrophysics Data System (ADS)

Pavlov, Alexey K.; Silyakova, Anna; Granskog, Mats A.; Bellerby, Richard G. J.; Engel, Anja; Schulz, Kai G.; Brussaard, Corina P. D.

2014-06-01

A large-scale multidisciplinary mesocosm experiment in an Arctic fjord (Kongsfjorden, Svalbard; 78°56.2'N) was used to study Arctic marine food webs and biogeochemical elements cycling at natural and elevated future carbon dioxide (CO2) levels. At the start of the experiment, marine-derived chromophoric dissolved organic matter (CDOM) dominated the CDOM pool. Thus, this experiment constituted a convenient case to study production of autochthonous CDOM, which is typically masked by high levels of CDOM of terrestrial origin in the Arctic Ocean proper. CDOM accumulated during the experiment in line with an increase in bacterial abundance; however, no response was observed to increased pCO2 levels. Changes in CDOM absorption spectral slopes indicate that bacteria were most likely responsible for the observed CDOM dynamics. Distinct absorption peaks (at 330 and 360 nm) were likely associated with mycosporine-like amino acids (MAAs). Due to the experimental setup, MAAs were produced in absence of ultraviolet exposure providing evidence for MAAs to be considered as multipurpose metabolites rather than simple photoprotective compounds. We showed that a small increase in CDOM during the experiment made it a major contributor to total absorption in a range of photosynthetically active radiation (PAR, 400-700 nm) and, therefore, is important for spectral light availability and may be important for photosynthesis and phytoplankton groups composition in a rapidly changing Arctic marine ecosystem.

Will Global Change Effect Primary Productivity in Coastal Ecosystems?

NASA Technical Reports Server (NTRS)

Rothschild, Lynn J.; Peterson, David L. (Technical Monitor)

1997-01-01

Algae are the base of coastal food webs because they provide the source of organic carbon for the remaining members of the community. Thus, the rate that they produce organic carbon to a large extent controls the productivity of the entire ecosystem. Factors that control algal productivity range from the physical (e.g., temperature, light), chemical (e.g., nutrient levels) to the biological (e.g., grazing). Currently, levels of atmospheric carbon dioxide surficial fluxes of ultraviolet radiation are rising. Both of these environmental variables can have a profound effect on algal productivity. Atmospheric carbon dioxide may increase surficial levels of dissolved inorganic carbon. Our laboratory and field studies of algal mats and phytoplankton cultures under ambient and elevated levels of pCO2 show that elevated levels of inorganic carbon can cause an increase in photosynthetic rates. In some cases, this increase will cause an increase in phytoplankton numbers. There may be an increase in the excretion of fixed carbon, which in turn may enhance bacterial productivity. Alternatively, in analogy with studies on the effect of elevated pCO2 on plants, the phytoplankton could change their carbon to nitrogen ratios, which will effect the feeding of the planktonic grazers. The seasonal depletion of stratospheric ozone has resulted in elevated fluxes of UVB radiation superimposed on the normal seasonal variation. Present surface UV fluxes have a significant impact on phytoplankton physiology, including the inhibition of the light and dark reactions of photosynthesis, inhibition of nitrogenase activity, inhibition of heterocyst formation, reduction in motility, increased synthesis of the UV-screening pigment scytonemin, and mutation. After reviewing these issues, recent work in our lab on measuring the effect of UV radiation on phytoplankton in the San Francisco Bay Estuary will be presented.

Limits to the Positive Effect of Ocean Acidification on Macroalgal Primary Production, Interactions with Light and Temperature

NASA Astrophysics Data System (ADS)

Kubler, J.; Dudgeon, S. R.; Nisumaa, A. M.

2016-02-01

About one third of macroalgal species lack any carbon concentrating mechanism (CCM), which prevents carbon limitation under air equilibrium in other seaweed species. It is predicted that those species lacking CCM's will benefit from ongoing ocean acidification in terms of primary productivity and growth. The absolute sizes and pattern of those benefits are not known. Here, we compare the results of a model based on composite data from the literature, with a growth experiment using Plocamium cartilagineum, a broadly distributed rhodophyte species lacking a carbon concentrating mechanism and hypothesized to be carbon limited under current conditions. We grew P. cartilagineum, at 15 and 20°C in seawater aerated with a total of 53 different pCO2s (from 344 to 1053µatm), in 8 multiweek trials over 12 months. We measured growth and photosynthetic rates. A linear mixed model analysis was used to partition the effect sizes of drivers of variation in the experiment. The growth rates and maximum photosynthetic rates responded nonlinearly to OA, increasing with elevated pCO2 from recent atmospheric level to up 450µatm and decreasing at higher pCO2. Light harvesting efficiency was unaffected by pCO2 and inversely related to temperature. We were able to compare the results of the growth experiment directly to the model based on the additive effects of temperature and pCO2 on photosynthetic rates, finding concordance of the pattern of response. The size of the effect of pCO2 on growth rate in the experiment was greater than the effect predicted by the model for net primary productivity. These results predict that the benefit of OA for macroalgal growth may disappear as ocean acidification continues through this century.

European sea bass, Dicentrarchus labrax, in a changing ocean

NASA Astrophysics Data System (ADS)

Pope, E. C.; Ellis, R. P.; Scolamacchia, M.; Scolding, J. W. S.; Keay, A.; Chingombe, P.; Shields, R. J.; Wilcox, R.; Speirs, D. C.; Wilson, R. W.; Lewis, C.; Flynn, K. J.

2014-05-01

Ocean acidification, caused by rising concentrations of carbon dioxide (CO2), is widely considered to be a major global threat to marine ecosystems. To investigate the potential effects of ocean acidification on the early life stages of a commercially important fish species, European sea bass (Dicentrarchus labrax), 12 000 larvae were incubated from hatch through metamorphosis under a matrix of two temperatures (17 and 19 °C) and two seawater pCO2 levels (ambient and 1,000 μatm) and sampled regularly for 42 days. Calculated daily mortality was significantly affected by both temperature and pCO2, with both increased temperature and elevated pCO2 associated with lower daily mortality and a significant interaction between these two factors. There was no significant pCO2 effect noted on larval morphology during this period but larvae raised at 19 °C possessed significantly larger eyes and lower carbon:nitrogen ratios at the end of the study compared to those raised under 17 °C. Similarly, when the incubation was continued to post-metamorphic (juvenile) animals (day 67-69), fish raised under a combination of 19 °C and 1000 μatm pCO2 were significantly heavier. However, juvenile D. labrax raised under this combination of 19 °C and 1000 μatm pCO2 also exhibited lower aerobic scopes than those incubated at 19 °C and ambient pCO2. Most studies investigating the effects of near-future oceanic conditions on the early life stages of marine fish have used incubations of relatively short durations and suggested that these animals are resilient to ocean acidification. Whilst the increased survival and growth observed in this study supports this view, we conclude that more work is required to investigate whether the differences in juvenile physiology observed in this study manifest as negative impacts in adult fish.

Proteomic and metabolomic responses of Pacific oyster Crassostrea gigas to elevated pCO2 exposure.

PubMed

Wei, Lei; Wang, Qing; Wu, Huifeng; Ji, Chenglong; Zhao, Jianmin

2015-01-01

The gradually increased atmospheric CO2 partial pressure (pCO2) has thrown the carbonate chemistry off balance and resulted in decreased seawater pH in marine ecosystem, termed ocean acidification (OA). Anthropogenic OA is postulated to affect the physiology of many marine calcifying organisms. However, the susceptibility and metabolic pathways of change in most calcifying animals are still far from being well understood. In this work, the effects of exposure to elevated pCO2 were characterized in gills and hepatopancreas of Crassostrea gigas using integrated proteomic and metabolomic approaches. Metabolic responses indicated that high CO2 exposure mainly caused disturbances in energy metabolism and osmotic regulation marked by differentially altered ATP, glucose, glycogen, amino acids and organic osmolytes in oysters, and the depletions of ATP in gills and the accumulations of ATP, glucose and glycogen in hepatopancreas accounted for the difference in energy distribution between these two tissues. Proteomic responses suggested that OA could not only affect energy and primary metabolisms, stress responses and calcium homeostasis in both tissues, but also influence the nucleotide metabolism in gills and cytoskeleton structure in hepatopancreas. This study demonstrated that the combination of proteomics and metabolomics could provide an insightful view into the effects of OA on oyster C. gigas. The gradually increased atmospheric CO2 partial pressure (pCO2) has thrown the carbonate chemistry off balance and resulted in decreased seawater pH in marine ecosystem, termed ocean acidification (OA). Anthropogenic OA is postulated to affect the physiology of many marine calcifying organisms. However, the susceptibility and metabolic pathways of change in most calcifying animals are still far from being understood. To our knowledge, few studies have focused on the responses induced by pCO2 at both protein and metabolite levels. The pacific oyster C. gigas, widely distributed throughout most of the world's oceans, is a model organism for marine environmental science. In the present study, an integrated metabolomic and proteomic approach was used to elucidate the effects of ocean acidification on Pacific oyster C. gigas, hopefully shedding light on the physiological responses of marine mollusk to the OA stress. Copyright © 2014 Elsevier B.V. All rights reserved.

Painted Goby Larvae under High-CO2 Fail to Recognize Reef Sounds.

PubMed

Castro, Joana M; Amorim, M Clara P; Oliveira, Ana P; Gonçalves, Emanuel J; Munday, Philip L; Simpson, Stephen D; Faria, Ana M

2017-01-01

Atmospheric CO2 levels have been increasing at an unprecedented rate due to anthropogenic activity. Consequently, ocean pCO2 is increasing and pH decreasing, affecting marine life, including fish. For many coastal marine fishes, selection of the adult habitat occurs at the end of the pelagic larval phase. Fish larvae use a range of sensory cues, including sound, for locating settlement habitat. This study tested the effect of elevated CO2 on the ability of settlement-stage temperate fish to use auditory cues from adult coastal reef habitats. Wild late larval stages of painted goby (Pomatoschistus pictus) were exposed to control pCO2 (532 μatm, pH 8.06) and high pCO2 (1503 μatm, pH 7.66) conditions, likely to occur in nearshore regions subjected to upwelling events by the end of the century, and tested in an auditory choice chamber for their preference or avoidance to nighttime reef recordings. Fish reared in control pCO2 conditions discriminated reef soundscapes and were attracted by reef recordings. This behaviour changed in fish reared in the high CO2 conditions, with settlement-stage larvae strongly avoiding reef recordings. This study provides evidence that ocean acidification might affect the auditory responses of larval stages of temperate reef fish species, with potentially significant impacts on their survival.

Painted Goby Larvae under High-CO2 Fail to Recognize Reef Sounds

PubMed Central

Castro, Joana M.; Amorim, M. Clara P.; Oliveira, Ana P.; Gonçalves, Emanuel J.; Munday, Philip L.; Simpson, Stephen D.

2017-01-01

Atmospheric CO2 levels have been increasing at an unprecedented rate due to anthropogenic activity. Consequently, ocean pCO2 is increasing and pH decreasing, affecting marine life, including fish. For many coastal marine fishes, selection of the adult habitat occurs at the end of the pelagic larval phase. Fish larvae use a range of sensory cues, including sound, for locating settlement habitat. This study tested the effect of elevated CO2 on the ability of settlement-stage temperate fish to use auditory cues from adult coastal reef habitats. Wild late larval stages of painted goby (Pomatoschistus pictus) were exposed to control pCO2 (532 μatm, pH 8.06) and high pCO2 (1503 μatm, pH 7.66) conditions, likely to occur in nearshore regions subjected to upwelling events by the end of the century, and tested in an auditory choice chamber for their preference or avoidance to nighttime reef recordings. Fish reared in control pCO2 conditions discriminated reef soundscapes and were attracted by reef recordings. This behaviour changed in fish reared in the high CO2 conditions, with settlement-stage larvae strongly avoiding reef recordings. This study provides evidence that ocean acidification might affect the auditory responses of larval stages of temperate reef fish species, with potentially significant impacts on their survival. PMID:28125690

Developmental Effects of Ocean Acidification Conditions and Elevated Temperature on Homarus Americanus Larvae

NASA Astrophysics Data System (ADS)

Mcveigh, H.; Waller, J. D.

2016-02-01

The Gulf of Maine is experiencing a rapid warming in sea surface temperature and a marked decrease in pH. This study aimed to quantify the impact of elevated temperature and acidification on the larval development of the iconic American lobster (Homarus americanus). Experimental conditions were reflective of current and IPCC predicted levels of temperature and pCO2 to be reached by the end of the century. Larvae were measured for growth (carapace length), development time, and survivorship over the larval duration. Treatments of elevated temperatures experienced decreased development time across the larval stages of H. americanus. Consequently mortality increased at a significantly higher rate under elevated temperature. An increase in larval mortality may decrease recruitment to the commercial fishery, thus impacting the most valuable single species in the state of Maine. Furthermore, experimental pCO2 treatments yielded a significantly decreased development time between larval stages II and III, yet did not have a significant impact on carapace length or mortality. This study indicates that warmer temperatures may have a greater influence than decreased pH on larval development and survival. Determining how this species may respond to changing climactic conditions will better inform the sustainability efforts of such a critical marine fishery.

DOE Office of Scientific and Technical Information (OSTI.GOV)

John, David E.; Wang, Zhaohui A.; Liu, Xuewu

River plumes deliver large quantities of nutrients to oligotrophic oceans, often resulting in significant CO 2 drawdown. To determine the relationship between expression of the major gene in carbon fixation (large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase, RuBisCO) and CO 2 dynamics, we evaluated rbcL mRNA abundance using novel quantitative PCR assays, phytoplankton cell analyses, photophysiological parameters, and pCO 2 in and around the Mississippi River plume (MRP) in the Gulf of Mexico. Lower salinity (30–32) stations were dominated by rbcL mRNA concentrations from heterokonts, such as diatoms and pelagophytes, which were at least an order of magnitude greater than haptophytes, alpha-Synechococcusmore » or high-light Prochlorococcus. However, rbcL transcript abundances were similar among these groups at oligotrophic stations (salinity 34–36). Diatom cell counts and heterokont rbcL RNA showed a strong negative correlation to seawater pCO 2. While Prochlorococcus cells did not exhibit a large difference between low and high pCO 2 water, Prochlorococcus rbcL RNA concentrations had a strong positive correlation to pCO 2, suggesting a very low level of RuBisCO RNA transcription among Prochlorococcus in the plume waters, possibly due to their relatively poor carbon concentrating mechanisms (CCMs). These results provide molecular evidence that diatom/pelagophyte productivity is largely responsible for the large CO 2 drawdown occurring in the MRP, based on the co-occurrence of elevated RuBisCO gene transcript concentrations from this group and reduced seawater pCO 2 levels. This may partly be due to efficient CCMs that enable heterokont eukaryotes such as diatoms to continue fixing CO 2 in the face of strong CO 2 drawdown. Finally, our work represents the first attempt to relate in situ microbial gene expression to contemporaneous CO 2 flux measurements in the ocean.« less

Tolerance of allogromiid Foraminifera to severely elevated carbon dioxide concentrations: Implications to future ecosystem functioning and paleoceanographic interpretations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernhard, Joan M.; Mollo-Christensen, Elizabeth; Eisenkolb, Nadine

2009-02-01

Increases in the partial pressure of carbon dioxide (pCO2) in the atmosphere will significantly affect a wide variety of terrestrial fauna and flora. Because of tight atmospheric oceanic coupling, shallow-water marine species are also expected to be affected by increases in atmospheric carbon dioxide concentrations. One proposed way to slow increases in atmospheric pCO2 is to sequester CO2 in the deep sea. Thus, over the next few centuries marine species will be exposed to changing seawater chemistry caused by ocean atmospheric exchange and/or deep-ocean sequestration. This initial case study on one allogromiid foraminiferal species (Allogromia laticollaris) was conducted to beginmore » to ascertain the effect of elevated pCO2 on benthic Foraminifera, which are a major meiofaunal constituent of shallow- and deep-water marine communities. Cultures of this thecate foraminiferan protist were used for 10-14-day experiments. Experimental treatments were executed in an incubator that controlled CO2 (15000; 30 000; 60 000; 90 000; 200 000 ppm), temperature and humidity; atmospheric controls (i.e., ~375 ppm CO2) were executed simultaneously. Although the experimental elevated pCO2 values are far above foreseeable surface water pCO2, they were selected to represent the spectrum of conditions expected for the benthos if deep-sea CO2 sequestration becomes a reality. Survival was assessed in two independent ways: pseudopodial presence/absence and measurement of adenosine triphosphate (ATP), which is an indicator of cellular energy. Substantial proportions of A. laticollaris populations survived 200 000 ppm CO2 although the mean of the median [ATP] of survivors was statistically lower for this treatment than for that of atmospheric control specimens. After individuals that had been incubated in 200 000 ppm CO2 for 12 days were transferred to atmospheric conditions for ~24 h, the [ATP] of live specimens (survivors) approximated those of the comparable atmospheric control treatment. Incubation in 200 000 ppm CO2 also resulted in reproduction by some individuals. Results suggest that certain Foraminifera are able to tolerate deep-sea CO2 sequestration and perhaps thrive as a result of elevated pCO2 that is predicted for the next few centuries, in a high-pCO2 world. Thus, allogromiid foraminiferal blooms may result from climate change. Furthermore, because allogromiids consume a variety of prey, it is likely that they will be major players in ecosystem dynamics of future coastal sedimentary environments.« less

Tolerance of allogromiid Foraminifera to severely elevated carbon dioxide concentrations: Implications to future ecosystem functioning and paleoceanographic interpretations

NASA Astrophysics Data System (ADS)

Bernhard, Joan M.; Mollo-Christensen, Elizabeth; Eisenkolb, Nadine; Starczak, Victoria R.

2009-02-01

Increases in the partial pressure of carbon dioxide (pCO 2) in the atmosphere will significantly affect a wide variety of terrestrial fauna and flora. Because of tight atmospheric-oceanic coupling, shallow-water marine species are also expected to be affected by increases in atmospheric carbon dioxide concentrations. One proposed way to slow increases in atmospheric pCO 2 is to sequester CO 2 in the deep sea. Thus, over the next few centuries marine species will be exposed to changing seawater chemistry caused by ocean-atmospheric exchange and/or deep-ocean sequestration. This initial case study on one allogromiid foraminiferal species ( Allogromia laticollaris) was conducted to begin to ascertain the effect of elevated pCO 2 on benthic Foraminifera, which are a major meiofaunal constituent of shallow- and deep-water marine communities. Cultures of this thecate foraminiferan protist were used for 10-14-day experiments. Experimental treatments were executed in an incubator that controlled CO 2 (15 000; 30 000; 60 000; 90 000; 200 000 ppm), temperature and humidity; atmospheric controls (i.e., ~ 375 ppm CO 2) were executed simultaneously. Although the experimental elevated pCO 2 values are far above foreseeable surface water pCO 2, they were selected to represent the spectrum of conditions expected for the benthos if deep-sea CO 2 sequestration becomes a reality. Survival was assessed in two independent ways: pseudopodial presence/absence and measurement of adenosine triphosphate (ATP), which is an indicator of cellular energy. Substantial proportions of A. laticollaris populations survived 200 000 ppm CO 2 although the mean of the median [ATP] of survivors was statistically lower for this treatment than for that of atmospheric control specimens. After individuals that had been incubated in 200 000 ppm CO 2 for 12 days were transferred to atmospheric conditions for ~ 24 h, the [ATP] of live specimens (survivors) approximated those of the comparable atmospheric control treatment. Incubation in 200 000 ppm CO 2 also resulted in reproduction by some individuals. Results suggest that certain Foraminifera are able to tolerate deep-sea CO 2 sequestration and perhaps thrive as a result of elevated pCO 2 that is predicted for the next few centuries, in a high-pCO 2 world. Thus, allogromiid foraminiferal "blooms" may result from climate change. Furthermore, because allogromiids consume a variety of prey, it is likely that they will be major players in ecosystem dynamics of future coastal sedimentary environments.

Framework of barrier reefs threatened by ocean acidification.

PubMed

Comeau, Steeve; Lantz, Coulson A; Edmunds, Peter J; Carpenter, Robert C

2016-03-01

To date, studies of ocean acidification (OA) on coral reefs have focused on organisms rather than communities, and the few community effects that have been addressed have focused on shallow back reef habitats. The effects of OA on outer barrier reefs, which are the most striking of coral reef habitats and are functionally and physically different from back reefs, are unknown. Using 5-m long outdoor flumes to create treatment conditions, we constructed coral reef communities comprised of calcified algae, corals, and reef pavement that were assembled to match the community structure at 17 m depth on the outer barrier reef of Moorea, French Polynesia. Communities were maintained under ambient and 1200 μatm pCO2 for 7 weeks, and net calcification rates were measured at different flow speeds. Community net calcification was significantly affected by OA, especially at night when net calcification was depressed ~78% compared to ambient pCO2 . Flow speed (2-14 cm s(-1) ) enhanced net calcification only at night under elevated pCO2 . Reef pavement also was affected by OA, with dissolution ~86% higher under elevated pCO2 compared to ambient pCO2 . These results suggest that net accretion of outer barrier reef communities will decline under OA conditions predicted within the next 100 years, largely because of increased dissolution of reef pavement. Such extensive dissolution poses a threat to the carbonate foundation of barrier reef communities. © 2015 John Wiley & Sons Ltd.

Spatio-temporal environmental variation mediates geographical differences in phenotypic responses to ocean acidification

PubMed Central

Villanueva, Paola A.; Lopez, Jorge; Torres, Rodrigo; Navarro, Jorge M.; Bacigalupe, Leonardo D.

2017-01-01

Phenotypic plasticity is expected to play a major adaptive role in the response of species to ocean acidification (OA), by providing broader tolerances to changes in pCO2 conditions. However, tolerances and sensitivities to future OA may differ among populations within a species because of their particular environmental context and genetic backgrounds. Here, using the climatic variability hypothesis (CVH), we explored this conceptual framework in populations of the sea urchin Loxechinus albus across natural fluctuating pCO2/pH environments. Although elevated pCO2 affected the morphology, physiology, development and survival of sea urchin larvae, the magnitude of these effects differed among populations. These differences were consistent with the predictions of the CVH showing greater tolerance to OA in populations experiencing greater local variation in seawater pCO2/pH. Considering geographical differences in plasticity, tolerances and sensitivities to increased pCO2 will provide more accurate predictions for species responses to future OA. PMID:28179409

Effect of temperature rise and ocean acidification on growth of calcifying tubeworm shells (Spirorbis spirorbis): an in situ benthocosm approach

NASA Astrophysics Data System (ADS)

Ni, Sha; Taubner, Isabelle; Böhm, Florian; Winde, Vera; Böttcher, Michael E.

2018-03-01

The calcareous tubeworm Spirorbis spirorbis is a widespread serpulid species in the Baltic Sea, where it commonly grows as an epibiont on brown macroalgae (genus Fucus). It lives within a Mg-calcite shell and could be affected by ocean acidification and temperature rise induced by the predicted future atmospheric CO2 increase. However, Spirorbis tubes grow in a chemically modified boundary layer around the algae, which may mitigate acidification. In order to investigate how increasing temperature and rising pCO2 may influence S. spirorbis shell growth we carried out four seasonal experiments in the Kiel Outdoor Benthocosms at elevated pCO2 and temperature conditions. Compared to laboratory batch culture experiments the benthocosm approach provides a better representation of natural conditions for physical and biological ecosystem parameters, including seasonal variations. We find that growth rates of S. spirorbis are significantly controlled by ontogenetic and seasonal effects. The length of the newly grown tube is inversely related to the initial diameter of the shell. Our study showed no significant difference of the growth rates between ambient atmospheric and elevated (1100 ppm) pCO2 conditions. No influence of daily average CaCO3 saturation state on the growth rates of S. spirorbis was observed. We found, however, net growth of the shells even in temporarily undersaturated bulk solutions, under conditions that concurrently favoured selective shell surface dissolution. The results suggest an overall resistance of S. spirorbis growth to acidification levels predicted for the year 2100 in the Baltic Sea. In contrast, S. spirorbis did not survive at mean seasonal temperatures exceeding 24 °C during the summer experiments. In the autumn experiments at ambient pCO2, the growth rates of juvenile S. spirorbis were higher under elevated temperature conditions. The results reveal that S. spirorbis may prefer moderately warmer conditions during their early life stages but will suffer from an excessive temperature increase and from increasing shell corrosion as a consequence of progressing ocean acidification.

Physiological basis for high CO2 tolerance in marine ectothermic animals: pre-adaptation through lifestyle and ontogeny?

NASA Astrophysics Data System (ADS)

Melzner, F.; Gutowska, M. A.; Langenbuch, M.; Dupont, S.; Lucassen, M.; Thorndyke, M. C.; Bleich, M.; Pörtner, H.-O.

2009-10-01

Future ocean acidification has the potential to adversely affect many marine organisms. A growing body of evidence suggests that many species could suffer from reduced fertilization success, decreases in larval- and adult growth rates, reduced calcification rates, and even mortality when being exposed to near-future levels (year 2100 scenarios) of ocean acidification. Little research focus is currently placed on those organisms/taxa that might be less vulnerable to the anticipated changes in ocean chemistry; this is unfortunate, as the comparison of more vulnerable to more tolerant physiotypes could provide us with those physiological traits that are crucial for ecological success in a future ocean. Here, we attempt to summarize some ontogenetic and lifestyle traits that lead to an increased tolerance towards high environmental pCO2. In general, marine ectothermic metazoans with an extensive extracellular fluid volume may be less vulnerable to future acidification as their cells are already exposed to much higher pCO2 values (0.1 to 0.4 kPa, ca. 1000 to 3900 μatm) than those of unicellular organisms and gametes, for which the ocean (0.04 kPa, ca. 400 μatm) is the extracellular space. A doubling in environmental pCO2 therefore only represents a 10% change in extracellular pCO2 in some marine teleosts. High extracellular pCO2 values are to some degree related to high metabolic rates, as diffusion gradients need to be high in order to excrete an amount of CO2 that is directly proportional to the amount of O2 consumed. In active metazoans, such as teleost fish, cephalopods and many brachyuran crustaceans, exercise induced increases in metabolic rate require an efficient ion-regulatory machinery for CO2 excretion and acid-base regulation, especially when anaerobic metabolism is involved and metabolic protons leak into the extracellular space. These ion-transport systems, which are located in highly developed gill epithelia, form the basis for efficient compensation of pH disturbances during exposure to elevated environmental pCO2. Compensation of extracellular acid-base status in turn may be important in avoiding metabolic depression. So far, maintained "performance" at higher seawater pCO2 (>0.3 to 0.6 kPa) has only been observed in adults/juveniles of active, high metabolic species with a powerful ion regulatory apparatus. However, while some of these taxa are adapted to cope with elevated pCO2 during their regular embryonic development, gametes, zygotes and early embryonic stages, which lack specialized ion-regulatory epithelia, may be the true bottleneck for ecological success - even of the more tolerant taxa. Our current understanding of which marine animal taxa will be affected adversely in their physiological and ecological fitness by projected scenarios of anthropogenic ocean acidification is quite incomplete. While a growing amount of empirical evidence from CO2 perturbation experiments suggests that several taxa might react quite sensitively to ocean acidification, others seem to be surprisingly tolerant. However, there is little mechanistic understanding on what physiological traits are responsible for the observed differential sensitivities (see reviews of Seibel and Walsh, 2003; Pörtner et al., 2004; Fabry et al., 2008; Pörtner, 2008). This leads us to the first very basic question of how to define general CO2 tolerance on the species level.

Physiological basis for high CO2 tolerance in marine ectothermic animals: pre-adaptation through lifestyle and ontogeny?

NASA Astrophysics Data System (ADS)

Melzner, F.; Gutowska, M. A.; Langenbuch, M.; Dupont, S.; Lucassen, M.; Thorndyke, M. C.; Bleich, M.; Pörtner, H.-O.

2009-05-01

Future ocean acidification has the potential to adversely affect many marine organisms. A growing body of evidence suggests that many species could suffer from reduced fertilization success, decreases in larval- and adult growth rates, reduced calcification rates, metabolic depression and even mortality when being exposed to near-future levels (year 2100 scenarios) of ocean acidification. Little research focus is currently placed on those organisms/taxa that might be less vulnerable to the anticipated changes in ocean chemistry; this is unfortunate, as the comparison of more vulnerable to more tolerant physiotypes could provide us with those physiological traits that are crucial for ecological success in a future ocean. Here, we attempt to summarize some ontogenetic and lifestyle traits that lead to an increased tolerance towards high environmental pCO2. In general, marine ectothermic metazoans with an extensive extracellular fluid volume may be less vulnerable to future acidification as their cells are already exposed to much higher pCO2 values (0.1 to 0.4 kPa, 1000 to 4000 μatm) than those of unicellular organisms and gametes, for which the ocean (0.04 kPa, 400 μatm) is the extracellular space. A doubling in environmental pCO2 therefore only represents a 10% change in extracellular CO2 in some marine teleosts. High extracellular pCO2 values are to some degree related to high metabolic rates, as diffusion gradients need to be high in order to excrete an amount of CO2 that is directly proportional to the amount of O2 consumed. In active metazoans, such as teleost fish, cephalopods and many brachyuran crustaceans, exercise induced increases in metabolic rate require an efficient ion-regulatory machinery for CO2 excretion and acid-base regulation, especially when anaerobic metabolism is involved and metabolic protons leak into the extracellular space. These ion-transport systems, which are located in highly developed gill epithelia, form the basis for efficient compensation of pH disturbances during exposure to elevated environmental pCO2. Compensation of extracellular acid-base status in turn may be extremely important in avoiding metabolic depression. So far, maintained "performance" at higher seawater pCO2 (>0.3 to 0.6 kPa) has only been observed in adults/juveniles of active, high metabolic species with a powerful ion regulatory apparatus. However, while some of these taxa are adapted to cope with elevated pCO2 during their regular embryonic development, unicellular gametes, which lack specialized ion-regulatory epithelia, may be the true bottleneck for ecological success - even of the more tolerant taxa.

Short- versus long-term responses to changing CO2 in a coastal dinoflagellate bloom: implications for interspecific competitive interactions and community structure.

PubMed

Tatters, Avery O; Schnetzer, Astrid; Fu, Feixue; Lie, Alle Y A; Caron, David A; Hutchins, David A

2013-07-01

Increasing pCO2 (partial pressure of CO2 ) in an "acidified" ocean will affect phytoplankton community structure, but manipulation experiments with assemblages briefly acclimated to simulated future conditions may not accurately predict the long-term evolutionary shifts that could affect inter-specific competitive success. We assessed community structure changes in a natural mixed dinoflagellate bloom incubated at three pCO2 levels (230, 433, and 765 ppm) in a short-term experiment (2 weeks). The four dominant species were then isolated from each treatment into clonal cultures, and maintained at all three pCO2 levels for approximately 1 year. Periodically (4, 8, and 12 months), these pCO2 -conditioned clones were recombined into artificial communities, and allowed to compete at their conditioning pCO2 level or at higher and lower levels. The dominant species in these artificial communities of CO2 -conditioned clones differed from those in the original short-term experiment, but individual species relative abundance trends across pCO2 treatments were often similar. Specific growth rates showed no strong evidence for fitness increases attributable to conditioning pCO2 level. Although pCO2 significantly structured our experimental communities, conditioning time and biotic interactions like mixotrophy also had major roles in determining competitive outcomes. New methods of carrying out extended mixed species experiments are needed to accurately predict future long-term phytoplankton community responses to changing pCO2 . © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

The Fossil Atmospheres Project: A novel approach for simultaneously refining the Ginkgo paleo-pCO2 barometer & educating citizens about climate change

NASA Astrophysics Data System (ADS)

Barclay, R. S.; Soul, L.; Bolton, A.; Wilson, J. P.; Megonigal, P.; Wing, S. L.

2017-12-01

During the Late Cretaceous and Paleogene, the Earth's climate was much warmer than today, often punctuated by rapid hyperthermal events. The background warmth and hyperthermals are often attributed to increased atmospheric carbon dioxide (pCO2), yet paleo-pCO2 proxy estimates for this interval often disagree widely, and there are few paired records of temperature and pCO2. Consequently, we have an inadequate understanding of what generated past warm climates, and of the magnitude of pCO2 change associated with hyperthermals. We aim to develop a more reliable stomatal proxy for paleo-pCO2 by quantifying the effect of pCO2 and other environmental variables on stomatal properties of living Ginkgo biloba trees. Herbarium collections of G. biloba demonstrate that the stomatal index proxy for paleo-pCO2 is strongly correlated with pCO2 over the range of 290-400 ppm. However, despite wide application of the Ginkgo paleo-pCO2 barometer, our understanding of pCO2 in the fossil record has been hindered because the morphological and physiological changes in Ginkgo biloba stomata under pCO2 above 400 ppm have been poorly constrained. To address this problem, we are conducting an elevated CO2 experiment that will quantify the response of Ginkgo to elevated pCO2, an experiment we call 'Fossil Atmospheres'. We are growing 15 Ginkgo biloba trees in open-topped chambers in natural field conditions, under atmospheres with ambient (400), 600, 800, and 1,000 ppm of CO2. Each tree is regularly monitored for changes in stomatal frequency, and rates of photosynthesis and transpiration to constrain parameters used in gas exchange models of paleo-pCO2. We have also involved citizen scientists in the process of collecting stomatal index measurements with the Zooniverse platform, utilizing the interaction to educate citizens about modern climate change from the less-menacing viewpoint of deep-time climate change events. Our results can then be used to infer paleo-pCO2 from stomatal features of Late Cretaceous-Paleogene fossils of the nearly identical species, Ginkgo wyomingensis, allowing for paleo-pCO2 estimates from these terrestrial fossils to be compared with temperature and paleo-pCO2 records derived from the marine realm.

The effects of elevated temperature and ocean acidification on the metabolic pathways of notothenioid fish

PubMed Central

Enzor, Laura A.; Hunter, Evan M.

2017-01-01

Abstract The adaptations used by notothenioid fish to combat extreme cold may have left these fish poorly poised to deal with a changing environment. As such, the expected environmental perturbations brought on by global climate change have the potential to significantly affect the energetic demands and subsequent cellular processes necessary for survival. Despite recent lines of evidence demonstrating that notothenioid fish retain the ability to acclimate to elevated temperatures, the underlying mechanisms responsible for temperature acclimation in these fish remain largely unknown. Furthermore, little information exists on the capacity of Antarctic fish to respond to changes in multiple environmental variables. We have examined the effects of increased temperature and pCO2 on the rate of oxygen consumption in three notothenioid species, Trematomus bernacchii, Pagothenia borchgrevinki, and Trematomus newnesi. We combined these measurements with analysis of changes in aerobic and anaerobic capacity, lipid reserves, fish condition, and growth rates to gain insight into the metabolic cost associated with acclimation to this dual stress. Our findings indicated that temperature is the major driver of the metabolic responses observed in these fish and that increased pCO2 plays a small, contributing role to the energetic costs of the acclimation response. All three species displayed varying levels of energetic compensation in response to the combination of elevated temperature and pCO2. While P. borchgrevinki showed nearly complete compensation of whole animal oxygen consumption rates and aerobic capacity, T. newnesi and T. bernacchii displayed only partial compensation in these metrics, suggesting that at least some notothenioids may require physiological trade-offs to fully offset the energetic costs of long-term acclimation to climate change related stressors. PMID:28852515

High resolution pCO2 monitoring reveals ventilation of Bunker Cave (NW Germany) and its impact on speleothem growth

NASA Astrophysics Data System (ADS)

Riechelmann, Sylvia; Breitenbach, Sebastian F. M.; Schröder-Ritzrau, Andrea; Immenhauser, Adrian

2017-04-01

Understanding the environmental processes that influence geochemical proxies archived in speleothems depends critically on detailed cave monitoring. Cave air pCO2 is one of the most important factors controlling speleothem growth. The pCO2 concentration of cave air depends on (i) the productivity of its source(s), (ii) CO2-transport dynamics through the epikarst and (iii) cave ventilation processes. We monitored the pCO2 concentration ca. 100 m from the lower entrance of the Bunker-Emst-Cave system (NW Germany) with a CORA CO2-logger at a two-hourly resolution between April 2012 and February 2014. Near-atmospheric minimum pCO2 concentrations of 408 ppm are observed in winter, while higher values up to 811 ppm are recorded in summer. Higher summer concentrations are due to increased plant and soil microbial activity, resulting in elevated CO2 in the soil, which is transferred to the cave with infiltrating water. Generally, the front passages of Bunker Cave are well ventilated. Besides the seasonal pattern, pCO2 concentrations vary at diurnal scale. Correlations of pCO2 with the temperature difference between surface and cave air are positive during summer and negative in winter, with no clear pattern for spring and autumn months. Thus, Bunker Cave ventilation is driven by temperature and density differences between cave and surface air, with two entrances at different elevations allowing dynamic ventilation. During summer, relatively cooler cave air flows from the upper to the lower entrance, while in winter this pattern is reversed due to ascending warm cave air. The situation is further complicated by preferential south/southwestern winds that point directly on the cave entrances. Thus, cave ventilation is frequently disturbed, especially during periods of higher wind speed. Modern ventilation systematics only developed when the two cave entrances were artificially opened (1863 and 1926). Before that, ventilation was restricted and cave pCO2 concentrations were presumably higher under natural conditions. Thus, the present-day ventilation system of Bunker Cave is not a direct analogue for natural ventilation conditions. pCO2 concentrations are relatively low compared to other caves, and because the difference between summer and winter pCO2 is relatively low (max. 400 ppm), a significant effect on seasonal speleothem growth rate is unlikely. In case of Bunker Cave, it is rather a combination of the availability of water, and thus of calcium and carbonate ions and pCO2 concentrations that allow higher carbonate precipitation during winter than summer. Holocene speleothems from Bunker Cave display relatively slow growth rates. We suggest that - with absence of major entrances to the cave system during the Holocene - ventilation was minimal and pCO2 concentrations significantly higher, making winterly water supply the governing factor regulating speleothem growth. Thus, stalagmites from Bunker Cave are likely to record a climatic signal biased towards the winter season.

High-resolution Atmospheric pCO2 Reconstruction across the Paleogene Using Marine and Terrestrial δ13C records

NASA Astrophysics Data System (ADS)

Cui, Y.; Schubert, B.

2016-02-01

The early Paleogene (63 to 47 Ma) is considered to have a greenhouse climate1 with proxies suggesting atmospheric CO2 levels (pCO2) approximately 2× pre-industrial levels. However, the proxy based pCO2 reconstructions are limited and do not allow for assessment of changes in pCO2 at million to sub-million year time scales. It has recently been recognized that changes in C3 land plant carbon isotope fractionation can be used as a proxy for pCO2 with quantifiable uncertainty2. Here, we present a high-resolution pCO2 reconstruction (n = 597) across the early Paleogene using published carbon isotope data from both terrestrial organic matter and marine carbonates. The minimum and maximum pCO2 values reconstructed using this method are broad (i.e., 170 +60/-40 ppmv to 2000 +4480/-1060 ppmv) and reflective of the wide range of environments sampled. However, the large number of measurements allows for a robust estimate of average pCO2 during this time interval ( 400 +260/-120 ppmv), and indicates brief (sub-million-year) excursions to very high pCO2 during hyperthermal events (e.g., the PETM). By binning our high-resolution pCO2 data at 1 million year intervals, we can compare our dataset to the other available pCO2 proxies. Our result is broadly consistent with pCO2 levels reconstructed using other proxies, with the exception of paleosol-based pCO2 estimates spanning 53 to 50 Ma. At this timescale, no proxy suggests pCO2 higher than 2000 ppmv, whereas the global surface ocean temperature is considered to be >10 oC warmer than today. Recent climate modeling suggests that low atmospheric pressure during this time period could help reconcile the apparent disconnect between pCO2 and temperature and contribute to the greenhouse climate3. References1. Huber, M., Caballero, R., 2011. Climate of the Past 7, 603-633. 2. Schubert, B.A., Jahren, A.H., 2015. Geology 43, 435-438. 3. Poulsen, C.J., Tabor, C., White, J.D., 2015. Science 348, 1238-1241.

Constraining Hesperian martian PCO2 from mineral analysis at Gale crater

NASA Astrophysics Data System (ADS)

Bristow, T.; Haberle, R. M.; Blake, D. F.; Vaniman, D. T.; Grotzinger, J. P.; Siebach, K. L.; Des Marais, D. J.; Rampe, E. B.; Eigenbrode, J. L.; Sutter, B.; Fairén, A. G.; Mischna, M.; Vasavada, A. R.

2016-12-01

Carbon dioxide is an essential atmospheric component in martian climate models that attempt to reconcile a faint young sun with widespread evidence of liquid water at the planet's surface in the Noachian and Early Hesperian. Current estimates of ancient martian CO2 levels, derived from global inventories of carbon, and orbital detections of Noachian and Early Hesperian clay mineral-bearing terrains indicate CO2 levels that are unable to support warm and wet conditions. These estimates are subject to various sources of uncertainty however. Mineral and contextual sedimentary environmental data collected by the Mars Science Laboratory rover Curiosity in Gale Crater provide a more direct means of estimating the atmospheric partial pressure of CO2 (PCO2) coinciding with a long-lived lake system in Gale crater at 3.5 Ga. Results from a reaction-transport model, which simulates mineralogy observed within the Sheepbed member at Yellowknife Bay by coupling mineral equilibria with carbonate precipitation kinetics and rates of sedimentation, indicate atmospheric levels in the 10's mbar range. At such low PCO2 levels, climate models are unable to warm Hesperian Mars anywhere near the freezing point of water and other gases are required to raise atmospheric pressure to prevent lakes from boiling away. Thus, lacustrine features of Gale formed in a cold environment by a mechanism yet to be determined, or the climate models lack an essential component that would serve to elevate surface temperatures, at least temporally and/or locally, on Hesperian Mars. Our results also impose restrictions on the potential role of atmospheric CO2 in inferred warmer conditions of the Noachian.

Accelerated skeletal muscle recovery after in vivo polyphenol administration.

PubMed

Myburgh, Kathryn H; Kruger, Maria J; Smith, Carine

2012-09-01

Acute skeletal muscle damage results in fiber disruption, oxidative stress and inflammation. We investigated cell-specific contributions to the regeneration process after contusion-induced damage (rat gastrocnemius muscle) with or without chronic grape seed-derived proanthocyanidolic oligomer (PCO) administration. In this placebo-controlled study, male Wistar rats were subjected to PCO administration for 2 weeks, after which they were subjected to a standardised contusion injury. Supplementation was continued after injury. Immune and satellite cell responses were assessed, as well as oxygen radical absorption capacity and muscle regeneration. PCO administration resulted in a rapid satellite cell response with an earlier peak in activation (Pax7⁺, CD56⁺, at 4 h post-contusion) vs. placebo groups (PLA) (P<.001: CD56⁺ on Day 5 and Pax7⁺ on Day 7). Specific immune-cell responses in PLA followed expected time courses (neutrophil elevation on Day 1; sustained macrophage elevation from Days 3 to 5). PCO dramatically decreased neutrophil elevation to nonsignificant, while macrophage responses were normal in extent, but significantly earlier (peak between Days 1 and 3) and completely resolved by Day 5. Anti-inflammatory cytokine, IL-10, increased significantly only in PCO (Day 3). Muscle fiber regeneration (MHC(f) content and central nuclei) started earlier and was complete by Day 14 in PCO, but not in PLA. Thus, responses by three crucial cell types involved in muscle recovery were affected by in vivo administration of a specific purified polyphenol in magnitude (neutrophil), time course (macrophages), or time course and activation state (satellite cell), explaining faster effective regeneration in the presence of proanthocyanidolic oligomers. Copyright © 2012 Elsevier Inc. All rights reserved.

Physical Controls on Carbon Flux from a Temperate Lake During Autumn Cooling

NASA Astrophysics Data System (ADS)

Czikowsky, M. J.; Miller, S. D.; Tedford, E. W.; MacIntyre, S.

2011-12-01

Seasonally-stratified temperate lakes are a source of carbon dioxide to the atmosphere during autumn overturning as CO2 trapped below the thermocline becomes available to the surface for release to the atmosphere. We made continuous measurements of the vertical profile of pCO2 in a ~600 ha temperate lake (Lake Pleasant, maximum depth ~24 m) in southwestern Adirondack Park, New York from mid-September to mid-October 2010 from a moored pontoon boat. Continuous eddy covariance flux measurements of momentum, sensible and latent heat, and CO2 were made in situ, and the water column thermal structure was measured using thermistor chains. The spatial variability (horizontal and vertical) of pCO2 throughout the lake was characterized periodically using a roving profiling system. At the beginning of the study interval, pCO2 at the pontoon boat varied from 500 ppm at the surface to > 3000 ppm below the thermocline. The vertical profile of pCO2 changed markedly during the campaign due to the effects of wind forcing and evaporation (buoyancy), with nearly uniform, high pCO2 throughout the water column at the end of the campaign (Figure 1). The elevated surface water pCO2 increased CO2 emission to the atmosphere.

High-resolution pCO2 reconstruction across the early Cenozoic greenhouse and late Cenozoic icehouse climates

NASA Astrophysics Data System (ADS)

Cui, Y.; Schubert, B.

2016-12-01

Historical data and ice core records provide the best-constrained data on global temperatures and atmospheric carbon dioxide concentrations (pCO2), which can be used to calculate short-term estimates of climate sensitivity. These data, however, may not be representative of longer timescales and represent a period of Earth history when pCO2 and global temperatures were relatively low; recent work suggests that climate sensitivity may change under different climate states and timescales. Here we present a new high-resolution pCO2 reconstruction for the early (65 to 50 Ma) and late (30 to 0 Ma) Cenozoic using a proxy based on changes in carbon isotope fractionation in C3 land plants. This work uses widely available carbon isotope data from various terrestrial organic substrates to produce a nearly continuous record of pCO2. This record identifies both large-scale trends (e.g., the early Cenozoic is characterized by higher pCO2 than the late Cenozoic), as well as transient, highly elevated pCO2 during the early Eocene hyperthermals. We discuss the uncertainties associated with this new pCO2 reconstruction, which include the effects of precipitation, plant community shifts, and source effects on the δ13C record. Additionally, uncertainty associated with the correlation in time between δ13C estimates of atmospheric CO2 and the terrestrial δ13C of organic matter is included in the error propagation. Comparison of the new pCO2 record to existing global average temperature records based on the δ18O value of well-preserved marine foraminifera can yield new insight into Earth system climate sensitivity across a wide range of climate states and timescales.

Differential proteomic responses of selectively bred and wild-type Sydney rock oyster populations exposed to elevated CO2.

PubMed

Thompson, E L; O'Connor, W; Parker, L; Ross, P; Raftos, D A

2015-03-01

Previous work suggests that larvae from Sydney rock oysters that have been selectively bred for fast growth and disease resistance are more resilient to the impacts of ocean acidification than nonselected, wild-type oysters. In this study, we used proteomics to investigate the molecular differences between oyster populations in adult Sydney rock oysters and to identify whether these form the basis for observations seen in larvae. Adult oysters from a selective breeding line (B2) and nonselected wild types (WT) were exposed for 4 weeks to elevated pCO2 (856 μatm) before their proteomes were compared to those of oysters held under ambient conditions (375 μatm pCO2 ). Exposure to elevated pCO2 resulted in substantial changes in the proteomes of oysters from both the selectively bred and wild-type populations. When biological functions were assigned, these differential proteins fell into five broad, potentially interrelated categories of subcellular functions, in both oyster populations. These functional categories were energy production, cellular stress responses, the cytoskeleton, protein synthesis and cell signalling. In the wild-type population, proteins were predominantly upregulated. However, unexpectedly, these cellular systems were downregulated in the selectively bred oyster population, indicating cellular dysfunction. We argue that this reflects a trade-off, whereby an adaptive capacity for enhanced mitochondrial energy production in the selectively bred population may help to protect larvae from the effects of elevated CO2 , whilst being deleterious to adult oysters. © 2015 John Wiley & Sons Ltd.

Variability and trends in surface seawater pCO2 and CO2 flux in the Pacific Ocean

NASA Astrophysics Data System (ADS)

Sutton, A. J.; Wanninkhof, R.; Sabine, C. L.; Feely, R. A.; Cronin, M. F.; Weller, R. A.

2017-06-01

Variability and change in the ocean sink of anthropogenic carbon dioxide (CO2) have implications for future climate and ocean acidification. Measurements of surface seawater CO2 partial pressure (pCO2) and wind speed from moored platforms are used to calculate high-resolution CO2 flux time series. Here we use the moored CO2 fluxes to examine variability and its drivers over a range of time scales at four locations in the Pacific Ocean. There are significant surface seawater pCO2, salinity, and wind speed trends in the North Pacific subtropical gyre, especially during winter and spring, which reduce CO2 uptake over the 10 year record of this study. Starting in late 2013, elevated seawater pCO2 values driven by warm anomalies cause this region to be a net annual CO2 source for the first time in the observational record, demonstrating how climate forcing can influence the timing of an ocean region shift from CO2 sink to source.

Intramucosal–arterial PCO2 gap fails to reflect intestinal dysoxia in hypoxic hypoxia

PubMed Central

Dubin, Arnaldo; Murias, Gastón; Estenssoro, Elisa; Canales, Héctor; Badie, Julio; Pozo, Mario; Sottile, Juan P; Barán, Marcelo; Pálizas, Fernando; Laporte, Mercedes

2002-01-01

Introduction An elevation in intramucosal–arterial PCO2 gradient (ΔPCO2) could be determined either by tissue hypoxia or by reduced blood flow. Our hypothesis was that in hypoxic hypoxia with preserved blood flow, ΔPCO2 should not be altered. Methods In 17 anesthetized and mechanically ventilated sheep, oxygen delivery was reduced by decreasing flow (ischemic hypoxia, IH) or arterial oxygen saturation (hypoxic hypoxia, HH), or no intervention was made (sham). In the IH group (n = 6), blood flow was lowered by stepwise hemorrhage; in the HH group (n = 6), hydrochloric acid was instilled intratracheally. We measured cardiac output, superior mesenteric blood flow, gases, hemoglobin, and oxygen saturations in arterial blood, mixed venous blood, and mesenteric venous blood, and ileal intramucosal PCO2 by tonometry. Systemic and intestinal oxygen transport and consumption were calculated, as was ΔPCO2. After basal measurements, measurements were repeated at 30, 60, and 90 minutes. Results Both progressive bleeding and hydrochloric acid aspiration provoked critical reductions in systemic and intestinal oxygen delivery and consumption. No changes occurred in the sham group. ΔPCO2 increased in the IH group (12 ± 10 [mean ± SD] versus 40 ± 13 mmHg; P < 0.001), but remained unchanged in HH and in the sham group (13 ± 6 versus 10 ± 13 mmHg and 8 ± 5 versus 9 ± 6 mmHg; not significant). Discussion In this experimental model of hypoxic hypoxia with preserved blood flow, ΔPCO2 was not modified during dependence of oxygen uptake on oxygen transport. These results suggest that ΔPCO2 might be determined primarily by blood flow. PMID:12493073

Atmospheric carbon dioxide concentrations before 2.2 billion years ago

NASA Technical Reports Server (NTRS)

Rye, R.; Kuo, P. H.; Holland, H. D.

1995-01-01

The composition of the Earth's early atmosphere is a subject of continuing debate. In particular, it has been suggested that elevated concentrations of atmospheric carbon dioxide would have been necessary to maintain normal surface temperatures in the face of lower solar luminosity in early Earth history. Fossil weathering profiles, known as palaeosols, have provided semi-quantitative constraints on atmospheric oxygen partial pressure (pO2) before 2.2 Gyr ago. Here we use the same well studied palaeosols to constrain atmospheric pCO2 between 2.75 and 2.2 Gyr ago. The observation that iron lost from the tops of these profiles was reprecipitated lower down as iron silicate minerals, rather than as iron carbonate, indicates that atmospheric pCO2 must have been less than 10(-1.4) atm--about 100 times today's level of 360 p.p.m., and at least five times lower than that required in one-dimensional climate models to compensate for lower solar luminosity at 2.75 Gyr. Our results suggest that either the Earth's early climate was much more sensitive to increases in pCO2 than has been thought, or that one or more greenhouse gases other than CO2 contributed significantly to the atmosphere's radiative balance during the late Archaean and early Proterozoic eons.

Physiological responses and scope for growth upon medium-term exposure to the combined effects of ocean acidification and temperature in a subtidal scavenger Nassarius conoidalis.

PubMed

Zhang, Haoyu; Shin, Paul K S; Cheung, S G

2015-05-01

Physiological responses (ingestion rate, absorption rate and efficiency, respiration, rate, excretion rate) and scope for growth of a subtidal scavenging gastropod Nassarius conoidalis under the combined effects of ocean acidification (pCO2 levels: 380, 950, 1250 μatm) and temperature (15, 30 °C) were investigated for 31 days. There was a significant reduction in all the physiological rates and scope for growth following short-term exposure (1-3 days) to elevated pCO2 except absorption efficiency at 15 °C and 30 °C, and respiration rate and excretion rate at 15 °C. The percentage change in the physiological rates ranged from 0% to 90% at 15 °C and from 0% to 73% at 30 °C when pCO2 was increased from 380 μatm to 1250 μatm. The effect of pCO2 on the physiological rates was enhanced at high temperature for ingestion, absorption, respiration and excretion. When the exposure period was extended to 31 days, the effect of pCO2 was significant on the ingestion rate only. All the physiological rates remained unchanged when temperature increased from 24 °C to 30 °C but the rates at 15 °C were significantly lower, irrespective of the duration of exposure. Our data suggested that a medium-term exposure to ocean acidification has no effect on the energetics of N. conoidalis. Nevertheless, the situation may be complicated by a longer term of exposure and/or a reduction in salinity in a warming world. Copyright © 2015 Elsevier Ltd. All rights reserved.

Enhanced acidification of global coral reefs driven by regional biogeochemical feedbacks

NASA Astrophysics Data System (ADS)

Cyronak, Tyler; Schulz, Kai G.; Santos, Isaac R.; Eyre, Bradley D.

2014-08-01

Physical uptake of anthropogenic CO2 is the dominant driver of ocean acidification (OA) in the open ocean. Due to expected decreases in calcification and increased dissolution of CaCO3 framework, coral reefs are thought to be highly susceptible to OA. However, biogeochemical processes can influence the pCO2 and pH of coastal ecosystems on diel and seasonal time scales, potentially modifying the long-term effects of increasing atmospheric CO2. By compiling data from the literature and removing the effects of short-term variability, we show that the average pCO2 of coral reefs throughout the globe has increased ~3.5-fold faster than in the open ocean over the past 20 years. This rapid increase in pCO2 has the potential to enhance the acidification and predicted effects of OA on coral reef ecosystems. A simple model demonstrates that potential drivers of elevated pCO2 include additional anthropogenic disturbances beyond increasing global atmospheric CO2 such as enhanced nutrient and organic matter inputs.

Temperature effects on CO2-sensitive intrapulmonary chemoreceptors in the lizard, Tupinambis nigropunctatus.

PubMed

Douse, M A; Mitchell, G S

1988-06-01

Body temperature (Tb) effects on CO2 responses of 17 intrapulmonary chemoreceptors (IPC) were investigated in 9 anesthetized (pentobarbital; 30 mg/kg) and unidirectionally ventilated tegu lizards (Tupinambis nigropunctatus). At 30 degrees C, all IPC (n = 15) had a stable discharge pattern. At 20 degrees C, IPC discharge (n = 14) was stable at high PCO2 but irregular at low PCO2 and often (10/14) consisted of bursts of activity separated by one or more seconds of quiescence. Responses of IPC to static and dynamic changes in PCO2 were quantified at both Tb and the discharge rate vs PCO2 response curves were compared. Static discharge frequency (fSTAT) decreased as PCO2 increased at both Tb. At 20 degrees C: (1) fSTAT was diminished at all PCO2 levels relative to 30 degrees C; and (2) the slope of the fSTAT vs PCO2 relationship was markedly attenuated. The Q10 was 3.7 +/- 0.5 and was independent of PCO2. The peak discharge associated with a step decrease in PCO2 (dynamic response; fDYN) also decreased as PCO2 increased. At 20 degrees C: (1) fDYN was diminished at all PCO2 levels relative to 30 degrees C; but (2) the slope of the fDYN vs PCO2 relationship was similar at both Tb. The Q10 was 2.6 +/- 0.3 and was significantly less than the Q10 of fSTAT (P less than 0.05). Acute changes in Tb exert large effects on the CO2 response and discharge pattern of IPC; these effects on IPC may be important in ventilatory control at different Tb in lizards.

Ocean Acidification Has Multiple Modes of Action on Bivalve Larvae

PubMed Central

Waldbusser, George G.; Hales, Burke; Langdon, Chris J.; Haley, Brian A.; Schrader, Paul; Brunner, Elizabeth L.; Gray, Matthew W.; Miller, Cale A.; Gimenez, Iria; Hutchinson, Greg

2015-01-01

Ocean acidification (OA) is altering the chemistry of the world’s oceans at rates unparalleled in the past roughly 1 million years. Understanding the impacts of this rapid change in baseline carbonate chemistry on marine organisms needs a precise, mechanistic understanding of physiological responses to carbonate chemistry. Recent experimental work has shown shell development and growth in some bivalve larvae, have direct sensitivities to calcium carbonate saturation state that is not modulated through organismal acid-base chemistry. To understand different modes of action of OA on bivalve larvae, we experimentally tested how pH, PCO2, and saturation state independently affect shell growth and development, respiration rate, and initiation of feeding in Mytilus californianus embryos and larvae. We found, as documented in other bivalve larvae, that shell development and growth were affected by aragonite saturation state, and not by pH or PCO2. Respiration rate was elevated under very low pH (~7.4) with no change between pH of ~ 8.3 to ~7.8. Initiation of feeding appeared to be most sensitive to PCO2, and possibly minor response to pH under elevated PCO2. Although different components of physiology responded to different carbonate system variables, the inability to normally develop a shell due to lower saturation state precludes pH or PCO2 effects later in the life history. However, saturation state effects during early shell development will carry-over to later stages, where pH or PCO2 effects can compound OA effects on bivalve larvae. Our findings suggest OA may be a multi-stressor unto itself. Shell development and growth of the native mussel, M. californianus, was indistinguishable from the Mediterranean mussel, Mytilus galloprovincialis, collected from the southern U.S. Pacific coast, an area not subjected to seasonal upwelling. The concordance in responses suggests a fundamental OA bottleneck during development of the first shell material affected only by saturation state. PMID:26061095

Ocean Acidification Has Multiple Modes of Action on Bivalve Larvae.

PubMed

Waldbusser, George G; Hales, Burke; Langdon, Chris J; Haley, Brian A; Schrader, Paul; Brunner, Elizabeth L; Gray, Matthew W; Miller, Cale A; Gimenez, Iria; Hutchinson, Greg

2015-01-01

Ocean acidification (OA) is altering the chemistry of the world's oceans at rates unparalleled in the past roughly 1 million years. Understanding the impacts of this rapid change in baseline carbonate chemistry on marine organisms needs a precise, mechanistic understanding of physiological responses to carbonate chemistry. Recent experimental work has shown shell development and growth in some bivalve larvae, have direct sensitivities to calcium carbonate saturation state that is not modulated through organismal acid-base chemistry. To understand different modes of action of OA on bivalve larvae, we experimentally tested how pH, PCO2, and saturation state independently affect shell growth and development, respiration rate, and initiation of feeding in Mytilus californianus embryos and larvae. We found, as documented in other bivalve larvae, that shell development and growth were affected by aragonite saturation state, and not by pH or PCO2. Respiration rate was elevated under very low pH (~7.4) with no change between pH of ~ 8.3 to ~7.8. Initiation of feeding appeared to be most sensitive to PCO2, and possibly minor response to pH under elevated PCO2. Although different components of physiology responded to different carbonate system variables, the inability to normally develop a shell due to lower saturation state precludes pH or PCO2 effects later in the life history. However, saturation state effects during early shell development will carry-over to later stages, where pH or PCO2 effects can compound OA effects on bivalve larvae. Our findings suggest OA may be a multi-stressor unto itself. Shell development and growth of the native mussel, M. californianus, was indistinguishable from the Mediterranean mussel, Mytilus galloprovincialis, collected from the southern U.S. Pacific coast, an area not subjected to seasonal upwelling. The concordance in responses suggests a fundamental OA bottleneck during development of the first shell material affected only by saturation state.

Effect of temperature, hydraulic residence time and elevated PCO2 on acid neutralization within a pulsed limestone bed reactor

USGS Publications Warehouse

Watten, B.J.; Lee, P.C.; Sibrell, P.L.; Timmons, M.B.

2007-01-01

Limestone has potential for reducing reagent costs and sludge volume associated with treatment of acid mine drainage, but its use is restricted by slow dissolution rates and the deposition of Fe, Al and Mn-based hydrolysis products on reactive surfaces. We evaluated a pulsed limestone bed (PLB) reactor (15 L/min capacity) that uses a CO2 pretreatment step to accelerate dissolution and hydraulic shearing forces provided by intermittent fluidization to abrade and carry away surface scales. We established the effects of hydraulic residence time (HRT, 5.1-15.9 min), temperature (T, 12-22 ??C) and CO2 tension (PCO2, 34.5-206.8 kPa) on effluent quality when inlet acidity (Acy) was fixed at 440 mg/L (pH=2.48) with H2SO4. The PLB reactor neutralized all H+ acidity (N=80) while concurrently providing unusually high levels of effluent alkalinity (247-1028 mg/L as CaCO3) that allow for side-stream treatment with blending. Alkalinity (Alk) yields rose with increases in PCO2, HRT and settled bed height (BH, cm) and decreased with T following the relationship (R2=0.926; p<0.001): (Alk)non-filtered=-548.726+33.571??(PCO2)0.5+33.671??(HRT)+7.734??(BH)-5.197??(T). Numerical modeling showed CO2 feed requirements for a target Alk yield decrease with increases in HRT, T and the efficiency of off-gas (CO2) recycling. ?? 2007 Elsevier Ltd. All rights reserved.

Predicted arterial oxygenation at commercial aircraft cabin altitudes.

PubMed

Muhm, J Michael

2004-10-01

The degree of hypoxia manifested by airline passengers during flight is not well characterized. Statistical models to predict age-specific levels of Pao2 manifest at altitudes between sea level and 8000 ft (Pao2alt) are described. The relationship between age and Pao2 at sea level (Pao2sl) and the relationship between Pao2alt, and Pao2sl, Pco2 at sea level (Pco2sl), and pulmonary health status were investigated using linear regression techniques to analyze previously published data. In persons with normal pulmonary health, the relationship between Pao2sl (mmHg) and age (yr) was Pao2sl = 105.9 - 0.44 * age (R2 = 0.582, MSE = 25.314); Pco2sl (38.1 +/- 2.8 mmHg) was not related to age over the range 18-75 yr. In persons with chronic obstructive lung disease (COPD), neither Pao2sl (78.2 +/- 11.3 mmHg) nor Pco2sl (40.5 +/- 5.7 mmHg) were related to age (77.0 +/- 9.0 yrs).The relationship between PaO2alt and Pao2sl, Pco2sl and altitude (ft) was: Pao2alt = 1.59 + 0.98 * Pao2sl + 0.0031 * Alt - 0.000061 * Pao2sl * Alt - 0.000065 * PCO(2)sl [corrected] * Alt + 0.000000092 * Alt2 (R2 = 0.932, MSE = 22.774). Pao2sl declines with age in persons with normal pulmonary health; Pco2sl remains constant. Neither vary with age in persons with COPD. Pao2alt can be estimated with acceptable precision from knowledge of Pao2sl, Pco2sl, and altitude. These models predict a substantial proportion of older passengers will manifest a Pao2alt at 8000 ft below the threshold at which supplemental oxygen is recommended.

Relative sensitivity of five Hawaiian coral species to high temperature under high-pCO2 conditions

NASA Astrophysics Data System (ADS)

Bahr, Keisha D.; Jokiel, Paul L.; Rodgers, Ku'ulei S.

2016-06-01

Coral reef ecosystems are presently undergoing decline due to anthropogenic climate change. The chief detrimental factors are increased temperature and increased pCO2. The purpose of this study was to evaluate the effect of these two stressors operating independently and in unison on the biological response of common Hawaiian reef corals. Manipulative experiments were performed using five species ( Porites compressa, Pocillopora damicornis, Fungia scutaria, Montipora capitata, and Leptastrea purpurea) in a continuous-flow mesocosm system under natural sunlight conditions. Corals were grown together as a community under treatments of high temperature (2 °C above normal maximum summer temperature), high pCO2 (twice present-day conditions), and with both factors acting in unison. Control corals were grown under present-day pCO2 and at normal summer temperatures. Leptastrea purpurea proved to be an extremely hardy coral. No change in calcification or mortality occurred under treatments of high temperature, high pCO2, or combined high temperature-high pCO2. The remaining four species showed reduced calcification in the high-temperature treatment. Two species ( L. purpurea and M. capitata) showed no response to increased pCO2. Also, high pCO2 ameliorated the negative effect of high temperature on the calcification rates of P. damicornis. Mortality was driven primarily by high temperature, with a negative synergistic effect in P. compressa only in the high-pCO2-high-temperature treatment. Results support the observation that biological response to temperature and pCO2 elevation is highly species-specific, so generalizations based on response of a single species might not apply to a diverse and complex coral reef community.

Modeling pCO2 variability in the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Xue, Z.; He, R.; Fennel, K.; Cai, W.-J.; Lohrenz, S.; Huang, W.-J.; Tian, H.

2014-08-01

A three-dimensional coupled physical-biogeochemical model was used to simulate and examine temporal and spatial variability of surface pCO2 in the Gulf of Mexico (GoM). The model is driven by realistic atmospheric forcing, open boundary conditions from a data-assimilative global ocean circulation model, and observed freshwater and terrestrial nutrient and carbon input from major rivers. A seven-year model hindcast (2004-2010) was performed and was validated against in situ measurements. The model revealed clear seasonality in surface pCO2. Based on the multi-year mean of the model results, the GoM is an overall CO2 sink with a flux of 1.34 × 1012 mol C yr-1, which, together with the enormous fluvial carbon input, is balanced by the carbon export through the Loop Current. A sensitivity experiment was performed where all biological sources and sinks of carbon were disabled. In this simulation surface pCO2 was elevated by ~ 70 ppm, providing the evidence that biological uptake is a primary driver for the observed CO2 sink. The model also provided insights about factors influencing the spatial distribution of surface pCO2 and sources of uncertainty in the carbon budget.

Modeling pCO2 Variability in the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Xue, Z. G.; He, R.; Fennel, K.; Cai, W. J.; Lohrenz, S. E.; Huang, W. J.; Tian, H.

2014-12-01

A three-dimensional coupled physical-biogeochemical model was used to simulate and examine temporal and spatial variability of surface pCO2 in the Gulf of Mexico (GoM). The model is driven by realistic atmospheric forcing, open boundary conditions from a data-assimilative global ocean circulation model, and observed freshwater and terrestrial nutrient and carbon input from major rivers. A seven-year model hindcast (2004-2010) was performed and was validated against in situ measurements. The model revealed clear seasonality in surface pCO2. Based on the multi-year mean of the model results, the GoM is an overall CO2 sink with a flux of 1.34 × 1012 mol C yr-1, which, together with the enormous fluvial carbon input, is balanced by the carbon export through the Loop Current. A sensitivity experiment was performed where all biological sources and sinks of carbon were disabled. In this simulation surface pCO2 was elevated by ~70 ppm, providing the evidence that biological uptake is a primary driver for the observed CO2 sink. The model also provided insights about factors influencing the spatial distribution of surface pCO2 and sources of uncertainty in the carbon budget.

Inference of pCO2 Levels during the Late Cretaceous Using Fossil Lauraceae

NASA Astrophysics Data System (ADS)

Richey, J. D.; Upchurch, G. R.

2011-12-01

Botanical estimates of pCO2 for the Late Cretaceous have most commonly used Stomatal Index (SI) in fossil Ginkgo. Recently, SI in fossil Lauraceae has been used to infer changes in pCO2 across the Cenomanian-Turonian boundary, based on the relation between SI and pCO2 in extant Laurus and Hypodaphnis. To provide a broad-scale picture of pCO2 based on fossil Lauraceae, we examined dispersed cuticle of the leaf macrofossil genus Pandemophyllum from: 1) the early to middle Cenomanian of the Potomac Group of Maryland (Mauldin Mountain locality, lower Zone III) and 2) the Maastrichtian of southern Colorado (Raton Basin, Starkville South and Berwind Canyon localities). These samples fall within the Late Cretaceous decline in pCO2 inferred from geochemical modeling and other proxies. SI was calculated from fossil cuticle fragments using ImageJ and counts of up to 56,000 cells per sample, a far greater number of cells than are counted in most studies. CO2 levels were estimated using the relation between SI and CO2 published for Laurus nobilis and Hypodaphnis zenkeri. Early to middle Cenomanian atmospheric pCO2 is estimated at 362-536 parts per million (ppm). This represents the absolute minimum and maximum estimated CO2 levels from the ±95% confidence intervals (CI) of the relation between SI and CO2 for the modern equivalents, and SI ± 1 Standard Deviation (SD) in the fossil genus Pandemophyllum. Late Maastrichtian atmospheric pCO2 is estimated at 358-534 ppm. The Maastrichtian estimates falls within the range of published estimates from other proxies. The Cenomanian estimate, in contrast, is low relative to most other estimates. The 95% confidence intervals of our pCO2 estimates overlap each other and many of the assemblages published by Barclay et al. (2010) for Lauraceae across the Cenomanian-Turonian boundary. This could indicate that 1) pCO2 did not undergo a major long-term decline during the Late Cretaceous, 2) Lauraceae show low sensitivity to high pCO2, or 3) additional sampling is necessary to find the mid-Cretaceous pCO2 maximum inferred by other proxy methods.

Combined effects of warming and ocean acidification on coral reef Foraminifera Marginopora vertebralis and Heterostegina depressa

NASA Astrophysics Data System (ADS)

Schmidt, Christiane; Kucera, Michal; Uthicke, Sven

2014-09-01

Warming and changes in ocean carbonate chemistry alter marine coastal ecosystems at an accelerating pace. The interaction between these stressors has been the subject of recent studies on reef organisms such as corals, bryozoa, molluscs, and crustose coralline algae. Here we investigated the combined effects of elevated sea surface temperatures and pCO2 on two species of photosymbiont-bearing coral reef Foraminifera: Heterostegina depressa (hosting diatoms) and Marginopora vertebralis (hosting dinoflagellates). The effects of single and combined stressors were studied by monitoring survivorship, growth, and physiological parameters, such as respiration, photochemistry (pulse amplitude modulation fluorometry and oxygen production), and chl a content. Specimens were exposed in flow-through aquaria for up to seven weeks to combinations of two pCO2 (~790 and ~490 µatm) and two temperature (28 and 31 °C) regimes. Elevated temperature had negative effects on the physiology of both species. Elevated pCO2 had negative effects on growth and apparent photosynthetic rate in H.depressa but a positive effect on effective quantum yield. With increasing pCO2, chl a content decreased in H. depressa and increased in M. vertebralis. The strongest stress responses were observed when the two stressors acted in combination. An interaction term was statistically significant in half of the measured parameters. Further exploration revealed that 75 % of these cases showed a synergistic (= larger than additive) interaction between the two stressors. These results indicate that negative physiological effects on photosymbiont-bearing coral reef Foraminifera are likely to be stronger under simultaneous acidification and temperature rise than what would be expected from the effect of each of the stressors individually.

Hydrogen ion secretion by the collecting duct as a determinant of the urine to blood PCO2 gradient in alkaline urine

DOE Office of Scientific and Technical Information (OSTI.GOV)

DuBose, T.D. Jr.

1982-01-01

Several theories have been advanced to explain the elevation in urinary PCO/sub 2/ during bicarbonate loading and include: (a) H+ secretion, (b) countercurrent system for CO/sub 2/, (c) the ampholyte properties of bicarbonate, and (d) mixing of urine of disparate bicarbonate and butter concentrations. In this study microelectrodes were used to measure in situ and equilibrium pH (pHis and pHeq) and PCO/sub 2/ in control and bicarbonate loaded rats before and after infusion of carbonic anhydrase. The disequilibrium pH method (pHdq . pHis - pHeq) was used to demonstrate H+ secretion. Control rats excreting an acid urine (pH . 6.04more » +/- 0.06) failed to display a significant disequilibrium pH at the base (BCD), or tip (TCD) of the papillary collecting duct. Urine pH (7.54 +/- 0.12), and urine to blood (U-B) PCO/sub 2/ increased significantly during NaHCO/sub 3/ loading while PCO/sub 2/ at the BCD and TCD also increased (95 +/- 4 and 122 +/- 4). Furthermore, an acid disequilibrium pH was present at both the BCD and TCD (-0.42 +/- 0.04 and -0.36 +/- 0.03) and was obliterated by carbonic anhydrase. Comparison of the PCO/sub 2/ in the BCD or TCD with the adjacent vasa recta revealed similar values (r . 0.97). It is concluded that H+ secretion by the collecting duct into bicarbonate containing fluid with delayed dehydration of H/sub 2/CO/sub 3/, is the most likely determinant of the U-B PCO/sub 2/ in alkaline urine. Similar values for PCO/sub 2/ in the collecting duct and the adjacent vasa recta suggests trapping of CO/sub 2/ in the medullary countercurrent system. The rise in PCO/sub 2/ occurs both along the collecting duct and after exit from the papilla.« less

Ocean acidification accelerates dissolution of experimental coral reef communities

NASA Astrophysics Data System (ADS)

Comeau, S.; Carpenter, R. C.; Lantz, C. A.; Edmunds, P. J.

2015-01-01

Ocean acidification (OA) poses a severe threat to tropical coral reefs, yet much of what is know about these effects comes from individual corals and algae incubated in isolation under high pCO2. Studies of similar effects on coral reef communities are scarce. To investigate the response of coral reef communities to OA, we used large outdoor flumes in which communities composed of calcified algae, corals, and sediment were combined to match the percentage cover of benthic communities in the shallow back reef of Moorea, French Polynesia. Reef communities in the flumes were exposed to ambient (~ 400 μatm) and high pCO2 (~ 1300 μatm) for 8 weeks, and calcification rates measured for the constructed communities including the sediments. Community calcification was reduced by 59% under high pCO2, with sediment dissolution explaining ~ 50% of this decrease; net calcification of corals and calcified algae remained positive but was reduced by 29% under elevated pCO2. These results show that, despite the capacity of coral reef calcifiers to maintain positive net accretion of calcium carbonate under OA conditions, reef communities might transition to net dissolution as pCO2 increases, particularly at night, due to enhanced sediment dissolution.

Ocean acidification accelerates dissolution of experimental coral reef communities

NASA Astrophysics Data System (ADS)

Comeau, S.; Carpenter, R. C.; Lantz, C. A.; Edmunds, P. J.

2014-08-01

Ocean acidification (OA) poses a severe threat to tropical coral reefs, yet much of what is know about these effects comes from individual corals and algae incubated in isolation under high pCO2. Studies of similar effects on coral reef communities are scarce. To investigate the response of coral reef communities to OA, we used large outdoor flumes in which communities composed of calcified algae, corals, and sediment were combined to match the percentage cover of benthic communities in the shallow back reef of Moorea, French Polynesia. Reef communities in the flumes were exposed to ambient (~400 μatm) and high pCO2 (~1300 μatm) for 8 weeks, and calcification rates measured for the constructed communities including the sediments. Community calcification was depressed 59% under high pCO2, with sediment dissolution explaining ~50% of this decrease; net calcification of corals and calcified algae remained positive, but was reduced 29% under elevated pCO2. These results show that despite the capacity of coral reef calcifiers to maintain positive net accretion of calcium carbonate under OA conditions, reef communities might switch to net dissolution as pCO2 increases, particularly at night, due to enhanced sediment dissolution.

Effects of elevated seawater pCO2 on early development of scallop Argopecten irradias (Lamarck, 1819)

NASA Astrophysics Data System (ADS)

Wang, Weimin; Liu, Guangxing; Zhang, Tianwen; Chen, Hongju; Tang, Liao; Mao, Xuewei

2016-12-01

To investigate the effects of elevated seawater pCO2 on the early developmental stages of marine benthic calcifying organisms, we exposed the eggs and larvae of Argopecten irradias, an important bivalve species in Chinese aquaculture, in seawater equilibrated with CO2-enriched (1000 ppm) gas mixtures. We demonstrated that elevated seawater pCO2 significantly interfered with fertilization and larval development and resulted in an increased aberration rate. Fertilization in the treatment (pH 7.6) was 74.3% ± 3.8%, which was 9.7% lower than that in the control (pH 8.3) (84.0% ±3.0%). Hatching success decreased by 23.7%, and aberration rate increased by 30.3% under acidic condition. Larvae in acidified seawater still developed a shell during the post-embryonic phase. However, the shell length and height in the treatment were smaller than those in the control. The development of embryos differed significantly at 12 h after fertilization between the two experimental groups. Embryos developed slower in acidified seawater. Nearly half of the embryos in the control developed into D-shaped larvae at 48 h after fertilization, which were considerably more than those in the treatment (11.7%). Results suggest that future ocean acidification (OA) would cause detrimental effects on the early development of A. irradias.

Ocean acidification increases the vulnerability of native oysters to predation by invasive snails

PubMed Central

Sanford, Eric; Gaylord, Brian; Hettinger, Annaliese; Lenz, Elizabeth A.; Meyer, Kirstin; Hill, Tessa M.

2014-01-01

There is growing concern that global environmental change might exacerbate the ecological impacts of invasive species by increasing their per capita effects on native species. However, the mechanisms underlying such shifts in interaction strength are poorly understood. Here, we test whether ocean acidification, driven by elevated seawater pCO2, increases the susceptibility of native Olympia oysters to predation by invasive snails. Oysters raised under elevated pCO2 experienced a 20% increase in drilling predation. When presented alongside control oysters in a choice experiment, 48% more high-CO2 oysters were consumed. The invasive snails were tolerant of elevated CO2 with no change in feeding behaviour. Oysters raised under acidified conditions did not have thinner shells, but were 29–40% smaller than control oysters, and these smaller individuals were consumed at disproportionately greater rates. Reduction in prey size is a common response to environmental stress that may drive increasing per capita effects of stress-tolerant invasive predators. PMID:24430847

Calcification in Caribbean reef-building corals at high pCO2 levels in a recirculating ocean acidification exposure system.

PubMed

Enzor, Laura A; Hankins, Cheryl; Vivian, Deborah N; Fisher, William S; Barron, Mace G

2018-02-01

Projected increases in ocean p CO 2 levels are anticipated to affect calcifying organisms more rapidly and to a greater extent than other marine organisms. The effects of ocean acidification (OA) have been documented in numerous species of corals in laboratory studies, largely tested using flow-through exposure systems. We developed a recirculating ocean acidification exposure system that allows precise p CO 2 control using a combination of off-gassing measures including aeration, water retention devices, venturi injectors, and CO 2 scrubbing. We evaluated the recirculating system performance in off-gassing effectiveness and maintenance of target p CO 2 levels over an 84-day experiment. The system was used to identify changes in calcification and tissue growth in response to elevated p CO 2 (1000 μatm) in three reef-building corals of the Caribbean: Pseudodiploria clivosa , Montastraea cavernosa , and Orbicella faveolata . All three species displayed an overall increase in net calcification over the 84-day exposure period regardless of p CO 2 level (control +0.28- 1.12 g, elevated p CO 2 +0.18- 1.16 g), and the system was effective at both off-gassing acidified water to ambient p CO 2 levels, and maintaining target elevated p CO 2 levels over the 3-month experiment.

Anomalously Low pCO2 Measured in the San Francisco Estuary

NASA Astrophysics Data System (ADS)

Fuller, J. R.; Wilkerson, F.; Parker, A. E.; Marchi, A.

2008-12-01

Estuaries have been identified as potential net sources of CO2 to the atmosphere. Bacterial respiration of organic matter entering the estuary leads to supersaturated levels of pCO2. The southern embayment of the San Francisco Estuary (SFE) is no exception due in part to wastewater treatment practices. Persistently high levels of pCO2 between 600 and 1000 μatm have been reported for this embayment by the U.S. Geological Survey over the period 1976-1980 and more recently (2007-2008) by the authors. However, both studies also found notable exceptions to the high pCO2 levels during the spring phytoplankton bloom. An average level of 375 μatm, slightly above the contemporary atmospheric level, was observed during an April 1980 transect. Our recent measurements over the same transect have observed an even greater drawdown of pCO2 to as low as 175 μatm. In addition the pCO2 drawdown persisted from early March 2008 until the end of May. These anomalously low levels correspond directly with an algal bloom as evidenced by high concentrations of chlorophyll a and supersaturated dissolved oxygen. To our knowledge these are the lowest levels reported for the SFE and they indicate that portions of the estuary are a sink for atmospheric CO2 during bloom conditions. The hydrology of the southern embayment is dominated at times by the input of wastewater which is often treated to the advanced secondary level with inorganic nitrate as the product. This possibly contributes to a healthy estuarine algal population that helps to maintain current pCO2 levels in the SFE to those of 30 years ago despite significant urban growth around the estuary over that period. These findings have major implications both to estuarine management and to estimates of the estuarine component in global air-sea CO2 exchange

Inorganic carbon dynamics in the upwelling system off the Oregon coast and implications for commercial shellfish hatcheries

NASA Astrophysics Data System (ADS)

Vance, J. M.; Hales, B. R.

2010-12-01

The increasing absorption of anthropogenic CO2 by the global ocean and concomitant decrease in pH will alter seawater carbonate chemistry in ways that may negatively impact calcifying organisms. In particular, the change in saturation state (Ω) of calcium carbonate minerals calcite and aragonite may be energetically unfavorable for shell formation while favoring shell dissolution. Eastern boundary upwelling systems may provide insights into how ecosystems respond to future conditions of ocean acidification when deep water with high dissolved inorganic carbon (DIC), low pH and low Ω is forced toward the surface. Mortality in commercial seed stock and reduced wild set of the oyster Crassostrea gigas in the northeast Pacific during 2005-2009 reinforced the need for understanding biological responses to acidified ocean water. In response, a long-term strategy to understand local carbonate chemistry dynamics, seasonal perturbations and the effects on development of calcifying bivalves was developed. At present, a time-series of pCO2 measurements was implemented in April 2010 in Netarts Bay, Oregon at Whiskey Creek Shellfish Hatchery (WCH). The intake sits at a depth of 0.5-8ft and water is pumped in at 100gpm. A line taken off the intake is run continuously through a thermosalinograph at approximately 1.5gpm into a showerhead style equilibrator in which the headspace is recirculated by aerating the water for enhanced gas exchange. CO2 in equilibrated air is analyzed by NDIR. Additionally two discrete samples of intake seawater were taken across tidal cycles weekly and analyzed for total CO2 (TCO2) according to the methods of Hales et al. (2004) and pCO2 for quality control. The pCO2 in the bay exhibits a diurnal cycle representative of daytime photosynthesis and nighttime respiration. However, the phasing and profiles of these cycles are dominated by tidal mixing and are affected by the introduction of high pCO2 water during upwelling events. Diurnal pCO2 during periods of low wind stress ranges from 100-700µatm. When strong equatorward winds induce upwelling, pCO2 levels exhibit a higher daily range of 300-2000µatm. The saturation state was calculated from the pCO2/TCO2 measurements of the discrete samples. The Ω for calcite and aragonite ranged from 2.07 and 1.15 to 8.58 and 4.69 respectively from April through August. Increased pCO2 and decreased pH have been shown to negatively impact larval development in C. gigas (Kurihara, 2007). Periods of elevated pCO2 in May and June 2010 correlated with commercial losses at WCH. The use of precise pCO2 measurements in real time has proven to be a valuable tool for use in aquaculture. As a commercial practice WCH has elected to only use source water that is below empirical pCO2 thresholds for spawning and culturing larvae. This has resulted in continued production and cost saving in an industry crucial to coast economies. A continuous TCO2/pCO2 monitoring system will be integrated into this long time-series to constrain inorganic carbon providing insight into carbonate chemistry dynamics in Netarts Bay, effects of ocean acidification on bivalve development and possible water treatment approaches for commercial aquaculture.

Availability of phosphate for phytoplankton and bacteria and of labile organic carbon for bacteria at different pCO2 levels in a mesocosm study

NASA Astrophysics Data System (ADS)

Tanaka, T.; Thingstad, T. F.; Løvdal, T.; Grossart, H.-P.; Larsen, A.; Schulz, K. G.; Riebesell, U.

2007-11-01

Availability of phosphate for phytoplankton and bacteria and of labile organic carbon for bacteria at different pCO2 levels were studied in a mesocosm experiment (PeECE III). Using nutrient-depleted SW Norwegian fjord waters, three different levels of pCO2 (350 μatm: 1×CO2; 750 μatm: 2×CO2; 1050 μatm: 3×CO2) were set up, and nitrate and phosphate were added at the start of the experiment in order to induce a phytoplankton bloom. Despite similar responses of total particulate P concentration and phosphate turnover time at the three different pCO2 levels, the size distribution of particulate P and 33PO4 uptake suggested that phosphate transferred to the >10 μm fraction was greater in the 3×CO2 mesocosm during the first 6-10 days when phosphate concentration was high. During the period of phosphate depletion (after Day 12), specific phosphate affinity and specific alkaline phosphatase activity (APA) suggested a P-deficiency (i.e. suboptimal phosphate supply) but not a P-limitation for the phytoplankton and bacterial community at the three different pCO2 levels. Although specific phosphate affinity and specific APA tended to be higher in 3×CO2 than in 2×CO2 and 1×CO2 mesocosms during the phosphate depletion period, no statistical differences were found. Responses of specific glucose affinity for bacteria were similar at the three different pCO2 levels. Measured specific glucose affinities were consistently much lower than the theoretical maximum predicted from the diffusion-limited model, suggesting that bacterial growth was not limited by the availability of labile dissolved organic carbon. These results suggest that availability of phosphate and glucose was similar at the three different pCO2 levels.

Altitude controls carbon dioxide in boreal lakes

NASA Astrophysics Data System (ADS)

Bhattacharya, Atreyee

2012-09-01

Organic matter present in lakes, derived either from land-based sources—such as plants, soil, and sediments—or from in situ processes—such as degrading detritus in the water—could be important in the global carbon cycle, and possibly a significant source of the atmospheric carbon dioxide (CO2) budget. The partial pressure of CO2 in surface waters (pCO2) drives the escape of CO2 to the atmosphere. Hence, scientists have long suspected that the relationship between pCO2 and the dissolved organic matter (DOC) in lake waters refects the relative contribution of the environment and in situ processes to the high-latitude carbon budget. Combining measurements of DOC and pCO2 from nearly 200 lakes across Quebec, Canada, with an additional 13 lake-based studies from temperate regions across the northern hemisphere, Lapierre and del Giorgio suggest that on a regional scale the A variety of lakes dominate the boreal landscape of Quebec, Canada. elevation of lakes is one of the strongest controls on the relationship between DOC and pCO2 in boreal lakes.

Atlantic cod actively avoid CO2 and predator odour, even after long-term CO2 exposure.

PubMed

Jutfelt, Fredrik; Hedgärde, Maria

2013-12-27

The rising atmospheric CO2 level is continuously driving the dissolution of more CO2 into the oceans, and some emission scenarios project that the surface waters may reach 1000 μatm by the end of the century. It is not known if fish can detect moderately elevated CO2 levels, and if they avoid areas with high CO2. If so, avoidance behaviour to water with high CO2 could affect movement patterns and migrations of fish in the future. It is also being increasingly recognized that fish behaviour can be altered by exposure to CO2. Therefore this study investigated how long-term exposure to elevated pCO2 affects predator avoidance and CO2 avoidance in juvenile Atlantic cod (Gadus morhua). The fish were exposed to control water or CO2-enriched water (1000 μatm) for six weeks before being subjected to tests of behaviour. Despite long term exposure to elevated pCO2 the cod still strongly avoided the smell of a predator. These data are surprising because several coral reef fish have demonstrated reversal of olfactory responses after CO2 exposure, turning avoidance of predator cues into preference for predator cues. Fish from both treatment groups also demonstrated strong avoidance of CO2 when presented with the choice of control or CO2-acidified water, indicating that habituation to the CO2 sensory stimuli is negligible. As Atlantic cod maintained normal behavioural responses to olfactory cues, they may be tolerant to CO2-induced behavioural changes. The results also suggest that despite the long-term exposure to CO2-acidified water, the fish still preferred the control water over CO2-acidified water. Therefore, in the future, fish may alter their movements and migrations in search of waters with a lower CO2 content.

Atlantic cod actively avoid CO2 and predator odour, even after long-term CO2 exposure

PubMed Central

2013-01-01

Introduction The rising atmospheric CO2 level is continuously driving the dissolution of more CO2 into the oceans, and some emission scenarios project that the surface waters may reach 1000 μatm by the end of the century. It is not known if fish can detect moderately elevated CO2 levels, and if they avoid areas with high CO2. If so, avoidance behaviour to water with high CO2 could affect movement patterns and migrations of fish in the future. It is also being increasingly recognized that fish behaviour can be altered by exposure to CO2. Therefore this study investigated how long-term exposure to elevated pCO2 affects predator avoidance and CO2 avoidance in juvenile Atlantic cod (Gadus morhua). The fish were exposed to control water or CO2-enriched water (1000 μatm) for six weeks before being subjected to tests of behaviour. Results Despite long term exposure to elevated pCO2 the cod still strongly avoided the smell of a predator. These data are surprising because several coral reef fish have demonstrated reversal of olfactory responses after CO2 exposure, turning avoidance of predator cues into preference for predator cues. Fish from both treatment groups also demonstrated strong avoidance of CO2 when presented with the choice of control or CO2-acidified water, indicating that habituation to the CO2 sensory stimuli is negligible. Conclusions As Atlantic cod maintained normal behavioural responses to olfactory cues, they may be tolerant to CO2-induced behavioural changes. The results also suggest that despite the long-term exposure to CO2-acidified water, the fish still preferred the control water over CO2-acidified water. Therefore, in the future, fish may alter their movements and migrations in search of waters with a lower CO2 content. PMID:24373523

Interactions between tectonics, silicate weathering, and climate explored with carbon cycle modeling

NASA Astrophysics Data System (ADS)

Penman, D. E.; Caves Rugenstein, J. K.; Ibarra, D. E.; Winnick, M.

2017-12-01

Earth's long-term carbon cycle is thought to benefit from a stabilizing negative feedback in the form of CO2 consumption by the chemical weathering of silicate minerals: during periods of elevated atmospheric pCO2, chemical weathering rates increase, thus consuming more atmospheric CO2 and cooling global climate, whereas during periods of low pCO2, weathering rates decrease, allowing buildup of CO2 in the atmosphere and warming. At equilibrium, CO2 consumption by silicate weathering balances volcanic CO2 degassing at a specific atmospheric pCO2 dictated by the relationship between total silicate weathering rate and pCO2: Earth's "weathering curve." We use numerical carbon cycle modeling to demonstrate that the shape and slope of the weathering curve is crucial to understanding proposed tectonic controls on pCO2 and climate. First, the shape of the weathering curve dictates the equilibrium response of the carbon cycle to changes in the rate of background volcanic/solid Earth CO2 degassing, which has been suggested to vary significantly with plate tectonic reorganizations over geologic timescales. Second, we demonstrate that if tectonic events can significantly change the weathering curve, this can act as an effective driver of pCO2 and climate on tectonic timescales by changing the atmospheric pCO2 at which silicate weathering balances a constant volcanic/solid Earth degassing rate. Finally, we review the complex interplay of environmental factors that affect modern weathering rates in the field and highlight how the resulting uncertainty surrounding the shape of Earth's weathering curve significantly hampers our ability to quantitatively predict the response of pCO2 and climate to tectonic forcing, and thus represents a substantial knowledge gap in Earth science. We conclude with strategies for closing this knowledge gap by using precise paleoclimatic reconstructions of intervals with known tectonic forcings.

Serum 11 beta-hydroxyandrostenedione as an indicator of the source of excess androgen production in women with polycystic ovaries.

PubMed

Polson, D W; Reed, M J; Franks, S; Scanlon, M J; James, V H

1988-05-01

Serum 11 beta-hydroxyandrostenedione levels (11-OHA) were measured in normal women and women with polycystic ovaries (PCO) to assess their value in localizing the source of excessive androgen production in women with PCO. Serum 11-OHA was undetectable (less than 1.5 nmol/L) in an adrenalectomized woman, a woman with 11-hydroxylase deficiency, and a woman receiving chronic dexamethasone therapy, confirming the specificity of the antiserum used in this study. Serum 11-OHA concentrations were similar in normal women [mean, 5.0 +/- 2.3 (+/- SD) nmol/L] and women with PCO (5.0 +/- 2.1 nmol/L); serum androstenedione concentrations were increased in women with PCO. Thus, the ratio of androstenedione to 11-OHA was significantly higher (P less than 0.001) in women with PCO (2.0 +/- 0.7) than in normal women (1.1 +/- 0.5). Serum 11-OHA levels after adrenal suppression or stimulation were similar in women with PCO who had an ovulatory response and those who failed to ovulate after clomiphene administration. Administration of dexamethasone (1 mg) and injection of ACTH (250 micrograms) were associated with marked suppression and subsequent stimulation of serum 11-OHA levels in both normal women and women with PCO, and the responses were similar in the two groups. Also, the hour to hour and diurnal variations in serum 11-OHA were similar to those of androstenedione and cortisol during a 24-h period, indicating the adrenal origin of 11-OHA. Our finding of similar serum 11-OHA levels in the presence of increased serum androstenedione levels in women with PCO supports the concept that the ovary is the major source of excess androgen production in women with PCO.

detrimentally affects tissue regeneration of Red Sea corals

NASA Astrophysics Data System (ADS)

Horwitz, Rael; Fine, Maoz

2014-09-01

Ocean acidification (OA) from rising atmospheric carbon dioxide (CO2) is threatening the future of coral reef ecosystems. Mounting experimental evidence suggests that OA negatively impacts fundamental life functions of scleractinian corals, including growth and sexual reproduction. Although regeneration is regarded as a chief life function in scleractinian corals and essential to maintain the colony's integrity, the effect of OA on regeneration processes has not yet been investigated. To evaluate the effects of OA on regeneration, the common Indo-Pacific corals Porites sp., Favia favus, Acropora eurystoma, and Stylophora pistillata were inflicted with lesions (314-350 mm2, depending on species) and incubated in different pCO2: (1) ambient seawater (400 µatm, pH 8.1), (2) intermediate (1,800 µatm, pH 7.6), and (3) high (4,000 µatm, pH 7.3) for extended periods of time (60-120 d). While all coral species after 60 d had significantly higher tissue regeneration in ambient conditions as compared to the intermediate and high treatments, reduction in regeneration rate was more pronounced in the slow-growing massive Porites sp. and F. favus than the relatively fast-growing, branching S. pistillata and A. eurystoma. This coincided with reduced tissue biomass of Porites sp., F. favus, and A. eurystoma in higher pCO2, but not in S. pistillata. Porites sp., F. favus, and S. pistillata also experienced a decrease in Symbiodinium density in higher pCO2, while in A. eurystoma there was no change. We hypothesize that a lowered regenerative capacity under elevated pCO2 may be related to resource trade-offs, energy cost of acid/base regulation, and/or decrease in total energy budget. This is the first study to demonstrate that elevated pCO2 could have a compounding influence on coral regeneration following injury, potentially affecting the capacity of reef corals to recover following physical disturbance.

CO2 induced seawater acidification impacts sea urchin larval development I: elevated metabolic rates decrease scope for growth and induce developmental delay.

PubMed

Stumpp, M; Wren, J; Melzner, F; Thorndyke, M C; Dupont, S T

2011-11-01

Anthropogenic CO(2) emissions are acidifying the world's oceans. A growing body of evidence is showing that ocean acidification impacts growth and developmental rates of marine invertebrates. Here we test the impact of elevated seawater pCO(2) (129 Pa, 1271 μatm) on early development, larval metabolic and feeding rates in a marine model organism, the sea urchin Strongylocentrotus purpuratus. Growth and development was assessed by measuring total body length, body rod length, postoral rod length and posterolateral rod length. Comparing these parameters between treatments suggests that larvae suffer from a developmental delay (by ca. 8%) rather than from the previously postulated reductions in size at comparable developmental stages. Further, we found maximum increases in respiration rates of +100% under elevated pCO(2), while body length corrected feeding rates did not differ between larvae from both treatments. Calculating scope for growth illustrates that larvae raised under high pCO(2) spent an average of 39 to 45% of the available energy for somatic growth, while control larvae could allocate between 78 and 80% of the available energy into growth processes. Our results highlight the importance of defining a standard frame of reference when comparing a given parameter between treatments, as observed differences can be easily due to comparison of different larval ages with their specific set of biological characters. Copyright © 2011 Elsevier Inc. All rights reserved.

Sensitivity to ocean acidification differs between populations of the Sydney rock oyster: Role of filtration and ion-regulatory capacities.

PubMed

Stapp, Laura S; Parker, Laura M; O'Connor, Wayne A; Bock, Christian; Ross, Pauline M; Pörtner, Hans O; Lannig, G

2018-04-01

Understanding mechanisms of intraspecific variation in resilience to environmental drivers is key to predict species' adaptive potential. Recent studies show a higher CO 2 resilience of Sydney rock oysters selectively bred for increased growth and disease resistance ('selected oysters') compared to the wild population. We tested whether the higher resilience of selected oysters correlates with an increased ability to compensate for CO 2 -induced acid-base disturbances. After 7 weeks of exposure to elevated seawater PCO 2 (1100 μatm), wild oysters had a lower extracellular pH (pH e = 7.54 ± 0.02 (control) vs. 7.40 ± 0.03 (elevated PCO 2 )) and increased hemolymph PCO 2 whereas extracellular acid-base status of selected oysters remained unaffected. However, differing pH e values between oyster types were not linked to altered metabolic costs of major ion regulators (Na + /K + -ATPase, H + -ATPase and Na + /H + -exchanger) in gill and mantle tissues. Our findings suggest that selected oysters possess an increased systemic capacity to eliminate metabolic CO 2 , possibly through higher and energetically more efficient filtration rates and associated gas exchange. Thus, effective filtration and CO 2 resilience might be positively correlated traits in oysters. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ocean acidification and nutrient limitation synergistically reduce growth and photosynthetic performances of a green tide alga Ulva linza

NASA Astrophysics Data System (ADS)

Gao, Guang; Beardall, John; Bao, Menglin; Wang, Can; Ren, Wangwang; Xu, Juntian

2018-06-01

Large-scale green tides have been invading the coastal zones of the western Yellow Sea annually since 2008. Meanwhile, oceans are becoming more acidic due to continuous absorption of anthropogenic carbon dioxide, and intensive seaweed cultivation in Chinese coastal areas is leading to severe regional nutrient limitation. However, little is known about the combined effects of global and local stressors on the eco-physiology of bloom-forming algae. We cultured Ulva linza for 9-16 days under two levels of pCO2 (400 and 1000 µatm) and four treatments of nutrients (nutrient repletion, N limitation, P limitation, and N-P limitation) to investigate the physiological responses of this green tide alga to the combination of ocean acidification and nutrient limitation. For both sporelings and adult plants, elevated pCO2 did not affect the growth rate when cultured under nutrient-replete conditions but reduced it under P limitation; N or P limitations by themselves reduced growth rate. P limitation resulted in a larger inhibition in growth for sporelings compared to adult plants. Sporelings under P limitation did not reach the mature stage after 16 days of culture while those under P repletion became mature by day 11. Elevated pCO2 reduced net photosynthetic rate for all nutrient treatments but increased nitrate reductase activity and soluble protein content under P-replete conditions. N or P limitation reduced nitrate reductase activity and soluble protein content. These findings indicate that ocean acidification and nutrient limitation would synergistically reduce the growth of Ulva species and may thus hinder the occurrence of green tides in a future ocean environment.

Stage-Specific Changes in Physiological and Life-History Responses to Elevated Temperature and Pco2 during the Larval Development of the European Lobster Homarus gammarus (L.).

PubMed

Small, Daniel P; Calosi, Piero; Boothroyd, Dominic; Widdicombe, Steve; Spicer, John I

2015-01-01

An organism's physiological processes form the link between its life-history traits and the prevailing environmental conditions, especially in species with complex life cycles. Understanding how these processes respond to changing environmental conditions, thereby affecting organismal development, is critical if we are to predict the biological implications of current and future global climate change. However, much of our knowledge is derived from adults or single developmental stages. Consequently, we investigated the metabolic rate, organic content, carapace mineralization, growth, and survival across each larval stage of the European lobster Homarus gammarus, reared under current and predicted future ocean warming and acidification scenarios. Larvae exhibited stage-specific changes in the temperature sensitivity of their metabolic rate. Elevated Pco2 increased C∶N ratios and interacted with elevated temperature to affect carapace mineralization. These changes were linked to concomitant changes in survivorship and growth, from which it was concluded that bottlenecks were evident during H. gammarus larval development in stages I and IV, the transition phases between the embryonic and pelagic larval stages and between the larval and megalopa stages, respectively. We therefore suggest that natural changes in optimum temperature during ontogeny will be key to larvae survival in a future warmer ocean. The interactions of these natural changes with elevated temperature and Pco2 significantly alter physiological condition and body size of the last larval stage before the transition from a planktonic to a benthic life style. Thus, living and growing in warm, hypercapnic waters could compromise larval lobster growth, development, and recruitment.

The acclimation process of phytoplankton biomass, carbon fixation and respiration to the combined effects of elevated temperature and pCO2 in the northern South China Sea.

PubMed

Gao, Guang; Jin, Peng; Liu, Nana; Li, Futian; Tong, Shanying; Hutchins, David A; Gao, Kunshan

2017-05-15

We conducted shipboard microcosm experiments at both off-shore (SEATS) and near-shore (D001) stations in the northern South China Sea (NSCS) under three treatments, low temperature and low pCO 2 (LTLC), high temperature and low pCO 2 (HTLC), and high temperature and high pCO 2 (HTHC). Biomass of phytoplankton at both stations were enhanced by HT. HTHC did not affect phytoplankton biomass at station D001 but decreased it at station SEATS. HT alone increased net primary productivity by 234% at station SEATS and by 67% at station D001 but the stimulating effect disappeared when HC was combined. HT also increased respiration rate by 236% at station SEATS and by 87% at station D001 whereas HTHC reduced it by 61% at station SEATS and did not affect it at station D001. Overall, our findings indicate that the positive effect of ocean warming on phytoplankton assemblages in NSCS could be damped or offset by ocean acidification. Copyright © 2017 Elsevier Ltd. All rights reserved.

The relative availability of inorganic carbon and inorganic nitrogen influences the response of the dinoflagellate Protoceratium reticulatum to elevated CO2.

PubMed

Pierangelini, Mattia; Raven, John A; Giordano, Mario

2017-04-01

This work originates from three facts: (i) changes in CO 2 availability influence metabolic processes in algal cells; (ii) Spatial and temporal variations of nitrogen availability cause repercussions on phytoplankton physiology; (iii) Growth and cell composition are dependent on the stoichiometry of nutritional resources. In this study, we assess whether the impact of rising pCO 2 is influenced by N availability, through the impact that it would have on the C/N stoichiometry, in conditions of N sufficiency. Our experiments used the dinoflagellate Protoceratium reticulatum, which we cultured under three CO 2 regimes (400, 1,000, and 5,000 ppmv, pH of 8.1) and either variable (the NO 3 - concentration was always 2.5 mmol · L -1 ) or constant (NO 3 - concentration varied to maintain the same C i /NO 3 - ratio at all pCO 2 ) C i /NO 3 - ratio. Regardless of N availability, cells had higher specific growth rates, but lower cell dry weight and C and N quotas, at elevated CO 2 . The carbohydrate pool size and the C/N was unaltered in all treatments. The lipid content only decreased at high pCO 2 at constant C i /NO 3 - ratio. In the variable C i /NO 3 - conditions, the relative abundance of Rubisco (and other proteins) also changed; this did not occur at constant C i /NO 3 - . Thus, the biomass quality of P. reticulatum for grazers was affected by the C i /NO 3 - ratio in the environment and not only by the pCO 2 , both with respect to the size of the main organic pools and the composition of the expressed proteome. © 2016 Phycological Society of America.

Calcification persists with CO2-induced ocean acidification but decreases with warming for the Caribbean coral Siderastrea siderea

NASA Astrophysics Data System (ADS)

Castillo, K. D.; Ries, J. B.; Westfield, I. T.; Weiss, J. M.; Bruno, J. F.

2012-12-01

Atmospheric carbon dioxide (pCO2) induced ocean acidification and rising seawater temperatures are identified as two of the greatest threats to modern coral reefs. Within this century, surface seawater pH is expected to decrease by at least 0.3 units, and sea surface temperature is predicted to rise by 1 to 3 °C. However, uncertainty remains as to whether ocean acidification or ocean warming will have a more deleterious impact on coral reefs by the end of the century. Here, we present results of 95-day laboratory experiments in which we investigated the impact of CO2-induced ocean acidification and temperature on the calcification rate of the tropical reef-building zooxanthellate scleractinian coral Siderastrea siderea. We found that calcification rates for S. siderea, estimated from buoyant weighing, increased as pCO2 increased from a pre-industrial value of 324 ppm to a near-present-day value of 477 ppm, remained unchanged as pCO2 increased from 477 ppm to the predicted end-of-century value of 604 ppm, and only declined at 6-times the modern pCO2 value of 2553 ppm. Corals reared at average pCO2 of 488 ppm and at temperatures of 25 and 32 °C, approximately the lower and upper temperature extremes for this species, calcified at lower rates relative to corals reared at 28 °C under equivalent pCO2. These results support the existing evidence that scleractinian corals such as S. siderea are able to manipulate the carbonate chemistry at their calcification site, enabling them to maintain their calcification rates under elevated pCO2 levels predicted for the end of this century. However, exposure of S. siderea corals to sea surface temperatures predicted for tropical waters for the end of this century grossly impaired their rate of calcification. These findings suggest that ocean warming poses a more immediate threat to the coral S. siderea than does ocean acidification, at least under scenarios (B1, A1T, and B2) predicted by the Intergovernmental Panel on Climate Change for the end of the 21st century. We are presently investigating the calcification responses of S. siderea to the combined effects of ocean acidification and warming, in order to better constrain how corals will respond to global CO2-induced changes that are predicted for the near future.

Adverse effects of ocean acidification on early development of squid (Doryteuthis pealeii).

PubMed

Kaplan, Maxwell B; Mooney, T Aran; McCorkle, Daniel C; Cohen, Anne L

2013-01-01

Anthropogenic carbon dioxide (CO2) is being absorbed into the ocean, altering seawater chemistry, with potentially negative impacts on a wide range of marine organisms. The early life stages of invertebrates with internal and external aragonite structures may be particularly vulnerable to this ocean acidification. Impacts to cephalopods, which form aragonite cuttlebones and statoliths, are of concern because of the central role they play in many ocean ecosystems and because of their importance to global fisheries. Atlantic longfin squid (Doryteuthis pealeii), an ecologically and economically valuable taxon, were reared from eggs to hatchlings (paralarvae) under ambient and elevated CO2 concentrations in replicated experimental trials. Animals raised under elevated pCO2 demonstrated significant developmental changes including increased time to hatching and shorter mantle lengths, although differences were small. Aragonite statoliths, critical for balance and detecting movement, had significantly reduced surface area and were abnormally shaped with increased porosity and altered crystal structure in elevated pCO2-reared paralarvae. These developmental and physiological effects could alter squid paralarvae behavior and survival in the wild, directly and indirectly impacting marine food webs and commercial fisheries.

Adverse Effects of Ocean Acidification on Early Development of Squid (Doryteuthis pealeii)

PubMed Central

Kaplan, Maxwell B.; Mooney, T. Aran; McCorkle, Daniel C.; Cohen, Anne L.

2013-01-01

Anthropogenic carbon dioxide (CO2) is being absorbed into the ocean, altering seawater chemistry, with potentially negative impacts on a wide range of marine organisms. The early life stages of invertebrates with internal and external aragonite structures may be particularly vulnerable to this ocean acidification. Impacts to cephalopods, which form aragonite cuttlebones and statoliths, are of concern because of the central role they play in many ocean ecosystems and because of their importance to global fisheries. Atlantic longfin squid (Doryteuthis pealeii), an ecologically and economically valuable taxon, were reared from eggs to hatchlings (paralarvae) under ambient and elevated CO2 concentrations in replicated experimental trials. Animals raised under elevated pCO2 demonstrated significant developmental changes including increased time to hatching and shorter mantle lengths, although differences were small. Aragonite statoliths, critical for balance and detecting movement, had significantly reduced surface area and were abnormally shaped with increased porosity and altered crystal structure in elevated pCO2-reared paralarvae. These developmental and physiological effects could alter squid paralarvae behavior and survival in the wild, directly and indirectly impacting marine food webs and commercial fisheries. PMID:23741298

Skeletal mineralogy of coral recruits under high temperature and pCO2

NASA Astrophysics Data System (ADS)

Foster, T.; Clode, P. L.

2015-08-01

Aragonite, which is the polymorph of CaCO3 precipitated by modern corals during skeletal formation, has a higher solubility than the more stable polymorph calcite. This higher solubility leaves animals that produce aragonitic skeletons more vulnerable to anthropogenic ocean acidification. It is therefore, important to determine whether scleractinian corals have the plasticity to adapt and produce calcite in their skeletons in response to changing environmental conditions. Both high pCO2 and lower Mg / Ca ratios in seawater are thought to have driven changes in the skeletal mineralogy of major marine calcifiers in the past ∼540 myr. Experimentally reduced Mg / Ca ratios in ambient seawater have been shown to induce some calcite precipitation in both adult and newly settled modern corals, however, the impact of high pCO2 on the mineralogy of recruits is unknown. Here we determined the skeletal mineralogy of one-month old Acropora spicifera coral recruits grown under high temperature (+3 °C) and pCO2 (∼900 μatm) conditions, using X-ray diffraction and Raman spectroscopy. We found that newly settled coral recruits produced entirely aragonitic skeletons regardless of the treatment. Our results show that elevated pCO2 alone is unlikely to drive changes in the skeletal mineralogy of young corals. Not having an ability to switch from aragonite to calcite precipitation may leave corals and ultimately coral reef ecosystems more susceptible to predicted ocean acidification. An important area for prospective research would be to investigate the combined impact of high pCO2 and reduced Mg / Ca ratio on coral skeletal mineralogy.

Skeletal mineralogy of coral recruits under high temperature and pCO2

NASA Astrophysics Data System (ADS)

Foster, T.; Clode, P. L.

2016-03-01

Aragonite, which is the polymorph of CaCO3 precipitated by modern corals during skeletal formation, has a higher solubility than the more stable polymorph calcite. This higher solubility may leave animals that produce aragonitic skeletons more vulnerable to anthropogenic ocean acidification. It is therefore important to determine whether scleractinian corals have the plasticity to adapt and produce calcite in their skeletons in response to changing environmental conditions. Both high pCO2 and lower Mg / Ca ratios in seawater are thought to have driven changes in the skeletal mineralogy of major marine calcifiers in the past ˜ 540 Ma. Experimentally reduced Mg / Ca ratios in ambient seawater have been shown to induce some calcite precipitation in both adult and newly settled modern corals; however, the impact of high pCO2 on the mineralogy of recruits is unknown. Here we determined the skeletal mineralogy of 1-month-old Acropora spicifera coral recruits grown under high temperature (+3 °C) and pCO2 (˜ 900 µatm) conditions, using X-ray diffraction and Raman spectroscopy. We found that newly settled coral recruits produced entirely aragonitic skeletons regardless of the treatment. Our results show that elevated pCO2 alone is unlikely to drive changes in the skeletal mineralogy of young corals. Not having an ability to switch from aragonite to calcite precipitation may leave corals and ultimately coral reef ecosystems more susceptible to predicted ocean acidification. An important area for prospective research would be the investigation of the combined impact of high pCO2 and reduced Mg / Ca ratio on coral skeletal mineralogy.

Neural control of breathing and CO2 homeostasis

PubMed Central

Guyenet, P.G.; Bayliss, D.A

2015-01-01

Summary Recent advances have clarified how the brain detects CO2 to regulate breathing (central respiratory chemoreception). These mechanisms are reviewed and their significance is presented in the general context of CO2/pH homeostasis through breathing. At rest, respiratory chemoreflexes initiated at peripheral and central sites mediate rapid stabilization of arterial PCO2 and pH. Specific brainstem neurons (e.g., retrotrapezoid nucleus, RTN; serotonergic) are activated by PCO2 and stimulate breathing. RTN neurons detect CO2 via intrinsic proton receptors (TASK-2, GPR4), synaptic input from peripheral chemoreceptors and signals from astrocytes. Respiratory chemoreflexes are arousal state-dependent whereas chemoreceptor stimulation produces arousal. When abnormal, these interactions lead to sleep-disordered breathing. During exercise, “central command” and reflexes from exercising muscles produce the breathing stimulation required to maintain arterial PCO2 and pH despite elevated metabolic activity. The neural circuits underlying central command and muscle afferent control of breathing remain elusive and represent a fertile area for future investigation. PMID:26335642

An ecophysiological study of the Azolla filiculoides- Anabaena azollae association

NASA Astrophysics Data System (ADS)

van Kempen, Monique; Smolders, Fons; Speelman, Eveline; Reichart, Gert Jan; Barke, Judith; Brinkhuis, Henk; Lotter, Andy; Roelofs, Jan

2010-05-01

The long term effects of salinity stress on the growth, nutrient content and amino acid composition of the Azolla filiculoides - Anabaena azollae association was studied in a laboratory experiment. It was demonstrated that the symbiosis could tolerate salt stress up to 90 mM NaCl, even after a 100 day period of preconditioning at salt concentrations that were 30 mM NaCl lower. In the 120 mM NaCl treatment the Azolla filiculoides survived, but hardly any new biomass was produced. It was shown that during the experiment, A. filiculoides became increasingly efficient in excluding salt ions from the plant tissue and was thus able to increase its salt tolerance. The amino acid analysis revealed that the naturally occurring high glutamine concentration in the plants was strongly reduced at salt concentrations of 120 mM NaCl and higher. This was the result of the reduced nitrogenase activity at these salt concentrations, as was demonstrated in an acetylene reduction assay. We suggest that the high glutamine concentration in the plants might play a role in the osmoregulatory response against salt stress, enabling growth of the A. filiculoides -Anabaena azollae association up to 90 mM NaCl. In a mesocosm experiment it furthermore was demonstrated that Azolla might manipulate its own microenvironment when grown at elevated salt concentration (up to ~50 mmol•L-1) by promoting salinity stratification, especially when it has formed a dense cover at the water surface. Beside salt stress, we also studied the growth of Azolla filiculoides in response to elevated atmospheric carbon dioxide concentration, in combination with different light intensities and different pH of the nutrient solution. The results demonstrated that as compared to the control (ambient pCO2 concentrations), Azolla filiculoides was able to produce twice as much biomass at carbon dioxide concentrations that were five times as high as the ambient pCO2 concentration. However, it was also shown that this response was much less pronounced at light intensities that were too high or too low, or when the nutrient solution had a higher pH. At higher light intensities and higher pH the growth response to elevated atmospheric CO2 was probably overruled by an increased competition with algae, while at low light intensities, light became limiting in the photosynthetic processes. In order to get a better understanding of the carbon metabolism of the Azolla -Anabena association we are currently performing experiments with labeled bicarbonate and/or carbon dioxide. Analysis of the samples is still in progress but should be ready at the time of the congress. The fore mentioned results might help to better understand the occurrence of ancestral Azolla species in the central Arctic Ocean some 50 mya, as was found by Brinkhuis et al. (2006). The results obtained in the experiment with elevated atmospheric pCO2 concentrations for example were useful in estimating the impact of the Arctic Azolla bloom on carbon drawdown. Speelman et al. (2009) estimated that storing 0,9• 10 18 to 3,5•10 18 g carbon would result in a 55 to 470 ppm drawdown of pCO2 under Eocene conditions, indicating that the Arctic Azolla bloom might have had a significant effect on global atmospheric pCO2 levels through enhanced burial of organic matter.

Reproductive trade-offs in a temperate reef fish under high pCO2 levels.

PubMed

Faria, A M; Lopes, A F; Silva, C S E; Novais, S C; Lemos, M F L; Gonçalves, E J

2018-06-01

Fishes are currently facing novel types of anthropogenic stressors that have never experienced in their evolutionary history, such as ocean acidification. Under these stressful conditions, energetically costly processes, such as reproduction, may be sacrificed for increased chances of survival. This trade-off does not only affect the organism itself but may result in reduced offspring fitness. In the present study, the effects of exposure to high pCO 2 levels were tested on the reproductive performance of a temperate species, the two-spotted goby, Gobiusculus flavescens. Breeding pairs were kept under control (∼600 μatm, pH∼ 8.05) and high pCO 2 levels (∼2300 μatm, pH∼ 7.60) conditions for a 4-month period. Additionally, oxidative stress and energy metabolism-related biomarkers were measured. Results suggest that reproductive activity is stimulated under high pCO 2 levels. Parental pairs in the simulated ocean acidification conditions exhibited increased reproductive output, with 50% more clutches and 44% more eggs per clutch than pairs under control conditions. However, there was an apparent trade-off between offspring number and size, as larvae of parental pairs under high pCO 2 levels hatched significantly smaller, suggesting differences in parental provisioning, which could be related to the fact that these females produce more eggs. Moreover, results support the hypothesis of different energy allocation strategies used by females under high pCO 2 conditions. These changes might, ultimately, affect individual fitness and population replenishment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Predicting Effects of Coastal Acidification on Marine Bivalve ...

EPA Pesticide Factsheets

The partial pressure of carbon dioxide (pCO2) is increasing in the oceans and causing changes in seawater pH commonly described as ocean or coastal acidification. It is now well-established that, when reproduced in laboratory experiments, these increases in pCO2 can reduce survival and growth of early life stage bivalves. However, the effects that these impairments would have on whole populations of bivalves are unknown. In this study, these laboratory responses were incorporated into field-parameterized population models to assess population-level sensitivities to acidification for two northeast bivalve species with different life histories: Mercenaria mercenaria (hard clam) and Argopecten irradians (bay scallop). The resulting models permitted translation of laboratory pCO2 response functions into population-level responses to examine population sensitivity to future pCO2 changes. Preliminary results from our models indicate that if the current M. mercenaria negative population growth rate was attributed to the effects of pCO2 on early life stages, the population would decline at a rate of 50% per ten years at 420 microatmospheres (µatm) pCO2. If the current population growth rate was attributed to other additive factors (e.g., harvest, harmful algal blooms), M. mercenaria populations were predicted to decline at a rate of 50% per ten years at the preliminary estimate of 1010 µatm pCO2. The estimated population growth rate was positive for A. irradians,

A deep-time CO2 barometer based on triple oxygen isotope compositions of dinosaurian eggshell carbonate

NASA Astrophysics Data System (ADS)

Hu, H.; Passey, B. H.; Montanari, S.; Levin, N.; Li, S.

2013-12-01

Photochemical reactions in the stratosphere lead to mass independent fractionation of oxygen isotopes: oxygen exchange among O2, O3, and CO2 produces 17O-enriched O3 and CO2, and 17O-depleted O2. This effect increases with increasing atmospheric CO2 concentration, and thus the 17O anomaly of O2, Δ17O (O2), is reflective of pCO2. Animals incorporate this signal into body water via respiration, and minerals such as bioapatite and eggshell calcite forming in equilibrium with body water can preserve the signal for millions of years. We contribute to the development of this new pCO2 barometer by developing analytical methods for high-precision triple oxygen isotope analysis of carbonates, by developing an ecophysiological model of body water triple oxygen isotopes, and by applying the method to eggshell from modern birds and late Cretaceous (Campanian and Maastrichtian) dinosaur eggshells. Our findings include the following: (1) If animal ecophysiology and climatic context are perfectly known, the sensitivity of Δ17O (body water) to atmospheric CO2 is on the order of 0.01 ‰ per 100 ppm CO2; our analytical precision is ~ 0.01 ‰, thus ultimately permitting sub -100 ppm - level pCO2 reconstructions. (2) However, the effect of ecophysiology and climate can lead to a range in Δ17O (body water) of about 0.15 ‰ for animals living under the same Δ17O (O2); this prediction, confirmed by analyses of eggshells and body water of modern birds, translates to an apparent pCO2 range of about 1500 ppm. (3) Animals that are highly dependent on unevaporated free surface water ('drinking water') and live in humid climates have Δ17O (body water) signals that mimic low pCO2, whereas animals that consume primarily evaporated water (e.g., leaf water) and living in arid environments have Δ17O (body water) signals that mimic high pCO2. (4) There is an upper limit to this 'evaporation / aridity' effect mimicking high pCO2, so Δ17O (fossil eggshell) can be modeled assuming such upper limits to produce conservative lower limits on estimates of past pCO2. (5) We find that late Cretaceous Δ17O (fossil eggshell) is generally lower than modern Δ17O (eggshell), implying generally higher pCO2 during the late Cretaceous. The lowest observed Δ17O (fossil eggshell) value implies CO2 levels of at least 1200 ppm, and probably closer to 2000 ppm, for at least a short interval of Campanian time. Overall, this triple oxygen isotope approach shows promise for placing constraints on past CO2 levels. While somewhat limited in precision, it has the benefits of little appreciable loss of sensitivity with increasing pCO2, no presently-known mechanism for generating 'false positive' estimates of high pCO2 (except for extremely low atmospheric O2 levels and low primary productivity), and a basis that is fundamentally different from existing methods, thus allowing for independent new constraints on past CO2 levels.

Growth habit and leaf economics determine gas exchange responses to high elevation in an evergreen tree, a deciduous shrub and a herbaceous annual

PubMed Central

Shi, Zuomin; Haworth, Matthew; Feng, Qiuhong; Cheng, Ruimei; Centritto, Mauro

2015-01-01

Plant growth at high elevations necessitates physiological and morphological plasticity to enable photosynthesis (A) under conditions of reduced temperature, increased radiation and the lower partial pressure of atmospheric gases, in particular carbon dioxide (pCO2). Previous studies have observed a wide range of responses to elevation in plant species depending on their adaptation to temperature, elevational range and growth habit. Here, we investigated the effect of an increase in elevation from 2500 to 3500 m above sea level (a.s.l.) on three montane species with contrasting growth habits and leaf economic strategies. While all of the species showed identical increases in foliar δ13C, dark respiration and nitrogen concentration with elevation, contrasting leaf gas exchange and photosynthetic responses were observed between species with different leaf economic strategies. The deciduous shrub Salix atopantha and annual herb Rumex dentatus exhibited increased stomatal (Gs) and mesophyll (Gm) conductance and enhanced photosynthetic capacity at the higher elevation. However, evergreen Quercus spinosa displayed reduced conductance to CO2 that coincided with lower levels of photosynthetic carbon fixation at 3500 m a.s.l. The lower Gs and Gm values of evergreen species at higher elevations currently constrains their rates of A. Future rises in the atmospheric concentration of CO2 ([CO2]) will likely predominantly affect evergreen species with lower specific leaf areas (SLAs) and levels of Gm rather than deciduous species with higher SLA and Gm values. We argue that climate change may affect plant species that compose high-elevation ecosystems differently depending on phenotypic plasticity and adaptive traits affecting leaf economics, as rising [CO2] is likely to benefit evergreen species with thick sclerophyllous leaves. PMID:26433706

Food Supply and Seawater pCO2 Impact Calcification and Internal Shell Dissolution in the Blue Mussel Mytilus edulis

PubMed Central

Melzner, Frank; Stange, Paul; Trübenbach, Katja; Thomsen, Jörn; Casties, Isabel; Panknin, Ulrike; Gorb, Stanislav N.; Gutowska, Magdalena A.

2011-01-01

Progressive ocean acidification due to anthropogenic CO2 emissions will alter marine ecosytem processes. Calcifying organisms might be particularly vulnerable to these alterations in the speciation of the marine carbonate system. While previous research efforts have mainly focused on external dissolution of shells in seawater under saturated with respect to calcium carbonate, the internal shell interface might be more vulnerable to acidification. In the case of the blue mussel Mytilus edulis, high body fluid pCO2 causes low pH and low carbonate concentrations in the extrapallial fluid, which is in direct contact with the inner shell surface. In order to test whether elevated seawater pCO2 impacts calcification and inner shell surface integrity we exposed Baltic M. edulis to four different seawater pCO2 (39, 142, 240, 405 Pa) and two food algae (310–350 cells mL−1 vs. 1600–2000 cells mL−1) concentrations for a period of seven weeks during winter (5°C). We found that low food algae concentrations and high pCO2 values each significantly decreased shell length growth. Internal shell surface corrosion of nacreous ( = aragonite) layers was documented via stereomicroscopy and SEM at the two highest pCO2 treatments in the high food group, while it was found in all treatments in the low food group. Both factors, food and pCO2, significantly influenced the magnitude of inner shell surface dissolution. Our findings illustrate for the first time that integrity of inner shell surfaces is tightly coupled to the animals' energy budget under conditions of CO2 stress. It is likely that under food limited conditions, energy is allocated to more vital processes (e.g. somatic mass maintenance) instead of shell conservation. It is evident from our results that mussels exert significant biological control over the structural integrity of their inner shell surfaces. PMID:21949698

Food supply and seawater pCO2 impact calcification and internal shell dissolution in the blue mussel Mytilus edulis.

PubMed

Melzner, Frank; Stange, Paul; Trübenbach, Katja; Thomsen, Jörn; Casties, Isabel; Panknin, Ulrike; Gorb, Stanislav N; Gutowska, Magdalena A

2011-01-01

Progressive ocean acidification due to anthropogenic CO(2) emissions will alter marine ecosystem processes. Calcifying organisms might be particularly vulnerable to these alterations in the speciation of the marine carbonate system. While previous research efforts have mainly focused on external dissolution of shells in seawater under saturated with respect to calcium carbonate, the internal shell interface might be more vulnerable to acidification. In the case of the blue mussel Mytilus edulis, high body fluid pCO(2) causes low pH and low carbonate concentrations in the extrapallial fluid, which is in direct contact with the inner shell surface. In order to test whether elevated seawater pCO(2) impacts calcification and inner shell surface integrity we exposed Baltic M. edulis to four different seawater pCO(2) (39, 142, 240, 405 Pa) and two food algae (310-350 cells mL(-1) vs. 1600-2000 cells mL(-1)) concentrations for a period of seven weeks during winter (5°C). We found that low food algae concentrations and high pCO(2) values each significantly decreased shell length growth. Internal shell surface corrosion of nacreous ( = aragonite) layers was documented via stereomicroscopy and SEM at the two highest pCO(2) treatments in the high food group, while it was found in all treatments in the low food group. Both factors, food and pCO(2), significantly influenced the magnitude of inner shell surface dissolution. Our findings illustrate for the first time that integrity of inner shell surfaces is tightly coupled to the animals' energy budget under conditions of CO(2) stress. It is likely that under food limited conditions, energy is allocated to more vital processes (e.g. somatic mass maintenance) instead of shell conservation. It is evident from our results that mussels exert significant biological control over the structural integrity of their inner shell surfaces.

Monthly CO2 at A4HDYD station in a productive shallow marginal sea (Yellow Sea) with a seasonal thermocline: Controlling processes

NASA Astrophysics Data System (ADS)

Xu, Xuemei; Zang, Kunpeng; Zhao, Huade; Zheng, Nan; Huo, Cheng; Wang, Juying

2016-07-01

Based upon 21 field surveys conducted from March 2011 to November 2013, monthly variation of carbon dioxide partial pressure (pCO2) and other carbon system parameters were investigated for the first time (to our knowledge) at A4HDYD station (38°40‧N, 122°10‧E) located in the North Yellow Sea, a region with a seasonal thermocline. Surface pCO2 was undersaturated from March to May and nearly in equilibrium with the atmosphere from June to August. During September and November, pCO2 declined to a lower level than that from June to August, but reached the highest level in December. In contrast, pCO2 declined to atmospheric CO2 levels in February. Overall, the study area was a net CO2 sink at a rate of 0.85 ± 0.59 mol C m- 2 yr- 1. The underlying processes governing the variation of pCO2 were also examined. In general, temperature had an important influence on the monthly variation of pCO2, but its effect was counterbalanced by biological production in spring and vertical mixing in early winter. Our study indicated that dynamic mechanism studies based on high temporal resolution observations are urgently needed to understand the complexity of the carbon cycle and detect biogeochemical changes or ecosystem responses to climate change on continental margins.

Effects of Temperature and pCO2 on Population Regulation of Symbiodinium spp. in a Tropical Reef Coral.

PubMed

Baghdasarian, Garen; Osberg, Andrew; Mihora, Danielle; Putnam, Hollie; Gates, Ruth D; Edmunds, Peter J

2017-04-01

This study tested the bleaching response of the Pacific coral Seriatopora caliendrum to short-term exposure to high temperature and elevated partial pressure of carbon dioxide (pCO 2 ). Juvenile colonies collected from Nanwan Bay, Taiwan, were used in a factorial experimental design in which 2 temperatures (∼27.6 °C and ∼30.4 °C) and 2 pCO 2 values (∼47.2 Pa and ∼90.7 Pa) were crossed to evaluate, over 12 days, the effects on the densities and physiology of the symbiotic dinoflagellates (Symbiodinium) in the corals. Thermal bleaching, as defined by a reduction of Symbiodinium densities at high temperature, was unaffected by high pCO 2 . The division, or mitotic index (MI), of Symbiodinium remaining in thermally bleached corals was about 35% lower than in control colonies, but they contained about 53% more chlorophyll. Bleaching was highly variable among colonies, but the differences were unrelated to MI or pigment content of Symbiodinium remaining in the coral host. At the end of the study, all of the corals contained clade C Symbiodinium (either C1d or C15), and the genetic variation of symbionts did not account for among-colony bleaching differences. These results showed that high temperature causes coral bleaching independent of pCO 2 , and underscores the potential role of the coral host in driving intraspecific variation in coral bleaching.

Elevated temperature and PCO2 shift metabolic pathways in differentially oxidative tissues of Notothenia rossii.

PubMed

Strobel, Anneli; Leo, Elettra; Pörtner, Hans O; Mark, Felix C

2013-09-01

Mitochondrial plasticity plays a central role in setting the capacity for acclimation of aerobic metabolism in ectotherms in response to environmental changes. We still lack a clear picture if and to what extent the energy metabolism and mitochondrial enzymes of Antarctic fish can compensate for changing temperatures or PCO2 and whether capacities for compensation differ between tissues. We therefore measured activities of key mitochondrial enzymes (citrate synthase (CS), cytochrome c oxidase (COX)) from heart, red muscle, white muscle and liver in the Antarctic fish Notothenia rossii after warm- (7°C) and hypercapnia- (0.2kPa CO2) acclimation vs. control conditions (1°C, 0.04kPa CO2). In heart, enzymes showed elevated activities after cold-hypercapnia acclimation, and a warm-acclimation-induced upward shift in thermal optima. The strongest increase in enzyme activities in response to hypercapnia occurred in red muscle. In white muscle, enzyme activities were temperature-compensated. CS activity in liver decreased after warm-normocapnia acclimation (temperature-compensation), while COX activities were lower after cold- and warm-hypercapnia exposure, but increased after warm-normocapnia acclimation. In conclusion, warm-acclimated N. rossii display low thermal compensation in response to rising energy demand in highly aerobic tissues, such as heart and red muscle. Chronic environmental hypercapnia elicits increased enzyme activities in these tissues, possibly to compensate for an elevated energy demand for acid-base regulation or a compromised mitochondrial metabolism, that is predicted to occur in response to hypercapnia exposure. This might be supported by enhanced metabolisation of liver energy stores. These patterns reflect a limited capacity of N. rossii to reorganise energy metabolism in response to rising temperature and PCO2. © 2013.

Calcification rates and the effect of ocean acidification on Mediterranean cold-water corals

PubMed Central

Maier, C.; Watremez, P.; Taviani, M.; Weinbauer, M. G.; Gattuso, J. P.

2012-01-01

Global environmental changes, including ocean acidification, have been identified as a major threat to scleractinian corals. General predictions are that ocean acidification will be detrimental to reef growth and that 40 to more than 80 per cent of present-day reefs will decline during the next 50 years. Cold-water corals (CWCs) are thought to be strongly affected by changes in ocean acidification owing to their distribution in deep and/or cold waters, which naturally exhibit a CaCO3 saturation state lower than in shallow/warm waters. Calcification was measured in three species of Mediterranean cold-water scleractinian corals (Lophelia pertusa, Madrepora oculata and Desmophyllum dianthus) on-board research vessels and soon after collection. Incubations were performed in ambient sea water. The species M. oculata was additionally incubated in sea water reduced or enriched in CO2. At ambient conditions, calcification rates ranged between −0.01 and 0.23% d−1. Calcification rates of M. oculata under variable partial pressure of CO2 (pCO2) were the same for ambient and elevated pCO2 (404 and 867 µatm) with 0.06 ± 0.06% d−1, while calcification was 0.12 ± 0.06% d−1 when pCO2 was reduced to its pre-industrial level (285 µatm). This suggests that present-day CWC calcification in the Mediterranean Sea has already drastically declined (by 50%) as a consequence of anthropogenic-induced ocean acidification. PMID:22130603

Reduced plant water status under sub-ambient pCO2 limits plant productivity in the wild progenitors of C3 and C4 cereals

PubMed Central

Cunniff, Jennifer; Charles, Michael; Jones, Glynis; Osborne, Colin P.

2016-01-01

Background and Aims The reduction of plant productivity by low atmospheric CO2 partial pressure (pCO2) during the last glacial period is proposed as a limiting factor for the establishment of agriculture. Supporting this hypothesis, previous work has shown that glacial pCO2 limits biomass in the wild progenitors of C3 and C4 founder crops, in part due to the direct effects of glacial pCO2 on photosynthesis. Here, we investigate the indirect role of pCO2 mediated via water status, hypothesizing that faster soil water depletion at glacial (18 Pa) compared to post-glacial (27 Pa) pCO2, due to greater stomatal conductance, feeds back to limit photosynthesis during drying cycles. Methods We grew four wild progenitors of C3 and C4 crops at glacial and post-glacial pCO2 and investigated physiological changes in gas exchange, canopy transpiration, soil water content and water potential between regular watering events. Growth parameters including leaf area were measured. Key Results Initial transpiration rates were higher at glacial pCO2 due to greater stomatal conductance. However, stomatal conductance declined more rapidly over the soil drying cycle in glacial pCO2 and was associated with decreased intercellular pCO2 and lower photosynthesis. Soil water content was similar between pCO2 levels as larger leaf areas at post-glacial pCO2 offset the slower depletion of water. Instead the feedback could be linked to reduced plant water status. Particularly in the C4 plants, soil–leaf water potential gradients were greater at 18 Pa compared with 27 Pa pCO2, suggesting an increased ratio of leaf evaporative demand to supply. Conclusions Reduced plant water status appeared to cause a negative feedback on stomatal aperture in plants at glacial pCO2, thereby reducing photosynthesis. The effects were stronger in C4 species, providing a mechanism for reduced biomass at 18 Pa. These results have added significance when set against the drier climate of the glacial period. PMID:27578764

Volcanic carbon dioxide vents show ecosystem effects of ocean acidification.

PubMed

Hall-Spencer, Jason M; Rodolfo-Metalpa, Riccardo; Martin, Sophie; Ransome, Emma; Fine, Maoz; Turner, Suzanne M; Rowley, Sonia J; Tedesco, Dario; Buia, Maria-Cristina

2008-07-03

The atmospheric partial pressure of carbon dioxide (p(CO(2))) will almost certainly be double that of pre-industrial levels by 2100 and will be considerably higher than at any time during the past few million years. The oceans are a principal sink for anthropogenic CO(2) where it is estimated to have caused a 30% increase in the concentration of H(+) in ocean surface waters since the early 1900s and may lead to a drop in seawater pH of up to 0.5 units by 2100 (refs 2, 3). Our understanding of how increased ocean acidity may affect marine ecosystems is at present very limited as almost all studies have been in vitro, short-term, rapid perturbation experiments on isolated elements of the ecosystem. Here we show the effects of acidification on benthic ecosystems at shallow coastal sites where volcanic CO(2) vents lower the pH of the water column. Along gradients of normal pH (8.1-8.2) to lowered pH (mean 7.8-7.9, minimum 7.4-7.5), typical rocky shore communities with abundant calcareous organisms shifted to communities lacking scleractinian corals with significant reductions in sea urchin and coralline algal abundance. To our knowledge, this is the first ecosystem-scale validation of predictions that these important groups of organisms are susceptible to elevated amounts of p(CO(2)). Sea-grass production was highest in an area at mean pH 7.6 (1,827 (mu)atm p(CO(2))) where coralline algal biomass was significantly reduced and gastropod shells were dissolving due to periods of carbonate sub-saturation. The species populating the vent sites comprise a suite of organisms that are resilient to naturally high concentrations of p(CO(2)) and indicate that ocean acidification may benefit highly invasive non-native algal species. Our results provide the first in situ insights into how shallow water marine communities might change when susceptible organisms are removed owing to ocean acidification.

Response of Spring Diatoms to CO2 Availability in the Western North Pacific as Determined by Next-Generation Sequencing.

PubMed

Endo, Hisashi; Sugie, Koji; Yoshimura, Takeshi; Suzuki, Koji

2016-01-01

Next-generation sequencing (NGS) technologies have enabled us to determine phytoplankton community compositions at high resolution. However, few studies have adopted this approach to assess the responses of natural phytoplankton communities to environmental change. Here, we report the impact of different CO2 levels on spring diatoms in the Oyashio region of the western North Pacific as estimated by NGS of the diatom-specific rbcL gene (DNA), which encodes the large subunit of RubisCO. We also examined the abundance and composition of rbcL transcripts (cDNA) in diatoms to assess their physiological responses to changing CO2 levels. A short-term (3-day) incubation experiment was carried out on-deck using surface Oyashio waters under different pCO2 levels (180, 350, 750, and 1000 μatm) in May 2011. During the incubation, the transcript abundance of the diatom-specific rbcL gene decreased with an increase in seawater pCO2 levels. These results suggest that CO2 fixation capacity of diatoms decreased rapidly under elevated CO2 levels. In the high CO2 treatments (750 and 1000 μatm), diversity of diatom-specific rbcL gene and its transcripts decreased relative to the control treatment (350 μatm), as well as contributions of Chaetocerataceae, Thalassiosiraceae, and Fragilariaceae to the total population, but the contributions of Bacillariaceae increased. In the low CO2 treatment, contributions of Bacillariaceae also increased together with other eukaryotes. These suggest that changes in CO2 levels can alter the community composition of spring diatoms in the Oyashio region. Overall, the NGS technology provided us a deeper understanding of the response of diatoms to changes in CO2 levels in terms of their community composition, diversity, and photosynthetic physiology.

Parameterization of the response of calcification to temperature and pCO2 in the coral Acropora pulchra and the alga Lithophyllum kotschyanum

NASA Astrophysics Data System (ADS)

Comeau, S.; Carpenter, R. C.; Lantz, C. A.; Edmunds, P. J.

2016-09-01

The response of tropical corals and calcifying algae to ocean acidification (OA) and warming has received much attention in the past decade. However, most studies have evaluated the response of organisms to two or three temperature treatments, which does not allow the functional relationship between calcification and temperature under ambient and future pCO2 to be determined. This study tested the hypothesis that the relationship between calcification and temperature is affected by OA in the coral Acropora pulchra and the calcified alga Lithophyllum kotschyanum. Pieces of each organism were incubated under five (24-30 °C) or six (24-31.5 °C) temperatures crossed with two pCO2 levels (400 and 1000 μatm), and calcification was assessed in trials conducted in the spring and summer. The response of coral calcification to temperature was a positive asymmetric parabola with a maximum at ~28 °C under both pCO2 levels and in both seasons; the effects of pCO2 on calcification were largest at ~28 °C and lowest in both cool and warm temperatures. In contrast, calcification of the alga at both levels of pCO2 was unaffected by temperature in spring, but declined linearly with temperature in summer. This study demonstrates that the calcification response of coral reef organisms to the crossed effect of warming and OA is complex and cannot be fully assessed without using multiple temperature treatments that are ecologically relevant.

Polycystic ovaries at ultrasound: normal variant or silent polycystic ovary syndrome?

PubMed

Catteau-Jonard, S; Bancquart, J; Poncelet, E; Lefebvre-Maunoury, C; Robin, G; Dewailly, D

2012-08-01

It is not known whether polycystic ovaries (PCO) are an ovarian appearance without pathological meaning or whether they share with polycystic ovary syndrome (PCOS) the same ovarian follicle abnormality. There are few studies including strictly selected women with PCO but without other criteria of PCOS. In order to address these issues, we compared hormonal, metabolic and ultrasound parameters obtained from patients with PCO only, patients with PCOS and controls. This was a comparative analysis including three age-matched groups of 95 patients, who were included consecutively in a database: controls, patients with sonographic PCO but no symptoms (PCO group) and patients with PCOS. A clinical examination, fasting serum sampling and pelvic ultrasound examination were performed between cycle days 2 and 5 and results were compared between groups. The median serum anti-Mullerian hormone (AMH) level in the PCO group was intermediate between that in controls and that in the PCOS group (33.6 pmol/L, 19.8 pmol/L and 63.3 pmol/L, respectively), the differences being significant after adjustment for follicle number (P < 0.05), while the mean androgen serum level in the PCO group was similar to that in the control group and significantly lower than that in the PCOS group (P < 0.05) (median serum testosterone levels: 0.90 nmol/L, 0.79 nmol/L and 1.39 nmol/L; median androstenedione levels: 5.25 nmol/L, 4.37 nmol/L and 6.09 nmol/L, respectively). Body mass index, waist circumference and insulin levels had no effect on these differences. PCO is an abnormal condition, affected women showing no evidence of hyperandrogenism but having higher AMH serum levels compared with controls, suggesting a granulosa cell abnormality in PCO similar to that observed in PCOS. The absence of hyperandrogenism in PCO does not seem linked to the metabolic status. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.

pCO2 effects on species composition and growth of an ...

EPA Pesticide Factsheets

The effects of ongoing changes in ocean carbonate chemistry on plankton ecology have important implications for food webs and biogeochemical cycling. However, conflicting results have emerged regarding species-specific responses to pCO2 enrichment and thus community responses have been difficult to predict. To assess community level effects (e.g., production) of altered carbonate chemistry, studies are needed that capitalize on the benefits of controlled experiments but also retain features of intact ecosystems that may exacerbate or ameliorate the effects observed in single-species or single cohort experiments. We performed incubations of natural plankton communities from Narragansett Bay, RI, USA in winter at ambient bay temperatures (5–13 °C), light and nutrient concentrations under three levels of controlled and constant CO2 concentrations, simulating past, present and future conditions at mean pCO2 levels of 224, 361, and 724 μatm respectively. Samples for carbonate analysis, chlorophyll a, plankton size-abundance, and plankton species composition were collected daily and phytoplankton growth rates in three different size fractions (20 μm) were measured at the end of the 7-day incubation period. Community composition changed during the incubation period with major increases in relative diatom abundance, which were similar across pCO2 treatments. At the end of the experiment, 24-hr growth responses to pCO2 levels varied as a function of cell size. The s

Responses of calcification of massive and encrusting corals to past, present, and near-future ocean carbon dioxide concentrations.

PubMed

Iguchi, Akira; Kumagai, Naoki H; Nakamura, Takashi; Suzuki, Atsushi; Sakai, Kazuhiko; Nojiri, Yukihiro

2014-12-15

In this study, we report the acidification impact mimicking the pre-industrial, the present, and near-future oceans on calcification of two coral species (Porites australiensis, Isopora palifera) by using precise pCO2 control system which can produce acidified seawater under stable pCO2 values with low variations. In the analyses, we performed Bayesian modeling approaches incorporating the variations of pCO2 and compared the results between our modeling approach and classical statistical one. The results showed highest calcification rates in pre-industrial pCO2 level and gradual decreases of calcification in the near-future ocean acidification level, which suggests that ongoing and near-future ocean acidification would negatively impact coral calcification. In addition, it was expected that the variations of parameters of carbon chemistry may affect the inference of the best model on calcification responses to these parameters between Bayesian modeling approach and classical statistical one even under stable pCO2 values with low variations. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ocean acidification effects on mesozooplankton community development: Results from a long-term mesocosm experiment.

PubMed

Algueró-Muñiz, María; Alvarez-Fernandez, Santiago; Thor, Peter; Bach, Lennart T; Esposito, Mario; Horn, Henriette G; Ecker, Ursula; Langer, Julia A F; Taucher, Jan; Malzahn, Arne M; Riebesell, Ulf; Boersma, Maarten

2017-01-01

Ocean acidification may affect zooplankton directly by decreasing in pH, as well as indirectly via trophic pathways, where changes in carbon availability or pH effects on primary producers may cascade up the food web thereby altering ecosystem functioning and community composition. Here, we present results from a mesocosm experiment carried out during 113 days in the Gullmar Fjord, Skagerrak coast of Sweden, studying plankton responses to predicted end-of-century pCO2 levels. We did not observe any pCO2 effect on the diversity of the mesozooplankton community, but a positive pCO2 effect on the total mesozooplankton abundance. Furthermore, we observed species-specific sensitivities to pCO2 in the two major groups in this experiment, copepods and hydromedusae. Also stage-specific pCO2 sensitivities were detected in copepods, with copepodites being the most responsive stage. Focusing on the most abundant species, Pseudocalanus acuspes, we observed that copepodites were significantly more abundant in the high-pCO2 treatment during most of the experiment, probably fuelled by phytoplankton community responses to high-pCO2 conditions. Physiological and reproductive output was analysed on P. acuspes females through two additional laboratory experiments, showing no pCO2 effect on females' condition nor on egg hatching. Overall, our results suggest that the Gullmar Fjord mesozooplankton community structure is not expected to change much under realistic end-of-century OA scenarios as used here. However, the positive pCO2 effect detected on mesozooplankton abundance could potentially affect biomass transfer to higher trophic levels in the future.

Ocean acidification effects on mesozooplankton community development: Results from a long-term mesocosm experiment

PubMed Central

Algueró-Muñiz, María; Alvarez-Fernandez, Santiago; Thor, Peter; Bach, Lennart T.; Esposito, Mario; Horn, Henriette G.; Ecker, Ursula; Langer, Julia A. F.; Taucher, Jan; Malzahn, Arne M.; Riebesell, Ulf; Boersma, Maarten

2017-01-01

Ocean acidification may affect zooplankton directly by decreasing in pH, as well as indirectly via trophic pathways, where changes in carbon availability or pH effects on primary producers may cascade up the food web thereby altering ecosystem functioning and community composition. Here, we present results from a mesocosm experiment carried out during 113 days in the Gullmar Fjord, Skagerrak coast of Sweden, studying plankton responses to predicted end-of-century pCO2 levels. We did not observe any pCO2 effect on the diversity of the mesozooplankton community, but a positive pCO2 effect on the total mesozooplankton abundance. Furthermore, we observed species-specific sensitivities to pCO2 in the two major groups in this experiment, copepods and hydromedusae. Also stage-specific pCO2 sensitivities were detected in copepods, with copepodites being the most responsive stage. Focusing on the most abundant species, Pseudocalanus acuspes, we observed that copepodites were significantly more abundant in the high-pCO2 treatment during most of the experiment, probably fuelled by phytoplankton community responses to high-pCO2 conditions. Physiological and reproductive output was analysed on P. acuspes females through two additional laboratory experiments, showing no pCO2 effect on females’ condition nor on egg hatching. Overall, our results suggest that the Gullmar Fjord mesozooplankton community structure is not expected to change much under realistic end-of-century OA scenarios as used here. However, the positive pCO2 effect detected on mesozooplankton abundance could potentially affect biomass transfer to higher trophic levels in the future. PMID:28410436

Atmospheric pCO2 reconstructed across five early Eocene global warming events

NASA Astrophysics Data System (ADS)

Cui, Ying; Schubert, Brian A.

2017-11-01

Multiple short-lived global warming events, known as hyperthermals, occurred during the early Eocene (56-52 Ma). Five of these events - the Paleocene-Eocene Thermal Maximum (PETM or ETM1), H1 (or ETM2), H2, I1, and I2 - are marked by a carbon isotope excursion (CIE) within both marine and terrestrial sediments. The magnitude of CIE, which is a function of the amount and isotopic composition of carbon added to the ocean-atmosphere system, varies significantly between marine versus terrestrial substrates. Here we use the increase in carbon isotope fractionation by C3 land plants in response to increased pCO2 to reconcile this difference and reconstruct a range of background pCO2 and peak pCO2 for each CIE, provided two potential carbon sources: methane hydrate destabilization and permafrost-thawing/organic matter oxidation. Although the uncertainty on each pCO2 estimate using this approach is low (e.g., median uncertainty = + 23% / - 18%), this work highlights the potential for significant systematic bias in the pCO2 estimate resulting from sampling resolution, substrate type, diagenesis, and environmental change. Careful consideration of each of these factors is required especially when applying this approach to a single marine-terrestrial CIE pair. Given these limitations, we provide an upper estimate for background early Eocene pCO2 of 463 +248/-131 ppmv (methane hydrate scenario) to 806 +127/-104 ppmv (permafrost-thawing/organic matter oxidation scenario). These results, which represent the first pCO2 proxy estimates directly tied to the Eocene hyperthermals, demonstrate that early Eocene warmth was supported by background pCO2 less than ∼3.5× preindustrial levels and that pCO2 > 1000 ppmv may have occurred only briefly, during hyperthermal events.

Calcification in Caribbean reef-building corals at high pCO2 levels in a recirculating ocean acidification exposure system

EPA Science Inventory

Projected increases in ocean pCO2 levels are anticipated to affect calcifying organisms more rapidly and to a greater extent than other marine organisms. The effects of ocean acidification (OA) have been documented in numerous species of corals in laboratory studies, largely test...

Dissolution Rates of Biogenic Carbonate Sediments from the Bermuda Platform

NASA Astrophysics Data System (ADS)

Finlay, A. J.; Andersson, A. J.

2016-02-01

The contribution of biogenic carbonate sediment dissolution rates to overall net reef accretion/erosion (under both present and future oceanic pCO2 levels) has been strikingly neglected, despite experimental results indicating that sediment dissolution might be more sensitive to ocean acidification (OA) than calcification. Dissolution of carbonate sediments could impact net reef accretion rates as well as the formation and preservation of valuable marine and terrestrial ecosystems. Bulk sediment dissolution rates of samples from the Bermuda carbonate platform were measured in natural seawater at pCO2 values ranging from approximately 3500 μatm to 9000 μatm. This range of pCO2 levels incorporates values currently observed in porewaters on the Bermuda carbonate platform as well as a potential future increase in porewater pCO2 levels due to OA. Sediment samples from two different stations on the reef platform were analyzed for grain size and mineralogy. Dissolution rates of sediments in the dominant grain size fraction of the platform (500-1000 μm) from both stations ranged between 16.25 and 47.19 (± 0.27 to 0.79) μmoles g-1 hr-1 and are comparable to rates previously obtained from laboratory experiments on other natural carbonate sediments. At a pCO2 of 3500 μatm, rates from both samples were similar, despite their differing mineralogy. However, at pCO2 levels above 3500 μatm, the sediment sample with a greater weight percent of Mg-calcite had slightly higher dissolution rates. Despite many laboratory studies on biogenic carbonate dissolution, a significant disparity still exists between laboratory measurements and field observations. Performing additional controlled, laboratory experiments on natural sediment may help to elucidate the reasons for this disparity.

Plant growth chamber design for subambient pCO2 and δ13 C studies.

PubMed

Hagopian, William M; Schubert, Brian A; Graper, Robert A; Jahren, A Hope

2018-05-23

Subambient pCO 2 has persisted across the major Phanerozoic ice ages, including the entire late Cenozoic (~30 Ma to present). Stable isotope analysis of plant-derived organic matter is used to infer changes in pCO 2 and climate in the geologic past, but a growth chamber that can precisely control environmental conditions, including pCO 2 and δ 13 C value of CO 2 (δ 13 C CO2 ) at subambient pCO 2 , is lacking. We designed and built five identical chambers specifically for plant growth under stable subambient pCO 2 (~100 to 400 ppm) and δ 13 C CO2 conditions. We tested the pCO 2 and δ 13 C CO2 stability of the chambers both with and without plants, across two 12-hour daytime experiments and two extended 9-day experiments. We also compared the temperature and relative humidity conditions among the chambers. The average δ 13 C CO2 value within the five chambers ranged from -18.76 ‰ to -19.10 ‰; the standard deviation never exceeded 0.14 ‰ across any experiment. This represents better δ 13 C CO2 stability than that achieved by all previous chamber designs, including superambient pCO 2 chambers. Every pCO 2 measurement (n = 1225) was within 5 % of mean chamber values. The temperature and relative humidity conditions differed by no more than 1.6 % and 0.4 °C, respectively, across all chambers within each growth experiment. This growth chamber design extends the range of pCO 2 conditions for which plants can be grown for δ 13 C analysis of their tissues at subambient levels. This new capability allows for careful isolation of environmental effects on plant 13 C discrimination across the entire range of pCO 2 experienced by terrestrial land plants. This article is protected by copyright. All rights reserved.

Availability of phosphate for phytoplankton and bacteria and of glucose for bacteria at different pCO2 levels in a mesocosm study

NASA Astrophysics Data System (ADS)

Tanaka, T.; Thingstad, T. F.; Løvdal, T.; Grossart, H.-P.; Larsen, A.; Allgaier, M.; Meyerhöfer, M.; Schulz, K. G.; Wohlers, J.; Zöllner, E.; Riebesell, U.

2008-05-01

Availability of phosphate for phytoplankton and bacteria and of glucose for bacteria at different pCO2 levels were studied in a mesocosm experiment (PeECE III). Using nutrient-depleted SW Norwegian fjord waters, three different levels of pCO2 (350 μatm: 1×CO2; 700 μatm: 2×CO2; 1050 μatm: 3×CO2) were set up, and nitrate and phosphate were added at the start of the experiment in order to induce a phytoplankton bloom. Despite similar responses of total particulate P concentration and phosphate turnover time at the three different pCO2 levels, the size distribution of particulate P and 33PO4 uptake suggested that phosphate transferred to the >10 μm fraction was greater in the 3×CO2 mesocosm during the first 6-10 days when phosphate concentration was high. During the period of phosphate depletion (after Day 12), specific phosphate affinity and specific alkaline phosphatase activity (APA) suggested a P-deficiency (i.e. suboptimal phosphate supply) rather than a P-limitation for the phytoplankton and bacterial community at the three different pCO2 levels. Specific phosphate affinity and specific APA tended to be higher in the 3×CO2 than in the 2×CO2 and 1×CO2 mesocosms during the phosphate depletion period, although no statistical differences were found. Glucose turnover time was correlated significantly and negatively with bacterial abundance and production but not with the bulk DOC concentration. This suggests that even though constituting a small fraction of the bulk DOC, glucose was an important component of labile DOC for bacteria. Specific glucose affinity of bacteria behaved similarly at the three different pCO2 levels with measured specific glucose affinities being consistently much lower than the theoretical maximum predicted from the diffusion-limited model. This suggests that bacterial growth was not severely limited by the glucose availability. Hence, it seems that the lower availability of inorganic nutrients after the phytoplankton bloom reduced the bacterial capacity to consume labile DOC in the upper mixed layer of the stratified mesocosms.

Effects of Ocean Acidification on Fish Eggs and Larvae in Laboratory Experiments and Naturally High-pCO2 Upwelling Systems

NASA Astrophysics Data System (ADS)

Shen, S.; Checkley, D. M., Jr.

2016-02-01

We investigated the effects of elevated pCO2 on (1) the morphology and behavior of fish larvae in laboratory experiments and (2) the distribution and abundance of fish eggs and larvae in an upwelling system. The vestibulo-ocular reflex (VOR) is a compensatory eye rotation that stabilizes images during movement and is initiated by utricular otolith movement. It is critically important for survival. We identified a 38% increase in the area of the utricular otoliths of larval white seabass (Atractoscion nobilis) reared at 2500 μatm pCO2 (treatment) compared to that of larvae reared at 400 μatm pCO2 (control). Despite the increase in otolith size, the mean gain of treatment larvae (0.39 ± 0.05, n= 28) was not statistically different from that of control larvae (0.30 ± 0.03, n= 20). During a fisheries research cruise in the Peruvian upwelling system in 2013, we collected eggs and larvae of Peruvian anchoveta (Engraulis ringens) over a wide range of pCO2, from 200-1200 μatm. Anchoveta support the world's largest single-species fishery and reside in arguably the most persistently high-pCO2 environment in the ocean. The probability of egg capture was maximal at the lowest (<350 μatm) as well as highest (>1000 μatm) pCO2 and increased with increasing chlorophyll a concentration. Larval abundance was maximal in the mid-range of zooplankton biovolume (1-3 cm3/1,000 m3). The occurrence of eggs in high pCO2 and relationship of eggs and larvae to food availability are consistent with the hypothesis that anchoveta tolerate a high pCO2 and food environment. Our research on the early life stages of these two fish leads us to believe that species that have evolved in high-pCO2 environments (e.g., anchoveta) may be able to cope with OA. Furthermore, OA may have only subtle effects on behaviors that are critical for survival (e.g., VOR).

High CO2 levels impair alveolar epithelial function independently of pH.

PubMed

Briva, Arturo; Vadász, István; Lecuona, Emilia; Welch, Lynn C; Chen, Jiwang; Dada, Laura A; Trejo, Humberto E; Dumasius, Vidas; Azzam, Zaher S; Myrianthefs, Pavlos M; Batlle, Daniel; Gruenbaum, Yosef; Sznajder, Jacob I

2007-11-28

In patients with acute respiratory failure, gas exchange is impaired due to the accumulation of fluid in the lung airspaces. This life-threatening syndrome is treated with mechanical ventilation, which is adjusted to maintain gas exchange, but can be associated with the accumulation of carbon dioxide in the lung. Carbon dioxide (CO2) is a by-product of cellular energy utilization and its elimination is affected via alveolar epithelial cells. Signaling pathways sensitive to changes in CO2 levels were described in plants and neuronal mammalian cells. However, it has not been fully elucidated whether non-neuronal cells sense and respond to CO2. The Na,K-ATPase consumes approximately 40% of the cellular metabolism to maintain cell homeostasis. Our study examines the effects of increased pCO2 on the epithelial Na,K-ATPase a major contributor to alveolar fluid reabsorption which is a marker of alveolar epithelial function. We found that short-term increases in pCO2 impaired alveolar fluid reabsorption in rats. Also, we provide evidence that non-excitable, alveolar epithelial cells sense and respond to high levels of CO2, independently of extracellular and intracellular pH, by inhibiting Na,K-ATPase function, via activation of PKCzeta which phosphorylates the Na,K-ATPase, causing it to endocytose from the plasma membrane into intracellular pools. Our data suggest that alveolar epithelial cells, through which CO2 is eliminated in mammals, are highly sensitive to hypercapnia. Elevated CO2 levels impair alveolar epithelial function, independently of pH, which is relevant in patients with lung diseases and altered alveolar gas exchange.

Emiliania huxleyi increases calcification but not expression of calcification-related genes in long-term exposure to elevated temperature and pCO2.

PubMed

Benner, Ina; Diner, Rachel E; Lefebvre, Stephane C; Li, Dian; Komada, Tomoko; Carpenter, Edward J; Stillman, Jonathon H

2013-01-01

Increased atmospheric pCO2 is expected to render future oceans warmer and more acidic than they are at present. Calcifying organisms such as coccolithophores that fix and export carbon into the deep sea provide feedbacks to increasing atmospheric pCO2. Acclimation experiments suggest negative effects of warming and acidification on coccolithophore calcification, but the ability of these organisms to adapt to future environmental conditions is not well understood. Here, we tested the combined effect of pCO2 and temperature on the coccolithophore Emiliania huxleyi over more than 700 generations. Cells increased inorganic carbon content and calcification rate under warm and acidified conditions compared with ambient conditions, whereas organic carbon content and primary production did not show any change. In contrast to findings from short-term experiments, our results suggest that long-term acclimation or adaptation could change, or even reverse, negative calcification responses in E. huxleyi and its feedback to the global carbon cycle. Genome-wide profiles of gene expression using RNA-seq revealed that genes thought to be essential for calcification are not those that are most strongly differentially expressed under long-term exposure to future ocean conditions. Rather, differentially expressed genes observed here represent new targets to study responses to ocean acidification and warming.

Ocean acidification exerts negative effects during warming conditions in a developing Antarctic fish

PubMed Central

Flynn, Erin E; Bjelde, Brittany E; Miller, Nathan A

2015-01-01

Abstract Anthropogenic CO2 is rapidly causing oceans to become warmer and more acidic, challenging marine ectotherms to respond to simultaneous changes in their environment. While recent work has highlighted that marine fishes, particularly during early development, can be vulnerable to ocean acidification, we lack an understanding of how life-history strategies, ecosystems and concurrent ocean warming interplay with interspecific susceptibility. To address the effects of multiple ocean changes on cold-adapted, slowly developing fishes, we investigated the interactive effects of elevated partial pressure of carbon dioxide (pCO2) and temperature on the embryonic physiology of an Antarctic dragonfish (Gymnodraco acuticeps), with protracted embryogenesis (∼10 months). Using an integrative, experimental approach, our research examined the impacts of near-future warming [−1 (ambient) and 2°C (+3°C)] and ocean acidification [420 (ambient), 650 (moderate) and 1000 μatm pCO2 (high)] on survival, development and metabolic processes over the course of 3 weeks in early development. In the presence of increased pCO2 alone, embryonic mortality did not increase, with greatest overall survival at the highest pCO2. Furthermore, embryos were significantly more likely to be at a later developmental stage at high pCO2 by 3 weeks relative to ambient pCO2. However, in combined warming and ocean acidification scenarios, dragonfish embryos experienced a dose-dependent, synergistic decrease in survival and developed more slowly. We also found significant interactions between temperature, pCO2 and time in aerobic enzyme activity (citrate synthase). Increased temperature alone increased whole-organism metabolic rate (O2 consumption) and developmental rate and slightly decreased osmolality at the cost of increased mortality. Our findings suggest that developing dragonfish are more sensitive to ocean warming and may experience negative physiological effects of ocean acidification only in the presence of an increased temperature. In addition to reduced hatching success, alterations in development and metabolism due to ocean warming and acidification could have negative ecological consequences owing to changes in phenology (i.e. early hatching) in the highly seasonal Antarctic ecosystem. PMID:27293718

Ocean acidification exerts negative effects during warming conditions in a developing Antarctic fish.

PubMed

Flynn, Erin E; Bjelde, Brittany E; Miller, Nathan A; Todgham, Anne E

2015-01-01

Anthropogenic CO2 is rapidly causing oceans to become warmer and more acidic, challenging marine ectotherms to respond to simultaneous changes in their environment. While recent work has highlighted that marine fishes, particularly during early development, can be vulnerable to ocean acidification, we lack an understanding of how life-history strategies, ecosystems and concurrent ocean warming interplay with interspecific susceptibility. To address the effects of multiple ocean changes on cold-adapted, slowly developing fishes, we investigated the interactive effects of elevated partial pressure of carbon dioxide (pCO2) and temperature on the embryonic physiology of an Antarctic dragonfish (Gymnodraco acuticeps), with protracted embryogenesis (∼10 months). Using an integrative, experimental approach, our research examined the impacts of near-future warming [-1 (ambient) and 2°C (+3°C)] and ocean acidification [420 (ambient), 650 (moderate) and 1000 μatm pCO2 (high)] on survival, development and metabolic processes over the course of 3 weeks in early development. In the presence of increased pCO2 alone, embryonic mortality did not increase, with greatest overall survival at the highest pCO2. Furthermore, embryos were significantly more likely to be at a later developmental stage at high pCO2 by 3 weeks relative to ambient pCO2. However, in combined warming and ocean acidification scenarios, dragonfish embryos experienced a dose-dependent, synergistic decrease in survival and developed more slowly. We also found significant interactions between temperature, pCO2 and time in aerobic enzyme activity (citrate synthase). Increased temperature alone increased whole-organism metabolic rate (O2 consumption) and developmental rate and slightly decreased osmolality at the cost of increased mortality. Our findings suggest that developing dragonfish are more sensitive to ocean warming and may experience negative physiological effects of ocean acidification only in the presence of an increased temperature. In addition to reduced hatching success, alterations in development and metabolism due to ocean warming and acidification could have negative ecological consequences owing to changes in phenology (i.e. early hatching) in the highly seasonal Antarctic ecosystem.

Sand smelt ability to cope and recover from ocean's elevated CO2 levels.

PubMed

Silva, Cátia S E; Lemos, Marco F L; Faria, Ana M; Lopes, Ana F; Mendes, Susana; Gonçalves, Emanuel J; Novais, Sara C

2018-06-15

Considered a major environmental concern, ocean acidification has induced a recent research boost into effects on marine biodiversity and possible ecological, physiological, and behavioural impacts. Although the majority of literature indicate negative effects of future acidification scenarios, most studies are conducted for just a few days or weeks, which may be insufficient to detect the capacity of an organism to adjust to environmental changes through phenotypic plasticity. Here, the effects and the capacity of sand smelt larvae Atherina presbyter to cope and recover (through a treatment combination strategy) from short (15 days) and long-term exposure (45 days) to increasing pCO 2 levels (control: ~515 μatm, pH = 8.07; medium: ~940 μatm, pH = 7.84; high: ~1500 μatm, pH = 7.66) were measured, addressing larval development traits, behavioural lateralization, and biochemical biomarkers related with oxidative stress and damage, and energy metabolism and reserves. Although behavioural lateralization was not affected by high pCO 2 exposure, morphometric changes, energetic costs, and oxidative stress damage were impacted differently through different exposures periods. Generally, short-time exposures led to different responses to either medium or high pCO 2 levels (e.g. development, cellular metabolism, or damage), while on the long-term the response patterns tend to become similar between them, with both acidification scenarios inducing DNA damage and tending to lower growth rates. Additionally, when organisms were transferred to lower acidified condition, they were not able to recover from the mentioned DNA damage impacts. Overall, results suggest that exposure to future ocean acidification scenarios can induce sublethal effects on early life-stages of fish, but effects are dependent on duration of exposure, and are likely not reversible. Furthermore, to improve our understanding on species sensitivity and adaptation strategies, results reinforce the need to use multiple biological endpoints when assessing the effects of ocean acidification on marine organisms. Copyright © 2018 Elsevier Inc. All rights reserved.

Combined effects of acidification and hypoxia on the estuarine ctenophore, Mnemiopsis leidyi

EPA Science Inventory

Estuaries are transitive zones which experience large fluctuations in environmental parameters (temperature, dissolved oxygen, pH, etc.). The interactive effects of reduced dissolved oxygen (DO) and elevated pCO2 on estuarine organisms is not currently well understood. Ctenophore...

Direct and indirect effects of high pCO2 on algal grazing by coral reef herbivores from the Gulf of Aqaba (Red Sea)

NASA Astrophysics Data System (ADS)

Borell, E. M.; Steinke, M.; Fine, M.

2013-12-01

Grazing on marine macroalgae is a key structuring process for coral reef communities. However, ocean acidification from rising atmospheric CO2 concentrations is predicted to adversely affect many marine animals, while seaweed communities may benefit and prosper. We tested how exposure to different pCO2 (400, 1,800 and 4,000 μatm) may affect grazing on the green alga Ulva lactuca by herbivorous fish and sea urchins from the coral reefs in the northern Gulf of Aqaba (Red Sea), either directly, by changing herbivore behaviour, or indirectly via changes in algal palatability. We also determined the effects of pCO2 on algal tissue concentrations of protein and the grazing-deterrent secondary metabolite dimethylsulfoniopropionate (DMSP). Grazing preferences and overall consumption were tested in a series of multiple-choice feeding experiments in the laboratory and in situ following exposure for 14 d (algae) and 28 d (herbivores). 4,000 μatm had a significant effect on the biochemical composition and palatability of U. lactuca. No effects were observed at 1,800 relative to 400 μatm (control). Exposure of U. lactuca to 4,000 μatm resulted in a significant decrease in protein and increase in DMSP concentration. This coincided with a reduced preference for these algae by the sea urchin Tripneustes gratilla and different herbivorous fish species in situ (Acanthuridae, Siganidae and Pomacanthidae). No feeding preferences were observed for the rabbitfish Siganus rivulatus under laboratory conditions. Exposure to elevated pCO2 had no direct effect on the overall algal consumption by T. gratilla and S. rivulatus. Our results show that CO2 has the potential to alter algal palatability to different herbivores which could have important implications for algal abundance and coral community structure. The fact that pCO2 effects were observed only at a pCO2 of 4,000 μatm, however, indicates that algal-grazer interactions may be resistant to predicted pCO2 concentrations in the near future.

Spatial and temporal variability of seawater pCO2 within the Canadian Arctic Archipelago and Baffin Bay during the summer and autumn 2011

NASA Astrophysics Data System (ADS)

Geilfus, N.-X.; Pind, M. L.; Else, B. G. T.; Galley, R. J.; Miller, L. A.; Thomas, H.; Gosselin, M.; Rysgaard, S.; Wang, F.; Papakyriakou, T. N.

2018-03-01

The partial pressure of CO2 in surface water (pCO2sw) measured within the Canadian Arctic Archipelago (CAA) and Baffin Bay was highly variable with values ranging from strongly undersaturated (118 μatm) to slightly supersaturated (419 μatm) with respect to the atmospheric levels ( 386 μatm) during summer and autumn 2011. During summer, melting sea ice contributed to cold and fresh surface water and enhanced the ice-edge bloom, resulting in strong pCO2sw undersaturation. Coronation Gulf was the only area with supersaturated pCO2sw, likely due to warm CO2-enriched freshwater input from the Coppermine River. During autumn, the entire CAA (including Coronation Gulf) was undersaturated, despite generally increasing pCO2sw. Coronation Gulf was the one place where pCO2sw decreased, likely due to seasonal reduction in discharge from the Coppermine River and the decreasing sea surface temperature. The seasonal summer-to-autumn increase in pCO2sw across the archipelago is attributed in part to the continuous uptake of atmospheric CO2 through both summer and autumn and to the seasonal deepening of the surface mixed layer, bringing CO2-rich waters to the surface. These observations demonstrate how freshwater from sea ice melt and rivers affect pCO2sw differently. The general pCO2sw undersaturation during summer-autumn 2011 throughout the CAA and Baffin Bay give an estimated net oceanic sink for atmospheric CO2 over the study period of 11.4 mmol CO2 m-2 d-1, assuming no sea-air CO2 flux exchange across the sea-ice covered areas.

Hypocapnic but Not Metabolic Alkalosis Impairs Alveolar Fluid Reabsorption

PubMed Central

Myrianthefs, Pavlos M.; Briva, Arturo; Lecuona, Emilia; Dumasius, Vidas; Rutschman, David H.; Ridge, Karen M.; Baltopoulos, George J.; Sznajder, Jacob Iasha

2005-01-01

Acid-base disturbances, such as metabolic or respiratory alkalosis, are relatively common in critically ill patients. We examined the effects of alkalosis (hypocapnic or metabolic alkalosis) on alveolar fluid reabsorption in the isolated and continuously perfused rat lung model. We found that alveolar fluid reabsorption after 1 hour was impaired by low levels of CO2 partial pressure (PCO2; 10 and 20 mm Hg) independent of pH levels (7.7 or 7.4). In addition, PCO2 higher than 30 mm Hg or metabolic alkalosis did not have an effect on this process. The hypocapnia-mediated decrease of alveolar fluid reabsorption was associated with decreased Na,K-ATPase activity and protein abundance at the basolateral membranes of distal airspaces. The effect of low PCO2 on alveolar fluid reabsorption was reversible because clearance normalized after correcting the PCO2 back to normal levels. These data suggest that hypocapnic but not metabolic alkalosis impairs alveolar fluid reabsorption. Conceivably, correction of hypocapnic alkalosis in critically ill patients may contribute to the normalization of lung ability to clear edema. PMID:15764729

Hypocapnic but not metabolic alkalosis impairs alveolar fluid reabsorption.

PubMed

Myrianthefs, Pavlos M; Briva, Arturo; Lecuona, Emilia; Dumasius, Vidas; Rutschman, David H; Ridge, Karen M; Baltopoulos, George J; Sznajder, Jacob Iasha

2005-06-01

Acid-base disturbances, such as metabolic or respiratory alkalosis, are relatively common in critically ill patients. We examined the effects of alkalosis (hypocapnic or metabolic alkalosis) on alveolar fluid reabsorption in the isolated and continuously perfused rat lung model. We found that alveolar fluid reabsorption after 1 hour was impaired by low levels of CO2 partial pressure (PCO2; 10 and 20 mm Hg) independent of pH levels (7.7 or 7.4). In addition, PCO2 higher than 30 mm Hg or metabolic alkalosis did not have an effect on this process. The hypocapnia-mediated decrease of alveolar fluid reabsorption was associated with decreased Na,K-ATPase activity and protein abundance at the basolateral membranes of distal airspaces. The effect of low PCO2 on alveolar fluid reabsorption was reversible because clearance normalized after correcting the PCO2 back to normal levels. These data suggest that hypocapnic but not metabolic alkalosis impairs alveolar fluid reabsorption. Conceivably, correction of hypocapnic alkalosis in critically ill patients may contribute to the normalization of lung ability to clear edema.

Ammonium excretion and oxygen respiration of tropical copepods and euphausiids exposed to oxygen minimum zone conditions

NASA Astrophysics Data System (ADS)

Kiko, R.; Hauss, H.; Buchholz, F.; Melzner, F.

2015-10-01

Calanoid copepods and euphausiids are key components of marine zooplankton communities worldwide. Most euphausiids and several copepod species perform diel vertical migrations (DVMs) that contribute to the export of particulate and dissolved matter to midwater depths. In vast areas of the global ocean, and in particular in the eastern tropical Atlantic and Pacific, the daytime distribution depth of many migrating organisms corresponds to the core of the oxygen minimum zone (OMZ). At depth, the animals experience reduced temperature and oxygen partial pressure (pO2) and an increased carbon dioxide partial pressure (pCO2) compared to their near-surface nighttime habitat. Although it is well known that low oxygen levels can inhibit respiratory activity, the respiration response of tropical copepods and euphausiids to relevant pCO2, pO2 and temperature conditions remains poorly parameterized. Further, the regulation of ammonium excretion at OMZ conditions is generally not well understood. It was recently estimated that DVM-mediated ammonium supply considerably fuels bacterial anaerobic ammonium oxidation - a major loss process for fixed nitrogen in the ocean. These estimates were based on the implicit assumption that hypoxia or anoxia in combination with hypercapnia (elevated pCO2) does not result in a downregulation of ammonium excretion. Here we show that exposure to OMZ conditions can result in strong depression of respiration and ammonium excretion in calanoid copepods and euphausiids from the Eastern Tropical North Atlantic and the Eastern Tropical South Pacific. These physiological responses need to be taken into account when estimating DVM-mediated fluxes of carbon and nitrogen into OMZs.

Ikaite crystals in melting sea ice - implications for pCO2 and pH levels in Arctic surface waters

NASA Astrophysics Data System (ADS)

Rysgaard, S.; Glud, R. N.; Lennert, K.; Cooper, M.; Halden, N.; Leakey, R. J. G.; Hawthorne, F. C.; Barber, D.

2012-08-01

A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air-sea CO2 exchange. This has been complicated by the recent discoveries of ikaite (a polymorph of CaCO3·6H2O) in Arctic and Antarctic sea ice, which indicate that multiple chemical transformations occur in sea ice with a possible effect on CO2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km2 (0.5-1 m thick) drifting ice floe in the Fram Strait during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced the ice floe thickness by 0.2 m per week and resulted in an estimated 3.8 ppm decrease of pCO2 in the ocean surface mixed layer. This corresponds to an air-sea CO2 uptake of 10.6 mmol m-2 sea ice d-1 or to 3.3 ton km-2 ice floe week-1. This is markedly higher than the estimated primary production within the ice floe of 0.3-1.3 mmol m-2 sea ice d-1. Finally, the presence of ikaite in sea ice and the dissolution of the mineral during melting of the sea ice and mixing of the melt water into the surface oceanic mixed layer accounted for half of the estimated pCO2 uptake.

[Effect of oxygen tubing connection site on percutaneous oxygen partial pressure and percutaneous carbon dioxide partial pressure in patients with chronic obstructive pulmonary disease during noninvasive positive pressure ventilation].

PubMed

Mi, S; Zhang, L M

2017-04-12

Objective: We evaluated the effects of administering oxygen through nasal catheters inside the mask or through the mask on percutaneous oxygen partial pressure (PcO(2))and percutaneous carbon dioxide partial pressure (PcCO(2)) during noninvasive positive pressure ventilation (NPPV) to find a better way of administering oxygen, which could increase PcO(2) by increasing the inspired oxygen concentration. Methods: Ten healthy volunteers and 9 patients with chronic obstructive pulmonary disease complicated by type Ⅱ respiratory failure were included in this study. Oxygen was administered through a nasal catheter inside the mask or through the mask (oxygen flow was 3 and 5 L/min) during NPPV. PcO(2) and PcCO(2) were measured to evaluate the effects of administering oxygen through a nasal catheter inside the mask or through the mask, indirectly reflecting the effects of administering oxygen through nasal catheter inside the mask or through the mask on inspired oxygen concentration. Results: Compared to administering oxygen through the mask during NPPV, elevated PcO(2) was measured in administering oxygen through the nasal catheter inside the mask, and the differences were statistically significant ( P <0.05). At the same time, there was no significant change in PcCO(2) ( P >0.05). Conclusion: Administering oxygen through a nasal catheter inside the mask during NPPV increased PcO(2) by increasing the inspired oxygen concentration but did not increase PcCO(2). This method of administering oxygen could conserve oxygen and be suitable for family NPPV. Our results also provided theoretical basis for the development of new masks.

Ocean acidification impacts spine integrity but not regenerative capacity of spines and tube feet in adult sea urchins

PubMed Central

Emerson, Chloe E.; Reinardy, Helena C.; Bates, Nicholas R.

2017-01-01

Increasing atmospheric carbon dioxide (CO2) has resulted in a change in seawater chemistry and lowering of pH, referred to as ocean acidification. Understanding how different organisms and processes respond to ocean acidification is vital to predict how marine ecosystems will be altered under future scenarios of continued environmental change. Regenerative processes involving biomineralization in marine calcifiers such as sea urchins are predicted to be especially vulnerable. In this study, the effect of ocean acidification on regeneration of external appendages (spines and tube feet) was investigated in the sea urchin Lytechinus variegatus exposed to ambient (546 µatm), intermediate (1027 µatm) and high (1841 µatm) partial pressure of CO2 (pCO2) for eight weeks. The rate of regeneration was maintained in spines and tube feet throughout two periods of amputation and regrowth under conditions of elevated pCO2. Increased expression of several biomineralization-related genes indicated molecular compensatory mechanisms; however, the structural integrity of both regenerating and homeostatic spines was compromised in high pCO2 conditions. Indicators of physiological fitness (righting response, growth rate, coelomocyte concentration and composition) were not affected by increasing pCO2, but compromised spine integrity is likely to have negative consequences for defence capabilities and therefore survival of these ecologically and economically important organisms. PMID:28573022

Conditions Leading to High CO2 (>5 kPa) in Waterlogged–Flooded Soils and Possible Effects on Root Growth and Metabolism

PubMed Central

GREENWAY, HANK; ARMSTRONG, WILLIAM; COLMER, TIMOTHY D.

2006-01-01

• Aims Soil waterlogging impedes gas exchange with the atmosphere, resulting in low PO2 and often high PCO2. Conditions conducive to development of high PCO2 (5–70 kPa) during soil waterlogging and flooding are discussed. The scant information on responses of roots to high PCO2 in terms of growth and metabolism is reviewed. • Scope PCO2 at 15–70 kPa has been reported for flooded paddy-field soils; however, even 15 kPa PCO2 may not always be reached, e.g. when soil pH is above 7. Increases of PCO2 in soils following waterlogging will develop much more slowly than decreases in PO2; in soil from rice paddies in pots without plants, maxima in PCO2 were reached after 2–3 weeks. There are no reliable data on PCO2 in roots when in waterlogged or flooded soils. In rhizomes and internodes, PCO2 sometimes reached 10 kPa, inferring even higher partial pressures in the roots, as a CO2 diffusion gradient will exist from the roots to the rhizomes and shoots. Preliminary modelling predicts that when PCO2 is higher in a soil than in roots, PCO2 in the roots would remain well below the PCO2 in the soil, particularly when there is ventilation via a well-developed gas-space continuum from the roots to the atmosphere. The few available results on the effects of PCO2 at > 5 kPa on growth have nearly all involved sudden increases to 10–100 kPa PCO2; consequently, the results cannot be extrapolated with certainty to the much more gradual increases of PCO2 in waterlogged soils. Nevertheless, rice in an anaerobic nutrient solution was tolerant to 50 kPa CO2 being suddenly imposed. By contrast, PCO2 at 25 kPa retarded germination of some maize genotypes by 50 %. With regard to metabolism, assuming that the usual pH of the cytoplasm of 7·5 was maintained, every increase of 10 kPa CO2 would result in an increase of 75–90 mm HCO3− in the cytoplasm. pH maintenance would depend on the biochemical and biophysical pH stats (i.e. regulatory systems). Furthermore, there are indications that metabolism is adversely affected when HCO3− in the cytoplasm rises above 50 mm, or even lower; succinic dehydrogenase and cytochrome oxidase are inhibited by HCO3− as low as 10 mm. Such effects could be mitigated by a decrease in the set point for the pH of the cytoplasm, thus lowering levels of HCO3− at the prevailing PCO2 in the roots. • Conclusions Measurements are needed on PCO2 in a range of soil types and in roots of diverse species, during waterlogging and flooding. Species well adapted to high PCO2 in the root zone, such as rice and other wetland plants, thrive even when PCO2 is well over 10 kPa; mechanisms of adaptation, or acclimatization, by these species need exploration. PMID:16644893

Ocean acidification and warming scenarios increase microbioerosion of coral skeletons.

PubMed

Reyes-Nivia, Catalina; Diaz-Pulido, Guillermo; Kline, David; Guldberg, Ove-Hoegh; Dove, Sophie

2013-06-01

Biological mediation of carbonate dissolution represents a fundamental component of the destructive forces acting on coral reef ecosystems. Whereas ocean acidification can increase dissolution of carbonate substrates, the combined impact of ocean acidification and warming on the microbioerosion of coral skeletons remains unknown. Here, we exposed skeletons of the reef-building corals, Porites cylindrica and Isopora cuneata, to present-day (Control: 400 μatm - 24 °C) and future pCO2 -temperature scenarios projected for the end of the century (Medium: +230 μatm - +2 °C; High: +610 μatm - +4 °C). Skeletons were also subjected to permanent darkness with initial sodium hypochlorite incubation, and natural light without sodium hypochlorite incubation to isolate the environmental effect of acidic seawater (i.e., Ωaragonite <1) from the biological effect of photosynthetic microborers. Our results indicated that skeletal dissolution is predominantly driven by photosynthetic microborers, as samples held in the dark did not decalcify. In contrast, dissolution of skeletons exposed to light increased under elevated pCO2 -temperature scenarios, with P. cylindrica experiencing higher dissolution rates per month (89%) than I. cuneata (46%) in the high treatment relative to control. The effects of future pCO2 -temperature scenarios on the structure of endolithic communities were only identified in P. cylindrica and were mostly associated with a higher abundance of the green algae Ostreobium spp. Enhanced skeletal dissolution was also associated with increased endolithic biomass and respiration under elevated pCO2 -temperature scenarios. Our results suggest that future projections of ocean acidification and warming will lead to increased rates of microbioerosion. However, the magnitude of bioerosion responses may depend on the structural properties of coral skeletons, with a range of implications for reef carbonate losses under warmer and more acidic oceans. © 2013 Blackwell Publishing Ltd.

GROWTH POTENTIAL OF RADISH IN A CONTROLLED ENVIRONMENT.

DTIC Science & Technology

Under optimized conditions (culture chamber and plant-supportive matrix, nutrients, elevated P(CO2), continuous light, etc.) the radish plant can...produce significantly large masses of edible plant material in a relatively short period of time. Certain strains of radish (HV White Icicle and Chinese

Species-specific responses to climate change and community composition determine future calcification rates of Florida Keys reefs.

PubMed

Okazaki, Remy R; Towle, Erica K; van Hooidonk, Ruben; Mor, Carolina; Winter, Rivah N; Piggot, Alan M; Cunning, Ross; Baker, Andrew C; Klaus, James S; Swart, Peter K; Langdon, Chris

2017-03-01

Anthropogenic climate change compromises reef growth as a result of increasing temperatures and ocean acidification. Scleractinian corals vary in their sensitivity to these variables, suggesting species composition will influence how reef communities respond to future climate change. Because data are lacking for many species, most studies that model future reef growth rely on uniform scleractinian calcification sensitivities to temperature and ocean acidification. To address this knowledge gap, calcification of twelve common and understudied Caribbean coral species was measured for two months under crossed temperatures (27, 30.3 °C) and CO 2 partial pressures (pCO 2 ) (400, 900, 1300 μatm). Mixed-effects models of calcification for each species were then used to project community-level scleractinian calcification using Florida Keys reef composition data and IPCC AR5 ensemble climate model data. Three of the four most abundant species, Orbicella faveolata, Montastraea cavernosa, and Porites astreoides, had negative calcification responses to both elevated temperature and pCO 2 . In the business-as-usual CO 2 emissions scenario, reefs with high abundances of these species had projected end-of-century declines in scleractinian calcification of >50% relative to present-day rates. Siderastrea siderea, the other most common species, was insensitive to both temperature and pCO 2 within the levels tested here. Reefs dominated by this species had the most stable end-of-century growth. Under more optimistic scenarios of reduced CO 2 emissions, calcification rates throughout the Florida Keys declined <20% by 2100. Under the most extreme emissions scenario, projected declines were highly variable among reefs, ranging 10-100%. Without considering bleaching, reef growth will likely decline on most reefs, especially where resistant species like S. siderea are not already dominant. This study demonstrates how species composition influences reef community responses to climate change and how reduced CO 2 emissions can limit future declines in reef calcification. © 2016 John Wiley & Sons Ltd.

Trichodesmium’s strategies to alleviate phosphorus limitation in the future acidified oceans.

PubMed

Spungin, Dina; Berman-Frank, Ilana; Levitan, Orly

2014-06-01

Global warming may exacerbate inorganic nutrient limitation, including phosphorus (P), in the surface waters of tropical oceans that are home to extensive blooms of the marine diazotrophic cyanobacterium, Trichodesmium. We examined the combined effects of P limitation and pCO(2), forecast under ocean acidification scenarios, on Trichodesmium erythraeum IMS101 cultures. We measured nitrogen acquisition,glutamine synthetase activity, C uptake rates, intracellular Adenosine Triphosphate (ATP) concentration and the pool sizes of related key proteins. Here, we present data supporting the idea that cellular energy re-allocation enables the higher growth and N(2) fixation rates detected in Trichodesmium cultured under high pCO(2). This is reflected in altered protein abundance and metabolic pools. Also modified are particulate organic carbon and nitrogen production rates,enzymatic activities, and cellular ATP concentrations. We suggest that adjusting these cellular pathways to changing environmental conditions enables Trichodesmium to compensate for low P availability and to thrive in acidified oceans. Moreover, elevated pCO(2) could provide Trichodesmium with a competitive dominance that would extend its niche, particularly in P-limited regions of the tropical and subtropical oceans.

Could artificial ocean alkalinization protect tropical coral ecosystems from ocean acidification?

NASA Astrophysics Data System (ADS)

Feng, Ellias Y.; Keller, David P.; Koeve, Wolfgang; Oschlies, Andreas

2016-07-01

Artificial ocean alkalinization (AOA) is investigated as a method to mitigate local ocean acidification and protect tropical coral ecosystems during a 21st century high CO2 emission scenario. Employing an Earth system model of intermediate complexity, our implementation of AOA in the Great Barrier Reef, Caribbean Sea and South China Sea regions, shows that alkalinization has the potential to counteract expected 21st century local acidification in regard to both oceanic surface aragonite saturation Ω and surface pCO2. Beyond preventing local acidification, regional AOA, however, results in locally elevated aragonite oversaturation and pCO2 decline. A notable consequence of stopping regional AOA is a rapid shift back to the acidified conditions of the target regions. We conclude that AOA may be a method that could help to keep regional coral ecosystems within saturation states and pCO2 values close to present-day values even in a high-emission scenario and thereby might ‘buy some time’ against the ocean acidification threat, even though regional AOA does not significantly mitigate the warming threat.

The influence of agricultural management on soil's CO2 regime in semi-arid and arid regions

NASA Astrophysics Data System (ADS)

Eshel, G.; Lifshithz, D.; Sternberg, M.; Ben-Dor, E.; Bonfile, D. J.; Arad, B.; Mingelgrin, U.; Fine, P.; Levy, G. J.

2008-12-01

Two of the more important parameters which may help us better evaluate the impact of agricultural practices on the global carbon cycle are the in-situ soil pCO2 profile and the corresponding CO2 fluxes to the atmosphere. In an ongoing study, we monitored the pCO2 to a depth of 5 m in two adjacent irrigated Avocado orchards in the coastal plain of Israel (semi-arid region), and to a depth of 2 m in a semi- arid rain-fed and a arid rain-fed wheat fields in southern Israel. The soil pCO2 profiles and CO2 fluxes measurements were supplemented by measurements of soil moisture and temperature. The results showed differences in the CO2 profiles (both in the depth of the highest concentration and its absolute values) and the CO2 fluxes between the orchards and the wheat fields as well as along the year. In the irrigated Avocado orchards pCO2 values were in the range of 1.5 kPa at a depth of 0.5 m up to 8 kPa at depths of 3-5 m (even though Avocado trees are characterized by shallow roots). Such levels could affect reactions (e.g., enhancement of inorganic carbon dissolution) that may take place in the soil and some of its chemical properties (e.g., pH). As expected, soil pCO2 was affected by soil moisture and temperature, and the distance from the trees. Maximum soil respiration was observed during the summer when the orchards are under irrigation. In the wheat fields pCO2 level ranged from 0.2- 0.6 kPa at a depth of 0.2 m to 0.2-1 kPa at depths of 1-1.5 m (in arid and semiarid respectively). These pCO2 levels were much lower than those obtained in the irrigated orchards and seemed to depend on the wheat growing cycle (high concentration were noted at depth of 1-1.5 m close to the end of grain filling) and precipitation gradient (arid vs. semiarid). Since CO2 fluxes are directly affected by the pCO2 profile and soil moister and temperature the CO2 fluxes from the wheat fields were much lower (0.02- 0.2 ml min-1 m-2) compared to those obtained from the Avocado orchards (2-7 ml min-1 m-2). Our results clearly demonstrate the large variability in soil pCO2 concentration and flux to the atmosphere, and its dependence on the soil moisture regime (annual precipitation and irrigation) and type of cropping (orchard vs. field crop).

Short-term and seasonal pH,pCO2and saturation state variability in a coral-reef ecosystem

NASA Astrophysics Data System (ADS)

Gray, Sarah E. C.; Degrandpre, Michael D.; Langdon, Chris; Corredor, Jorge E.

2012-09-01

Coral reefs are predicted to be one of the ecosystems most sensitive to ocean acidification. To improve predictions of coral reef response to acidification, we need to better characterize the natural range of variability of pH, partial pressure of carbon dioxide (pCO2) and calcium carbonate saturation states (Ω). In this study, autonomous sensors for pH and pCO2 were deployed on Media Luna reef, Puerto Rico over three seasons from 2007 to 2008. High temporal resolution CaCO3 saturation states were calculated from the in situ data, giving a much more detailed characterization of reef saturation states than previously possible. Reef pH, pCO2 and aragonite saturation (ΩAr) ranged from 7.89 to 8.17 pH units, 176-613 μatm and 2.7-4.7, respectively, in the range characteristic of most other previously studied reef ecosystems. The diel pH, pCO2 and Ω cycles were also large, encompassing about half of the seasonal range of variability. Warming explained about 50% of the seasonal supersaturation in mean pCO2, with the remaining supersaturation primarily due to net heterotrophy and net CaCO3 production. Net heterotrophy was likely driven by remineralization of mangrove derived organic carbon which continued into the fall, sustaining high pCO2 levels until early winter when the pCO2 returned to offshore values. As a consequence, the reef was a source of CO2 to the atmosphere during the summer and fall and a sink during winter, resulting in a net annual source of 0.73 ± 1.7 mol m-2 year-1. These results show that reefs are exposed to a wide range of saturation states in their natural environment. Mean ΩAr levels will drop to 3.0 when atmospheric CO2 increases to 500 μatm and ΩAr will be less than 3.0 for greater than 70% of the time in the summer. Long duration exposure to these low ΩAr levels are expected to significantly decrease calcification rates on the reef.

Change in Emiliania huxleyi Virus Assemblage Diversity but Not in Host Genetic Composition during an Ocean Acidification Mesocosm Experiment

PubMed Central

Highfield, Andrea; Joint, Ian; Gilbert, Jack A.; Crawfurd, Katharine J.; Schroeder, Declan C.

2017-01-01

Effects of elevated pCO2 on Emiliania huxleyi genetic diversity and the viruses that infect E. huxleyi (EhVs) have been investigated in large volume enclosures in a Norwegian fjord. Triplicate enclosures were bubbled with air enriched with CO2 to 760 ppmv whilst the other three enclosures were bubbled with air at ambient pCO2; phytoplankton growth was initiated by the addition of nitrate and phosphate. E. huxleyi was the dominant coccolithophore in all enclosures, but no difference in genetic diversity, based on DGGE analysis using primers specific to the calcium binding protein gene (gpa) were detected in any of the treatments. Chlorophyll concentrations and primary production were lower in the three elevated pCO2 treatments than in the ambient treatments. However, although coccolithophores numbers were reduced in two of the high-pCO2 treatments; in the third, there was no suppression of coccolithophores numbers, which were very similar to the three ambient treatments. In contrast, there was considerable variation in genetic diversity in the EhVs, as determined by analysis of the major capsid protein (mcp) gene. EhV diversity was much lower in the high-pCO2 treatment enclosure that did not show inhibition of E. huxleyi growth. Since virus infection is generally implicated as a major factor in terminating phytoplankton blooms, it is suggested that no study of the effect of ocean acidification in phytoplankton can be complete if it does not include an assessment of viruses. PMID:28282890

Ocean acidification disrupts prey responses to predator cues but not net prey shell growth in Concholepas concholepas (loco).

PubMed

Manríquez, Patricio H; Jara, María Elisa; Mardones, María Loreto; Navarro, Jorge M; Torres, Rodrigo; Lardies, Marcos A; Vargas, Cristian A; Duarte, Cristian; Widdicombe, Stephen; Salisbury, Joseph; Lagos, Nelson A

2013-01-01

Most research on Ocean Acidification (OA) has largely focused on the process of calcification and the physiological trade-offs employed by calcifying organisms to support the building of calcium carbonate structures. However, there is growing evidence that OA can also impact upon other key biological processes such as survival, growth and behaviour. On wave-swept rocky shores the ability of gastropods to self-right after dislodgement, and rapidly return to normal orientation, reduces the risk of predation. The impacts of OA on this self-righting behaviour and other important parameters such as growth, survival, shell dissolution and shell deposition in Concholepas concholepas (loco) were investigated under contrasting pCO2 levels. Although no impacts of OA on either growth or net shell calcification were found, the results did show that OA can significantly affect self-righting behaviour during the early ontogeny of this species with significantly faster righting times recorded for individuals of C. concholepas reared under increased average pCO2 concentrations (± SE) (716 ± 12 and 1036 ± 14 µatm CO2) compared to those reared at concentrations equivalent to those presently found in the surface ocean (388 ± 8 µatm CO2). When loco were also exposed to the predatory crab Acanthocyclus hassleri, righting times were again increased by exposure to elevated CO2, although self-righting times were generally twice as fast as those observed in the absence of the crab. These results suggest that self-righting in the early ontogeny of C. concholepas will be positively affected by pCO2 levels expected by the end of the 21st century and beginning of the next one. However, as the rate of self-righting is an adaptive trait evolved to reduce lethal predatory attacks, our result also suggest that OA may disrupt prey responses to predators in nature.

Ocean Acidification Disrupts Prey Responses to Predator Cues but Not Net Prey Shell Growth in Concholepas concholepas (loco)

PubMed Central

Manríquez, Patricio H.; Jara, María Elisa; Mardones, María Loreto; Navarro, Jorge M.; Torres, Rodrigo; Lardies, Marcos A.; Vargas, Cristian A.; Duarte, Cristian; Widdicombe, Stephen; Salisbury, Joseph; Lagos, Nelson A.

2013-01-01

Background Most research on Ocean Acidification (OA) has largely focused on the process of calcification and the physiological trade-offs employed by calcifying organisms to support the building of calcium carbonate structures. However, there is growing evidence that OA can also impact upon other key biological processes such as survival, growth and behaviour. On wave-swept rocky shores the ability of gastropods to self-right after dislodgement, and rapidly return to normal orientation, reduces the risk of predation. Methodology/Principal Findings The impacts of OA on this self-righting behaviour and other important parameters such as growth, survival, shell dissolution and shell deposition in Concholepas concholepas (loco) were investigated under contrasting pCO2 levels. Although no impacts of OA on either growth or net shell calcification were found, the results did show that OA can significantly affect self-righting behaviour during the early ontogeny of this species with significantly faster righting times recorded for individuals of C. concholepas reared under increased average pCO2 concentrations (± SE) (716±12 and 1036±14 µatm CO2) compared to those reared at concentrations equivalent to those presently found in the surface ocean (388±8 µatm CO2). When loco were also exposed to the predatory crab Acanthocyclus hassleri, righting times were again increased by exposure to elevated CO2, although self-righting times were generally twice as fast as those observed in the absence of the crab. Conclusions and Significance These results suggest that self-righting in the early ontogeny of C. concholepas will be positively affected by pCO2 levels expected by the end of the 21st century and beginning of the next one. However, as the rate of self-righting is an adaptive trait evolved to reduce lethal predatory attacks, our result also suggest that OA may disrupt prey responses to predators in nature. PMID:23844231

Dual targeting of TNF-α and free radical toxic stress as a promising strategy to manage experimental polycystic ovary.

PubMed

Rezvanfar, Mohammad Amin; Saeedi, Sarah; Mansoori, Parisa; Saadat, Sepideh; Goosheh, Maziar; Shojaei Saadi, Habib A; Baeeri, Maryam; Abdollahi, Mohammad

2016-01-01

It is now clear that oxidative stress (OS) and chronic low-grade inflammation are two main pathways involved in polycystic ovary syndrome (PCOS) pathogenesis. Therefore, simultaneous targeting of these pathways by means of carvedilol and Semelil (ANGIPARS™), as established medicines with dual anti-cytokine and anti-oxidant potential may be a therapeutic alternative approach to the current treatments. The objective of this study is to study the protective effects of carvedilol and ANGIPARS™ on inflammatory and oxidative response in hyperandrogenism-induced polycystic ovary (PCO). The murine model of PCO was induced by letrozole (1 mg/kg/d; orally) and effective doses of carvedilol (10 mg/kg/d; orally) and ANGIPARS™ (2.1 mg/kg/d; orally) were administrated for 21 d in PCO and non-PCO healthy rats. Ovarian folliculogenesis, sex hormones concentrations, OS, inflammatory, and metabolic biomarkers were assessed in serum and ovaries. PCO rats exhibited ovarian cystogenesis which was preserved by the application of carvedilol and ANGIPARS™. In comparison with controls, decreased level of the total antioxidant power (TAP) and higher levels of reactive oxygen species (ROS) and lipid peroxidation (LPO) in serum and ovaries (2.41 ± 0.67 versus 0.72 ± 0.11; and 0.17 ± 0.04 versus 0.05 ± 0.01; 5.48 ± 1.30 versus 10.56 ± 0.77; and 7.06 ± 1.94 versus 17.98 ± 0.98; p < 0.05, respectively) were detected in PCO rats. Moreover, the PCO rats exhibited hyperandrogenism due to a 3.7-fold increase in serum testosterone concentration (35.04 ± 3.17 versus 131.09 ± 13.24; p < 0.05) along with a 2.98-fold decrease in serum progesterone (6.19 ± 0.40 versus 18.50 ± 1.03; p < 0.05) and 5.2-fold decrease in serum estradiol (9.30 ± 0.61 versus 48.3 ± 2.10; p < 0.05) when compared with those of the control group. However, similar to the control group, normal levels of OS markers and sex hormones were detected in ANGIPARS™ and carvedilol co-treated PCO rats. Besides, when compared with controls, increased levels of TNF-α (770.75 ± 42.06 versus 477.14 ± 28.77; p < 0.05) and insulin (1.27 ± 0.10 versus 0.36 ± 0.05; p < 0.05) in PCO rats were significantly inhibited by carvedilol and ANGIPARS™ co-treatment. We evidenced the beneficial effects of carvedilol and ANGIPARS™ in PCO, which underpin the new alternative approach in using these kinds of medicines in female reproductive disorders.

Effect of ocean acidification on otolith development in larvae of a tropical marine fish

NASA Astrophysics Data System (ADS)

Munday, P. L.; Hernaman, V.; Dixson, D. L.; Thorrold, S. R.

2011-06-01

Calcification in many invertebrate species is predicted to decline due to ocean acidification. The potential effects of elevated CO2 and reduced carbonate saturation state on other species, such as fish, are less well understood. Fish otoliths (earbones) are composed of aragonite, and thus, might be susceptible to either the reduced availability of carbonate ions in seawater at low pH, or to changes in extracellular concentrations of bicarbonate and carbonate ions caused by acid-base regulation in fish exposed to high pCO2. We reared larvae of the clownfish Amphiprion percula from hatching to settlement at three pHNBS and pCO2 levels (control: ~pH 8.15 and 404 μatm CO2; intermediate: pH 7.8 and 1050 μatm CO2; extreme: pH 7.6 and 1721 μatm CO2) to test the possible effects of ocean acidification on otolith development. There was no effect of the intermediate treatment (pH 7.8 and 1050 μatm CO2) on otolith size, shape, symmetry between left and right otoliths, or otolith elemental chemistry, compared with controls. However, in the more extreme treatment (pH 7.6 and 1721 μatm CO2) otolith area and maximum length were larger than controls, although no other traits were significantly affected. Our results support the hypothesis that pH regulation in the otolith endolymph can lead to increased precipitation of CaCO3 in otoliths of larval fish exposed to elevated CO2, as proposed by an earlier study, however, our results also show that sensitivity varies considerably among species. Importantly, our results suggest that otolith development in clownfishes is robust to even the more pessimistic changes in ocean chemistry predicted to occur by 2100.

The potential impact of ocean acidification upon eggs and larvae of yellowfin tuna (Thunnus albacares)

NASA Astrophysics Data System (ADS)

Bromhead, Don; Scholey, Vernon; Nicol, Simon; Margulies, Daniel; Wexler, Jeanne; Stein, Maria; Hoyle, Simon; Lennert-Cody, Cleridy; Williamson, Jane; Havenhand, Jonathan; Ilyina, Tatiana; Lehodey, Patrick

2015-03-01

Anthropogenic carbon dioxide (CO2) emissions are resulting in increasing absorption of CO2 by the earth's oceans, which has led to a decline in ocean pH, a process known as ocean acidification (OA). Evidence suggests that OA may have the potential to affect the distribution and population dynamics of many marine organisms. Early life history processes (e.g. fertilization) and stages (eggs, larvae, juveniles) may be relatively more vulnerable to potential OA impacts, with implications for recruitment in marine populations. The potential impact of OA upon tuna populations has not been investigated, although tuna are key components of pelagic ecosystems and, in the Pacific Ocean, form the basis of one of the largest and most valuable fisheries in the world. This paper reviews current knowledge of potential OA impacts on fish and presents results from a pilot study investigating how OA may affect eggs and larvae of yellowfin tuna, Thunnus albacares. Two separate trials were conducted to test the impact of pCO2 on yellowfin egg stage duration, larval growth and survival. The pCO2 levels tested ranged from present day ( 400 μatm) to levels predicted to occur in some areas of the spawning habitat within the next 100 years (<2500 μatm) to 300 years ( <5000 μatm) to much more extreme levels ( 10,000 μatm). In trial 1, there was evidence for significantly reduced larval survival (at mean pCO2 levels≥4730 μatm) and growth (at mean pCO2 levels≥2108 μatm), while egg hatch time was increased at extreme pCO2 levels≥10,000 μatm (*intermediate levels were not tested). In trial 2, egg hatch times were increased at mean pCO2 levels≥1573 μatm, but growth was only impacted at higher pCO2 (≥8800 μatm) and there was no relationship with survival. Unstable ambient conditions during trial 2 are likely to have contributed to the difference in results between trials. Despite the technical challenges with these experiments, there is a need for future empirical work which can in turn support modeling-based approaches to assess how OA will affect the ecologically and economically important tropical tuna resources.

Shallow water marine sediment bacterial community shifts along a natural CO2 gradient in the Mediterranean Sea off Vulcano, Italy.

PubMed

Kerfahi, Dorsaf; Hall-Spencer, Jason M; Tripathi, Binu M; Milazzo, Marco; Lee, Junghoon; Adams, Jonathan M

2014-05-01

The effects of increasing atmospheric CO(2) on ocean ecosystems are a major environmental concern, as rapid shoaling of the carbonate saturation horizon is exposing vast areas of marine sediments to corrosive waters worldwide. Natural CO(2) gradients off Vulcano, Italy, have revealed profound ecosystem changes along rocky shore habitats as carbonate saturation levels decrease, but no investigations have yet been made of the sedimentary habitat. Here, we sampled the upper 2 cm of volcanic sand in three zones, ambient (median pCO(2) 419 μatm, minimum Ω(arag) 3.77), moderately CO(2)-enriched (median pCO(2) 592 μatm, minimum Ω(arag) 2.96), and highly CO(2)-enriched (median pCO(2) 1611 μatm, minimum Ω(arag) 0.35). We tested the hypothesis that increasing levels of seawater pCO(2) would cause significant shifts in sediment bacterial community composition, as shown recently in epilithic biofilms at the study site. In this study, 454 pyrosequencing of the V1 to V3 region of the 16S rRNA gene revealed a shift in community composition with increasing pCO(2). The relative abundances of most of the dominant genera were unaffected by the pCO(2) gradient, although there were significant differences for some 5 % of the genera present (viz. Georgenia, Lutibacter, Photobacterium, Acinetobacter, and Paenibacillus), and Shannon Diversity was greatest in sediments subject to long-term acidification (>100 years). Overall, this supports the view that globally increased ocean pCO(2) will be associated with changes in sediment bacterial community composition but that most of these organisms are resilient. However, further work is required to assess whether these results apply to other types of coastal sediments and whether the changes in relative abundance of bacterial taxa that we observed can significantly alter the biogeochemical functions of marine sediments.

Continental-scale variation in controls of summer CO2 in United States lakes

NASA Astrophysics Data System (ADS)

Lapierre, Jean-Francois; Seekell, David A.; Filstrup, Christopher T.; Collins, Sarah M.; Emi Fergus, C.; Soranno, Patricia A.; Cheruvelil, Kendra S.

2017-04-01

Understanding the broad-scale response of lake CO2 dynamics to global change is challenging because the relative importance of different controls of surface water CO2 is not known across broad geographic extents. Using geostatistical analyses of 1080 lakes in the conterminous United States, we found that lake partial pressure of CO2 (pCO2) was controlled by different chemical and biological factors related to inputs and losses of CO2 along climate, topography, geomorphology, and land use gradients. Despite weak spatial patterns in pCO2 across the study extent, there were strong regional patterns in the pCO2 driver-response relationships, i.e., in pCO2 "regulation." Because relationships between lake CO2 and its predictors varied spatially, global models performed poorly in explaining the variability in CO2 for U.S. lakes. The geographically varying driver-response relationships of lake pCO2 reflected major landscape gradients across the study extent and pointed to the importance of regional-scale variation in pCO2 regulation. These results indicate a higher level of organization for these physically disconnected systems than previously thought and suggest that changes in climate and land use could induce shifts in the main pathways that determine the role of lakes as sources and sinks of atmospheric CO2.

Emiliania huxleyi increases calcification but not expression of calcification-related genes in long-term exposure to elevated temperature and pCO2

PubMed Central

Benner, Ina; Diner, Rachel E.; Lefebvre, Stephane C.; Li, Dian; Komada, Tomoko; Carpenter, Edward J.; Stillman, Jonathon H.

2013-01-01

Increased atmospheric pCO2 is expected to render future oceans warmer and more acidic than they are at present. Calcifying organisms such as coccolithophores that fix and export carbon into the deep sea provide feedbacks to increasing atmospheric pCO2. Acclimation experiments suggest negative effects of warming and acidification on coccolithophore calcification, but the ability of these organisms to adapt to future environmental conditions is not well understood. Here, we tested the combined effect of pCO2 and temperature on the coccolithophore Emiliania huxleyi over more than 700 generations. Cells increased inorganic carbon content and calcification rate under warm and acidified conditions compared with ambient conditions, whereas organic carbon content and primary production did not show any change. In contrast to findings from short-term experiments, our results suggest that long-term acclimation or adaptation could change, or even reverse, negative calcification responses in E. huxleyi and its feedback to the global carbon cycle. Genome-wide profiles of gene expression using RNA-seq revealed that genes thought to be essential for calcification are not those that are most strongly differentially expressed under long-term exposure to future ocean conditions. Rather, differentially expressed genes observed here represent new targets to study responses to ocean acidification and warming. PMID:23980248

Ocean Acidification and Increased Temperature Have Both Positive and Negative Effects on Early Ontogenetic Traits of a Rocky Shore Keystone Predator Species

PubMed Central

Manríquez, Patricio H.; Jara, María Elisa; Seguel, Mylene E.; Torres, Rodrigo; Alarcon, Emilio; Lee, Matthew R.

2016-01-01

The combined effect of ocean acidification and warming is expected to have significant effects on several traits of marine organisms. The gastropod Concholepas concholepas is a rocky shore keystone predator characteristic of the south-eastern Pacific coast of South America and an important natural resource exploited by small-scale artisanal fishermen along the coast of Chile and Peru. In this study, we used small juveniles of C. concholepas collected from the rocky intertidal habitats of southern Chile (39°S) to evaluate under laboratory conditions the potential consequences of projected near-future levels of ocean acidification and warming for important early ontogenetic traits. The individuals were exposed long-term (5.8 months) to contrasting pCO2 (ca. 500 and 1400 μatm) and temperature (15 and 19°C) levels. After this period we compared body growth traits, dislodgement resistance, predator-escape response, self-righting and metabolic rates. With respect to these traits there was no evidence of a synergistic interaction between pCO2 and temperature. Shell growth was negatively affected by high pCO2 levels only at 15°C. High pCO2 levels also had a negative effect on the predator-escape response. Conversely, dislodgement resistance and self-righting were positively affected by high pCO2 levels at both temperatures. High tenacity and fast self-righting would reduce predation risk in nature and might compensate for the negative effects of high pCO2 levels on other important defensive traits such as shell size and escape behaviour. We conclude that climate change might produce in C. concholepas positive and negative effects in physiology and behaviour. In fact, some of the behavioural responses might be a consequence of physiological effects, such as changes in chemosensory capacity (e.g. predator-escape response) or secretion of adhesive mucous (e.g. dislodgement resistance). Moreover, we conclude that positive behavioural responses may assist in the adaptation to negative physiological impacts, and that this may also be the case for other benthic organisms. PMID:27028118

Ocean Acidification and Increased Temperature Have Both Positive and Negative Effects on Early Ontogenetic Traits of a Rocky Shore Keystone Predator Species.

PubMed

Manríquez, Patricio H; Jara, María Elisa; Seguel, Mylene E; Torres, Rodrigo; Alarcon, Emilio; Lee, Matthew R

2016-01-01

The combined effect of ocean acidification and warming is expected to have significant effects on several traits of marine organisms. The gastropod Concholepas concholepas is a rocky shore keystone predator characteristic of the south-eastern Pacific coast of South America and an important natural resource exploited by small-scale artisanal fishermen along the coast of Chile and Peru. In this study, we used small juveniles of C. concholepas collected from the rocky intertidal habitats of southern Chile (39 °S) to evaluate under laboratory conditions the potential consequences of projected near-future levels of ocean acidification and warming for important early ontogenetic traits. The individuals were exposed long-term (5.8 months) to contrasting pCO2 (ca. 500 and 1400 μatm) and temperature (15 and 19 °C) levels. After this period we compared body growth traits, dislodgement resistance, predator-escape response, self-righting and metabolic rates. With respect to these traits there was no evidence of a synergistic interaction between pCO2 and temperature. Shell growth was negatively affected by high pCO2 levels only at 15 °C. High pCO2 levels also had a negative effect on the predator-escape response. Conversely, dislodgement resistance and self-righting were positively affected by high pCO2 levels at both temperatures. High tenacity and fast self-righting would reduce predation risk in nature and might compensate for the negative effects of high pCO2 levels on other important defensive traits such as shell size and escape behaviour. We conclude that climate change might produce in C. concholepas positive and negative effects in physiology and behaviour. In fact, some of the behavioural responses might be a consequence of physiological effects, such as changes in chemosensory capacity (e.g. predator-escape response) or secretion of adhesive mucous (e.g. dislodgement resistance). Moreover, we conclude that positive behavioural responses may assist in the adaptation to negative physiological impacts, and that this may also be the case for other benthic organisms.

The Carbon Isotopic Composition of Organic Matter in the Microfossils of Planktonic Foraminifera

NASA Astrophysics Data System (ADS)

Swart, K. A.; Oleynik, S.; Sigman, D. M.

2016-12-01

Surface ocean pCO2 is an important measure of the ocean/atmosphere C cycle. Reconstruction of euphotic zone pCO2 over glacial cycles has the potential to indicate the roles of different ocean regions in atmospheric pCO2 changes. Moreover, pCO2 in some surface ocean regions should provide a measure of atmospheric pCO2 change over periods predating the ice core record. The δ13C values of phytoplankton biomass have been used as a proxy for surface ocean pCO2, although carbon fixation rate and other parameters are also important. We have investigated "foraminifera-bound organic matter" (FBOM) as an alternative to bulk sedimentary organic matter for δ13C measurement. One motivation is the ubiquity of foraminifera in unproductive regions where conditions are best for reconstruction of pCO2 but where sedimentary organic matter concentrations are low. We have modified an elemental analyzer so that, interfaced with a stable isotope ratio mass spectrometer, precision for δ13C is 0.2‰ down to 20 nmol C, 1500-fold less C than typically required. This allows for measurements of 10 tests. Cleaning and decalcification protocols have been developed for the analysis of FBOM δ13C (1SD = .4‰). In Holocene sediments from the tropical N. Atlantic, FBOM C content is 65-95 µm C/g CaCO3, with a C/N of 20. For G. ruber, the Holocene δ13C value is -25.0±0.4‰, 2-3‰ lower than surface water suspended POM and expected photosynthate. This difference, along with the high C/N, suggests that FBOM has a substantial lipid component. G. ruber and G. sacculifer, which share similar ecological niches, δ13C values and downcore trends are similar. We do not see systemic differences among species in Holocene sediments that relate to depth of habitat or the presence of endosymbionts. We have examined three tropical N. Atlantic sediment cores back to the last ice age. Given ice core information on pCO2 and reconstruction of local SST, FBOM δ13C values in G. ruber from one core show the expected amplitude of δ13C elevation during the LGM, while 2 other records do not show this shift, with instead a slightly lower FBOM δ13C value during the LGM. Possible explanations for these findings will be offered. Moreover, measurements will be reported on coretop samples from the equatorial Pacific.

Evolution of a Heavy Metal Homeostasis/Resistance Island Reflects Increasing Copper Stress in Enterobacteria

PubMed Central

Staehlin, Benjamin M.; Gibbons, John G.; Rokas, Antonis; O’Halloran, Thomas V.; Slot, Jason C.

2016-01-01

Copper homeostasis in bacteria is challenged by periodic elevation of copper levels in the environment, arising from both natural sources and human inputs. Several mechanisms have evolved to efflux copper from bacterial cells, including the cus (copper sensing copper efflux system), and pco (plasmid-borne copper resistance system) systems. The genes belonging to these two systems can be physically clustered in a Copper Homeostasis and Silver Resistance Island (CHASRI) on both plasmids and chromosomes in Enterobacteria. Increasing use of copper in agricultural and industrial applications raises questions about the role of human activity in the evolution of novel copper resistance mechanisms. Here we present evidence that CHASRI emerged and diversified in response to copper deposition across aerobic and anaerobic environments. An analysis of diversification rates and a molecular clock model suggest that CHASRI experienced repeated episodes of elevated diversification that could correspond to peaks in human copper production. Phylogenetic analyses suggest that CHASRI originated in a relative of Enterobacter cloacae as the ultimate product of sequential assembly of several pre-existing two-gene modules. Once assembled, CHASRI dispersed via horizontal gene transfer within Enterobacteriaceae and also to certain members of Shewanellaceae, where the original pco module was replaced by a divergent pco homolog. Analyses of copper stress mitigation suggest that CHASRI confers increased resistance aerobically, anaerobically, and during shifts between aerobic and anaerobic environments, which could explain its persistence in facultative anaerobes and emergent enteric pathogens. PMID:26893455

Spectroscopy of Cu(II)-PcoC and the multicopper oxidase function of PcoA, two essential components of Escherichia coli pco copper resistance operon.

PubMed

Huffman, David L; Huyett, Jennifer; Outten, F Wayne; Doan, Peter E; Finney, Lydia A; Hoffman, Brian M; O'Halloran, Thomas V

2002-08-06

The plasmid-encoded pco copper resistance operon in Escherichia coli consists of seven genes that are expressed from two pco promoters in response to elevated copper; however, little is known about how they mediate resistance to excess environmental copper. Two of the genes encode the soluble periplasmic proteins PcoA and PcoC. We show here that inactivation of PcoC, and PcoA to a lesser extent, causes cells to become more sensitive to copper than wild-type nonresistant strains, consistent with a tightly coupled detoxification pathway. Periplasmic extracts show copper-inducible oxidase activity, attributed to the multicopper oxidase function of PcoA. PcoC, a much smaller protein than PcoA, binds one Cu(II) and exhibits a weak electronic transition characteristic of a type II copper center. ENDOR and ESEEM spectroscopy of Cu(II)-PcoC and the (15)N- and Met-CD(3)-labeled samples are consistent with a tetragonal ligand environment of three nitrogens and one aqua ligand "in the plane". A weakly associated S-Met and aqua are likely axial ligands. At least one N is a histidine and is likely trans to the in-plane aqua ligand. The copper chemistry of PcoC and the oxidase function of PcoA are consistent with the emerging picture of the chromosomally encoded copper homeostasis apparatus in the E. coli cell envelope [Outten, F. W., Huffman, D. L., Hale, J. A., and O'Halloran, T. V. (2001) J. Biol. Chem. 276, 30670-30677]. We propose a model for the plasmid system in which Cu(I)-PcoC functions in this copper efflux pathway as a periplasmic copper binding protein that docks with the multiple repeats of Met-rich domains in PcoA to effect oxidation of Cu(I) to the less toxic Cu(II) form. The solvent accessibility of the Cu(II) in PcoC may allow for metal transfer to other plasmid and chromosomal factors and thus facilitate removal of Cu(II) from the cell envelope.

on the growth and photochemical efficiency of Acropora cervicornis

NASA Astrophysics Data System (ADS)

Enochs, I. C.; Manzello, D. P.; Carlton, R.; Schopmeyer, S.; van Hooidonk, R.; Lirman, D.

2014-06-01

The effects of light and elevated pCO2 on the growth and photochemical efficiency of the critically endangered staghorn coral, Acropora cervicornis, were examined experimentally. Corals were subjected to high and low treatments of CO2 and light in a fully crossed design and monitored using 3D scanning and buoyant weight methodologies. Calcification rates, linear extension, as well as colony surface area and volume of A. cervicornis were highly dependent on light intensity. At pCO2 levels projected to occur by the end of the century from ocean acidification (OA), A. cervicornis exhibited depressed calcification, but no change in linear extension. Photochemical efficiency ( F v / F m ) was higher at low light, but unaffected by CO2. Amelioration of OA-depressed calcification under high-light treatments was not observed, and we suggest that the high-light intensity necessary to reach saturation of photosynthesis and calcification in A. cervicornis may limit the effectiveness of this potentially protective mechanism in this species. High CO2 causes depressed skeletal density, but not linear extension, illustrating that the measurement of extension by itself is inadequate to detect CO2 impacts. The skeletal integrity of A. cervicornis will be impaired by OA, which may further reduce the resilience of the already diminished populations of this endangered species.

Experimental evidence of nitrogen control on pCO(2) in phosphorus-enriched humic and clear coastal lagoon waters.

PubMed

Peixoto, Roberta B; Marotta, Humberto; Enrich-Prast, Alex

2013-01-01

Natural and human-induced controls on carbon dioxide (CO(2)) in tropical waters may be very dynamic (over time and among or within ecosystems) considering the potential role of warmer temperatures intensifying metabolic responses and playing a direct role on the balance between photosynthesis and respiration. The high magnitude of biological processes at low latitudes following eutrophication by nitrogen (N) and phosphorus (P) inputs into coastal lagoons waters may be a relevant component of the carbon cycle, showing controls on partial pressure of CO(2) (pCO(2)) that are still poorly understood. Here we assessed the strength of N control on pCO(2) in P-enriched humic and clear coastal lagoons waters, using four experimental treatments in microcosms: control (no additional nutrients) and three levels of N additions coupled to P enrichments. In humic coastal lagoons waters, a persistent CO(2) supersaturation was reported in controls and all nutrient-enriched treatments, ranging from 24- to 4-fold the atmospheric equilibrium value. However, both humic and clear coastal lagoons waters only showed significant decreases in pCO(2) in relation to the controlled microcosms in the two treatments with higher N addition levels. Additionally, clear coastal lagoons water microcosms showed a shift from CO(2) sources to CO(2) sinks, in relation to the atmosphere. Only in the two more N-enriched treatments did pCO(2) substantially decrease, from 650 µatm in controls and less N-enriched treatments to 10 µatm in more N-enriched microcosms. Humic substrates and N inputs can modulate pCO(2) even in P-enriched coastal lagoons waters, thereby being important drivers on CO(2) outgassing from inland waters.

Experimental evidence of nitrogen control on pCO2 in phosphorus-enriched humic and clear coastal lagoon waters

PubMed Central

Peixoto, Roberta B.; Marotta, Humberto; Enrich-Prast, Alex

2013-01-01

Natural and human-induced controls on carbon dioxide (CO2) in tropical waters may be very dynamic (over time and among or within ecosystems) considering the potential role of warmer temperatures intensifying metabolic responses and playing a direct role on the balance between photosynthesis and respiration. The high magnitude of biological processes at low latitudes following eutrophication by nitrogen (N) and phosphorus (P) inputs into coastal lagoons waters may be a relevant component of the carbon cycle, showing controls on partial pressure of CO2 (pCO2) that are still poorly understood. Here we assessed the strength of N control on pCO2 in P-enriched humic and clear coastal lagoons waters, using four experimental treatments in microcosms: control (no additional nutrients) and three levels of N additions coupled to P enrichments. In humic coastal lagoons waters, a persistent CO2 supersaturation was reported in controls and all nutrient-enriched treatments, ranging from 24- to 4-fold the atmospheric equilibrium value. However, both humic and clear coastal lagoons waters only showed significant decreases in pCO2 in relation to the controlled microcosms in the two treatments with higher N addition levels. Additionally, clear coastal lagoons water microcosms showed a shift from CO2 sources to CO2 sinks, in relation to the atmosphere. Only in the two more N-enriched treatments did pCO2 substantially decrease, from 650 µatm in controls and less N-enriched treatments to 10 µatm in more N-enriched microcosms. Humic substrates and N inputs can modulate pCO2 even in P-enriched coastal lagoons waters, thereby being important drivers on CO2 outgassing from inland waters. PMID:23390422

An atmospheric pCO2 reconstruction across the Cretaceous-Tertiary boundary from leaf megafossils

PubMed Central

Beerling, D. J.; Lomax, B. H.; Royer, D. L.; Upchurch, G. R.; Kump, L. R.

2002-01-01

The end-Cretaceous mass extinctions, 65 million years ago, profoundly influenced the course of biotic evolution. These extinctions coincided with a major extraterrestrial impact event and massive volcanism in India. Determining the relative importance of each event as a driver of environmental and biotic change across the Cretaceous-Tertiary boundary (KTB) crucially depends on constraining the mass of CO2 injected into the atmospheric carbon reservoir. Using the inverse relationship between atmospheric CO2 and the stomatal index of land plant leaves, we reconstruct Late Cretaceous-Early Tertiary atmospheric CO2 concentration (pCO2) levels with special emphasis on providing a pCO2 estimate directly above the KTB. Our record shows stable Late Cretaceous/Early Tertiary background pCO2 levels of 350–500 ppm by volume, but with a marked increase to at least 2,300 ppm by volume within 10,000 years of the KTB. Numerical simulations with a global biogeochemical carbon cycle model indicate that CO2 outgassing during the eruption of the Deccan Trap basalts fails to fully account for the inferred pCO2 increase. Instead, we calculate that the postboundary pCO2 rise is most consistent with the instantaneous transfer of ≈4,600 Gt C from the lithic to the atmospheric reservoir by a large extraterrestrial bolide impact. A resultant climatic forcing of +12 W⋅m−2 would have been sufficient to warm the Earth's surface by ≈7.5°C, in the absence of counter forcing by sulfate aerosols. This finding reinforces previous evidence for major climatic warming after the KTB impact and implies that severe and abrupt global warming during the earliest Paleocene was an important factor in biotic extinction at the KTB. PMID:12060729

Soil pCO2, soil respiration, and root activity in CO2 - fumigated and nitrogen-fertilized ponderosa pine

Treesearch

Dale Johnson; Donn Geisinger; Roger Walker; John Newman; James Vose; Katherine Elliott; Timothy Ball

1994-01-01

The purpose of this paper is to describe the effects of C02 and N treatments on soil pC02, calculated CO2 efflux, root biomass and soil carbon in open-top chambers planted with Pinus ponderosa seedlings. Based upon the literature, it was hypothesized that both elevated CO...

The impact of dissolved organic carbon and bacterial respiration on pCO2 in experimental sea ice

NASA Astrophysics Data System (ADS)

Zhou, J.; Kotovitch, M.; Kaartokallio, H.; Moreau, S.; Tison, J.-L.; Kattner, G.; Dieckmann, G.; Thomas, D. N.; Delille, B.

2016-02-01

Previous observations have shown that the partial pressure of carbon dioxide (pCO2) in sea ice brines is generally higher in Arctic sea ice compared to those from the Antarctic sea ice, especially in winter and early spring. We hypothesized that these differences result from the higher dissolved organic carbon (DOC) content in Arctic seawater: Higher concentrations of DOC in seawater would be reflected in a greater DOC incorporation into sea ice, enhancing bacterial respiration, which in turn would increase the pCO2 in the ice. To verify this hypothesis, we performed an experiment using two series of mesocosms: one was filled with seawater (SW) and the other one with seawater with an addition of filtered humic-rich river water (SWR). The addition of river water increased the DOC concentration of the water from a median of 142 μmol Lwater-1 in SW to 249 μmol Lwater-1 in SWR. Sea ice was grown in these mesocosms under the same physical conditions over 19 days. Microalgae and protists were absent, and only bacterial activity has been detected. We measured the DOC concentration, bacterial respiration, total alkalinity and pCO2 in sea ice and the underlying seawater, and we calculated the changes in dissolved inorganic carbon (DIC) in both media. We found that bacterial respiration in ice was higher in SWR: median bacterial respiration was 25 nmol C Lice-1 h-1 compared to 10 nmol C Lice-1 h-1 in SW. pCO2 in ice was also higher in SWR with a median of 430 ppm compared to 356 ppm in SW. However, the differences in pCO2 were larger within the ice interiors than at the surfaces or the bottom layers of the ice, where exchanges at the air-ice and ice-water interfaces might have reduced the differences. In addition, we used a model to simulate the differences of pCO2 and DIC based on bacterial respiration. The model simulations support the experimental findings and further suggest that bacterial growth efficiency in the ice might approach 0.15 and 0.2. It is thus credible that the higher pCO2 in Arctic sea ice brines compared with those from the Antarctic sea ice were due to an elevated bacterial respiration, sustained by higher riverine DOC loads. These conclusions should hold for locations and time frames when bacterial activity is relatively dominant compared to algal activity, considering our experimental conditions.

Daily variation in net primary production and net calcification in coral reef communities exposed to elevated pCO2

NASA Astrophysics Data System (ADS)

Comeau, Steeve; Edmunds, Peter J.; Lantz, Coulson A.; Carpenter, Robert C.

2017-07-01

The threat represented by ocean acidification (OA) for coral reefs has received considerable attention because of the sensitivity of calcifiers to changing seawater carbonate chemistry. However, most studies have focused on the organismic response of calcification to OA, and only a few have addressed community-level effects, or investigated parameters other than calcification, such as photosynthesis. Light (photosynthetically active radiation, PAR) is a driver of biological processes on coral reefs, and the possibility that these processes might be perturbed by OA has important implications for community function. Here we investigate how CO2 enrichment affects the relationships between PAR and community net O2 production (Pnet), and between PAR and community net calcification (Gnet), using experiments on three coral communities constructed to match (i) the back reef of Mo'orea, French Polynesia, (ii) the fore reef of Mo'orea, and (iii) the back reef of O'ahu, Hawaii. The results were used to test the hypothesis that OA affects the relationship between Pnet and Gnet. For the three communities tested, pCO2 did not affect the Pnet-PAR relationship, but it affected the intercept of the hyperbolic tangent curve fitting the Gnet-PAR relationship for both reef communities in Mo'orea (but not in O'ahu). For the three communities, the slopes of the linear relationships between Pnet and Gnet were not affected by OA, although the intercepts were depressed by the inhibitory effect of high pCO2 on Gnet. Our result indicates that OA can modify the balance between net calcification and net photosynthesis of reef communities by depressing community calcification, but without affecting community photosynthesis.

Ocean acidification and viral replication cycles: Frequency of lytically infected and lysogenic cells during a mesocosm experiment in the NW Mediterranean Sea

NASA Astrophysics Data System (ADS)

Tsiola, Anastasia; Pitta, Paraskevi; Giannakourou, Antonia; Bourdin, Guillaume; Marro, Sophie; Maugendre, Laure; Pedrotti, Maria Luiza; Gazeau, Frédéric

2017-02-01

The frequency of lytically infected and lysogenic cells (FLIC and FLC, respectively) was estimated during an in situ mesocosm experiment studying the impact of ocean acidification on the plankton community of a low nutrient low chlorophyll (LNLC) system in the north-western Mediterranean Sea (Bay of Villefranche, France) in February/March 2013. No direct effect of elevated partial pressure of CO2 (pCO2) on viral replication cycles could be detected. FLC variability was negatively correlated to heterotrophic bacterial and net community production as well as the ambient bacterial abundance, confirming that lysogeny is a prevailing life strategy under unfavourable-for-the-hosts conditions. Further, the phytoplankton community, assessed by chlorophyll a concentration and the release of >0.4 μm transparent exopolymeric particles, was correlated with the occurrence of lysogeny, indicating a possible link between photosynthetic processes and bacterial growth. Higher FLC was found occasionally at the highest pCO2-treated mesocosm in parallel to subtle differences in the phytoplankton community. This observation suggests that elevated pCO2 could lead to short-term alterations in lysogenic dynamics coupled to phytoplankton-derived processes. Correlation of FLIC with any environmental parameter could have been obscured by the sampling time or the synchronization of lysis to microbial processes not assessed in this experiment. Furthermore, alterations in microbial and viral assemblage composition and gene expression could be a confounding factor. Viral-induced modifications in organic matter flow affect bacterial growth and could interact with ocean acidification with unpredictable ecological consequences.

Comparison of Interstitial Fluid pH, PCO2, PO2 with Venous Blood Values During Repetitive Handgrip Exercise

NASA Technical Reports Server (NTRS)

Hagan, Ronald Donald; Soller, Babs R.; Shear, Michael; Walz, Matthias; Landry, Michelle; Heard, Stephen

2006-01-01

We evaluated the use of a small, fiber optic sensor to measure pH, PCO2 and PO2 from forearm muscle interstitial fluid (IF) during handgrip dynamometry. PURPOSE: Compare pH, PCO2 and PO2 values obtained from venous blood with those from the IF of the flexor digitorum superficialis (FDS) during three levels of exercise intensity. METHODS: Six subjects (5M/1F), average age 29+/-5 yrs, participated in the study. A venous catheter was placed in the retrograde direction in the antecubital space and a fiber optic sensor (Paratrend, Diametrics Medical, Inc.) was placed through a 22 G catheter into the FDS muscle under ultrasound guidance. After a 45 min rest period, subjects performed three 5-min bouts of repetitive handgrip exercise (2s contraction/1 s relaxation) at attempted levels of 15%, 30% and 45% of maximal voluntary contraction. The order of the exercise bouts was random with the second and third bouts started after blood lactate had returned to baseline. Venous blood was sampled every minute during exercise and analyzed with an I-Stat CG-4+ cartridge, while IF fiber optic sensor measurements were obtained every 2 s. Change from pre-exercise baseline to end of exercise was computed for pH, PCO2 and PO2. Blood and IF values were compared with a paired t-test. RESULTS: Baseline values for pH, PCO2 and PO2 were 7.37+/-0.02, 46+/-4 mm Hg, and 36+/-6 mm Hg respectively in blood and 7.39+/-0.02, 44+/-6 mm Hg, and 35+/-14 mm Hg in IF. Average changes over all exercise levels are noted in the Table below. For each parameter the exercise-induced change was at least twice as great in IF as in blood. In blood and IF, pH and PCO2 increases were directly related to exercise intensity. Change in venous PO2 was unrelated to exercise intensity, while IF PO2 decreased with increases in exercise intensity. CONCLUSIONS: Measurement of IF pH, PCO2 and PO2 is more sensitive to exercise intensity than measurement of the same parameters in venous blood and provides continuous assessment during and after exercise.

Seasonal and spatial variations in surface pCO2 and air-sea CO2 flux in the Chesapeake Bay

NASA Astrophysics Data System (ADS)

Cai, W. J.; Chen, B.

2017-12-01

Bay-wide observations of surface water partial pressure of carbon dioxide (pCO2) were conducted in May, June, August, and October 2016 to study the spatial and seasonal variations in surface pCO2 and to estimate air-sea CO2 flux in the Chesapeake Bay. Overall, high surface pCO2 in the upper-bay decreased downstream rapidly below the atmospheric value near the bay bridge in the mid-bay and then increased slightly to the lower-bay where pCO2 approached the atmospheric level. Over the course of a year, pCO2 was higher than 1000 µatm in the upper bay and the highest pCO2 (2500 µatm) was observed in August. Significant biologically-induced pCO2 undersaturation was observed at the upper part of the mid-bay in August with pCO2 as low as 50 µatm and oversaturated DO% of 200%. In addition to biological control, vertical mixing and upwelling controlled by wind direction and tidal stage played an important role in controlling surface pCO2 in the mid-bay as is evidenced by co-occurrence of high pCO2 with low temperature and low oxygen or high salinity from the subsurface. These physical processes occurred regularly and in short time scale of hours, suggesting they must be considered in the assessment of annual air-sea CO2 flux. Seasonally, the upper-bay acted as a source for atmospheric CO2 over the course of a year. The boundary of upper and mid bay transited from a CO2 source to a sink from May to August and was a source again in October due to strong biological production in summer. In contrast, the mid-bay represented as a CO2 source with large temporal variation due to dynamic hydrographic settings. The lower-bay transited from a weak sink in May to equilibrated with the atmosphere from June to August, while became a source again in October. Moreover, the CO2 flux could be reversed very quickly under episodic severe weather events. Thus further research, including the influence of severe weather and subsequent bloom, is needed to get better understanding of the carbon cycling in the Chesapeake Bay.

Lingual, splanchnic, and systemic hemodynamic and carbon dioxide tension changes during endotoxic shock and resuscitation.

PubMed

Guzman, Jorge A; Dikin, Mathew S; Kruse, James A

2005-01-01

Sublingual and intestinal mucosal blood flow and Pco(2) were studied in a canine model of endotoxin-induced circulatory shock and resuscitation. Sublingual Pco(2) (Ps(CO(2))) was measured by using a novel fluorescent optrode-based technique and compared with lingual measurements obtained by using a Stowe-Severinghaus electrode [lingual Pco(2) (Pl(CO(2)))]. Endotoxin caused parallel changes in cardiac output, and in portal, intestinal mucosal, and sublingual blood flow (Q(s)). Different blood flow patterns were observed during resuscitation: intestinal mucosal blood flow returned to near baseline levels postfluid resuscitation and decreased by 21% after vasopressor resuscitation, whereas Q(s) rose to twice that of the preshock level and was maintained throughout the resuscitation period. Electrochemical and fluorescent Pco(2) measurements showed similar changes throughout the experiments. The shock-induced increases in Ps(CO(2)) and Pl(CO(2)) were nearly reversed after fluid resuscitation, despite persistent systemic arterial hypotension. Vasopressor administration induced a rebound of Ps(CO(2)) and Pl(CO(2)) to shock levels, despite higher cardiac output and Q(s), possibly due to blood flow redistribution and shunting. Changes in Pl(CO(2)) and Ps(CO(2)) paralleled gastric and intestinal Pco(2) changes during shock but not during resuscitation. We found that the lingual, splanchnic, and systemic circulations follow a similar pattern of blood flow variations in response to endotoxin shock, although discrepancies were observed during resuscitation. Restoration of systemic, splanchnic, and lingual perfusion can be accompanied by persistent tissue hypercarbia, mainly lingual and intestinal, more so when a vasopressor agent is used to normalize systemic hemodynamic variables.

Ovarian ultrasound and ovarian and adrenal hormones before and after treatment for hyperthyroidism.

PubMed

Skjöldebrand Sparre, L; Kollind, M; Carlström, K

2002-01-01

To relate thyroid, steroid and pituitary hormones to ovarian ultrasonographic findings in hyperthyroid patients before and during treatment. Ultrasonography of the ovaries and serum hormone determination by immunoassay were performed before and during thiamazole therapy in 18 women of fertile age treated for hyperthyroidism at the Danderyd Hospital from 1996 to 1998. When hyperthyreotic, the patients had elevated serum levels of sex hormone-binding globulin (SHBG) and subnormal values of cortisol, free testosterone (fT) and dehydroepiandrosterone (DHEA). In the euthyreotic state following treatment, endocrine variables were normalized. Patients with a short duration of the disease had higher pretreatment levels of free thyroxine (fT4), SHBG and testosterone and lower corticosteroid binding globulin (CBG) and cortisol levels compared to patients with a long duration of the disease. The pretreatment ultrasonographic picture was abnormal in 16 of 18 patients. Of the 8 patients who were examined by ultrasonography after 3 months of treatment, all but 1 showed a normal picture. Samples from patients showing an abnormal ultrasonographic picture had significantly higher fT4 and lower free testosterone (fT) values than samples from patients with a normal ultrasonographic picture. Ultrasonographic findings showing a multicystic/multifollicular picture, resembling polycystic ovaries (PCO), in hyperthyroidism may be related to direct effects of thyroid hormones on the ovaries and/or altered intraovarian androgen environment due to elevated SHBG levels. It is highly recommended to assess the thyroid status in patients with multicystic/multifollicular ovaries/PCO. Copyright 2002 S. Karger AG, Basel

Interpreting terrestrial organic carbon isotope records across natural and anthropogenic pCO2 change

NASA Astrophysics Data System (ADS)

Schubert, B.; Jahren, H.

2014-12-01

Changes in the net carbon isotope fractionation (Δδ13C) measured in organic carbon from terrestrial substrates results from changes in climate, plant community shifts, and pCO2 level, but separating out these effects in the geologic record can be difficult. Here we present a compilation of 614 Δδ13C measurements on bulk terrestrial organic matter (TOM) and fossil leaves from 23 distinct records within 19 published studies that span the last 30,000 years up to the industrial revolution. To this dataset we add 2735 Δδ13C measurements made on tree ring tissue from 51 records that extend from 1950 to 2010. These records together span the ~80 ppm rise in pCO2 from the Late Glacial to through the Holocene (190-270 ppm; fossil leaves and TOM), and the ~70 ppm rise observed across the last 60 years (310-380 ppm; tree-ring tissue). We find a 2.0‰ relative increase in Δδ13C value across Termination 1 (18,000-11,500 years BP) and a 1.0‰ increase in Δδ13C value recorded in tree rings between 1950 and 2010. We use our recently developed relationship between pCO2 and Δδ13C to show that both increases in Δδ13C value exactly match, in trend and absolute magnitude, the increase in Δδ13C value we predict from our equations in response to rising pCO2 levels. These results have significance for the interpretation of terrestrial organic isotope records spanning both natural and anthropogenic pCO2 changes; we contend that environmental reconstructions based on long-term terrestrial Δδ13C records cannot be accurately interpreted until the isotope data are adjusted for known changes in pCO2 concentration.

Integrated Cost Analysis Teams: How ICATs Support Better Buying Power 2.0

DTIC Science & Technology

2014-06-01

and its procuring contracting officer ( PCO ) with a supportable and sustainable starting position for negotiation. The ICAT can deliver full pricing...proposals as well, arming the PCO with an all-encompassing report. Requesting DCMA assistance is straightforward. The cus- tomer receives a proposal in...any level of support needed to assist the PCO . Conversely, if the schedule is the determining factor, the ICAT can tailor the scope to meet the

Impact of CO2 leakage from sub-seabed carbon dioxide capture and storage (CCS) reservoirs on benthic virus-prokaryote interactions and functions.

PubMed

Rastelli, Eugenio; Corinaldesi, Cinzia; Dell'Anno, Antonio; Amaro, Teresa; Queirós, Ana M; Widdicombe, Stephen; Danovaro, Roberto

2015-01-01

Atmospheric CO2 emissions are a global concern due to their predicted impact on biodiversity, ecosystems functioning, and human life. Among the proposed mitigation strategies, CO2 capture and storage, primarily the injection of CO2 into marine deep geological formations has been suggested as a technically practical option for reducing emissions. However, concerns have been raised that possible leakage from such storage sites, and the associated elevated levels of pCO2 could locally impact the biodiversity and biogeochemical processes in the sediments above these reservoirs. Whilst a number of impact assessment studies have been conducted, no information is available on the specific responses of viruses and virus-host interactions. In the present study, we tested the impact of a simulated CO2 leakage on the benthic microbial assemblages, with specific focus on microbial activity and virus-induced prokaryotic mortality (VIPM). We found that exposure to levels of CO2 in the overlying seawater from 1,000 to 20,000 ppm for a period up to 140 days, resulted in a marked decrease in heterotrophic carbon production and organic matter degradation rates in the sediments, associated with lower rates of VIPM, and a progressive accumulation of sedimentary organic matter with increasing CO2 concentrations. These results suggest that the increase in seawater pCO2 levels that may result from CO2 leakage, can severely reduce the rates of microbial-mediated recycling of the sedimentary organic matter and viral infections, with major consequences on C cycling and nutrient regeneration, and hence on the functioning of benthic ecosystems.

Chemosensitivity of the osphradium of the pond snail Lymnaea stagnalis

PubMed

Wedemeyer; Schild

1995-01-01

The osphradium of the pond snail Lymnaea stagnalis was studied to determine the stimuli to which this organ responds. The following stimuli were tested: hypoxia, hypercapnia, a mixture of amino acids, a mixture of citralva and amyl acetate and a mixture of lyral, lilial and ethylvanillin. The mean nerve activity consistently increased with elevated PCO2, whereas hypoxia produced variable effects. The nerve activity became rhythmic upon application of citralva and amyl acetate, but it increased in a non-rhythmic way upon application of the other two odorant mixtures tested. Whole-cell patch-clamp recordings were made from a group of 15 neurones that lay next to the issuing osphradial nerve, to determine whether ganglion cells were involved in olfactory signal processing. All neurones tested responded to at least one of the three mixtures of odorants. Both excitatory and inhibitory responses occurred. Our results indicate that the osphradium of the pond snail Lymnaea stagnalis is sensitive to elevated PCO2 as well as to three different classes of odorants. In addition, at least some neurones within the osphradium are involved in the processing of olfactory information.

Natural acidification changes the timing and rate of succession, alters community structure, and increases homogeneity in marine biofouling communities.

PubMed

Brown, Norah E M; Milazzo, Marco; Rastrick, Samuel P S; Hall-Spencer, Jason M; Therriault, Thomas W; Harley, Christopher D G

2018-01-01

Ocean acidification may have far-reaching consequences for marine community and ecosystem dynamics, but its full impacts remain poorly understood due to the difficulty of manipulating pCO 2 at the ecosystem level to mimic realistic fluctuations that occur on a number of different timescales. It is especially unclear how quickly communities at various stages of development respond to intermediate-scale pCO 2 change and, if high pCO 2 is relieved mid-succession, whether past acidification effects persist, are reversed by alleviation of pCO 2 stress, or are worsened by departures from prior high pCO 2 conditions to which organisms had acclimatized. Here, we used reciprocal transplant experiments along a shallow water volcanic pCO 2 gradient to assess the importance of the timing and duration of high pCO 2 exposure (i.e., discrete events at different stages of successional development vs. continuous exposure) on patterns of colonization and succession in a benthic fouling community. We show that succession at the acidified site was initially delayed (less community change by 8 weeks) but then caught up over the next 4 weeks. These changes in succession led to homogenization of communities maintained in or transplanted to acidified conditions, and altered community structure in ways that reflected both short- and longer-term acidification history. These community shifts are likely a result of interspecific variability in response to increased pCO 2 and changes in species interactions. High pCO 2 altered biofilm development, allowing serpulids to do best at the acidified site by the end of the experiment, although early (pretransplant) negative effects of pCO 2 on recruitment of these worms were still detectable. The ascidians Diplosoma sp. and Botryllus sp. settled later and were more tolerant to acidification. Overall, transient and persistent acidification-driven changes in the biofouling community, via both past and more recent exposure, could have important implications for ecosystem function and food web dynamics. © 2017 John Wiley & Sons Ltd.

Impact of pCO2 on the energy, reproduction and growth of the shell of the pearl oyster Pinctada margaritifera

NASA Astrophysics Data System (ADS)

Le Moullac, G.; Soyez, C.; Vidal-Dupiol, J.; Belliard, C.; Fievet, J.; Sham-Koua, M.; Lo-Yat, A.; Saulnier, D.; Gaertner-Mazouni, N.; Gueguen, Y.

2016-12-01

The possible consequences of acidification on pearl farming are disruption of oyster metabolism and change in growth. In the laboratory, we studied the impact of pCO2 (3540, 1338 and 541 μatm) on the physiology of pearl oysters exposed for 100 days. This experiment was repeated after an interval of one year. Several physiological compartments were examined in pearl oysters: the scope for growth by measuring ingestion, assimilation and oxygen consumption, gametogenesis by means of histological observations, shell growth by measurement and observation by optical and electronic microscopy, and at molecular level by measuring the expression of nine genes of mantle cells implied in the biomineralisation process. Results from both experiments showed that high pCO2 had no effect on scope for growth and gametogenesis. High pCO2 (3540 μatm) significantly slowed down the shell deposit rate at the ventral side and SEM observations of the inside of the shell found signs of chemical dissolution. Of the nine examined genes high pCO2significantly decreased the expression level of one gene (Pmarg-PUSP 6). This study showed that shell growth of the pearl oyster would be slowed down without threatening the species since the management of energy and reproduction functions appeared to be preserved. Further investigations should be conducted on the response of offspring to acidification.

Ikaite crystals in melting sea ice - implications for pCO2 and pH levels in Arctic surface waters

NASA Astrophysics Data System (ADS)

Rysgaard, S.; Glud, R. N.; Lennert, K.; Cooper, M.; Halden, N.; Leakey, R. J. G.; Hawthorne, F. C.; Barber, D.

2012-03-01

A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air-sea CO2 exchange. This has been complicated by the recent discoveries of ikaite (CaCO3·6H2O) in Arctic and Antarctic sea ice, which indicate that multiple chemical transformations occur in sea ice with a possible effect on CO2 and pH conditions in surface waters. Here we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from an actively melting 1.7 km2 (0.5-1 m thick) drifting ice floe in the Fram Strait during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures gradually disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced the ice flow thickness by ca. 0.2 m per week and resulted in an estimated 1.6 ppm decrease of pCO2 in the ocean surface mixed layer. This corresponds to an air-sea CO2 uptake of 11 mmol m-2 sea ice d-1 or to 3.5 ton km-2 ice floe week-1.

A new positive relationship between pCO2 and stomatal frequency in Quercus guyavifolia (Fagaceae): a potential proxy for palaeo-CO2 levels

PubMed Central

Hu, Jin-Jin; Xing, Yao-Wu; Turkington, Roy; Jacques, Frédéric M. B.; Su, Tao; Huang, Yong-Jiang; Zhou, Zhe-Kun

2015-01-01

Background and Aims The inverse relationship between atmospheric CO2 partial pressure (pCO2) and stomatal frequency in many species of plants has been widely used to estimate palaeoatmospheric CO2 (palaeo-CO2) levels; however, the results obtained have been quite variable. This study attempts to find a potential new proxy for palaeo-CO2 levels by analysing stomatal frequency in Quercus guyavifolia (Q. guajavifolia, Fagaceae), an extant dominant species of sclerophyllous forests in the Himalayas with abundant fossil relatives. Methods Stomatal frequency was analysed for extant samples of Q. guyavifolia collected from17 field sites at altitudes ranging between 2493 and 4497 m. Herbarium specimens collected between 1926 and 2011 were also examined. Correlations of pCO2–stomatal frequency were determined using samples from both sources, and these were then applied to Q. preguyavaefolia fossils in order to estimate palaeo-CO2 concentrations for two late-Pliocene floras in south-western China. Key Results In contrast to the negative correlations detected for most other species that have been studied, a positive correlation between pCO2 and stomatal frequency was determined in Q. guyavifolia sampled from both extant field collections and historical herbarium specimens. Palaeo-CO2 concentrations were estimated to be approx. 180–240 ppm in the late Pliocene, which is consistent with most other previous estimates. Conclusions A new positive relationship between pCO2 and stomatal frequency in Q. guyavifolia is presented, which can be applied to the fossils closely related to this species that are widely distributed in the late-Cenozoic strata in order to estimate palaeo-CO2 concentrations. The results show that it is valid to use a positive relationship to estimate palaeo-CO2 concentrations, and the study adds to the variety of stomatal density/index relationships that available for estimating pCO2. The physiological mechanisms underlying this positive response are unclear, however, and require further research. PMID:25681824

Bryozoans as indicators of global change: predictable shifts in morphology and carbonate mineralogy in response to warming and ocean acidification

NASA Astrophysics Data System (ADS)

Swezey, D. S.; Bean, J. R.; Ninokawa, A. T.; Sanford, E.

2014-12-01

Recent studies have documented variation in skeletal structure and carbonate mineralogy across a broad range of marine invertebrate taxa. Intraspecific changes in growth, morphology, and carbonate composition may occur in response to local and global changes in temperature, carbonate saturation state, and nutrient availability. Recurring upwelling along the west coast of the United States creates an alongshore mosaic of Ocean Acidification (OA), which may induce plastic responses and/or select for adaptive skeletal construction that can withstand pCO2 and temperature changes. Calcifying bryozoans provide a unique study system for investigating carbonate precipitation under variable conditions. Using a newly constructed flow-through CO2 control apparatus, we tested whether three laboratory-reared populations of the bryozoans Membranipora serrilamella, M. tuberculata and Celleporella cornuta showed differences in growth, calcification, and skeletal composition in response to simulated future OA conditions. Under elevated pCO2 (1200 μatm), bryozoans showed no significant differences in growth rate (new zooids added) compared to clones reared under current atmospheric values. However, C. cornuta colonies raised under high CO2 were significantly lighter, with less carbonate per zooid compared to colonies grown in present-day conditions (400 μatm). Scanning electron microscopy revealed that elevated pCO2 led to dissolution of bryozoan skeletons, which did not occur at 400 μatm. Structural changes in M. tuberculata and C. cornuta colonies may be related to the dissolution of high magnesium calcite skeletal components. Analyses of bryozoan morphological responses along with environmental proxies (δ13C, δ18O, and Mg/Ca ratios) could yield high resolution records of temperature and pH, which could be used to help reconstruct environmental variation along the California coast.

Paleobotanical Evidence for Coupling of Temperature and pCO2 during the Early Eocene Climatic Optimum

NASA Astrophysics Data System (ADS)

Smith, R. Y.; Greenwood, D. R.; Basinger, J. F.

2009-12-01

The Early Eocene Climatic Optimum (EECO) was the warmest period of the Cenozoic, indicated by multiple proxy mean annual temperature estimates for sea and land surface. However, estimates of pCO2 from geochemical, modeling, and paleontological proxies show a wide range of values, from near modern day levels to an order of magnitude greater. Resolving the pCO2 record for this time period, and correlating it with trends in temperature, is a key task in understanding the interaction of climate and pCO2 in globally warm periods. Here we present a fine scale study of trends in temperature and pCO2 based on paleobotanical data from an early Eocene site from the Okanagan Highlands of British Columbia, Canada. Plant macrofossils were collected using an unbiased census approach from three informal units, allowing for quantitative comparison of trends within the site. Temperature estimates derived from multiple paleobotanical techniques (physiognomic and floristic approaches) suggest microthermal (MAT <13°C) but equable (CMMT >0°C) conditions for this upland site, and show a trend in declining MAT over time reflected in the three units. At the same time, stomatal frequency of Ginkgo suggests that pCO2 was high (>2x modern values), but also declining over time. These results suggest that temperature and pCO2 were coupled during this globally warm period, and that fine scale trends on the order of 103 - 104 years can be tracked within fossil sites to provide a window on climate/pCO2 interactions.

Connecting the Mississippi River with Carbon Variability in the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Xue, Z. G.; He, R.; Fennel, K.; Cai, W. J.; Lohrenz, S. E.; Huang, W. J.; Tian, H.; Ren, W.

2016-02-01

To understand the linkage between landuse/land-cover change within the Mississippi basin and the carbon dynamics in the Gulf of Mexico, a three-dimensional coupled physical-biogeochemical model was used to the examine temporal and spatial variability of surface ocean pCO2 in the Gulf of Mexico (GoM). The model is driven by realistic atmospheric forcing, open boundary conditions from a data-assimilative global ocean circulation model, and freshwater and terrestrial nutrient and carbon input from major rivers provided by the Dynamic Land Ecosystem Model (DLEM). A seven-year model hindcast (2004-2010) was performed and was validated against the recently updated Lamont-Doherty Earth Observatory global ocean carbon dataset. Model simulated seawater pCO2 and air-sea CO2 flux are in good agreement with in-situ measurements. An inorganic carbon budget was estimated based on the multi-year mean of the model results. Overall, the GoM is a sink of atmospheric CO2 with a flux of 0.92 × 1012 mol C yr-1, which, together with the enormous fluvial carbon input, is balanced by carbon export through the Loop Current. In a sensitivity experiment with all biological sources and sinks of carbon disabled surface pCO2 was elevated by 70 ppm, suggesting that biological uptake is the most important reason for the simulated CO2 sink. The impact from landuse and land-cover changes within the Mississippi River basin on coastal pCO2 dynamics is also discussed based on a scenario run driven by river conditions during the 1904-1910 provided by the DLEM model.

Implications of observed inconsistencies in carbonate chemistry measurements for ocean acidification studies

NASA Astrophysics Data System (ADS)

Hoppe, C. J. M.; Langer, G.; Rokitta, S. D.; Wolf-Gladrow, D. A.; Rost, B.

2012-07-01

The growing field of ocean acidification research is concerned with the investigation of organism responses to increasing pCO2 values. One important approach in this context is culture work using seawater with adjusted CO2 levels. As aqueous pCO2 is difficult to measure directly in small-scale experiments, it is generally calculated from two other measured parameters of the carbonate system (often AT, CT or pH). Unfortunately, the overall uncertainties of measured and subsequently calculated values are often unknown. Especially under high pCO2, this can become a severe problem with respect to the interpretation of physiological and ecological data. In the few datasets from ocean acidification research where all three of these parameters were measured, pCO2 values calculated from AT and CT are typically about 30% lower (i.e. ~300 μatm at a target pCO2 of 1000 μatm) than those calculated from AT and pH or CT and pH. This study presents and discusses these discrepancies as well as likely consequences for the ocean acidification community. Until this problem is solved, one has to consider that calculated parameters of the carbonate system (e.g. pCO2, calcite saturation state) may not be comparable between studies, and that this may have important implications for the interpretation of CO2 perturbation experiments.

Implications of observed inconsistencies in carbonate chemistry measurements for ocean acidification studies

NASA Astrophysics Data System (ADS)

Hoppe, C. J. M.; Langer, G.; Rokitta, S. D.; Wolf-Gladrow, D. A.; Rost, B.

2012-02-01

The growing field of ocean acidification research is concerned with the investigation of organisms' responses to increasing pCO2 values. One important approach in this context is culture work using seawater with adjusted CO2 levels. As aqueous pCO2 is difficult to measure directly in small scale experiments, it is generally calculated from two other measured parameters of the carbonate system (often AT, CT or pH). Unfortunately, the overall uncertainties of measured and subsequently calculated values are often unknown. Especially under high pCO2, this can become a severe problem with respect to the interpretation of physiological and ecological data. In the few datasets from ocean acidification research where all three of these parameters were measured, pCO2 values calculated from AT and CT are typically about 30 % lower (i.e. ~300 μatm at a target pCO2 of 1000 μatm) than those calculated from AT and pH or CT and pH. This study presents and discusses these discrepancies as well as likely consequences for the ocean acidification community. Until this problem is solved, one has to consider that calculated parameters of the carbonate system (e.g. pCO2, calcite saturation state) may not be comparable between studies, and that this may have important implications for the interpretation of CO2 perturbation experiments.

Is the perceived resiliency of fish larvae to ocean acidification masking more subtle effects?

NASA Astrophysics Data System (ADS)

Pope, E. C.; Ellis, R. P.; Scolamacchia, M.; Scolding, J. W. S.; Keay, A.; Chingombe, P.; Shields, R. J.; Wilcox, R.; Speirs, D. C.; Wilson, R. W.; Lewis, C.; Flynn, K. J.

2013-10-01

Ocean acidification, caused by rising concentrations of carbon dioxide (CO2), is widely considered to be a major global threat to marine ecosystems. To investigate the potential effects of ocean acidification on the early life stages of a commercially important fish species, European sea bass (Dicentrarchus labrax), 12 000 larvae were incubated from hatch through metamorphosis under a matrix of two temperatures (17 and 19 °C) and two seawater pCO2s (400 and 750 μatm) and sampled regularly for 42 days. Calculated daily mortality was significantly affected by both temperature and pCO2, with both increased temperature and elevated pCO2 associated with lower daily mortality and a significant interaction between these two factors. There was no significant pCO2 effect noted on larval morphology during this period but larvae raised at 19 °C possessed significantly larger eyes and lower carbon:nitrogen ratios at the end of the study compared to those raised under 17 °C. These results suggest that D. labrax larvae are resilient to near-future oceanic conditions. However, when the incubation was continued to post-metamorphic (juvenile) animals (day 67-69), fish raised under a combination of 19 °C and 750 μatm pCO2 were significantly heavier and exhibited lower aerobic scopes than those incubated at 19 °C and 400 μatm. Most other studies investigating the effects of near-future oceanic conditions on the early life stages of marine fish have used incubations of relatively short durations and suggested these animals are resilient to ocean acidification. We propose the durations of these other studies may be insufficient for more subtle effects, such as those observed in this study, to become apparent. These findings may have important implications for both sea bass in a changing ocean and also for the interpretation of results from other studies that have shown resiliency in marine teleosts exposed to higher atmospheric concentrations of CO2.

Relationship of 133Xe cerebral blood flow to middle cerebral arterial flow velocity in men at rest

NASA Technical Reports Server (NTRS)

Clark, J. M.; Skolnick, B. E.; Gelfand, R.; Farber, R. E.; Stierheim, M.; Stevens, W. C.; Beck, G. Jr; Lambertsen, C. J.

1996-01-01

Cerebral blood flow (CBF) was measured by 133Xe clearance simultaneously with the velocity of blood flow through the left middle cerebral artery (MCA) over a wide range of arterial PCO2 in eight normal men. Average arterial PCO2, which was varied by giving 4% and 6% CO2 in O2 and by controlled hyperventilation on O2, ranged from 25.3 to 49.9 mm Hg. Corresponding average values of global CBF15 were 27.2 and 65.0 ml 100 g min-1, respectively, whereas MCA blood-flow velocity ranged from 42.8 to 94.2 cm/s. The relationship of CBF to MCA blood-flow velocity over the imposed range of arterial PCO2 was described analytically by a parabola with the equation: CBF = 22.8 - 0.17 x velocity + 0.006 x velocity2 The observed data indicate that MCA blood-flow velocity is a useful index of CBF response to change in arterial PCO2 during O2 breathing at rest. With respect to baseline values measured while breathing 100% O2 spontaneously, percent changes in velocity were significantly smaller than corresponding percent changes in CBF at increased levels of arterial PCO2 and larger than CBF changes at the lower arterial PCO2. These observed relative changes are consistent with MCA vasodilation at the site of measurement during exposure to progressive hypercapnia and also during extreme hyperventilation hypocapnia.

In vitro effects of bicarbonate and bicarbonate-lactate buffered peritoneal dialysis solutions on mesothelial and neutrophil function.

PubMed

Topley, N; Kaur, D; Petersen, M M; Jörres, A; Williams, J D; Faict, D; Holmes, C J

1996-02-01

The inclusion of bicarbonate in the formulation of peritoneal dialysis solutions may avoid the in vitro impairment of certain cell functions seen with acidic lactate-based fluids. The supranormal physiological levels of HCO3- and PCO2 inherent in such formulations may, however, not be biocompatible. This study compared the in vitro biocompatibility of a pH 5.2 lactate-based formulation with formulations containing either 40 mM lactate at pH 7.4, 38 mM HCO3- at pH 6.8 (PCO2 at approximately 240 mm Hg) or 7.4 (PCO2 at approximately 60 mm Hg), and 25 mM HCO3- plus 15 mM lactate at pH 6.8 (PCO2 at approximately 160 mm Hg) or 7.4 (PCO2 at approximately 40 mm Hg). Significant release of lactate dehydrogenase or decreases in ATP content by human peritoneal mesothelial cells (HPMC) and human peripheral polymorphonuclear leukocytes (PMN) after a 30-min exposure to each test solution was only seen with the pH 5.2 lactate-based fluid. The ATP content of HPMC exposed to this fluid returned to control levels after 30 min of recovery in M199 control medium but showed a trend toward decreasing ATP content at 240 min. Similarly, interleukin (IL)-1 beta-induced IL-6 synthesis by HPMC was also only significantly reduced by the pH 5.2 lactate solution. PMN chemiluminescence was unaffected by 30-min exposure to all test solutions except for the pH 5.2 lactate formulation. Staphylococcus epidermidis phagocytosis was reduced to between 46 to 57% of control with all test solutions except the pH 5.2 lactate solution, which further suppressed the chemiluminescence response to 17% of control. These data suggest that short exposure to supranormal physiological levels of HCO3- and PCO2 does not impair HPMC or PMN viability and function. Furthermore, neutral pH lactate-containing solutions show equivalent biocompatibility to bicarbonate-based ones.

Independence of nutrient limitation and carbon dioxide impacts on the Southern Ocean coccolithophore Emiliania huxleyi.

PubMed

Müller, Marius N; Trull, Thomas W; Hallegraeff, Gustaaf M

2017-08-01

Future oceanic conditions induced by anthropogenic greenhouse gas emissions include warming, acidification and reduced nutrient supply due to increased stratification. Some parts of the Southern Ocean are expected to show rapid changes, especially for carbonate mineral saturation. Here we compare the physiological response of the model coccolithophore Emiliania huxleyi (strain EHSO 5.14, originating from 50 o S, 149 o E) with pH/CO 2 gradients (mimicking ocean acidification ranging from 1 to 4 × current pCO 2 levels) under nutrient-limited (nitrogen and phosphorus) and -replete conditions. Both nutrient limitations decreased per cell photosynthesis (particulate organic carbon (POC) production) and calcification (particulate inorganic carbon (PIC) production) rates for all pCO 2 levels, with more than 50% reductions under nitrogen limitation. These impacts, however, became indistinguishable from nutrient-replete conditions when normalized to cell volume. Calcification decreased three-fold and linearly with increasing pCO 2 under all nutrient conditions, and was accompanied by a smaller ~30% nonlinear reduction in POC production, manifested mainly above 3 × current pCO 2 . Our results suggest that normalization to cell volume allows the major impacts of nutrient limitation (changed cell sizes and reduced PIC and POC production rates) to be treated independently of the major impacts of increasing pCO 2 and, additionally, stresses the importance of including cell volume measurements to the toolbox of standard physiological analysis of coccolithophores in field and laboratory studies.

Independence of nutrient limitation and carbon dioxide impacts on the Southern Ocean coccolithophore Emiliania huxleyi

PubMed Central

Müller, Marius N; Trull, Thomas W; Hallegraeff, Gustaaf M

2017-01-01

Future oceanic conditions induced by anthropogenic greenhouse gas emissions include warming, acidification and reduced nutrient supply due to increased stratification. Some parts of the Southern Ocean are expected to show rapid changes, especially for carbonate mineral saturation. Here we compare the physiological response of the model coccolithophore Emiliania huxleyi (strain EHSO 5.14, originating from 50oS, 149oE) with pH/CO2 gradients (mimicking ocean acidification ranging from 1 to 4 × current pCO2 levels) under nutrient-limited (nitrogen and phosphorus) and -replete conditions. Both nutrient limitations decreased per cell photosynthesis (particulate organic carbon (POC) production) and calcification (particulate inorganic carbon (PIC) production) rates for all pCO2 levels, with more than 50% reductions under nitrogen limitation. These impacts, however, became indistinguishable from nutrient-replete conditions when normalized to cell volume. Calcification decreased three-fold and linearly with increasing pCO2 under all nutrient conditions, and was accompanied by a smaller ~30% nonlinear reduction in POC production, manifested mainly above 3 × current pCO2. Our results suggest that normalization to cell volume allows the major impacts of nutrient limitation (changed cell sizes and reduced PIC and POC production rates) to be treated independently of the major impacts of increasing pCO2 and, additionally, stresses the importance of including cell volume measurements to the toolbox of standard physiological analysis of coccolithophores in field and laboratory studies. PMID:28430186

Chemical microenvironments and single-cell carbon and nitrogen uptake in field-collected colonies of Trichodesmium under different pCO2

PubMed Central

Eichner, Meri J; Klawonn, Isabell; Wilson, Samuel T; Littmann, Sten; Whitehouse, Martin J; Church, Matthew J; Kuypers, Marcel MM; Karl, David M; Ploug, Helle

2017-01-01

Gradients of oxygen (O2) and pH, as well as small-scale fluxes of carbon (C), nitrogen (N) and O2 were investigated under different partial pressures of carbon dioxide (pCO2) in field-collected colonies of the marine dinitrogen (N2)-fixing cyanobacterium Trichodesmium. Microsensor measurements indicated that cells within colonies experienced large fluctuations in O2, pH and CO2 concentrations over a day–night cycle. O2 concentrations varied with light intensity and time of day, yet colonies exposed to light were supersaturated with O2 (up to ~200%) throughout the light period and anoxia was not detected. Alternating between light and dark conditions caused a variation in pH levels by on average 0.5 units (equivalent to 15 nmol l−1 proton concentration). Single-cell analyses of C and N assimilation using secondary ion mass spectrometry (SIMS; large geometry SIMS and nanoscale SIMS) revealed high variability in metabolic activity of single cells and trichomes of Trichodesmium, and indicated transfer of C and N to colony-associated non-photosynthetic bacteria. Neither O2 fluxes nor C fixation by Trichodesmium were significantly influenced by short-term incubations under different pCO2 levels, whereas N2 fixation increased with increasing pCO2. The large range of metabolic rates observed at the single-cell level may reflect a response by colony-forming microbial populations to highly variable microenvironments. PMID:28398346

Net loss of CaCO3 from coral reef communities due to human induced seawater acidification

USGS Publications Warehouse

Andersson, A.J.; Kuffner, I.B.; MacKenzie, F.T.; Jokiel, P.L.; Rodgers, K.S.; Tan, A.

2009-01-01

Acidification of seawater owing to oceanic uptake of atmospheric CO2 originating from human activities such as burning of fossil fuels and land-use changes has raised serious concerns regarding its adverse effects on corals and calcifying communities. Here we demonstrate a net loss of calcium carbonate (CaCO3) material as a result of decreased calcification and increased carbonate dissolution from replicated subtropical coral reef communities (n=3) incubated in continuous-flow mesocosms subject to future seawater conditions. The calcifying community was dominated by the coral Montipora capitata. Daily average community calcification or Net Ecosystem Calcification (NEC=CaCO3 production – dissolution) was positive at 3.3 mmol CaCO3 m−2 h−1 under ambient seawater pCO2 conditions as opposed to negative at −0.04 mmol CaCO3 m−2h−1 under seawater conditions of double the ambient pCO2. These experimental results provide support for the conclusion that some net calcifying communities could become subject to net dissolution in response to anthropogenic ocean acidification within this century. Nevertheless, individual corals remained healthy, actively calcified (albeit slower than at present rates), and deposited significant amounts of CaCO3 under the prevailing experimental seawater conditions of elevated pCO2.

Net Loss of CaCO3 from a subtropical calcifying community due to seawater acidification: Mesocosm-scale experimental evidence

USGS Publications Warehouse

Andersson, A.J.; Kuffner, I.B.; MacKenzie, F.T.; Jokiel, P.L.; Rodgers, K.S.; Tan, A.

2009-01-01

Acidification of seawater owing to oceanic uptake of atmospheric CO 2 originating from human activities such as burning of fossil fuels and land-use changes has raised serious concerns regarding its adverse effects on corals and calcifying communities. Here we demonstrate a net loss of calcium carbonate (CaCO3) material as a result of decreased calcification and increased carbonate dissolution from replicated subtropical coral reef communities (N=3) incubated in continuous-flow mesocosms subject to future seawater conditions. The calcifying community was dominated by the coral Montipora capitata. Daily average community calcification or Net Ecosystem Calcification (NECC=CaCO3 production - dissolution) was positive at 3.3 mmol CaCO3 m-2 h-1 under ambient seawater pCO2 conditions as opposed to negative at -0.04 mmol CaCO3 m-2 h-1 under seawater conditions of double the ambient pCO2. These experimental results provide support for the conclusion that some net calcifying communities could become subject to net dissolution in response to anthropogenic ocean acidification within this century. Nevertheless, individual corals remained healthy, actively calcified (albeit slower than at present rates), and deposited significant amounts of CaCO3 under the prevailing experimental seawater conditions of elevated pCO2.

Contrasting Extreme Flooding Events and their Influence on Carbon Dynamics in a Salt Marsh

NASA Astrophysics Data System (ADS)

Vargas, R.; Kowalska, N.; Lule, A. V.; Seyfferth, A.; Reimer, J.; Cai, W. J.; Moffat, C. F.

2017-12-01

Coastal ecosystems are threatened by sea level rise, making them vulnerable to more frequent extreme flooding events. Thus, it is critical to understand the effect of different flooding events on carbon dynamics to test the resiliency of these ecosystems. We used the eddy covariance method to measure CO2 and CH4 fluxes and instrumented an adjacent creek to measure pCO2 and pCH4 in a temperate salt marsh. The site was influenced by flooding caused by a hurricane storm surge and then a freshwater flood during September-October of 2015 and 2016, respectively. Water level, salinity, dissolved oxygen and turbidity were significantly influenced by the events. Daily mean CO2 fluxes show that during the hurricane surge, the ecosystem became a source of CO2 to the atmosphere releasing about 1.8 umol CO2 m-2 s-1 daily. Ecosystem CH4 fluxes were generally low ( 0.05 umol CH4 m-2 s-1) and showed high temporal variability (maximum of 0.6 umol CH4 m-2 s-1). There was an intermittent temporal coherence at 12-hour period (i.e., subdaily tides) between water level and net ecosystem exchange (NEE) or ecosystem CH4 fluxes. There was strong temporal coherence between water level and pCO2 at 12-hour period during the hurricane surge. During the freshwater surge we did not observe temporal coherence between water level and pCO2 or pCH4, but concentrations of both gases increased in the water of the marsh. These results show that extreme flooding events significantly influence short-term carbon dynamics and provide insights on ecosystem resiliency and lateral transport of pCO2 and pCH4 to the coastal ocean.

Large Uncertainty in Estimating pCO2 From Carbonate Equilibria in Lakes

NASA Astrophysics Data System (ADS)

Golub, Malgorzata; Desai, Ankur R.; McKinley, Galen A.; Remucal, Christina K.; Stanley, Emily H.

2017-11-01

Most estimates of carbon dioxide (CO2) evasion from freshwaters rely on calculating partial pressure of aquatic CO2 (pCO2) from two out of three CO2-related parameters using carbonate equilibria. However, the pCO2 uncertainty has not been systematically evaluated across multiple lake types and equilibria. We quantified random errors in pH, dissolved inorganic carbon, alkalinity, and temperature from the North Temperate Lakes Long-Term Ecological Research site in four lake groups across a broad gradient of chemical composition. These errors were propagated onto pCO2 calculated from three carbonate equilibria, and for overlapping observations, compared against uncertainties in directly measured pCO2. The empirical random errors in CO2-related parameters were mostly below 2% of their median values. Resulting random pCO2 errors ranged from ±3.7% to ±31.5% of the median depending on alkalinity group and choice of input parameter pairs. Temperature uncertainty had a negligible effect on pCO2. When compared with direct pCO2 measurements, all parameter combinations produced biased pCO2 estimates with less than one third of total uncertainty explained by random pCO2 errors, indicating that systematic uncertainty dominates over random error. Multidecadal trend of pCO2 was difficult to reconstruct from uncertain historical observations of CO2-related parameters. Given poor precision and accuracy of pCO2 estimates derived from virtually any combination of two CO2-related parameters, we recommend direct pCO2 measurements where possible. To achieve consistently robust estimates of CO2 emissions from freshwater components of terrestrial carbon balances, future efforts should focus on improving accuracy and precision of CO2-related parameters (including direct pCO2) measurements and associated pCO2 calculations.

Human respiration at rest in rapid compression and at high pressures and gas densities

NASA Technical Reports Server (NTRS)

Gelfand, R.; Lambertsen, C. J.; Strauss, R.; Clark, J. M.; Puglia, C. D.

1983-01-01

The ventilation (V), end-tidal PCO2 (PACO2), and CO2 elimination rate were determined in men at rest breathing CO2-free gas over the pressure range 1-50 ATA and the gas density range 0.4-25 g/l, during slow and rapid compressions, at stable elevated ambient pressures and during slow decompressions. Progressive increase in pulmonary gas flow resistance due to elevation of ambient pressure and inspired gas density to the He-O2 equivalent of 5000 feet of seawater was found to produce a complex pattern of change in PACO2. It was found that as both ambient pressure and pulmonary gas flow resistance were progressively raised, PACO2 at first increased, went through a maximum, and then declined towards values near the 1 ATA level. It is concluded that this pattern of PACO2 change results from the interaction on ventilation of the increase in pulmonary resistance due to the elevation of gas density with the increase in respiratory drive postulated as due to generalized central nervous system excitation associated with exposure to high hydrostatic pressure. It is suggested that a similar interaction exists between increased gas flow resistance and the increase in respiratory drive related to nitrogen partial pressure and the resulting narcosis.

Calcification is not the Achilles' heel of cold-water corals in an acidifying ocean.

PubMed

Rodolfo-Metalpa, Riccardo; Montagna, Paolo; Aliani, Stefano; Borghini, Mireno; Canese, Simonepietro; Hall-Spencer, Jason M; Foggo, Andy; Milazzo, Marco; Taviani, Marco; Houlbrèque, Fanny

2015-06-01

Ocean acidification is thought to be a major threat to coral reefs: laboratory evidence and CO2 seep research has shown adverse effects on many coral species, although a few are resilient. There are concerns that cold-water corals are even more vulnerable as they live in areas where aragonite saturation (Ωara ) is lower than in the tropics and is falling rapidly due to CO2 emissions. Here, we provide laboratory evidence that net (gross calcification minus dissolution) and gross calcification rates of three common cold-water corals, Caryophyllia smithii, Dendrophyllia cornigera, and Desmophyllum dianthus, are not affected by pCO2 levels expected for 2100 (pCO2  1058 μatm, Ωara 1.29), and nor are the rates of skeletal dissolution in D. dianthus. We transplanted D. dianthus to 350 m depth (pHT 8.02; pCO2  448 μatm, Ωara 2.58) and to a 3 m depth CO2 seep in oligotrophic waters (pHT 7.35; pCO2  2879 μatm, Ωara 0.76) and found that the transplants calcified at the same rates regardless of the pCO2 confirming their resilience to acidification, but at significantly lower rates than corals that were fed in aquaria. Our combination of field and laboratory evidence suggests that ocean acidification will not disrupt cold-water coral calcification although falling aragonite levels may affect other organismal physiological and/or reef community processes. © 2015 John Wiley & Sons Ltd.

Intramuscular injection of malignant hyperthermia trigger agents induces hypermetabolism in susceptible and nonsusceptible individuals.

PubMed

Metterlein, Thomas; Schuster, Frank; Kranke, Peter; Roewer, Norbert; Anetseder, Martin

2010-01-01

A new minimally invasive metabolic test for the diagnosis of susceptibility for malignant hyperthermia measuring intramuscular p(CO(2)) and lactate following local application of caffeine and halothane in humans was recently proposed. The present study tested the hypothesis that a more simplified test protocol allows a differentiation between malignant hyperthermia susceptible (MHS) and malignant hyperthermia nonsusceptible (MHN) and control individuals. With approval of the local ethics committee and informed consent, microdialysis and p(CO(2)) probes with attached microtubing were placed into the lateral vastus muscle of six MHS, seven MHN and seven control individuals. Following equilibration, boluses of 500 microl caffeine 80 mmol l(-1) and halothane 10 vol% dissolved in soybean oil were injected locally. p(CO(2)) and lactate were measured spectrophotometrically. The maximal rate of p(CO(2)) increase was significantly higher in MHS than in MHN and control individuals following application of halothane and caffeine, respectively. Intramuscular caffeine injection leads to a significantly higher increase of local lactate levels in MHS than in MHN and control individuals, whereas halothane increased local lactate levels in all investigated groups. Haemodynamic and systemic metabolic parameters did not differ between the investigated groups. Local caffeine and halothane injection increased intramuscular metabolism in MHS individuals significantly more than in the two other groups. In contrast to previous investigations, direct injection of the concentrations of halothane described here increased lactate and p(CO(2)) even in MHN skeletal muscle.

Riverine CO2 supersaturation and outgassing in a subtropical monsoonal mountainous area (Three Gorges Reservoir Region) of China

NASA Astrophysics Data System (ADS)

Li, Siyue; Ni, Maofei; Mao, Rong; Bush, Richard T.

2018-03-01

Rivers are an important source of CO2 to the atmosphere, however, mountainous rivers and streams with high emission rates are not well studied particularly in China. We report the first detailed investigation on monsoonal mountainous rivers in the Three Gorges Reservoir (TGR) region, with a focus on the riverine CO2 partial pressure (pCO2), CO2 degassing and their potential controls. The pCO2 levels ranged from 50 to 6019 μatm with averages of 1573 (SD. ±1060) in dry Autumn and 1276 (SD. ±1166) μatm in wet Summer seasons. 94% of samples were supersaturated with CO2 with respect to the atmospheric equilibrium (410 μatm). Monsoonal precipitation controlled pCO2 seasonality, with both the maximal and minimal levels occurring in the wet season, and showing the overall effects of dilution. Riverine pCO2 could be predicted better in the dry season using pH, DO% and DTP, whereas pH and DOC were better predictors in the wet season. We conclude that in-situ respiration of allochthonous organic carbon, rather than photosynthesis, resulted in negative relationships between pCO2 and DO and pH, and thus CO2 supersaturation. Photosynthetic primary production was effectively limited by rapid flow velocity and short residence time. The estimated water-to-air CO2 emission rate in the TGR rivers was 350 ± 319 in the Autumn and lower, yet more variable at 326 ± 439 mmol/m2/d in Summer. Our calculated CO2 areal fluxes were in the upper-level magnitude of published data, demonstrating the importance of mountainous rivers and streams as a global greenhouse gas source, and urgency for more detailed studies on CO2 degassing, to address a global data gap for these environments.

Effects of humoral factors on ventilation kinetics during recovery after impulse-like exercise.

PubMed

Afroundeh, R; Arimitsu, T; Yamanaka, R; Lian, C; Yunoki, T; Yano, Tokuo

2012-06-01

To clarify the ventilatory kinetics during recovery after impulse-like exercise, subjects performed one impulse-like exercise test (one-impulse) and a five-times repeated impulse-like exercises test (five-impulse). Duration and intensity of the impulse-like exercise were 20 sec and 400 watts (80 rpm), respectively. Although blood pH during recovery (until 10 min) was significantly lower in the five-impulse test than in the one-impulse test, ventilation (.VE) in the two tests was similar except during the first 30 sec of recovery, in which it was higher in the five-impulse test. In one-impulse, blood CO2 pressure (PCO2) was significantly increased at 1 min during recovery and then returned to the pre-exercise level at 5 min during recovery. In the five-impulse test, PCO2 at 1 min during recovery was similar to the pre-exercise level, and then it decreased to a level lower than the pre-exercise level at 5 min during recovery. Accordingly, PCO2 during recovery (until 30 min) was significantly lower in the five-impulse than in one-impulse test..VE and pH during recovery showed a curvilinear relationship, and at the same pH, ventilation was higher in the one-impulse test. These results suggest that ventilatory kinetics during recovery after impulse-like exercise is attributed partly to pH, but the stimulatory effect of lower pH is diminished by the inhibitory effect of lower PCO2.

Effect of leuprolide and dexamethasone on hair growth and hormone levels in hirsute women: the relative importance of the ovary and the adrenal in the pathogenesis of hirsutism.

PubMed

Rittmaster, R S; Thompson, D L

1990-04-01

Ten hirsute women with polycystic ovarian syndrome (PCO) and nine with idiopathic hirsutism (IH) underwent selective ovarian suppression with leuprolide for 5-6 months and then were randomized to receive, in addition, dexamethasone or placebo for 4 more months. Serum hormone levels and hair growth rates were determined before and after each treatment period. During the initial treatment period with leuprolide alone, testosterone decreased by 54 +/- 6% (mean +/- SEM) in PCO and by 36 +/- 3% in IH (P = 0.02). Androstenedione decreased by 53 +/- 6% in PCO and by 31 +/- 7% in IH (P = 0.02). Androstanediol glucuronide (Adiol-G) decreased by 14 +/- 6% in PCO and by 7 +/- 3% in IH. There was no change in dehydroepiandrosterone sulfate (DHEAS). While initial serum androgen levels were higher in PCO than in IH, they were similar after ovarian suppression in the two groups. After ovarian suppression, Adiol-G was more consistently correlated with testosterone and androstenedione than was DHEAS, suggesting that Adiol-G may be a better marker than DHEAS of adrenal androgen secretion. Hair growth rates decreased by 37 +/- 6% in PCO and by 14 +/- 10% in IH (P = 0.07). The change in hair growth correlated with the change in androstenedione (r = 0.66; P = 0.002), but not significantly with the change in testosterone (r = 0.29; P = 0.2). After the addition of dexamethasone therapy (0.5 mg daily), testosterone, androstenedione, and DHEAS levels fell to near or below assay detection limits, while Adiol-G decreased by 80 +/- 3%. Hair growth rates decreased slightly more in women during dexamethasone (46 +/- 6%) than during placebo (26 +/- 9%; P = 0.18). In summary, the ovary was the major source of circulating testosterone and androstenedione in PCO. The adrenal contributed a substantial minority of these hormones in PCO and was the major source of androgen secretion in IH. Adrenal hyperandrogenism was common in both IH and PCO. Hair growth rates correlated best with changes in serum androstenedione levels. Adiol-G, which was derived primarily from adrenal precursors, was a better marker of adrenal androgen secretion than was DHEAS in these subjects.

The mineralogical responses of marine calcifiers to CO2-induced ocean acidification

NASA Astrophysics Data System (ADS)

Ries, J. B.; Cohen, A. L.; McCorkle, D. C.

2008-12-01

We have conducted 6-month laboratory experiments to investigate the effect of pCO2-induced reductions in seawater CaCO3 saturation state on biocalcification by 18 aragonitic and calcitic (low-high Mg) taxa representing eight of the major marine calcifying groups: Chlorophyta; Rhodophyta; Crustacea; Bivalvia; Gastropoda; Annelida; Cnidaria; and Echinodermata. The CaCO3 saturation states of the experimental seawaters, constrained by intercalibrated determinations of pH, alkalinity, and DIC, were attained with bubbled air-CO2 mixtures of 400 (ambient), 600, 900, and 2850 ppm pCO2, yielding Ωarag of 2.5 (ambient), 2.0, 1.5, 0.7, respectively. We previously showed that while rates of net calcification obtained from buoyant weighing declined with increasing pCO2 for nearly half of the species investigated, a nearly equal number exhibited constant or, in some cases, increased calcification under moderately (600 ppm) or extremely (900 or 2850 ppm) elevated pCO2. The organisms' investigated in this study secrete various forms of CaCO3, which differ in crystallographic structure and therefore solubility: aragonite and high-Mg are generally more soluble than low-Mg calcite. We have employed powder x-ray diffraction, Raman spectroscopy, inductively-coupled-plasma mass-spectrometry, and scanning electron microscopy to quantify changes in the organisms' skeletal mineralogy (aragonite:calcite ratio) and Mg-content (MgCO3:CaCO3 ratio) that occurred in response to the prescribed reductions in seawater CaCO3 saturation state. We will compare calcification and mineralogical response patterns amongst the organisms to elucidate the role of mineral lability in driving species-specific responses to CO2-induced ocean acidification.

Impacts of food availability and pCO2 on planulation, juvenile survival, and calcification of the azooxanthellate scleractinian coral Balanophyllia elegans

NASA Astrophysics Data System (ADS)

Crook, E. D.; Cooper, H.; Potts, D. C.; Lambert, T.; Paytan, A.

2013-11-01

Ocean acidification, the assimilation of atmospheric CO2 by the oceans that decreases the pH and CaCO3 saturation state (Ω) of seawater, is projected to have severe adverse consequences for calcifying organisms. While strong evidence suggests calcification by tropical reef-building corals containing algal symbionts (zooxanthellae) will decline over the next century, likely responses of azooxanthellate corals to ocean acidification are less well understood. Because azooxanthellate corals do not obtain photosynthetic energy from symbionts, they provide a system for studying the direct effects of acidification on energy available for calcification. The solitary azooxanthellate orange cup coral Balanophyllia elegans often lives in low-pH, upwelled waters along the California coast. In an 8-month factorial experiment, we measured the effects of three pCO2 treatments (410, 770, and 1220 μatm) and two feeding frequencies (3-day and 21-day intervals) on "planulation" (larval release) by adult B. elegans, and on the survival, skeletal growth, and calcification of newly settled juveniles. Planulation rates were affected by food level but not pCO2. Juvenile mortality was highest under high pCO2 (1220 μatm) and low food (21-day intervals). Feeding rate had a greater impact on calcification of B. elegans than pCO2. While net calcification was positive even at 1220 μatm (~3 times current atmospheric pCO2), overall calcification declined by ~25-45%, and skeletal density declined by ~35-45% as pCO2 increased from 410 to 1220 μatm. Aragonite crystal morphology changed at high pCO2, becoming significantly shorter but not wider at 1220 μatm. We conclude that food abundance is critical for azooxanthellate coral calcification, and that B. elegans may be partially protected from adverse consequences of ocean acidification in habitats with abundant heterotrophic food.

Photocatalytic oxidation of nitrogen oxides using TiO2 loading on woven glass fabric.

PubMed

Wang, Haiqiang; Wu, Zhongbiao; Zhao, Weirong; Guan, Baohong

2007-01-01

TiO2 loading on woven glass fabric is applied to treat nitrogen oxides (NOx) by photocatalytic oxidation (PCO). In this paper, the PCO behavior of NO at high concentrations was studied by PCO of NOx at source levels (20-168 ppm). The PCO efficiency reached 27% in this experiment, while the inlet NOx concentration was 168 ppm (147 ppm NO). The dependency of the reaction rate on several key influencing factors (relative humidity, space time, inlet concentration, oxygen percentage) was also studied. The results illustrate that the resulting hydroxyl radical and active oxide play an important role in the oxidation of NOx. The reactions are limited by the thermodynamic equilibrium after ca. 15s space time. A possible explanation for the catalyst deactivation is the accumulation of nitric acid and nitrous acid on the TiO2 surface during the PCO of NOx. However, the photocatalytic activity can be recovered with a simple heat treatment. The results from the study of the effect of the inlet concentration were described with the Langmuir-Hinshelwood model.

Estimating temporal and spatial variation of ocean surface pCO2 in the North Pacific using a Self Organizing Map neural network technique

NASA Astrophysics Data System (ADS)

Nakaoka, S.; Telszewski, M.; Nojiri, Y.; Yasunaka, S.; Miyazaki, C.; Mukai, H.; Usui, N.

2013-03-01

This study produced maps of the partial pressure of oceanic carbon dioxide (pCO2sea) in the North Pacific on a 0.25° latitude × 0.25° longitude grid from 2002 to 2008. The pCO2sea values were estimated by using a self-organizing map neural network technique to explain the non-linear relationships between observed pCO2sea data and four oceanic parameters: sea surface temperature (SST), mixed layer depth, chlorophyll a concentration, and sea surface salinity (SSS). The observed pCO2sea data was obtained from an extensive dataset generated by the volunteer observation ship program operated by the National Institute for Environmental Studies. The reconstructed pCO2sea values agreed rather well with the pCO2sea measurements, the root mean square error being 17.6 μatm. The pCO2sea estimates were improved by including SSS as one of the training parameters and by taking into account secular increases of pCO2sea that have tracked increases in atmospheric CO2. Estimated pCO2sea values accurately reproduced pCO2sea data at several stations in the North Pacific. The distributions of pCO2sea revealed by seven-year averaged monthly pCO2sea maps were similar to Lamont-Doherty Earth Observatory pCO2sea climatology and more precisely reflected oceanic conditions. The distributions of pCO2sea anomalies over the North Pacific during the winter clearly showed regional contrasts between El Niño and La Niña years related to changes of SST and vertical mixing.

Coral Reefs on the Edge? Carbon Chemistry on Inshore Reefs of the Great Barrier Reef

PubMed Central

Uthicke, Sven; Furnas, Miles; Lønborg, Christian

2014-01-01

While increasing atmospheric carbon dioxide (CO2) concentration alters global water chemistry (Ocean Acidification; OA), the degree of changes vary on local and regional spatial scales. Inshore fringing coral reefs of the Great Barrier Reef (GBR) are subjected to a variety of local pressures, and some sites may already be marginal habitats for corals. The spatial and temporal variation in directly measured parameters: Total Alkalinity (TA) and dissolved inorganic carbon (DIC) concentration, and derived parameters: partial pressure of CO2 (pCO2); pH and aragonite saturation state (Ωar) were measured at 14 inshore reefs over a two year period in the GBR region. Total Alkalinity varied between 2069 and 2364 µmol kg−1 and DIC concentrations ranged from 1846 to 2099 µmol kg−1. This resulted in pCO2 concentrations from 340 to 554 µatm, with higher values during the wet seasons and pCO2 on inshore reefs distinctly above atmospheric values. However, due to temperature effects, Ωar was not further reduced in the wet season. Aragonite saturation on inshore reefs was consistently lower and pCO2 higher than on GBR reefs further offshore. Thermodynamic effects contribute to this, and anthropogenic runoff may also contribute by altering productivity (P), respiration (R) and P/R ratios. Compared to surveys 18 and 30 years ago, pCO2 on GBR mid- and outer-shelf reefs has risen at the same rate as atmospheric values (∼1.7 µatm yr−1) over 30 years. By contrast, values on inshore reefs have increased at 2.5 to 3 times higher rates. Thus, pCO2 levels on inshore reefs have disproportionately increased compared to atmospheric levels. Our study suggests that inshore GBR reefs are more vulnerable to OA and have less buffering capacity compared to offshore reefs. This may be caused by anthropogenically induced trophic changes in the water column and benthos of inshore reefs subjected to land runoff. PMID:25295864

Effect of ocean acidification on the fatty acid composition of a natural plankton community

NASA Astrophysics Data System (ADS)

Leu, E.; Daase, M.; Schulz, K. G.; Stuhr, A.; Riebesell, U.

2012-07-01

The effect of ocean acidification on the fatty acid composition of a natural plankton community in the Arctic was studied in a large-scale mesocosm experiment, carried out in Kongsfjorden (Svalbard, Norway) at 79° N. Nine mesocosms of ~50 cbm each were exposed to different pCO2 levels (from natural background conditions to ~1420 μatm), yielding pH values (on the total scale) from ~8.3 to 7.5. Inorganic nutrients were added on day 13. The phytoplankton development during this 30 days experiment passed three distinct phases: (1) prior to the addition of inorganic nutrients, (2) first bloom after nutrient addition, and (3) second bloom after nutrient addition. The fatty acid composition of the natural plankton community was analysed and showed, in general, high percentages of polyunsaturated fatty acids (PUFAs): 44-60% of total fatty acids. Positive correlations with pCO2 were found for most PUFAs during phases 2 and/or 3, with the exception of 20:5n3 (eicosapentaenoic acid, EPA), an important diatom marker. There are strong indications for these correlations being mediated indirectly through taxonomic changes and the natural development of the communities in the mesocosms exposed to different pCO2 levels. While diatoms increased during phase 3 mainly in the low and intermediate pCO2 treatments, dinoflagellates were favoured by high CO2 concentrations during the same time period. This is reflected in the development of group-specific fatty acid trophic markers. No indications were found for a generally detrimental effect of ocean acidification on the planktonic food quality in terms of essential fatty acids. The significant positive correlations between most PUFAs and pCO2 reflected treatment-dependent differences in the community composition between the mesocosms rather than a direct positive effect of pCO2 on specific fatty acids.

Differential response to ocean acidification in physiological traits of Concholepas concholepas populations

NASA Astrophysics Data System (ADS)

Lardies, Marco A.; Arias, María Belén; Poupin, María Josefina; Manríquez, Patricio H.; Torres, Rodrigo; Vargas, Cristian A.; Navarro, Jorge M.; Lagos, Nelson A.

2014-07-01

Phenotypic adaptation to environmental fluctuations frequently occurs by preexisting plasticity and its role as a major component of variation in physiological diversity is being widely recognized. Few studies have considered the change in phenotypic flexibility among geographic populations in marine calcifiers to ocean acidification projections, despite the fact that this type of study provides understanding about how the organism may respond to this chemical change in the ocean. We examined the geographic variation in CO2 seawater concentrations in the phenotype and in the reaction norm of physiological traits using a laboratory mesocosm approach with short-term acclimation in two contrasting populations (Antofagasta and Calfuco) of the intertidal snail Concholepas concholepas. Our results show that elevated pCO2 conditions increase standard metabolic rates in both populations of the snail juveniles, likely due to the higher energy cost of homeostasis. Juveniles of C. concholepas in the Calfuco (southern) population showed a lower increment of metabolic rate in high-pCO2 environments concordant with a lesser gene expression of a heat shock protein with respect to the Antofagasta (northern) population. Combined these results indicate a negative effect of ocean acidification on whole-organism functioning of C. concholepas. Finally, the significant Population × pCO2 level interaction in both studied traits indicates that there is variation between populations in response to high-pCO2 conditions.

A coccolithophore concept for constraining the Cenozoic carbon cycle

NASA Astrophysics Data System (ADS)

Henderiks, J.; Rickaby, R. E. M.

2007-06-01

An urgent question for future climate, in light of increased burning of fossil fuels, is the temperature sensitivity of the climate system to atmospheric carbon dioxide (pCO>sub>2). To date, no direct proxy for past levels of pCO2 exists beyond the reach of the polar ice core records. We propose a new methodology for placing a constraint on pCO2 over the Cenozoic based on the physiological plasticity of extant coccolithophores. Specifically, our premise is that the contrasting calcification tolerance of various extant species of coccolithophore to raised pCO2 reflects an "evolutionary memory" of past atmospheric composition. The different times of evolution of certain morphospecies allows an upper constraint of past pCO2 to be placed on Cenozoic timeslices. Further, our hypothesis has implications for the response of marine calcifiers to ocean acidification. Geologically "ancient" species, which have survived large changes in ocean chemistry, are likely more resilient to predicted acidification.

Effect of Ocean Acidification on the Food Quality of the Coccolithophore Emiliania huxleyi

NASA Astrophysics Data System (ADS)

Maine, J. E.; White, M. M.; Balch, W. M.; Milke, L. M.

2016-02-01

The anthropogenic burning of fossil fuels has doubled atmospheric carbon dioxide (CO2) levels over the last 200 years. Atmospheric CO2 diffuses into the ocean, changing the chemistry and decreasing the pH of seawater in a process called Ocean Acidification (OA). Calcifying marine phytoplankton, coccolithophores, are vulnerable to OA. Emiliania huxleyi is a lipid-dense and globally-abundant species of coccolithophore, therefore it is a vital food source for higher marine trophic levels. The objective of this project was to determine how OA affects the lipid profile and calcification of E. huxleyi CCMP #371. Gas chromatography was used to determine how the proportions of saturated (SFA), monounsaturated (MUFA), and polyunsaturated fatty acids (PUFA) in E. huxleyi varied with increasing pCO2. Flow cytometry was used to measure how the distribution of highly calcified cells, partially calcified cells, and un-calcified cells changed with increasing pCO2. The proportion of MUFA increased with pCO2. The proportion of un-calcified and partially calcified cells increased with increasing pCO2, however, the results varied across two experimental runs. In conclusion, the lipid-profile and calcification properties of E. huxleyi, and likely its food quality to predators, are affected by OA.

Extreme ecosystem instability suppressed tropical dinosaur dominance for 30 million years.

PubMed

Whiteside, Jessica H; Lindström, Sofie; Irmis, Randall B; Glasspool, Ian J; Schaller, Morgan F; Dunlavey, Maria; Nesbitt, Sterling J; Smith, Nathan D; Turner, Alan H

2015-06-30

A major unresolved aspect of the rise of dinosaurs is why early dinosaurs and their relatives were rare and species-poor at low paleolatitudes throughout the Late Triassic Period, a pattern persisting 30 million years after their origin and 10-15 million years after they became abundant and speciose at higher latitudes. New palynological, wildfire, organic carbon isotope, and atmospheric pCO2 data from early dinosaur-bearing strata of low paleolatitudes in western North America show that large, high-frequency, tightly correlated variations in δ(13)Corg and palynomorph ecotypes occurred within a context of elevated and increasing pCO2 and pervasive wildfires. Whereas pseudosuchian archosaur-dominated communities were able to persist in these same regions under rapidly fluctuating extreme climatic conditions until the end-Triassic, large-bodied, fast-growing tachymetabolic dinosaurian herbivores requiring greater resources were unable to adapt to unstable high CO2 environmental conditions of the Late Triassic.

Extreme ecosystem instability suppressed tropical dinosaur dominance for 30 million years

NASA Astrophysics Data System (ADS)

Whiteside, Jessica H.; Lindström, Sofie; Irmis, Randall B.; Glasspool, Ian J.; Schaller, Morgan F.; Dunlavey, Maria; Nesbitt, Sterling J.; Smith, Nathan D.; Turner, Alan H.

2015-06-01

A major unresolved aspect of the rise of dinosaurs is why early dinosaurs and their relatives were rare and species-poor at low paleolatitudes throughout the Late Triassic Period, a pattern persisting 30 million years after their origin and 10-15 million years after they became abundant and speciose at higher latitudes. New palynological, wildfire, organic carbon isotope, and atmospheric pCO2 data from early dinosaur-bearing strata of low paleolatitudes in western North America show that large, high-frequency, tightly correlated variations in δ13Corg and palynomorph ecotypes occurred within a context of elevated and increasing pCO2 and pervasive wildfires. Whereas pseudosuchian archosaur-dominated communities were able to persist in these same regions under rapidly fluctuating extreme climatic conditions until the end-Triassic, large-bodied, fast-growing tachymetabolic dinosaurian herbivores requiring greater resources were unable to adapt to unstable high CO2 environmental conditions of the Late Triassic.

Impact of elevated CO2 on shellfish calcification

NASA Astrophysics Data System (ADS)

Gazeau, Frédéric; Quiblier, Christophe; Jansen, Jeroen M.; Gattuso, Jean-Pierre; Middelburg, Jack J.; Heip, Carlo H. R.

2007-04-01

Ocean acidification resulting from human emissions of carbon dioxide has already lowered and will further lower surface ocean pH. The consequent decrease in calcium carbonate saturation potentially threatens calcareous marine organisms. Here, we demonstrate that the calcification rates of the edible mussel (Mytilus edulis) and Pacific oyster (Crassostrea gigas) decline linearly with increasing pCO2. Mussel and oyster calcification may decrease by 25 and 10%, respectively, by the end of the century, following the IPCC IS92a scenario (~740 ppmv in 2100). Moreover, mussels dissolve at pCO2 values exceeding a threshold value of ~1800 ppmv. As these two species are important ecosystem engineers in coastal ecosystems and represent a large part of worldwide aquaculture production, the predicted decrease of calcification in response to ocean acidification will probably have an impact on coastal biodiversity and ecosystem functioning as well as potentially lead to significant economic loss.

Extreme ecosystem instability suppressed tropical dinosaur dominance for 30 million years

PubMed Central

Whiteside, Jessica H.; Lindström, Sofie; Irmis, Randall B.; Glasspool, Ian J.; Schaller, Morgan F.; Dunlavey, Maria; Nesbitt, Sterling J.; Smith, Nathan D.; Turner, Alan H.

2015-01-01

A major unresolved aspect of the rise of dinosaurs is why early dinosaurs and their relatives were rare and species-poor at low paleolatitudes throughout the Late Triassic Period, a pattern persisting 30 million years after their origin and 10–15 million years after they became abundant and speciose at higher latitudes. New palynological, wildfire, organic carbon isotope, and atmospheric pCO2 data from early dinosaur-bearing strata of low paleolatitudes in western North America show that large, high-frequency, tightly correlated variations in δ13Corg and palynomorph ecotypes occurred within a context of elevated and increasing pCO2 and pervasive wildfires. Whereas pseudosuchian archosaur-dominated communities were able to persist in these same regions under rapidly fluctuating extreme climatic conditions until the end-Triassic, large-bodied, fast-growing tachymetabolic dinosaurian herbivores requiring greater resources were unable to adapt to unstable high CO2 environmental conditions of the Late Triassic. PMID:26080428

Ocean acidification alleviates low-temperature effects on growth and photosynthesis of the red alga Neosiphonia harveyi (Rhodophyta).

PubMed

Olischläger, Mark; Wiencke, Christian

2013-12-01

This study aimed to examine interactive effects between ocean acidification and temperature on the photosynthetic and growth performance of Neosiphonia harveyi. N. harveyi was cultivated at 10 and 17.5 °C at present (~380 µatm), expected future (~800 µatm), and high (~1500 µatm) pCO2. Chlorophyll a fluorescence, net photosynthesis, and growth were measured. The state of the carbon-concentrating mechanism (CCM) was examined by pH-drift experiments (with algae cultivated at 10 °C only) using ethoxyzolamide, an inhibitor of external and internal carbonic anhydrases (exCA and intCA, respectively). Furthermore, the inhibitory effect of acetazolamide (an inhibitor of exCA) and Tris (an inhibitor of the acidification of the diffusive boundary layer) on net photosynthesis was measured at both temperatures. Temperature affected photosynthesis (in terms of photosynthetic efficiency, light saturation point, and net photosynthesis) and growth at present pCO2, but these effects decreased with increasing pCO2. The relevance of the CCM decreased at 10 °C. A pCO2 effect on the CCM could only be shown if intCA and exCA were inhibited. The experiments demonstrate for the first time interactions between ocean acidification and temperature on the performance of a non-calcifying macroalga and show that the effects of low temperature on photosynthesis can be alleviated by increasing pCO2. The findings indicate that the carbon acquisition mediated by exCA and acidification of the diffusive boundary layer decrease at low temperatures but are not affected by the cultivation level of pCO2, whereas the activity of intCA is affected by pCO2. Ecologically, the findings suggest that ocean acidification might affect the biogeographical distribution of N. harveyi.

Effects of eustatic sea-level change, ocean dynamics, and nutrient utilization on atmospheric pCO2 and seawater composition over the last 130 000 years: a model study

NASA Astrophysics Data System (ADS)

Wallmann, K.; Schneider, B.; Sarnthein, M.

2016-02-01

We have developed and employed an Earth system model to explore the forcings of atmospheric pCO2 change and the chemical and isotopic evolution of seawater over the last glacial cycle. Concentrations of dissolved phosphorus (DP), reactive nitrogen, molecular oxygen, dissolved inorganic carbon (DIC), total alkalinity (TA), 13C-DIC, and 14C-DIC were calculated for 24 ocean boxes. The bi-directional water fluxes between these model boxes were derived from a 3-D circulation field of the modern ocean (Opa 8.2, NEMO) and tuned such that tracer distributions calculated by the box model were consistent with observational data from the modern ocean. To model the last 130 kyr, we employed records of past changes in sea-level, ocean circulation, and dust deposition. According to the model, about half of the glacial pCO2 drawdown may be attributed to marine regressions. The glacial sea-level low-stands implied steepened ocean margins, a reduced burial of particulate organic carbon, phosphorus, and neritic carbonate at the margin seafloor, a decline in benthic denitrification, and enhanced weathering of emerged shelf sediments. In turn, low-stands led to a distinct rise in the standing stocks of DIC, TA, and nutrients in the global ocean, promoted the glacial sequestration of atmospheric CO2 in the ocean, and added 13C- and 14C-depleted DIC to the ocean as recorded in benthic foraminifera signals. The other half of the glacial drop in pCO2 was linked to inferred shoaling of Atlantic meridional overturning circulation and more efficient utilization of nutrients in the Southern Ocean. The diminished ventilation of deep water in the glacial Atlantic and Southern Ocean led to significant 14C depletions with respect to the atmosphere. According to our model, the deglacial rapid and stepwise rise in atmospheric pCO2 was induced by upwelling both in the Southern Ocean and subarctic North Pacific and promoted by a drop in nutrient utilization in the Southern Ocean. The deglacial sea-level rise led to a gradual decline in nutrient, DIC, and TA stocks, a slow change due to the large size and extended residence times of dissolved chemical species in the ocean. Thus, the rapid deglacial rise in pCO2 can be explained by fast changes in ocean dynamics and nutrient utilization whereas the gradual pCO2 rise over the Holocene may be linked to the slow drop in nutrient and TA stocks that continued to promote an ongoing CO2 transfer from the ocean into the atmosphere.

Emissions of carbon dioxide and methane from a headwater stream network of interior Alaska

USGS Publications Warehouse

Crawford, John T.; Striegl, Robert G.; Wickland, Kimberly P.; Dornblaser, Mark M.; Stanley, Emily H.

2013-01-01

Boreal ecosystems store significant quantities of organic carbon (C) that may be vulnerable to degradation as a result of a warming climate. Despite their limited coverage on the landscape, streams play a significant role in the processing, gaseous emission, and downstream export of C, and small streams are thought to be particularly important because of their close connection with the surrounding landscape. However, ecosystem carbon studies do not commonly incorporate the role of the aquatic conduit. We measured carbon dioxide (CO2) and methane (CH4) concentrations and emissions in a headwater stream network of interior Alaska underlain by permafrost to assess the potential role of stream gas emissions in the regional carbon balance. First-order streams exhibited the greatest variability in fluxes of CO2 and CH4,and the greatest mean pCO2. High-resolution time series of stream pCO2 and discharge at two locations on one first-order stream showed opposing pCO2 responses to storm events, indicating the importance of hydrologic flowpaths connecting CO2-rich soils with surface waters. Repeated longitudinal surveys on the stream showed consistent areas of elevated pCO2 and pCH4, indicative of discrete hydrologic flowpaths delivering soil water and groundwater having varying chemistry. Up-scaled basin estimates of stream gas emissions suggest that streams may contribute significantly to catchment-wide CH4 emissions. Overall, our results indicate that while stream-specific gas emission rates are disproportionately high relative to the terrestrial landscape, both stream surface area and catchment normalized emission rates were lower than those documented for the Yukon River Basin as a whole. This may be due to limitations of C sources and/or C transport to surface waters.

INTERACTIONS BETWEEN OCEAN ACIDIFICATION AND WARMING ON THE MORTALITY AND DISSOLUTION OF CORALLINE ALGAE(1).

PubMed

Diaz-Pulido, Guillermo; Anthony, Kenneth R N; Kline, David I; Dove, Sophie; Hoegh-Guldberg, Ove

2012-02-01

Coralline algae are among the most sensitive calcifying organisms to ocean acidification as a result of increased atmospheric carbon dioxide (pCO2 ). Little is known, however, about the combined impacts of increased pCO2 , ocean acidification, and sea surface temperature on tissue mortality and skeletal dissolution of coralline algae. To address this issue, we conducted factorial manipulative experiments of elevated CO2 and temperature and examined the consequences on tissue survival and skeletal dissolution of the crustose coralline alga (CCA) Porolithon (=Hydrolithon) onkodes (Heydr.) Foslie (Corallinaceae, Rhodophyta) on the southern Great Barrier Reef (GBR), Australia. We observed that warming amplified the negative effects of high pCO2 on the health of the algae: rates of advanced partial mortality of CCA increased from <1% to 9% under high CO2 (from 400 to 1,100 ppm) and exacerbated to 15% under warming conditions (from 26°C to 29°C). Furthermore, the effect of pCO2 on skeletal dissolution strongly depended on temperature. Dissolution of P. onkodes only occurred in the high-pCO2 treatment and was greater in the warm treatment. Enhanced skeletal dissolution was also associated with a significant increase in the abundance of endolithic algae. Our results demonstrate that P. onkodes is particularly sensitive to ocean acidification under warm conditions, suggesting that previous experiments focused on ocean acidification alone have underestimated the impact of future conditions on coralline algae. Given the central role that coralline algae play within coral reefs, these conclusions have serious ramifications for the integrity of coral-reef ecosystems. © 2011 Phycological Society of America.

The acid and alkalinity budgets of weathering in the Andes-Amazon system: Insights into the erosional control of global biogeochemical cycles

NASA Astrophysics Data System (ADS)

Torres, Mark A.; West, A. Joshua; Clark, Kathryn E.; Paris, Guillaume; Bouchez, Julien; Ponton, Camilo; Feakins, Sarah J.; Galy, Valier; Adkins, Jess F.

2016-09-01

The correlation between chemical weathering fluxes and denudation rates suggests that tectonic activity can force variations in atmospheric pCO2 by modulating weathering fluxes. However, the effect of weathering on pCO2 is not solely determined by the total mass flux. Instead, the effect of weathering on pCO2 also depends upon the balance between 1) alkalinity generation by carbonate and silicate mineral dissolution and 2) sulfuric acid generation by the oxidation of sulfide minerals. In this study, we explore how the balance between acid and alkalinity generation varies with tectonic uplift to better understand the links between tectonics and the long-term carbon cycle. To trace weathering reactions across the transition from the Peruvian Andes to the Amazonian foreland basin, we measured a suite of elemental concentrations (Na, K, Ca, Mg, Sr, Si, Li, SO4, and Cl) and isotopic ratios (87Sr/86Sr and δ34S) on both dissolved and solid phase samples. Using an inverse model, we quantitatively link systematic changes in solute geochemistry with elevation to downstream declines in sulfuric acid weathering as well as the proportion of cations sourced from silicates. With a new carbonate-system framework, we show that weathering in the Andes Mountains is a CO2 source whereas foreland weathering is a CO2 sink. These results are consistent with the theoretical expectation that the ratio of sulfide oxidation to silicate weathering increases with increasing erosion. Altogether, our results suggest that the effect of tectonically-enhanced weathering on atmospheric pCO2 is strongly modulated by sulfide mineral oxidation.

[Study on the oxidative stress in the ovaries of a rat model of polycystic ovary].

PubMed

Gong, Jin; Wu, Dong-bo; Zhang, Lan-lan; Li, Jia; Zhao, Xing; Zhang, Dan

2015-03-01

To establish a pathological animal model of polycystic ovary (PCO) by letrozole in rats. Investigate whether PCO were mediated by the effect of oxidative stress by measuring oxidative stress levels in this cohort of rats with PCO, and proceed a new way of treatment for polycystic ovary syndrom (PCOS). 90 SD female rats aged 6 weeks were randomly divided into two groups, including a control group of 45 rats that received vehicle only [19% aqueous solution of carboxmethlycellulose (CMC), 1 mL/d] once daily orally (p.o.), and an experimental group of 45 rats, which were administered letrozole at concentrations of 1 mg/kg p.o. dissolved in 1% CMC (1 mL/d) once daily. The treatment period was 28 d. During this period, vaginal smears were collected daily for estrus cycle determination and body masses were measured every 7 d. On the day subsequent to the last letrozole dose administration, rats were killed; Uteri and ovaries were then excised and weighed for the calculation of organ indexes. Serum hormone levels, SHBG and histologic changes in the ovaries were examined. Then testosterone free index (FAD) was calculated. Oxidant status was evaluated by determination of ovarian total oxidant status (TOS), malondialdehyde (MDA) concentration and intracellular reactive oxygen species (ROS) level, while antioxidant status was evaluated by determination of total antioxidant status (TAS) and superoxide dismutase (SOD) concentration. Vaginal smear test showed the estrus cycle began to disappear from day 12 to day 15. A statistically significant difference in growth curves, ovarian weights, uterine weights and organ indexes between the groups were also observed. In rats with PCO serum testosterone (T), follicle-stimulating hormone (FSH) concentrations and free androgen index (FADI) were significantly increased compared with the control group (rats without PCO). However, rats with PCO had decreased levels of estrogen (E2), luteinizing hormone (LH), and progesterone (P) compared with the control group. In a rat model of PCO achieved via letrozole, it was found that the levels of TOS, MDA, oxidative stress index (OSI) and intracellular ROS were significantly increased, while the TAS level, SOD content were significantly decreased in the ovary homogenates (P<0.05). The results indicated that the PCOS pathological process significantly increased the oxidative stress production. PCO rat model successfully induced via letrozole, and it is a suitable model for study of ovarian lesions. Oxidative stress also contributes to the PCO rat model, the protective effect of antioxidant might provide a new insight into the potential therapeutic solution to PCOS.

CO2 outgassing in a combined fracture and conduit karst aquifer near lititz spring, Pennsylvania

USGS Publications Warehouse

Toran, L.; Roman, E.

2006-01-01

Lititz Spring in southeastern Pennsylvania and a nearby domestic well were sampled for 9 months. Although both locations are connected to conduits (as evidenced by a tracer test), most of the year they were saturated with respect to calcite, which is more typical of matrix flow. Geochemical modeling (PHREEQC) was used to explain this apparent paradox and to infer changes in matrix and conduit contribution to flow. The saturation index varied from 0.5 to 0 most of the year, with a few samples in springtime dropping below saturation. The log PCO2 value varied from -2.5 to -1.7. Lower log PCO2 values (closer to the atmospheric value of -3.5) were observed when the solutions were at or above saturation with respect to calcite. In contrast, samples collected in the springtime had high PCO2, low saturation indices, and high water levels. Geochemical modeling showed that when outgassing occurs from a water with initially high PCO2, the saturation index of calcite increases. In the Lititz Spring area, the recharge water travels through the soil zone, where it picks up CO2 from soil gas, and excess CO 2 subsequently is outgassed when this recharge water reaches the conduit. At times of high water level (pipe full), recharge with excess CO 2 enters the system but the outgassing does not occur. Instead the recharge causes dilution, reducing the calcite saturation index. Understanding the temporal and spatial variation in matrix and conduit flow in karst aquifers benefited here by geochemical modeling and calculation of PCO2 values. ?? 2006 Geological Society of America.

A limited role for carbonic anhydrase in C 4 photosynthesis as revealed by a ca1ca2 double mutant in maize.

DOE PAGES

Studer, Anthony J.; Gandin, Anthony; Kolbe, Allison R.; ...

2014-04-04

Carbonic anhydrase (CA) catalyzes the first biochemical step of the carbon concentrating mechanism of C 4 plants, and in C 4 monocots, it has been suggested that CA activity is near limiting for photosynthesis. Here, we test this hypothesis through the characterization of transposon induced mutant alleles of Ca1 and Ca2 in Zea mays. In addition, these two isoforms account for more than 85% of the CA transcript pool. A significant change in isotopic discrimination is observed in mutant plants, which have as little as 3% of wild-type CA activity, but surprisingly, photosynthesis is not reduced under current or elevatedmore » pCO 2. However, growth and rates of photosynthesis under sub-ambient pCO 2 are significantly impaired in the mutants. These findings suggest, that while CA is not limiting for C 4 photosynthesis in Z. mays at current pCO 2, it likely maintains high rates of photosynthesis when CO 2 availability is reduced. Current atmospheric CO 2 levels now exceed 400 ppm (~40.53 Pa) and contrast the low CO 2 partial pressure (pCO 2) conditions under which C 4 plants expanded their range ~10 million years ago when the global atmospheric CO 2 was below 300 ppm (~30.40 Pa). Thus, as CO 2 levels continue to rise, selective pressures for high levels of CA may be limited to arid climates where stomatal closure reduces CO 2 availability to the leaf.« less

Changes in microbial communities, photosynthesis and calcification of the coral Acropora gemmifera in response to ocean acidification.

PubMed

Zhou, Guowei; Yuan, Tao; Cai, Lin; Zhang, Weipeng; Tian, Renmao; Tong, Haoya; Jiang, Lei; Yuan, Xiangcheng; Liu, Sheng; Qian, Peiyuan; Huang, Hui

2016-10-27

With the increasing anthropogenic CO 2 concentration, ocean acidification (OA) can have dramatic effects on coral reefs. However, the effects of OA on coral physiology and the associated microbes remain largely unknown. In the present study, reef-building coral Acropora gemmifera collected from a reef flat with highly fluctuating environmental condition in the South China Sea were exposed to three levels of partial pressure of carbon dioxide (pCO 2 ) (i.e., 421, 923, and 2070 μatm) for four weeks. The microbial community structures associated with A. gemmifera under these treatments were analyzed using 16S rRNA gene barcode sequencing. The results revealed that the microbial community associated with A. gemmifera was highly diverse at the genus level and dominated by Alphaproteobacteria. More importantly, the microbial community structure remained rather stable under different pCO 2 treatments. Photosynthesis and calcification in A. gemmifera, as indicated by enrichment of δ 18 O and increased depletion of δ 13 C in the coral skeleton, were significantly impaired only at the high pCO 2 (2070 μatm). These results suggest that A. gemmifera can maintain a high degree of stable microbial communities despite of significant physiological changes in response to extremely high pCO 2 .

Changes in microbial communities, photosynthesis and calcification of the coral Acropora gemmifera in response to ocean acidification

NASA Astrophysics Data System (ADS)

Zhou, Guowei; Yuan, Tao; Cai, Lin; Zhang, Weipeng; Tian, Renmao; Tong, Haoya; Jiang, Lei; Yuan, Xiangcheng; Liu, Sheng; Qian, Peiyuan; Huang, Hui

2016-10-01

With the increasing anthropogenic CO2 concentration, ocean acidification (OA) can have dramatic effects on coral reefs. However, the effects of OA on coral physiology and the associated microbes remain largely unknown. In the present study, reef-building coral Acropora gemmifera collected from a reef flat with highly fluctuating environmental condition in the South China Sea were exposed to three levels of partial pressure of carbon dioxide (pCO2) (i.e., 421, 923, and 2070 μatm) for four weeks. The microbial community structures associated with A. gemmifera under these treatments were analyzed using 16S rRNA gene barcode sequencing. The results revealed that the microbial community associated with A. gemmifera was highly diverse at the genus level and dominated by Alphaproteobacteria. More importantly, the microbial community structure remained rather stable under different pCO2 treatments. Photosynthesis and calcification in A. gemmifera, as indicated by enrichment of δ18O and increased depletion of δ13C in the coral skeleton, were significantly impaired only at the high pCO2 (2070 μatm). These results suggest that A. gemmifera can maintain a high degree of stable microbial communities despite of significant physiological changes in response to extremely high pCO2.

Nitrate fertilisation does not enhance CO2 responses in two tropical seagrass species

NASA Astrophysics Data System (ADS)

Ow, Y. X.; Vogel, N.; Collier, C. J.; Holtum, J. A. M.; Flores, F.; Uthicke, S.

2016-03-01

Seagrasses are often considered “winners” of ocean acidification (OA); however, seagrass productivity responses to OA could be limited by nitrogen availability, since nitrogen-derived metabolites are required for carbon assimilation. We tested nitrogen uptake and assimilation, photosynthesis, growth, and carbon allocation responses of the tropical seagrasses Halodule uninervis and Thalassia hemprichii to OA scenarios (428, 734 and 1213 μatm pCO2) under two nutrients levels (0.3 and 1.9 μM NO3-). Net primary production (measured as oxygen production) and growth in H. uninervis increased with pCO2 enrichment, but were not affected by nitrate enrichment. However, nitrate enrichment reduced whole plant respiration in H. uninervis. Net primary production and growth did not show significant changes with pCO2 or nitrate by the end of the experiment (24 d) in T. hemprichii. However, nitrate incorporation in T. hemprichii was higher with nitrate enrichment. There was no evidence that nitrogen demand increased with pCO2 enrichment in either species. Contrary to our initial hypothesis, nutrient increases to levels approximating present day flood plumes only had small effects on metabolism. This study highlights that the paradigm of increased productivity of seagrasses under ocean acidification may not be valid for all species under all environmental conditions.

Nitrate fertilisation does not enhance CO2 responses in two tropical seagrass species.

PubMed

Ow, Y X; Vogel, N; Collier, C J; Holtum, J A M; Flores, F; Uthicke, S

2016-03-15

Seagrasses are often considered "winners" of ocean acidification (OA); however, seagrass productivity responses to OA could be limited by nitrogen availability, since nitrogen-derived metabolites are required for carbon assimilation. We tested nitrogen uptake and assimilation, photosynthesis, growth, and carbon allocation responses of the tropical seagrasses Halodule uninervis and Thalassia hemprichii to OA scenarios (428, 734 and 1213 μatm pCO2) under two nutrients levels (0.3 and 1.9 μM NO3(-)). Net primary production (measured as oxygen production) and growth in H. uninervis increased with pCO2 enrichment, but were not affected by nitrate enrichment. However, nitrate enrichment reduced whole plant respiration in H. uninervis. Net primary production and growth did not show significant changes with pCO2 or nitrate by the end of the experiment (24 d) in T. hemprichii. However, nitrate incorporation in T. hemprichii was higher with nitrate enrichment. There was no evidence that nitrogen demand increased with pCO2 enrichment in either species. Contrary to our initial hypothesis, nutrient increases to levels approximating present day flood plumes only had small effects on metabolism. This study highlights that the paradigm of increased productivity of seagrasses under ocean acidification may not be valid for all species under all environmental conditions.

Nitrate fertilisation does not enhance CO2 responses in two tropical seagrass species

PubMed Central

Ow, Y. X.; Vogel, N.; Collier, C. J.; Holtum, J. A. M.; Flores, F.; Uthicke, S.

2016-01-01

Seagrasses are often considered “winners” of ocean acidification (OA); however, seagrass productivity responses to OA could be limited by nitrogen availability, since nitrogen-derived metabolites are required for carbon assimilation. We tested nitrogen uptake and assimilation, photosynthesis, growth, and carbon allocation responses of the tropical seagrasses Halodule uninervis and Thalassia hemprichii to OA scenarios (428, 734 and 1213 μatm pCO2) under two nutrients levels (0.3 and 1.9 μM NO3−). Net primary production (measured as oxygen production) and growth in H. uninervis increased with pCO2 enrichment, but were not affected by nitrate enrichment. However, nitrate enrichment reduced whole plant respiration in H. uninervis. Net primary production and growth did not show significant changes with pCO2 or nitrate by the end of the experiment (24 d) in T. hemprichii. However, nitrate incorporation in T. hemprichii was higher with nitrate enrichment. There was no evidence that nitrogen demand increased with pCO2 enrichment in either species. Contrary to our initial hypothesis, nutrient increases to levels approximating present day flood plumes only had small effects on metabolism. This study highlights that the paradigm of increased productivity of seagrasses under ocean acidification may not be valid for all species under all environmental conditions. PMID:26976685

Changes in microbial communities, photosynthesis and calcification of the coral Acropora gemmifera in response to ocean acidification

PubMed Central

Zhou, Guowei; Yuan, Tao; Cai, Lin; Zhang, Weipeng; Tian, Renmao; Tong, Haoya; Jiang, Lei; Yuan, Xiangcheng; Liu, Sheng; Qian, Peiyuan; Huang, Hui

2016-01-01

With the increasing anthropogenic CO2 concentration, ocean acidification (OA) can have dramatic effects on coral reefs. However, the effects of OA on coral physiology and the associated microbes remain largely unknown. In the present study, reef-building coral Acropora gemmifera collected from a reef flat with highly fluctuating environmental condition in the South China Sea were exposed to three levels of partial pressure of carbon dioxide (pCO2) (i.e., 421, 923, and 2070 μatm) for four weeks. The microbial community structures associated with A. gemmifera under these treatments were analyzed using 16S rRNA gene barcode sequencing. The results revealed that the microbial community associated with A. gemmifera was highly diverse at the genus level and dominated by Alphaproteobacteria. More importantly, the microbial community structure remained rather stable under different pCO2 treatments. Photosynthesis and calcification in A. gemmifera, as indicated by enrichment of δ18O and increased depletion of δ13C in the coral skeleton, were significantly impaired only at the high pCO2 (2070 μatm). These results suggest that A. gemmifera can maintain a high degree of stable microbial communities despite of significant physiological changes in response to extremely high pCO2. PMID:27786309

A critical analysis of carbonic anhydrase function, respiratory gas exchange, and the acid-base control of secretion in the rectal gland of Squalus acanthias.

PubMed

Shuttleworth, Trevor J; Thompson, Jill; Munger, R Stephen; Wood, Chris M

2006-12-01

We compared in vivo responses of rectal gland secretion to carbonic anhydrase (CA) inhibition (10(-4) mol l(-1) acetazolamide) in volume-loaded dogfish with in vitro responses in an isolated-perfused gland stimulated with 5 x 10(-6) mol l(-1) forskolin and removed from systemic influences. We also measured respiratory gas exchange in the perfused gland, described the acid-base status of the secreted fluid, and determined the relative importance of various extracellular and intracellular acid-base parameters in controlling rectal gland secretion in vitro. In vivo, acetazolamide inhibited Cl(-) secretion and decreased pHi in the rectal gland, but interpretation was confounded by an accompanying systemic respiratory acidosis, which would also have contributed to the inhibition. In the perfused gland, M(CO(2)) and M(O(2)) increased in linear relation to increases in Cl(-) secretion rate. CA inhibition (10(-4) mol l(-1) acetazolamide) had no effect on Cl(-) secretion rate or pHi in the perfused gland, in contrast to in vivo, but caused a transitory 30% inhibition of M(CO(2)) (relative to stable M(O(2))) and elevation in secretion P(CO(2)) effects, which peaked at 2 h and attenuated by 3.5-4 h. Secretion was inhibited by acidosis and stimulated by alkalosis; the relationship between relative Cl(-) secretion rate and pHe was almost identical to that seen in vivo. Experimental manipulations of perfusate pH, P(CO(2)) and HCO(3)(-) concentration, together with measurements of pHi, demonstrated that these responses were most strongly correlated with changes in pHe, and were not related to changes in P(CO(2)), extracellular HCO(3)(-), or intracellular HCO(3)(-) levels, though changes in pHi may also have played a role. The acid-base status of the secreted fluid varied with that of the perfusate, secretion pH remaining about 0.3-0.5 units lower, and changing in concert with pHe rather than pHi; secretion HCO(3)(-) concentrations remained low, even in the face of greatly elevated perfusate HCO(3)(-) concentrations. We conclude that pH effects on rectal gland secretion rate are adaptive, that CA functions to catalyze the hydration of CO(2), thereby maintaining a gradient for diffusive efflux of CO(2) from the working cells, and that differences in response to CA inhibition likely reflect the higher perfusion-to-secretion ratio in vitro than in vivo.

Estimating temporal and spatial variation of ocean surface pCO2 in the North Pacific using a self-organizing map neural network technique

NASA Astrophysics Data System (ADS)

Nakaoka, S.; Telszewski, M.; Nojiri, Y.; Yasunaka, S.; Miyazaki, C.; Mukai, H.; Usui, N.

2013-09-01

This study uses a neural network technique to produce maps of the partial pressure of oceanic carbon dioxide (pCO2sea) in the North Pacific on a 0.25° latitude × 0.25° longitude grid from 2002 to 2008. The pCO2sea distribution was computed using a self-organizing map (SOM) originally utilized to map the pCO2sea in the North Atlantic. Four proxy parameters - sea surface temperature (SST), mixed layer depth, chlorophyll a concentration, and sea surface salinity (SSS) - are used during the training phase to enable the network to resolve the nonlinear relationships between the pCO2sea distribution and biogeochemistry of the basin. The observed pCO2sea data were obtained from an extensive dataset generated by the volunteer observation ship program operated by the National Institute for Environmental Studies (NIES). The reconstructed pCO2sea values agreed well with the pCO2sea measurements, with the root-mean-square error ranging from 17.6 μatm (for the NIES dataset used in the SOM) to 20.2 μatm (for independent dataset). We confirmed that the pCO2sea estimates could be improved by including SSS as one of the training parameters and by taking into account secular increases of pCO2sea that have tracked increases in atmospheric CO2. Estimated pCO2sea values accurately reproduced pCO2sea data at several time series locations in the North Pacific. The distributions of pCO2sea revealed by 7 yr averaged monthly pCO2sea maps were similar to Lamont-Doherty Earth Observatory pCO2sea climatology, allowing, however, for a more detailed analysis of biogeochemical conditions. The distributions of pCO2sea anomalies over the North Pacific during the winter clearly showed regional contrasts between El Niño and La Niña years related to changes of SST and vertical mixing.

Hypolipidemic activity of P-methoxycinnamic diester (PCO-C) isolated from Copernicia prunífera against Triton WR-1339 and hyperlipidemic diet in mice.

PubMed

Filho, A C V A; Rodrigues, P A S; Benjamin, S R; Paim, R T T; Holanda, M O; Silva, J Y G; Milo, T S; Vieira, I G P; Queiroz, M G R; Guedes, M I F

2017-12-01

Carnauba wax is extracted from the leaves of the Copernicia prunífera and contains approximately 80% of esters in its composition. The purpose of the present study was evaluate the hypolipidemic effect of p-methoxycinnamic diesters (PCO-C) extracted from Copernicia prunífera in a model of acute and chronic dyslipidemia in mice. The levels of total cholesterol and triglycerides were significantly reduced plasma levels in PCO-C at the dose of 100mg/kg in a model of acute and chronic dyslipidemia. Histological studies showed that PCO-C has no hepatotoxic effect and reduces hepatic steatosis in animals that consumed hyperlipidemic ration. Thus, it was concluded that PCO-C isolated from Copernicia Prunifera was effective in reducing total cholesterol and triglyceride levels in both dyslipidemia induction models. The finding indicates that PCO-C might be beneficial in treatment of hyperlipidemia and atherosclerosis. Copyright © 2017 Elsevier B.V. All rights reserved.

Do Unexpected Panic Attacks Occur Spontaneously?

PubMed Central

Meuret, Alicia E.; Rosenfield, David; Wilhelm, Frank H.; Zhou, Enlu; Conrad, Ansgar; Ritz, Thomas; Roth, Walton T.

2012-01-01

Background Spontaneous or unexpected panic attacks, per definition, occur out-of-the blue, in absence of cues or triggers. Accordingly, physiological arousal or instability should occur at the onset of or during the attack, but not preceding it. To test this hypothesisweexaminedif points of significant autonomic changes preceded the onset of spontaneous panic attacks. Methods Forty-three panic disorder patients underwent repeated 24-hour ambulatory monitoring. Thirteen naturally panic attacks were recorded during 1,960 hours of monitoring. Minute-by-minute epochs beginning 60 minutes before, and continuing to 10 minutes after, the onset of individual attacks were examined for respiration, heart rate, and skin conductance level. Measures were controlled for physical activity and vocalization, and compared to time matched control periods within the same person. Results Significant patterns of instability across a numberof autonomic and respiratory variables were detected as early as 47 minutes before panic onset. The final minutes prior to onset were dominated by respiratory changes, with significant decreases in tidal volume followed by abrupt PCO2 increases. Panic attack onset was characterized by heart rate and tidal volume increases and a drop in PCO2. Symptom report was consistent with these changes. Skin conductance levels were generally elevated in the hour before and duringthe attacks. Changes in the matched control periods were largely absent. Conclusions Significant autonomic irregularities preceded the onset of attacks that were reported as abrupt and unexpected. The findings invite reconsideration of the current diagnostic distinction betweenuncuedand cued panic attacks. PMID:21783179

Characteristics of the surface water DMS and pCO2 distributions and their relationships in the Southern Ocean, southeast Indian Ocean, and northwest Pacific Ocean

NASA Astrophysics Data System (ADS)

Zhang, Miming; Marandino, C. A.; Chen, Liqi; Sun, Heng; Gao, Zhongyong; Park, Keyhong; Kim, Intae; Yang, Bo; Zhu, Tingting; Yan, Jinpei; Wang, Jianjun

2017-08-01

Oceanic dimethyl sulfide (DMS) is of interest due to its critical influence on atmospheric sulfur compounds in the marine atmosphere and its hypothesized significant role in global climate. High-resolution shipboard underway measurements of surface seawater DMS and the partial pressure of carbon dioxide (pCO2) were conducted in the Atlantic Ocean and Indian Ocean sectors of the Southern Ocean (SO), the southeast Indian Ocean, and the northwest Pacific Ocean from February to April 2014 during the 30th Chinese Antarctic Research Expedition. The SO, particularly in the region south of 58°S, had the highest mean surface seawater DMS concentration of 4.1 ± 8.3 nM (ranged from 0.1 to 73.2 nM) and lowest mean seawater pCO2 level of 337 ± 50 μatm (ranged from 221 to 411 μatm) over the entire cruise. Significant variations of surface seawater DMS and pCO2 in the seasonal ice zone (SIZ) of SO were observed, which are mainly controlled by biological process and sea ice activity. We found a significant negative relationship between DMS and pCO2 in the SO SIZ using 0.1° resolution, [DMS] seawater = -0.160 [pCO2] seawater + 61.3 (r2 = 0.594, n = 924, p < 0.001). We anticipate that the relationship may possibly be utilized to reconstruct the surface seawater DMS climatology in the SO SIZ. Further studies are necessary to improve the universality of this approach.

Natural variability of pCO2 and pH in the Atlantic and Pacific coastal margins of the U.S

NASA Astrophysics Data System (ADS)

Sutton, A. J.; Sabine, C. L.; Feely, R. A.; Newton, J.; Salisbury, J.; Vandemark, D. C.; Musielewicz, S. B.; Maenner-Jones, S.; Bott, R.; Lawrence-Slavas, N.

2011-12-01

The discovery that seawater chemistry is changing as a result of carbon dioxide (CO2) emissions, referred to as "ocean acidification", has prompted a large effort to understand how this changing chemistry will impact marine life. Changes in carbon chemistry have been documented in the open ocean; however, in dynamic coastal systems where many marine species live, ocean acidification and the natural biogeochemical variability that organisms are currently exposed to are poorly quantified. In 2010 we began equipping coastal moorings currently measuring pCO2 with pH and other biogeochemical sensors to measure ocean acidification parameters at 3 hour intervals in the surface water. Here we present the magnitude and diurnal to seasonal variability of pCO2 and pH during the first year of observations at 2 sites in the Atlantic and Pacific coastal margins of the U.S.: the Gulf of Maine and outer coast of Washington state. Both the magnitude and range of pCO2 and pH values were much greater at the coastal moorings compared to the open ocean mooring at Ocean Station Papa in the North Pacific and also varied between the two coastal mooring sites. We observed maximum pCO2 values in coastal waters exceeding predicted values for the open ocean at 2x pre-industrial CO2 levels. The range of pCO2 and pH values during this time series was approximately 4 times the range observed at open ocean mooring Papa (2007-2011 time series). In many cases, large variance was observed at short time scales, with values fluctuating more than 200 μatm pCO2 and 0.2 pH between 3-hour cycles. These types of observations are critical for understanding how ocean acidification will manifest in naturally dynamic coastal systems and for informing the experimental design of species response studies that aim to mimic carbon chemistry experienced by coastal marine organisms.

Low pCO2 Air-Polarized CO2 Concentrator Development

NASA Technical Reports Server (NTRS)

Schubert, Franz H.

1997-01-01

Life Systems completed a Ground-based Space Station Experiment Development Study Program which verifies through testing the performance and applicability of the electrochemical Air-Polarized Carbon Dioxide Concentrator (APC) process technology for space missions requiring low (i.e., less than 3 mm Hg) CO2 partial pressure (pCO2) in the cabin atmosphere. Required test hardware was developed and testing was accomplished at an approximate one-person capacity CO2 removal level. Initially, two five-cell electrochemical modules using flight-like 0.5 sq ft cell hardware were tested individually, following by their testing at the integrated APC system level. Testing verified previously projected performance and established a database for sizing of APC systems. A four person capacity APC system was sized and compared with four candidate CO2 removal systems. At its weight of 252 lb, a volume of 7 cu ft and a power consumption of 566 W while operating at 2.2 mm Hg pCO2, the APC was surpassed only by an Electrochemical Depolarized CO2 Concentrator (EDC) (operating with H2), when compared on a total equivalent basis.

Combined effects of ocean acidification and warming on physiological response of the diatom Thalassiosira pseudonana to light challenges.

PubMed

Yuan, Wubiao; Gao, Guang; Shi, Qi; Xu, Zhiguang; Wu, Hongyan

2018-04-01

Diatoms are one of the most important groups of phytoplankton in terms of abundance and ecological functionality in the ocean. They usually dominate the phytoplankton communities in coastal waters and experience frequent and large fluctuations in light. In order to evaluate the combined effects of ocean warming and acidification on the diatom's exploitation of variable light environments, we grew a globally abundant diatom Thalassiosira pseudonana under two levels of temperature (18, 24 °C) and pCO 2 (400, 1000 μatm) to examine its physiological performance after light challenge. It showed that the higher temperature increased the photoinactivation rate in T. pseudonana at 400 μatm pCO 2 , while the higher pCO 2 alleviated the negative effect of the higher temperature on PSII photoinactivation. Higher pCO 2 stimulated much faster PsbA removal, but it still lagged behind the photoinactivation of PSII under high light. Although the sustained phase of nonphotochemical quenching (NPQs) and activity of superoxide dismutase (SOD) were provoked during the high light exposure in T. pseudonana under the combined pCO 2 and temperature conditions, it could not offset the damage caused by these multiple environmental changes, leading to decreased maximum photochemical yield. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effects of acidified seawater on coral calcification and variations of U/Ca ratio in their skeletons

NASA Astrophysics Data System (ADS)

Inoue, M.; Ozaki, S.; Iguchi, A.; Sakai, K.; Suzuki, A.; Kawahata, H.

2011-12-01

The rising CO2 concentration in the atmosphere is changing the carbonate chemistry of the ocean. Elevated partial pressure of CO2 (pCO2) has caused significant decrease in surface seawater pH and carbonate ion concentration. Therefore, ocean acidification has a negative effect on calcification of marine calcifying organisms. Especially, hermatypic corals are dominant organisms in coral reef ecosystems, so their calcificication is a key to determine the health of reef ecosystems. On the other hand, recent study has suggested that there is a negative correlation between U/Ca ratio in coral skeleton and seawater pH, based on the culture experiment using primary polyps of Acropora digitifera. In this study, primary polyps and adult colonies of A. digitifera and adult colonies of Porites australiensis, which are the dominant species around the Ryukyu Islands, Japan, were reared in seawater with different pCO2 (300, 400, 600, 800, 1000ppm) and pH (7.4, 7.6, 8.0) settings controlled by CO2 bubbling. Calcification rate of adult coral was estimated by buoyant method, while skeletal growth of polyps was evaluated by measuring the dry weight of each skeleton after the experiments. In order to evaluate the relationship between U/Ca ratios in coral skeletons and seawater pH, U/Ca ratios in reared corals were analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The results of A. digitifera showed that the growth rate of adult corals had no significant correlation against pCO2, but dry weight of polyp skeletons decreased with increase in pCO2. Growth rate of P. australiensis typically showed a positive correlation with pH. However, growth rates were different among colonies, suggesting that their responses to acidification may vary among the colonies. Regarding the variations of U/Ca ratios, there were positive correlations between U/Ca ratios in adults of A. digitifera and P. australiensis and seawater pCO2 (pH), while no relation was observed in polyp corals.

Stomatal response of swordfern to volcanogenic CO2 and SO2 from Kilauea volcano

NASA Astrophysics Data System (ADS)

Tanner, Lawrence H.; Smith, David L.; Allan, Amanda

2007-08-01

The experimentally determined relationship between atmospheric pCO2 and plant stomata has been used to interpret large but transient changes in atmospheric composition, such as may have resulted from the eruptions of flood basalt. However, this relationship has not been tested in the field, i.e. in the vicinity of active volcanoes, to examine the specific effects of volcanogenic emissions. Moreover, the interpretation of paleoatmospheric pCO2 from fossil stomatal data assumes that the stomatal response resulted solely from variation in pCO2 and ignores the potential effect of outgassed SO2. We hypothesize that volcanogenic SO2 also has a significant effect on leaf stomata and test this hypothesis by measuring the stomatal index of the common swordfern (Nephrolepis exaltata) in the plumes of the actively outgassing vents of Kilauea volcano. We find that, compared to control locations, stomatal index is lowest at sample sites in the plume of Halema'uma'u Crater, where concentrations of both CO2 and SO2 are much higher than background. However, sites located directly in the plume of Pu'u O'o, where SO2 levels are high, but CO2 levels are not, also yield low values of stomatal index. We propose that shifts in the stomatal index of fossil leaves may record transient atmospheric increases in both SO2 and CO2, such as may be caused by eruptions of flood basalts. Calculations of pCO2 based on stomatal frequency are likely to be exaggerated.

Anthropogenic Carbon Pump in an Urbanized Estuary

NASA Astrophysics Data System (ADS)

Park, J. H.; Yoon, T. K.; Jin, H.; Begum, M. S.

2015-12-01

The importance of estuaries as a carbon source has been increasingly recognized over the recent decades. However, constraining sources of CO2 evasion from urbanized estuaries remains incomplete, particularly in densely populated river systems receiving high loads of organic carbon from anthropogenic sources. To account for major factors regulating carbon fluxes the tidal reach of the Han River estuary along the metropolitan Seoul, characterization of organic carbon in the main stem and major urban tributaries were combined with continuous, submersible sensor measurements of pCO2 at a mid-channel location over a year and continuous underway measurements using a submersible sensor and two equilibrator sytems across the estuarine section receiving urban streams. Single-site continuous measurements exhibited large seasonal and diurnal variations in pCO2, ranging from sub-ambient air levels to exceptionally high values approaching 10,000 ppm. Diurnal variations of pCO2 were pronounced in summer and had an inverse relationship with dissolved oxygen, pointing to a potential role of day-time algal consumption of CO2. Cruise measurements displayed sharp pCO2 pulses along the confluences of urban streams as compared with relatively low values along the upper estuary receiving low-CO2 outflows from upstream dams. Large downstream increases in pCO2, concurrent with increases in DOC concentrations and fluorescence intensities indicative of microbially processed organic components, imply a translocation and subsequent dilution of CO2 carried by urban streams and/or fast transformations of labile C during transit along downstream reaches. The unique combination of spatial and temporal continuous measurements of pCO2 provide insights on estuarine CO2 pulses that might have resulted from the interplay between high loads of CO2 and organic C of anthropogenic origin and their priming effects on estuarine microbial processing of terrigenous and algal organic matter.

Relationships between CO 2, thermodynamic limits on silicate weathering, and the strength of the silicate weathering feedback

DOE PAGES

Winnick, Matthew J.; Maher, Kate

2018-01-27

Recent studies have suggested that thermodynamic limitations on chemical weathering rates exert a first-order control on riverine solute fluxes and by extension, global chemical weathering rates. As such, these limitations may play a prominent role in the regulation of carbon dioxide levels (pCO 2) over geologic timescales by constraining the maximum global weathering flux. In this study, we develop a theoretical scaling relationship between equilibrium solute concentrations and pCO 2 based on equilibrium constants and reaction stoichiometry relating primary mineral dissolution and secondary mineral precipitation. Here, we test this theoretical scaling relationship against reactive transport simulations of chemical weathering profilesmore » under open-and closed-system conditions, representing partially and fully water-saturated regolith, respectively. Under open-system conditions, equilibrium bicarbonate concentrations vary as a power-law function of pCO 2(y =kx n)where nis dependent on reaction stoichiometry and kis dependent on both reaction stoichiometry and the equilibrium constant. Under closed-system conditions, bicarbonate concentrations vary linearly with pCO 2 at low values and approach open-system scaling at high pCO 2. To describe the potential role of thermodynamic limitations in the global silicate weathering feedback, we develop a new mathematical framework to assess weathering feedback strength in terms of both (1) steady-state atmospheric pCO 2 concentrations, and (2) susceptibility to secular changes in degassing rates and transient carbon cycle perturbations, which we term 1st and 2nd order feedback strength, respectively. Finally, we discuss the implications of these results for the effects of vascular land plant evolution on feedback strength, the potential role of vegetation in controlling modern solute fluxes, and the application of these frameworks to a more complete functional description of the silicate weathering feedback. Most notably, the dependence of equilibrium solute concentrations on pCO 2 may represent a direct weathering feedback largely independent of climate and modulated by belowground organic carbon respiration.« less

Relationships between CO 2, thermodynamic limits on silicate weathering, and the strength of the silicate weathering feedback

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winnick, Matthew J.; Maher, Kate

Recent studies have suggested that thermodynamic limitations on chemical weathering rates exert a first-order control on riverine solute fluxes and by extension, global chemical weathering rates. As such, these limitations may play a prominent role in the regulation of carbon dioxide levels (pCO 2) over geologic timescales by constraining the maximum global weathering flux. In this study, we develop a theoretical scaling relationship between equilibrium solute concentrations and pCO 2 based on equilibrium constants and reaction stoichiometry relating primary mineral dissolution and secondary mineral precipitation. Here, we test this theoretical scaling relationship against reactive transport simulations of chemical weathering profilesmore » under open-and closed-system conditions, representing partially and fully water-saturated regolith, respectively. Under open-system conditions, equilibrium bicarbonate concentrations vary as a power-law function of pCO 2(y =kx n)where nis dependent on reaction stoichiometry and kis dependent on both reaction stoichiometry and the equilibrium constant. Under closed-system conditions, bicarbonate concentrations vary linearly with pCO 2 at low values and approach open-system scaling at high pCO 2. To describe the potential role of thermodynamic limitations in the global silicate weathering feedback, we develop a new mathematical framework to assess weathering feedback strength in terms of both (1) steady-state atmospheric pCO 2 concentrations, and (2) susceptibility to secular changes in degassing rates and transient carbon cycle perturbations, which we term 1st and 2nd order feedback strength, respectively. Finally, we discuss the implications of these results for the effects of vascular land plant evolution on feedback strength, the potential role of vegetation in controlling modern solute fluxes, and the application of these frameworks to a more complete functional description of the silicate weathering feedback. Most notably, the dependence of equilibrium solute concentrations on pCO 2 may represent a direct weathering feedback largely independent of climate and modulated by belowground organic carbon respiration.« less

Relationships between CO2, thermodynamic limits on silicate weathering, and the strength of the silicate weathering feedback

NASA Astrophysics Data System (ADS)

Winnick, Matthew J.; Maher, Kate

2018-03-01

Recent studies have suggested that thermodynamic limitations on chemical weathering rates exert a first-order control on riverine solute fluxes and by extension, global chemical weathering rates. As such, these limitations may play a prominent role in the regulation of carbon dioxide levels (pCO2) over geologic timescales by constraining the maximum global weathering flux. In this study, we develop a theoretical scaling relationship between equilibrium solute concentrations and pCO2 based on equilibrium constants and reaction stoichiometry relating primary mineral dissolution and secondary mineral precipitation. We test this theoretical scaling relationship against reactive transport simulations of chemical weathering profiles under open- and closed-system conditions, representing partially and fully water-saturated regolith, respectively. Under open-system conditions, equilibrium bicarbonate concentrations vary as a power-law function of pCO2 (y = kxn) where n is dependent on reaction stoichiometry and k is dependent on both reaction stoichiometry and the equilibrium constant. Under closed-system conditions, bicarbonate concentrations vary linearly with pCO2 at low values and approach open-system scaling at high pCO2. To describe the potential role of thermodynamic limitations in the global silicate weathering feedback, we develop a new mathematical framework to assess weathering feedback strength in terms of both (1) steady-state atmospheric pCO2 concentrations, and (2) susceptibility to secular changes in degassing rates and transient carbon cycle perturbations, which we term 1st and 2nd order feedback strength, respectively. Finally, we discuss the implications of these results for the effects of vascular land plant evolution on feedback strength, the potential role of vegetation in controlling modern solute fluxes, and the application of these frameworks to a more complete functional description of the silicate weathering feedback. Most notably, the dependence of equilibrium solute concentrations on pCO2 may represent a direct weathering feedback largely independent of climate and modulated by belowground organic carbon respiration.

Seasonal carbonate chemistry covariation with temperature, oxygen, and salinity in a fjord estuary: implications for the design of ocean acidification experiments.

PubMed

Reum, Jonathan C P; Alin, Simone R; Feely, Richard A; Newton, Jan; Warner, Mark; McElhany, Paul

2014-01-01

Carbonate chemistry variability is often poorly characterized in coastal regions and patterns of covariation with other biologically important variables such as temperature, oxygen concentration, and salinity are rarely evaluated. This absence of information hampers the design and interpretation of ocean acidification experiments that aim to characterize biological responses to future pCO2 levels relative to contemporary conditions. Here, we analyzed a large carbonate chemistry data set from Puget Sound, a fjord estuary on the U.S. west coast, and included measurements from three seasons (winter, summer, and fall). pCO2 exceeded the 2008-2011 mean atmospheric level (392 µatm) at all depths and seasons sampled except for the near-surface waters (< 10 m) in the summer. Further, undersaturated conditions with respect to the biogenic carbonate mineral aragonite were widespread (Ωar<1). We show that pCO2 values were relatively uniform throughout the water column and across regions in winter, enriched in subsurface waters in summer, and in the fall some values exceeded 2500 µatm in near-surface waters. Carbonate chemistry covaried to differing levels with temperature and oxygen depending primarily on season and secondarily on region. Salinity, which varied little (27 to 31), was weakly correlated with carbonate chemistry. We illustrate potential high-frequency changes in carbonate chemistry, temperature, and oxygen conditions experienced simultaneously by organisms in Puget Sound that undergo diel vertical migrations under present-day conditions. We used simple calculations to estimate future pCO2 and Ωar values experienced by diel vertical migrators based on an increase in atmospheric CO2. Given the potential for non-linear interactions between pCO2 and other abiotic variables on physiological and ecological processes, our results provide a basis for identifying control conditions in ocean acidification experiments for this region, but also highlight the wide range of carbonate chemistry conditions organisms may currently experience in this and similar coastal ecosystems.

Seasonal Carbonate Chemistry Covariation with Temperature, Oxygen, and Salinity in a Fjord Estuary: Implications for the Design of Ocean Acidification Experiments

PubMed Central

Reum, Jonathan C. P.; Alin, Simone R.; Feely, Richard A.; Newton, Jan; Warner, Mark; McElhany, Paul

2014-01-01

Carbonate chemistry variability is often poorly characterized in coastal regions and patterns of covariation with other biologically important variables such as temperature, oxygen concentration, and salinity are rarely evaluated. This absence of information hampers the design and interpretation of ocean acidification experiments that aim to characterize biological responses to future pCO2 levels relative to contemporary conditions. Here, we analyzed a large carbonate chemistry data set from Puget Sound, a fjord estuary on the U.S. west coast, and included measurements from three seasons (winter, summer, and fall). pCO2 exceeded the 2008–2011 mean atmospheric level (392 µatm) at all depths and seasons sampled except for the near-surface waters (< 10 m) in the summer. Further, undersaturated conditions with respect to the biogenic carbonate mineral aragonite were widespread (Ωar<1). We show that pCO2 values were relatively uniform throughout the water column and across regions in winter, enriched in subsurface waters in summer, and in the fall some values exceeded 2500 µatm in near-surface waters. Carbonate chemistry covaried to differing levels with temperature and oxygen depending primarily on season and secondarily on region. Salinity, which varied little (27 to 31), was weakly correlated with carbonate chemistry. We illustrate potential high-frequency changes in carbonate chemistry, temperature, and oxygen conditions experienced simultaneously by organisms in Puget Sound that undergo diel vertical migrations under present-day conditions. We used simple calculations to estimate future pCO2 and Ωar values experienced by diel vertical migrators based on an increase in atmospheric CO2. Given the potential for non-linear interactions between pCO2 and other abiotic variables on physiological and ecological processes, our results provide a basis for identifying control conditions in ocean acidification experiments for this region, but also highlight the wide range of carbonate chemistry conditions organisms may currently experience in this and similar coastal ecosystems. PMID:24586915

Energetic plasticity underlies a variable response to ocean acidification in the pteropod, Limacina helicina antarctica.

PubMed

Seibel, Brad A; Maas, Amy E; Dierssen, Heidi M

2012-01-01

Ocean acidification, caused by elevated seawater carbon dioxide levels, may have a deleterious impact on energetic processes in animals. Here we show that high PCO(2) can suppress metabolism, measured as oxygen consumption, in the pteropod, L. helicina forma antarctica, by ∼20%. The rates measured at 180-380 µatm (MO(2)  =  1.25 M(-0.25), p  =  0.007) were significantly higher (ANCOVA, p  =  0.004) than those measured at elevated target CO(2) levels in 2007 (789-1000 µatm,  =  0.78 M(-0.32), p  =  0.0008; Fig. 1). However, we further demonstrate metabolic plasticity in response to regional phytoplankton concentration and that the response to CO(2) is dependent on the baseline level of metabolism. We hypothesize that reduced regional Chl a levels in 2008 suppressed metabolism and masked the effect of ocean acidification. This effect of food limitation was not, we postulate, merely a result of gut clearance and specific dynamic action, but rather represents a sustained metabolic response to regional conditions. Thus, pteropod populations may be compromised by climate change, both directly via CO(2)-induced metabolic suppression, and indirectly via quantitative and qualitative changes to the phytoplankton community. Without the context provided by long-term observations (four seasons) and a multi-faceted laboratory analysis of the parameters affecting energetics, the complex response of polar pteropods to ocean acidification may be masked or misinterpreted.

Energetic Plasticity Underlies a Variable Response to Ocean Acidification in the Pteropod, Limacina helicina antarctica

PubMed Central

Seibel, Brad A.; Maas, Amy E.; Dierssen, Heidi M.

2012-01-01

Ocean acidification, caused by elevated seawater carbon dioxide levels, may have a deleterious impact on energetic processes in animals. Here we show that high PCO2 can suppress metabolism, measured as oxygen consumption, in the pteropod, L. helicina forma antarctica, by ∼20%. The rates measured at 180–380 µatm (MO2  = 1.25 M−0.25, p = 0.007) were significantly higher (ANCOVA, p  =  0.004) than those measured at elevated target CO2 levels in 2007 (789–1000 µatm,  =  0.78 M−0.32, p  =  0.0008; Fig. 1). However, we further demonstrate metabolic plasticity in response to regional phytoplankton concentration and that the response to CO2 is dependent on the baseline level of metabolism. We hypothesize that reduced regional Chl a levels in 2008 suppressed metabolism and masked the effect of ocean acidification. This effect of food limitation was not, we postulate, merely a result of gut clearance and specific dynamic action, but rather represents a sustained metabolic response to regional conditions. Thus, pteropod populations may be compromised by climate change, both directly via CO2-induced metabolic suppression, and indirectly via quantitative and qualitative changes to the phytoplankton community. Without the context provided by long-term observations (four seasons) and a multi-faceted laboratory analysis of the parameters affecting energetics, the complex response of polar pteropods to ocean acidification may be masked or misinterpreted. PMID:22536312

Variability of pCO2 in surface waters and development of prediction model.

PubMed

Chung, Sewoong; Park, Hyungseok; Yoo, Jisu

2018-05-01

Inland waters are substantial sources of atmospheric carbon, but relevant data are rare in Asian monsoon regions including Korea. Emissions of CO 2 to the atmosphere depend largely on the partial pressure of CO 2 (pCO 2 ) in water; however, measured pCO 2 data are scarce and calculated pCO 2 can show large uncertainty. This study had three objectives: 1) to examine the spatial variability of pCO 2 in diverse surface water systems in Korea; 2) to compare pCO 2 calculated using pH-total alkalinity (Alk) and pH-dissolved inorganic carbon (DIC) with pCO 2 measured by an in situ submersible nondispersive infrared detector; and 3) to characterize the major environmental variables determining the variation of pCO 2 based on physical, chemical, and biological data collected concomitantly. Of 30 samples, 80% were found supersaturated in CO 2 with respect to the overlying atmosphere. Calculated pCO 2 using pH-Alk and pH-DIC showed weak prediction capability and large variations with respect to measured pCO 2 . Error analysis indicated that calculated pCO 2 is highly sensitive to the accuracy of pH measurements, particularly at low pH. Stepwise multiple linear regression (MLR) and random forest (RF) techniques were implemented to develop the most parsimonious model based on 10 potential predictor variables (pH, Alk, DIC, Uw, Cond, Turb, COD, DOC, TOC, Chla) by optimizing model performance. The RF model showed better performance than the MLR model, and the most parsimonious RF model (pH, Turb, Uw, Chla) improved pCO 2 prediction capability considerably compared with the simple calculation approach, reducing the RMSE from 527-544 to 105μatm at the study sites. Copyright © 2017 Elsevier B.V. All rights reserved.

Equatorial convergence of India and early Cenozoic climate trends

PubMed Central

Kent, Dennis V.; Muttoni, Giovanni

2008-01-01

India's northward flight and collision with Asia was a major driver of global tectonics in the Cenozoic and, we argue, of atmospheric CO2 concentration (pCO2) and thus global climate. Subduction of Tethyan oceanic crust with a carpet of carbonate-rich pelagic sediments deposited during transit beneath the high-productivity equatorial belt resulted in a component flux of CO2 delivery to the atmosphere capable to maintain high pCO2 levels and warm climate conditions until the decarbonation factory shut down with the collision of Greater India with Asia at the Early Eocene climatic optimum at ≈50 Ma. At about this time, the India continent and the highly weatherable Deccan Traps drifted into the equatorial humid belt where uptake of CO2 by efficient silicate weathering further perturbed the delicate equilibrium between CO2 input to and removal from the atmosphere toward progressively lower pCO2 levels, thus marking the onset of a cooling trend over the Middle and Late Eocene that some suggest triggered the rapid expansion of Antarctic ice sheets at around the Eocene-Oligocene boundary. PMID:18809910

Equatorial convergence of India and early Cenozoic climate trends.

PubMed

Kent, Dennis V; Muttoni, Giovanni

2008-10-21

India's northward flight and collision with Asia was a major driver of global tectonics in the Cenozoic and, we argue, of atmospheric CO(2) concentration (pCO(2)) and thus global climate. Subduction of Tethyan oceanic crust with a carpet of carbonate-rich pelagic sediments deposited during transit beneath the high-productivity equatorial belt resulted in a component flux of CO(2) delivery to the atmosphere capable to maintain high pCO(2) levels and warm climate conditions until the decarbonation factory shut down with the collision of Greater India with Asia at the Early Eocene climatic optimum at approximately 50 Ma. At about this time, the India continent and the highly weatherable Deccan Traps drifted into the equatorial humid belt where uptake of CO(2) by efficient silicate weathering further perturbed the delicate equilibrium between CO(2) input to and removal from the atmosphere toward progressively lower pCO(2) levels, thus marking the onset of a cooling trend over the Middle and Late Eocene that some suggest triggered the rapid expansion of Antarctic ice sheets at around the Eocene-Oligocene boundary.

Increased serum advanced glycation end-products is a distinct finding in lean women with polycystic ovary syndrome (PCOS).

PubMed

Diamanti-Kandarakis, Evanthia; Katsikis, Ilias; Piperi, Christina; Kandaraki, Eleni; Piouka, Athanasia; Papavassiliou, Athanasios G; Panidis, Dimitrios

2008-10-01

Nonenzymatic advanced glycation and oxidation end-products, advanced glycation end-products (AGEs), impart a potent impact on vessels and other tissues in diabetic state and in euglycaemic conditions with increased oxidative stress. Insulin resistant (IR) polycystic ovary syndrome (PCOS) women, have elevated serum AGEs, increased receptor (RAGE) expression, and increased deposition with differential localization in the polycystic ovarian tissue (theca and granulosa) compared to normal. To determine whether the raised AGE levels in noninsulin resistant women with PCOS is a distinct finding compared with those presenting the isolated components of the syndrome and among PCOS subphenotypes. Noninsulin resistant women were selected in order to show that serum AGEs are elevated in PCOS independently of the presence of IR. Clinical trial. One hundred and ninety-three age- and BMI-matched young lean noninsulin resistant women were studied. Among them, 100 women were diagnosed with PCOS according to Rotterdam criteria, and divided to subphenotypes (hyperandrogenaemia with or without PCO morphology and with or without anovulation). Sixty-eight women with the isolated components of the PCOS phenotype were also studied along with 25 healthy women. Serum AGE levels, metabolic, hormonal profiles and intravaginal ultrasound were determined in all subjects. The studied population did not differ in BMI, fasting insulin concentration, waist : hip and glucose : insulin ratios. PCOS women exhibited statistically higher AGEs levels (7.96 +/- 1.87 U/ml, P < 0.001) compared with those with isolated hyperandrogenaemia (5.61 +/- 0.61 U/ml), anovulation (5.53 +/- 1.06 U/ml), US-PCO morphology (5.26 +/- 0.25 U/ml) and controls (5.86 +/- 0.89 U/ml). In PCOS, serum AGEs are distinctly elevated compared with women having the isolated characteristics of the syndrome. No difference was observed between PCOS subphenotypes. As chronic inflammation and increased oxidant stress have been incriminated in the pathophysiology of PCOS, the role of AGEs as inflammatory and oxidant mediators, may be linked with the metabolic and reproductive abnormalities of the syndrome.

Estimates of late middle Eocene pCO2 based on stomatal density of modern and fossil Nageia leaves

NASA Astrophysics Data System (ADS)

Liu, X. Y.; Gao, Q.; Han, M.; Jin, J. H.

2016-02-01

Atmospheric pCO2 concentrations have been estimated for intervals of the Eocene using various models and proxy information. Here we reconstruct late middle Eocene (42.0-38.5 Ma) pCO2 based on the fossil leaves of Nageia maomingensis Jin et Liu collected from the Maoming Basin, Guangdong Province, China. We first determine relationships between atmospheric pCO2 concentrations, stomatal density (SD) and stomatal index (SI) using "modern" leaves of N. motleyi (Parl.) De Laub, the nearest living species to the Eocene fossils. This work indicates that the SD inversely responds to pCO2, while SI has almost no relationship with pCO2. Eocene pCO2 concentrations can be reconstructed based on a regression approach and the stomatal ratio method by using the SD. The first approach gives a pCO2 of 351.9 ± 6.6 ppmv, whereas the one based on stomatal ratio gives a pCO2 of 537.5 ± 56.5 ppmv. Here, we explored the potential of N. maomingensis in pCO2 reconstruction and obtained different results according to different methods, providing a new insight for the reconstruction of paleoclimate and paleoenvironment in conifers.

Physical and Biological Controls on the Carbonate Chemistry of Coral Reef Waters: Effects of Metabolism, Wave Forcing, Sea Level, and Geomorphology

PubMed Central

Falter, James L.; Lowe, Ryan J.; Zhang, Zhenlin; McCulloch, Malcolm

2013-01-01

We present a three-dimensional hydrodynamic-biogeochemical model of a wave-driven coral-reef lagoon system using the circulation model ROMS (Regional Ocean Modeling System) coupled with the wave transformation model SWAN (Simulating WAves Nearshore). Simulations were used to explore the sensitivity of water column carbonate chemistry across the reef system to variations in benthic reef metabolism, wave forcing, sea level, and system geomorphology. Our results show that changes in reef-water carbonate chemistry depend primarily on the ratio of benthic metabolism to the square root of the onshore wave energy flux as well as on the length and depth of the reef flat; however, they are only weakly dependent on channel geometry and the total frictional resistance of the reef system. Diurnal variations in pCO2, pH, and aragonite saturation state (Ωar) are primarily dependent on changes in net production and are relatively insensitive to changes in net calcification; however, net changes in pCO2, pH, and Ωar are more strongly influenced by net calcification when averaged over 24 hours. We also demonstrate that a relatively simple one-dimensional analytical model can provide a good description of the functional dependence of reef-water carbonate chemistry on benthic metabolism, wave forcing, sea level, reef flat morphology, and total system frictional resistance. Importantly, our results indicate that any long-term (weeks to months) net offsets in reef-water pCO2 relative to offshore values should be modest for reef systems with narrow and/or deep lagoons. Thus, the long-term evolution of water column pCO2 in many reef environments remains intimately connected to the regional-scale oceanography of offshore waters and hence directly influenced by rapid anthropogenically driven increases in pCO2. PMID:23326411

Physical and biological controls on the carbonate chemistry of coral reef waters: effects of metabolism, wave forcing, sea level, and geomorphology.

PubMed

Falter, James L; Lowe, Ryan J; Zhang, Zhenlin; McCulloch, Malcolm

2013-01-01

We present a three-dimensional hydrodynamic-biogeochemical model of a wave-driven coral-reef lagoon system using the circulation model ROMS (Regional Ocean Modeling System) coupled with the wave transformation model SWAN (Simulating WAves Nearshore). Simulations were used to explore the sensitivity of water column carbonate chemistry across the reef system to variations in benthic reef metabolism, wave forcing, sea level, and system geomorphology. Our results show that changes in reef-water carbonate chemistry depend primarily on the ratio of benthic metabolism to the square root of the onshore wave energy flux as well as on the length and depth of the reef flat; however, they are only weakly dependent on channel geometry and the total frictional resistance of the reef system. Diurnal variations in pCO(2), pH, and aragonite saturation state (Ω(ar)) are primarily dependent on changes in net production and are relatively insensitive to changes in net calcification; however, net changes in pCO(2), pH, and Ω(ar) are more strongly influenced by net calcification when averaged over 24 hours. We also demonstrate that a relatively simple one-dimensional analytical model can provide a good description of the functional dependence of reef-water carbonate chemistry on benthic metabolism, wave forcing, sea level, reef flat morphology, and total system frictional resistance. Importantly, our results indicate that any long-term (weeks to months) net offsets in reef-water pCO(2) relative to offshore values should be modest for reef systems with narrow and/or deep lagoons. Thus, the long-term evolution of water column pCO(2) in many reef environments remains intimately connected to the regional-scale oceanography of offshore waters and hence directly influenced by rapid anthropogenically driven increases in pCO(2).

Calcification responses of symbiotic and aposymbiotic corals to near-future levels of ocean acidification

NASA Astrophysics Data System (ADS)

Ohki, S.; Irie, T.; Inoue, M.; Shinmen, K.; Kawahata, H.; Nakamura, T.; Kato, A.; Nojiri, Y.; Suzuki, A.; Sakai, K.; van Woesik, R.

2013-11-01

Increasing the acidity of ocean waters will directly threaten calcifying marine organisms such as reef-building scleractinian corals, and the myriad of species that rely on corals for protection and sustenance. Ocean pH has already decreased by around 0.1 pH units since the beginning of the industrial revolution, and is expected to decrease by another 0.2-0.4 pH units by 2100. This study mimicked the pre-industrial, present, and near-future levels of pCO2 using a precise control system (± 5% pCO2), to assess the impact of ocean acidification on the calcification of recently settled primary polyps of Acropora digitifera, both with and without symbionts, and adult fragments with symbionts. The increase in pCO2 of ~100 μatm between the pre-industrial period and the present had more effect on the calcification rate of adult A. digitifera than the anticipated future increases of several hundreds of micro-atmospheres of pCO2. The primary polyps with symbionts showed higher calcification rates than primary polyps without symbionts, suggesting that: (i) primary polyps housing symbionts are more tolerant to near-future ocean acidification than organisms without symbionts, and (ii) corals acquiring symbionts from the environment (i.e., broadcasting species) will be more vulnerable to ocean acidification than corals that maternally acquire symbionts.

The relative roles of external and internal CO(2) versus H(+) in eliciting the cardiorespiratory responses of Salmo salar and Squalus acanthias to hypercarbia.

PubMed

Perry, S F; McKendry, J E

2001-11-01

Fish breathing hypercarbic water encounter externally elevated P(CO(2)) and proton levels ([H(+)]) and experience an associated internal respiratory acidosis, an elevation of blood P(CO(2)) and [H(+)]. The objective of the present study was to assess the potential relative contributions of CO(2) versus H(+) in promoting the cardiorespiratory responses of dogfish (Squalus acanthias) and Atlantic salmon (Salmo salar) to hypercarbia and to evaluate the relative contributions of externally versus internally oriented receptors in dogfish. In dogfish, the preferential stimulation of externally oriented branchial chemoreceptors using bolus injections (50 ml kg(-1)) of CO(2)-enriched (4 % CO(2)) sea water into the buccal cavity caused marked cardiorespiratory responses including bradycardia (-4.1+/-0.9 min(-1)), a reduction in cardiac output (-3.2+/-0.6 ml min(-1) kg(-1)), an increase in systemic vascular resistance (+0.3+/-0.2 mmHg ml min(-1) kg(-1)), arterial hypotension (-1.6+/-0.2 mmHg) and an increase in breathing amplitude (+0.3+/-0.09 mmHg) (means +/- S.E.M., N=9-11). Similar injections of CO(2)-free sea water acidified to the corresponding pH of the hypercarbic water (pH 6.3) did not significantly affect any of the measured cardiorespiratory variables (when compared with control injections). To preferentially stimulate putative internal CO(2)/H(+) chemoreceptors, hypercarbic saline (4 % CO(2)) was injected (2 ml kg(-1)) into the caudal vein. Apart from an increase in arterial blood pressure caused by volume loading, internally injected CO(2) was without effect on any measured variable. In salmon, injection of hypercarbic water into the buccal cavity caused a bradycardia (-13.9+/-3.8 min(-1)), a decrease in cardiac output (-5.3+/-1.2 ml min(-1) kg(-1)), an increase in systemic resistance (0.33+/-0.08 mmHg ml min(-1) kg(-1)) and increases in breathing frequency (9.7+/-2.2 min(-1)) and amplitude (1.2+/-0.2 mmHg) (means +/- S.E.M., N=8-12). Apart from a small increase in breathing amplitude (0.4+/-0.1 mmHg), these cardiorespiratory responses were not observed after injection of acidified water. These results demonstrate that, in dogfish and salmon, the external chemoreceptors linked to the initiation of cardiorespiratory responses during hypercarbia are predominantly stimulated by the increase in water P(CO(2)) rather than by the accompanying decrease in water pH. Furthermore, in dogfish, the cardiorespiratory responses to hypercarbia are probably exclusively derived from the stimulation of external CO(2) chemoreceptors, with no apparent contribution from internally oriented receptors.

The elemental composition of purple sea urchin (Strongylocentrotus purpuratus) calcite and potential effects of pCO2 during early life stages

NASA Astrophysics Data System (ADS)

LaVigne, M.; Hill, T. M.; Sanford, E.; Gaylord, B.; Russell, A. D.; Lenz, E. A.; Hosfelt, J. D.; Young, M. K.

2013-06-01

Ocean acidification will likely have negative impacts on invertebrates producing skeletons composed of calcium carbonate. Skeletal solubility is partly controlled by the incorporation of "foreign" ions (e.g. magnesium) into the crystal lattice of these skeletal structures, a process that is sensitive to a variety of biological and environmental factors. Here we explore effects of life stage, oceanographic region of origin, and changes in the partial pressure of carbon dioxide in seawater (pCO2) on trace elemental composition in the purple sea urchin (Strongylocentrotus purpuratus). We show that, similar to other urchin taxa, adult purple sea urchins have the ability to precipitate skeleton composed of a range of biominerals spanning low- to high-Mg calcites. Mg / Ca and Sr / Ca ratios were substantially lower in adult spines compared to adult tests. On the other hand, trace elemental composition was invariant among adults collected from four oceanographically distinct regions spanning a range of carbonate chemistry conditions (Oregon, Northern California, Central California, and Southern California). Skeletons of newly settled juvenile urchins that originated from adults from the four regions exhibited intermediate Mg / Ca and Sr / Ca between adult spine and test endmembers, indicating that skeleton precipitated during early life stages is more soluble than adult spines and less soluble than adult tests. Mean skeletal Mg / Ca or Sr / Ca of juvenile skeleton did not vary with source region when larvae were reared under present-day, global-average seawater carbonate conditions (400 μatm; pHT = 8.02 ± 0.03 1 SD; Ωcalcite = 3.3 ± 0.2 1 SD). However, when reared under elevated pCO2 (900 μatm; pHT = 7.73 ± 0.03; Ωcalcite = 1.8 ± 0.1), skeletal Sr / Ca in juveniles exhibited increased variance across the four regions. Although larvae from the northern populations (Oregon, Northern California, Central California) did not exhibit differences in Mg or Sr incorporation under elevated pCO2 (Sr / Ca = 2.10 ± 0.06 mmol mol-1; Mg / Ca = 67.4 ± 3.9 mmol mol-1), juveniles of Southern California origin partitioned ~8% more Sr into their skeletons when exposed to higher pCO2 (Sr / Ca = 2.26 ± 0.08 vs. 2.09 ± 0.005 mmol mol-1 1 SD). Together these results suggest that the diversity of carbonate minerologies present across different skeletal structures and life stages in purple sea urchins does not translate into an equivalent geochemical plasticity of response associated with geographic variation or temporal shifts in seawater properties. Rather, composition of S. purpuratus skeleton precipitated during both early and adult life history stages appears relatively robust to spatial gradients and predicted future changes in carbonate chemistry. An exception to this trend may arise during early life stages, where certain populations of purple sea urchins may alter skeletal mineral precipitation rates and composition beyond a given pCO2 threshold. This potential for geochemical plasticity during early development in contrast to adult stage geochemical resilience adds to the growing body of evidence that ocean acidification can have differing effects across organismal life stages.

Nannofossil carbonate fluxes during the Early Cretaceous: Phytoplankton response to nutrification episodes, atmospheric CO2, and anoxia

NASA Astrophysics Data System (ADS)

Erba, Elisabetta; Tremolada, Fabrizio

2004-03-01

Greenhouse episodes during the Valanginian and Aptian correlate with major perturbations in the C cycle and in marine ecosystems, carbonate crises, and widespread deposition of Corg-rich black shales. Quantitative analyses of nannofossil micrite were conducted on continuous pelagic sections from the Southern Alps (northern Italy), where high-resolution integrated stratigraphy allows precise dating of Early Cretaceous geological events. Rock-forming calcareous nannofloras were quantified in smear slides and thin sections to obtain relative and absolute abundances and paleofluxes that are interpreted as the response of calcareous phytoplankton to global changes in the ocean-atmosphere system. Increased rates of volcanism during the formation of Ontong Java and Manihiki Plateaus and the Paranà-Etendeka large igneous province (LIP) are proposed to have caused the geological responses associated with early Aptian oceanic anoxic event (OAE) 1a and the Valanginian event, respectively. Calcareous nannofloras reacted to the new conditions of higher pCO2 and fertility by drastically reducing calcification. The Valanginian event is marked by a 65% reduction in nannofossil paleofluxes that would correspond to a 2-3 times increase in pCO2 during formation of the Paranà-Endenteka LIP. A 90% reduction in nannofossil paleofluxes, which occurred in a 1.5 myr-long interval leading into OAE1a, is interpreted as the result of a 3-6 times increase in pCO2 produced by emplacement of the giant Ontong Java and Manihiki Plateaus. High pCO2 was balanced back by an accelerated biological pump during the Valanginian episode, but not during OAE1a, suggesting persisting high levels of pCO2 in the late Aptian and/or the inability of calcareous phytoplankton to absorb excess pCO2 above threshold values.

The larvae of congeneric gastropods showed differential responses to the combined effects of ocean acidification, temperature and salinity.

PubMed

Zhang, Haoyu; Cheung, S G; Shin, Paul K S

2014-02-15

The tolerance and physiological responses of the larvae of two congeneric gastropods, the intertidal Nassarius festivus and subtidal Nassarius conoidalis, to the combined effects of ocean acidification (pCO2 at 380, 950, 1250 ppm), temperature (15, 30°C) and salinity (10, 30 psu) were compared. Results of three-way ANOVA on cumulative mortality after 72-h exposure showed significant interactive effects in which mortality increased with pCO2 and temperature, but reduced at higher salinity for both species, with higher mortality being obtained for N. conoidalis. Similarly, respiration rate of the larvae increased with temperature and pCO2 level for both species, with a larger percentage increase for N. conoidalis. Larval swimming speed increased with temperature and salinity for both species whereas higher pCO2 reduced swimming speed in N. conoidalis but not N. festivus. The present findings indicated that subtidal congeneric species are more sensitive than their intertidal counterparts to the combined effects of these stressors. Copyright © 2014 Elsevier Ltd. All rights reserved.

Intertidal pool fish Girella laevifrons (Kyphosidae) shown strong physiological homeostasis but shy personality: The cost of living in hypercapnic habitats.

PubMed

Benítez, S; Duarte, C; Opitz, T; Lagos, N A; Pulgar, J M; Vargas, C A; Lardies, M A

2017-05-15

Tide pools habitats are naturally exposed to a high degree of environmental variability. The consequences of living in these extreme habitats are not well established. In particular, little it is known about of the effects of hypercanic seawater (i.e. high pCO 2 levels) on marine vertebrates such as intertidal pool fish. The aim of this study was to evaluate the effects of increased pCO 2 on the physiology and behavior in juveniles of the intertidal pool fish Girella laevifrons. Two nominal pCO 2 concentrations (400 and 1600μatm) were used. We found that exposure to hypercapnic conditions did not affect oxygen consumption and absorption efficiency. However, the lateralization and boldness behavior was significantly disrupted in high pCO 2 conditions. In general, a predator-risk cost of boldness is assumed, thus the increased occurrence of shy personality in juvenile fishes may result in a change in the balance of this biological interaction, with significant ecological consequences. Copyright © 2017 Elsevier Ltd. All rights reserved.

Environmental biogeography of near-surface phytoplankton in the southeast Pacific Ocean

NASA Astrophysics Data System (ADS)

Hardy, John; Hanneman, Andrew; Behrenfeldt, Michael; Horner, Rita

1996-10-01

Biogeographic interpretation of large-scale phytoplankton distribution patterns in relation to surface hydrography is essential to understanding pelagic food web dynamics and biogeochemical processes influencing global climate. We examined the abundance and biomass of phytoplankton in relation to physical and chemical parameters in the southeast Pacific Ocean. Samples were collected along longitude 110°W, between 10°N and 60°S during late austral summer. Patterns of taxa abundance and hydrographic variables were interpreted by principal components analysis. Five distinct phytohydrographic regions were identified: (i) a north equatorial region of moderate productivity dominated by small flagellates, low nitrate and low-to-moderate pCO 2; (ii) a south equatorial region characterized by high primary productivity dominated by diatoms, high nutrient levels, and relatively high pCO 2; (iii) a central gyre region characterized by low productivity dominated by small flagellates, low nitrate, and high pCO 2; (iv) a sub-Antarctic region with moderate productivity dominated by coccolithophores, moderate nitrate concentrations, and low pCO 2; and (v) an Antarctic region with high productivity dominated by diatoms, very high nitrate, and low pCO 2. Productivity and average phytoplankton cell size were positively correlated with nitrate concentration. Total phytoplankton abundance was negatively correlated with pCO 2, photosynthetically active radiation, and ultraviolet-B radiation. The interaction between phytoplankton carbon assimilation, atmospheric CO2, and the inhibitory effect of ultraviolet radiation could have implications for the global climate. These data suggest that the effects would be greatest at southern mid-latitudes (40-50°S) where present phytoplankton production and predicted future increases in UV-B are both relatively high.

Ocean acidification does not affect magnesium composition or dolomite formation in living crustose coralline algae, Porolithon onkodes in an experimental system

NASA Astrophysics Data System (ADS)

Nash, M. C.; Uthicke, S.; Negri, A. P.; Cantin, N. E.

2015-01-01

There are concerns that Mg-calcite crustose coralline algae (CCA), which are key reef builders on coral reefs, will be most susceptible to increased rates of dissolution under higher pCO2 and ocean acidification. Due to the higher solubility of Mg-calcite, it has been hypothesized that magnesium concentrations in CCA Mg-calcite will decrease as the ocean acidifies, and that this decrease will make their skeletons more chemically stable. In addition to Mg-calcite, CCA Porolithon onkodes the predominant encrusting species on tropical reefs, can have dolomite (Ca0.5Mg0.5CO3) infilling cell spaces which increases their stability. However, nothing is known about how bio-mineralised dolomite formation responds to higher pCO2. Using P. onkodes grown for 3 and 6 months in tank experiments, we aimed to determine (1) if mol % MgCO3 in new crust and new settlement affected by increasing pCO2 levels (365, 444, 676 and 904 ppm), (2) whether bio-mineralised dolomite formed within these time frames, and (3) if so, whether this was effected by pCO2. Our results show there was no significant effect of pCO2 on mol % MgCO3 in any sample set, indicating an absence of a plastic response under a wide range of experimental conditions. Dolomite within the CCA cells formed within 3 months and dolomite abundance did not vary significantly with pCO2 treatment. While evidence mounts that climate change will impact many sensitive coral and CCA species, the results from this study indicate that reef-building P. onkodes will continue to form stabilising dolomite infill under near-future acidification conditions, thereby retaining its higher resistance to dissolution.

Food availability and pCO2 impacts on planulation, juvenile survival, and calcification of the azooxanthellate scleractinian coral, Balanophyllia elegans

NASA Astrophysics Data System (ADS)

Crook, E. D.; Cooper, H.; Potts, D. C.; Lambert, T.; Paytan, A.

2013-05-01

Ocean acidification, the assimilation of atmospheric CO2 by the oceans that decreases the pH and CaCO3 saturation state (Ω) of seawater, is projected to have severe consequences for calcifying organisms. Strong evidence suggests that tropical reef-building corals containing algal symbionts (zooxanthellae) will experience dramatic declines in calcification over the next century. The responses of azooxanthellate corals to ocean acidification are less well understood, and because they cannot obtain extra photosynthetic energy from symbionts, they provide a system for studying the direct effects of acidification on the energy available for calcification. The orange cup coral Balanophyllia elegans is a solitary, azooxanthellate scleractinian species common on the California coast where it thrives in the low pH waters of an upwelling regime. During an 8 month study, we addressed the effects of three pCO2 treatments (410, 770, and 1230 μatm) and two feeding frequencies (High Food and Low Food) on adult Balanophyllia elegans planulation (larval release) rates, and on the survival, growth, and calcification of their juvenile offspring. Planulation rates were affected by food level but not pCO2, while juvenile survival was highest under 410 μatm and High Food conditions. Our results suggest that feeding rate has a greater impact on calcification of B. elegans than pCO2. Net calcification was positive even at 1230 μatm (~ 3 times current atmospheric pCO2), although the increase from 410 to 1230 μatm reduced overall calcification by ~ 25-45%, and reduced skeletal density by ~ 35-45%. Higher pCO2 also altered aragonite crystal morphology significantly. We discuss how feeding frequency affects azooxanthellate coral calcification, and how B. elegans may respond to ocean acidification in coastal upwelling waters.

Tropomyosin 2 heterozygous knockout in mice using CRISPR-Cas9 system displays the inhibition of injury-induced epithelial-mesenchymal transition, and lens opacity

PubMed Central

Shibata, Teppei; Shibata, Shinsuke; Ishigaki, Yasuhito; Kiyokawa, Etsuko; Ikawa, Masahito; Singh, Dhirendra P.; Sasaki, Hiroshi; Kubo, Eri

2018-01-01

The process of epithelial–mesenchymal transition (EMT) of lens epithelial cells (LECs) after cataract surgery contributes to tissue fibrosis, wound healing and lens regeneration via a mechanism not yet fully understood. Here, we show that tropomyosin 2 (Tpm2) plays a critical role in wound healing and lens aging. Posterior capsular opacification (PCO) after lens extraction surgery was accompanied by elevated expression of Tpm2. Tpm2 heterozygous knockout mice, generated via the clustered regularly interspaced short palindromic repeat/ Cas9 (CRISPR/Cas9) system showed promoted progression of cataract with age. Further, injury-induced EMT of the mouse lens epithelium, as evaluated histologically and by the expression patterns of Tpm1 and Tpm2, was attenuated in the absence of Tpm2. In conclusion, Tpm2 may be important in maintaining lens physiology and morphology. However, Tpm2 is involved in the progression of EMT during the wound healing process of mouse LECs, suggesting that inhibition of Tpm2 may suppress PCO. PMID:29510160

Mitochondrial respiration and ROS emission during β-oxidation in the heart: An experimental-computational study

PubMed Central

Sollott, Steven J.

2017-01-01

Lipids are main fuels for cellular energy and mitochondria their major oxidation site. Yet unknown is to what extent the fuel role of lipids is influenced by their uncoupling effects, and how this affects mitochondrial energetics, redox balance and the emission of reactive oxygen species (ROS). Employing a combined experimental-computational approach, we comparatively analyze β-oxidation of palmitoyl CoA (PCoA) in isolated heart mitochondria from Sham and streptozotocin (STZ)-induced type 1 diabetic (T1DM) guinea pigs (GPs). Parallel high throughput measurements of the rates of oxygen consumption (VO2) and hydrogen peroxide (H2O2) emission as a function of PCoA concentration, in the presence of L-carnitine and malate, were performed. We found that PCoA concentration < 200 nmol/mg mito protein resulted in low H2O2 emission flux, increasing thereafter in Sham and T1DM GPs under both states 4 and 3 respiration with diabetic mitochondria releasing higher amounts of ROS. Respiratory uncoupling and ROS excess occurred at PCoA > 600 nmol/mg mito prot, in both control and diabetic animals. Also, for the first time, we show that an integrated two compartment mitochondrial model of β-oxidation of long-chain fatty acids and main energy-redox processes is able to simulate the relationship between VO2 and H2O2 emission as a function of lipid concentration. Model and experimental results indicate that PCoA oxidation and its concentration-dependent uncoupling effect, together with a partial lipid-dependent decrease in the rate of superoxide generation, modulate H2O2 emission as a function of VO2. Results indicate that keeping low levels of intracellular lipid is crucial for mitochondria and cells to maintain ROS within physiological levels compatible with signaling and reliable energy supply. PMID:28598967

Mitochondrial respiration and ROS emission during β-oxidation in the heart: An experimental-computational study.

PubMed

Cortassa, Sonia; Sollott, Steven J; Aon, Miguel A

2017-06-01

Lipids are main fuels for cellular energy and mitochondria their major oxidation site. Yet unknown is to what extent the fuel role of lipids is influenced by their uncoupling effects, and how this affects mitochondrial energetics, redox balance and the emission of reactive oxygen species (ROS). Employing a combined experimental-computational approach, we comparatively analyze β-oxidation of palmitoyl CoA (PCoA) in isolated heart mitochondria from Sham and streptozotocin (STZ)-induced type 1 diabetic (T1DM) guinea pigs (GPs). Parallel high throughput measurements of the rates of oxygen consumption (VO2) and hydrogen peroxide (H2O2) emission as a function of PCoA concentration, in the presence of L-carnitine and malate, were performed. We found that PCoA concentration < 200 nmol/mg mito protein resulted in low H2O2 emission flux, increasing thereafter in Sham and T1DM GPs under both states 4 and 3 respiration with diabetic mitochondria releasing higher amounts of ROS. Respiratory uncoupling and ROS excess occurred at PCoA > 600 nmol/mg mito prot, in both control and diabetic animals. Also, for the first time, we show that an integrated two compartment mitochondrial model of β-oxidation of long-chain fatty acids and main energy-redox processes is able to simulate the relationship between VO2 and H2O2 emission as a function of lipid concentration. Model and experimental results indicate that PCoA oxidation and its concentration-dependent uncoupling effect, together with a partial lipid-dependent decrease in the rate of superoxide generation, modulate H2O2 emission as a function of VO2. Results indicate that keeping low levels of intracellular lipid is crucial for mitochondria and cells to maintain ROS within physiological levels compatible with signaling and reliable energy supply.

The carbon and oxygen isotope records of reef-dwelling foraminifers subjected to five varied pCO2 seawater

NASA Astrophysics Data System (ADS)

Hikami, M.; Ishimura, T.; Suzuki, A.; Nojiri, Y.; Kawahata, H.

2013-12-01

Ocean acidification (OA) in response to rising atmospheric pCO2 is generally expected to reduce rates of calcification by reef calcifying organisms, with potentially severe implications for coral reef ecosystems. Reef dwelling foraminifera is one of the most important primary and carbonate producers in coral reef environments. Their shells are composed of high-Mg calcite and they are host to algal endosymbionts. In our previous culture experiment with two algal reef dwelling foraminifers, Amphisorus kudakajimensis and Calcarina gaudichaudii in the seawater of five different pCO2 conditions, net calcification of A. kudakajimensis was reduced under higher pCO2, whereas net calcification of C. gaudichaudii showed continued increasing trend with pCO2. These contrasting responses between the two species are possibly due to differences in calcification mechanisms and to links between calcification by the foraminifers and photosynthesis by the algal endosymbionts. But the factors affecting these calcification mechanisms are poorly understood. In this study, to get a better understanding of the effect of OA on their calcification, we cultured three reef dwelling foraminifers: Amphisorus hemprichii, belong to imperforate species, Baculogypsina sphaerulata, and C. gaudichaudii belong to perforate species, in the seawater of five different pCO2 conditions and we address the response of carbon and oxygen isotopes of the carbonate shells of foraminifers. The oxygen isotope ratio of cultured foraminiferal tests under five varied pCO2 seawater indicated no significant correlation to pCO2 values. On the other hand, the carbon isotope ratio of foraminiferal tests indicated heavy trend with rising pCO2 in all species. Alteration of carbonate chemistry result from ocean acidification may be effect strongly on carbon isotope composition relate to metabolic system (i.e. photosynthesis and respiration). In perforate species, both of oxygen and carbon isotope ratio were lighter than that in imperforate. For oxygen isotope ratio variation possibility among species would be caused by their Mg-content concentration in calcite shells. The distinct difference in the level of carbon isotope ratio between pure calcite and perforate foraminifera might be influenced by the degree of dependency on metabolic CO2 used for shell construction. The imperforate species would use most carbon derived from bicarbonate ion of seawater directly because the carbon isotope ratio of shell is almost same to that of pure calcite. Therefore, oxygen and carbon isotope ratio of foraminiferal test have the potential to reveal calcification mechanism of two species.

End-tidal pCO2 in blood phobics during viewing of emotion- and disease-related films.

PubMed

Ritz, Thomas; Wilhelm, Frank H; Gerlach, Alexander L; Kullowatz, Antje; Roth, Walton T

2005-01-01

Many patients with blood, injection, and injury (BII) phobia respond to specific stimuli with vasovagal dysregulation and fainting. However, little is known about the role of hyperventilation in the distress of these patients. Hyperventilation, defined by subnormal arterial pCO2 levels, induces anxiety and may promote the development of fainting. We studied end-tidal pCO2 in 12 patients with BII phobia and 14 nonanxious controls during presentation of emotional films. Ten film clips were shown, two in each of 5 categories: pleasant, unpleasant, neutral, BII-related (surgery), and asthma-related (portraying labored breathing). For each subject, two subsets were created, each containing one clip from each category. For one subset, the instruction was simply to view the film, and for the other subset, to view the film while tensing the leg muscles. PCO2, heart rate, blood pressure, and leg electromyogram were recorded continuously during viewing, and self-report of symptoms and emotion was collected after each film. Patients reported the greatest anxiety and disgust during surgery films. PCO2 was relatively stable throughout all categories except surgery films, during which minima were below 30 mm Hg, indicating significant hypocapnia. Cardiovascular variables suggested biphasic patterns in two patients with BII phobia. These patients, together with one additional patient and one control who were close to fainting after or during one surgery film, also showed a marked fall in pCO2) Leg muscle tension raised heart rate and systolic blood pressure for all films, but was not related to near-fainting or endurance in surgery film viewing. Hyperventilation is part of the fear response of patients with BII phobia, but was transitory in experimental fear induction using surgery films. Its role in real-life exposure and fainting deserves further study.

Venous-to-arterial carbon dioxide difference in the resuscitation of patients with severe sepsis and septic shock: A systematic review.

PubMed

Diaztagle Fernández, J J; Rodríguez Murcia, J C; Sprockel Díaz, J J

2017-10-01

The way to assess tissue perfusion during the resuscitation of patients with severe sepsis and septic shock is a current subject of research and debate. Venous oxygen saturation and lactate concentration have been the most frequently used criteria, though they involve known limitations. The venous-to-arterial difference of carbon dioxide (pCO 2 delta) is a parameter than can be used to indicate tissue perfusion, and its determination therefore may be useful in these patients. A qualitative systematic review of the literature was made, comprising studies that assessed pCO 2 delta in adult patients with severe sepsis or septic shock, and published between January 1966 and November 2016 in the Medline-PubMed, Embase-Elsevier, Cochrane Library, and LILACS databases. There was no language restriction. The PRISMA statement was followed, and methodological quality was evaluated. Twelve articles were included, all of an observational nature, and including 10 prospective studies (9 published since 2010). Five documented greater mortality among patients with high pCO 2 delta values, in 3 cases even when achieving venous oxygen saturation targets. In 4 studies, a high pCO 2 delta was related to lower venous oxygen saturation and higher lactate levels, and another 3 documented lesser percentage lactate reductions. The parameter pCO 2 delta has been more frequently assessed in the management of patients with severe sepsis during the last few years. The studies demonstrate its correlation to mortality and other clinical outcomes, defining pCO 2 delta as a useful tool in the management of these patients. Copyright © 2017 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

Sources and Dynamics of Inorganic Carbon within the Upper Reaches of the Xi River Basin, Southwest China

PubMed Central

Zou, Junyu

2016-01-01

The carbon isotopic composition (δ13C) of dissolved and particulate inorganic carbon (DIC; PIC) was used to compare and analyze the origin, dynamics and evolution of inorganic carbon in two headwater tributaries of the Xi River, Southwest China. Carbonate dissolution and soil CO2 were regarded as the primary sources of DIC on the basis of δ13CDIC values which varied along the Nanpan and Beipan Rivers, from −13.9‰ to 8.1‰. Spatial trends in DIC differed between the two rivers (i.e., the tributaries), in part because factors controlling pCO2, which strongly affected carbonate dissolution, differed between the two river basins. Transport of soil CO2 and organic carbon through hydrologic conduits predominately controlled the levels of pCO2 in the Nanpan River. However, pCO2 along the upper reaches of the Nanpan River also was controlled by the extent of urbanization and industrialization relative to agriculture. DIC concentrations in the highly urbanized upper reaches of the Nanpan River were typical higher than in other carbonate-dominated areas of the upper Xi River. Within the Beipan River, the oxidation of organic carbon is the primary process that maintains pCO2 levels. The pCO2 within the Beipan River was more affected by sulfuric acid from coal industries, inputs from a scenic spot, and groundwater than along the Nanpan River. With regards to PIC, the contents and δ13C values in the Nanpan River were generally lower than those in the Beipan River, indicating that chemical and physical weathering contributes more marine carbonate detritus to the PIC along the Beipan River. The CO2 evasion flux from the Nanpan River was higher than that in the Beipan River, and generally higher than along the middle and lower reaches of the Xi River, demonstrating that the Nanpan River is an important net source of atmospheric CO2 in Southwest China. PMID:27513939

Continuous pCO2 time series from Ocean Networks Canada cabled observatories at the northeast Pacific shelf edge and in the sub-tidal Arctic

NASA Astrophysics Data System (ADS)

Juniper, S. Kim; Sastri, Akash; Mihaly, Steven; Duke, Patrick; Else, Brent; Thomas, Helmuth; Miller, Lisa

2017-04-01

Marine pCO2 sensor technology has progressed to the point where months-long time series from remotely-deployed pCO2 sensors can be used to document seasonal and higher frequency variability in pCO2 and its relationship to oceanographic processes. Ocean Networks Canada recently deployed pCO2 sensors on two cabled platforms: a bottom-moored (400 m depth), vertical profiler at the edge of the northeast Pacific continental shelf off Vancouver Island, Canada, and a subtidal seafloor platform in the Canadian High Arctic (69˚ N) at Cambridge Bay, Nunavut. Both platforms streamed continuous data to a shore-based archive from Pro-Oceanus pCO2 sensors and other oceanographic instruments. The vertical profiler time series revealed substantial intrusions of corrosive (high CO2/low O2), saltier, colder water masses during the summertime upwelling season and during winter-time reversals of along-slope currents. Step-wise profiles during the downcast provided the most reliable pCO2 data, permitting the sensor to equilibrate to the broad range of pCO2 concentrations encountered over the 400 metre depth interval. The Arctic pCO2 sensor was deployed in August 2015. Reversing seasonal trends in pCO2 and dissolved oxygen values can be related to the changing balance of photosynthesis and respiration under sea ice, as influenced by irradiance. Correlation of pCO2 and dissolved oxygen sensor data and the collection of calibration samples have permitted evaluation of sensor performance in relation to operational conditions encountered in vertical profiling and lengthy exposure to subzero seawater.

Long-term experiment on physiological responses to synergetic effects of ocean acidification and photoperiod in the Antarctic sea ice algae Chlamydomonas sp. ICE-L.

PubMed

Xu, Dong; Wang, Yitao; Fan, Xiao; Wang, Dongsheng; Ye, Naihao; Zhang, Xiaowen; Mou, Shanli; Guan, Zheng; Zhuang, Zhimeng

2014-07-15

Studies on ocean acidification have mostly been based on short-term experiments of low latitude with few investigations of the long-term influence on sea ice communities. Here, the combined effects of ocean acidification and photoperiod on the physiological response of the Antarctic sea ice microalgae Chlamydomonas sp. ICE-L were examined. There was a general increase in growth, PSII photosynthetic parameters, and N and P uptake in continuous light, compared to those exposed to regular dark and light cycles. Elevated pCO2 showed no consistent effect on growth rate (p=0.8) and N uptake (p=0.38) during exponential phrase, depending on the photoperiod but had a positive effect on PSII photosynthetic capacity and P uptake. Continuous dark reduced growth, photosynthesis, and nutrient uptake. Moreover, intracellular lipid, mainly in the form of PUFA, was consumed at 80% and 63% in low and high pCO2 in darkness. However, long-term culture under high pCO2 gave a more significant inhibition of growth and Fv/Fm to high light stress. In summary, ocean acidification may have significant effects on Chlamydomonas sp. ICE-L survival in polar winter. The current study contributes to an understanding of how a sea ice algae-based community may respond to global climate change at high latitudes.

Identification of sleep hypoventilation in young individuals with Becker muscular dystrophy: A pilot study.

PubMed

Nakamura, Yuko; Saito, Yoshiaki; Kubota, Norika; Matsumura, Wataru; Hosoda, Chika; Tamasaki-Kondo, Akiko; Nishimura, Yoko; Sunada, Yoshihide; Fukada, Masuyuki; Ohno, Takako; Maegaki, Yoshihiro; Matsuo, Masafumi; Tokita, Yasuko

2018-03-08

To report on sleep hypercapnia in Becker muscular dystrophy (BMD) at earlier stages than ever recognized. This retrospective study examined nocturnal hypercapnia in six young Becker muscular dystrophy (BMD) patients with deletions of one or more exons of DMD gene. Clinical information, consecutive data on forced vital capacity (FVC%), forced expiratory volume in one second (FEV1%), peak expiratory flow (PEF%), peak cough flow (PCF), average PCO 2 in all-night monitoring, and left ventricular ejection fraction (LVEF) were reviewed. In five BMD patients, including three who were still ambulant, nocturnal average PCO 2 was elevated to >45 mmHg at 12-31 years of age. Noninvasive positive pressure ventilation was initiated in four patients. Gradual declines in FVC% and PEF% were evident in one BMD patient with exon 3-7 deletion, whereas these functions did not change in the remaining BMD patients. PCF, FEV1%, and LVEF were less informative for the assessment of respiratory function in this patient series. Sleep hypercapnia was present in certain BMD patients, which was unexpected from the routine pulmonary function tests. Individualized assessment of nocturnal PCO 2 , partly based on the deletion types, should be further explored in the clinical practice of BMD patients. Copyright © 2018 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Effect of 1% Inspired CO2 During Head-Down Tilt on Ocular Structures, Cerebral Blood Flow, and Visual Acuity in Healthy Human Subjects

NASA Technical Reports Server (NTRS)

Laurie, S. S.; Hu, X.; Lee, S. M. C.; Martin, D. S.; Phillips, T. R.; Ploutz-Snyder, R.; Smith, S. M.; Stenger, M. B.; Taibbi, G.; Zwart, S. R.;

CO(2) partial pressure and calcite saturation in springs - useful data for identifying infiltration areas in mountainous environments.

PubMed

Hilberg, Sylke; Brandstätter, Jennifer; Glück, Daniel

2013-04-01

Mountainous regions such as the Central European Alps host considerable karstified or fractured groundwater bodies, which meet many of the demands concerning drinking water supply, hydropower or agriculture. Alpine hydrogeologists are required to describe the dynamics in fractured aquifers in order to assess potential impacts of human activities on water budget and quality. Delineation of catchment areas by means of stable isotopes and hydrochemical data is a well established method in alpine hydrogeology. To achieve reliable results, time series of (at least) one year and spatial and temporal close-meshed data are necessary. In reality, test sites in mountainous regions are often inaccessible due to the danger of avalanches in winter. The aim of our work was to assess a method based on the processes within the carbonic acid system to delineate infiltration areas by means of single datasets consisting of the main hydrochemical parameters of each spring. In three geologically different mountainous environments we managed to classify the investigated springs into four groups. (1) High PCO2 combined with slight super-saturation in calcite, indicating relatively low infiltration areas. (2) Low PCO2 near atmospheric conditions in combination with calcite saturation, which is indicative of relatively high infiltration areas and a fractured aquifer which is not covered by topsoil layers. (3) High PCO2 in combination with sub-saturation in calcite, representing a shallow aquifer with a significant influence of the topsoil layer. (4) The fourth group of waters is characterized by low PCO2 and sub-saturation in calcite, which is interpreted as evidence for a shallow aquifer without significant influence of any hard rock aquifer or topsoil layer. This study shows that CO2-partial pressure can be an ideal natural tracer to estimate the elevation of infiltration areas, especially in non-karstified fractured groundwater bodies.

Evidence for negative effects of elevated intra-abdominal pressure on pulmonary mechanics and oxidative stress.

PubMed

Davarcı, I; Karcıoğlu, M; Tuzcu, K; İnanoğlu, K; Yetim, T D; Motor, S; Ulutaş, K T; Yüksel, R

2015-01-01

To compare the effects of pneumoperitoneum on lung mechanics, end-tidal CO2 (ETCO2), arterial blood gases (ABG), and oxidative stress markers in blood and bronchoalveolar lavage fluid (BALF) during laparoscopic cholecystectomy (LC) by using lung-protective ventilation strategy. Forty-six patients undergoing LC and abdominal wall hernia (AWH) surgery were assigned into 2 groups. Measurements and blood samples were obtained before, during pneumoperitoneum, and at the end of surgery. BALF samples were obtained after anesthesia induction and at the end of surgery. Peak inspiratory pressure, ETCO2, and pCO2 values at the 30th minute were significantly increased, while there was a significant decrease in dynamic lung compliance, pH, and pO2 values in LC group. In BALF samples, total oxidant status (TOS), arylesterase, paraoxonase, and malondialdehyde levels were significantly increased; the glutathione peroxidase levels were significantly decreased in LC group. The serum levels of TOS and paraoxonase were significantly higher at the end of surgery in LC group. In addition, arylesterase level in the 30th minute was increased compared to baseline. Serum paraoxonase level at the end of surgery was significantly increased when compared to AWH group. Our study showed negative effects of pneumoperitoneum in both lung and systemic levels despite lung-protective ventilation strategy.

A direct CO2 control system for ocean acidification experiments: testing effects on the coralline red algae Phymatolithon lusitanicum

PubMed Central

Santos, Rui; Reis, Joao; Shulika, Alona

2016-01-01

Most ocean acidification (OA) experimental systems rely on pH as an indirect way to control CO2. However, accurate pH measurements are difficult to obtain and shifts in temperature and/or salinity alter the relationship between pH and pCO2. Here we describe a system in which the target pCO2 is controlled via direct analysis of pCO2 in seawater. This direct type of control accommodates potential temperature and salinity shifts, as the target variable is directly measured instead of being estimated. Water in a header tank is permanently re-circulated through an air-water equilibrator. The equilibrated air is then routed to an infrared gas analyzer (IRGA) that measures pCO2 and conveys this value to a Proportional-Integral-Derivative (PID) controller. The controller commands a solenoid valve that opens and closes the CO2 flush that is bubbled into the header tank. This low-cost control system allows the maintenance of stabilized levels of pCO2 for extended periods of time ensuring accurate experimental conditions. This system was used to study the long term effect of OA on the coralline red algae Phymatolithon lusitanicum. We found that after 11 months of high CO2 exposure, photosynthesis increased with CO2 as opposed to respiration, which was positively affected by temperature. Results showed that this system is adequate to run long-term OA experiments and can be easily adapted to test other relevant variables simultaneously with CO2, such as temperature, irradiance and nutrients. PMID:27703853

Projected near-future levels of temperature and pCO2 reduce coral fertilization success.

PubMed

Albright, Rebecca; Mason, Benjamin

2013-01-01

Increases in atmospheric carbon dioxide (pCO2) are projected to contribute to a 1.1-6.4°C rise in global average surface temperatures and a 0.14-0.35 reduction in the average pH of the global surface ocean by 2100. If realized, these changes are expected to have negative consequences for reef-building corals including increased frequency and severity of coral bleaching and reduced rates of calcification and reef accretion. Much less is known regarding the independent and combined effects of temperature and pCO2 on critical early life history processes such as fertilization. Here we show that increases in temperature (+3°C) and pCO2 (+400 µatm) projected for this century negatively impact fertilization success of a common Indo-Pacific coral species, Acropora tenuis. While maximum fertilization did not differ among treatments, the sperm concentration required to obtain 50% of maximum fertilization increased 6- to 8- fold with the addition of a single factor (temperature or CO2) and nearly 50- fold when both factors interact. Our results indicate that near-future changes in temperature and pCO2 narrow the range of sperm concentrations that are capable of yielding high fertilization success in A. tenuis. Increased sperm limitation, in conjunction with adult population decline, may have severe consequences for coral reproductive success. Impaired sexual reproduction will further challenge corals by inhibiting population recovery and adaptation potential.

Projected Near-Future Levels of Temperature and pCO2 Reduce Coral Fertilization Success

PubMed Central

Albright, Rebecca; Mason, Benjamin

2013-01-01

Increases in atmospheric carbon dioxide (pCO2) are projected to contribute to a 1.1–6.4°C rise in global average surface temperatures and a 0.14–0.35 reduction in the average pH of the global surface ocean by 2100. If realized, these changes are expected to have negative consequences for reef-building corals including increased frequency and severity of coral bleaching and reduced rates of calcification and reef accretion. Much less is known regarding the independent and combined effects of temperature and pCO2 on critical early life history processes such as fertilization. Here we show that increases in temperature (+3°C) and pCO2 (+400 µatm) projected for this century negatively impact fertilization success of a common Indo-Pacific coral species, Acropora tenuis. While maximum fertilization did not differ among treatments, the sperm concentration required to obtain 50% of maximum fertilization increased 6- to 8- fold with the addition of a single factor (temperature or CO2) and nearly 50- fold when both factors interact. Our results indicate that near-future changes in temperature and pCO2 narrow the range of sperm concentrations that are capable of yielding high fertilization success in A. tenuis. Increased sperm limitation, in conjunction with adult population decline, may have severe consequences for coral reproductive success. Impaired sexual reproduction will further challenge corals by inhibiting population recovery and adaptation potential. PMID:23457572

A 40-million-year history of atmospheric CO(2).

PubMed

Zhang, Yi Ge; Pagani, Mark; Liu, Zhonghui; Bohaty, Steven M; Deconto, Robert

2013-10-28

The alkenone-pCO2 methodology has been used to reconstruct the partial pressure of ancient atmospheric carbon dioxide (pCO2) for the past 45 million years of Earth's history (Middle Eocene to Pleistocene epochs). The present long-term CO2 record is a composite of data from multiple ocean localities that express a wide range of oceanographic and algal growth conditions that potentially bias CO2 results. In this study, we present a pCO2 record spanning the past 40 million years from a single marine locality, Ocean Drilling Program Site 925 located in the western equatorial Atlantic Ocean. The trends and absolute values of our new CO2 record site are broadly consistent with previously published multi-site alkenone-CO2 results. However, new pCO2 estimates for the Middle Miocene are notably higher than published records, with average pCO2 concentrations in the range of 400-500 ppm. Our results are generally consistent with recent pCO2 estimates based on boron isotope-pH data and stomatal index records, and suggest that CO2 levels were highest during a period of global warmth associated with the Middle Miocene Climatic Optimum (17-14 million years ago, Ma), followed by a decline in CO2 during the Middle Miocene Climate Transition (approx. 14 Ma). Several relationships remain contrary to expectations. For example, benthic foraminiferal δ(18)O records suggest a period of deglaciation and/or high-latitude warming during the latest Oligocene (27-23 Ma) that, based on our results, occurred concurrently with a long-term decrease in CO2 levels. Additionally, a large positive δ(18)O excursion near the Oligocene-Miocene boundary (the Mi-1 event, approx. 23 Ma), assumed to represent a period of glacial advance and retreat on Antarctica, is difficult to explain by our CO2 record alone given what is known of Antarctic ice sheet history and the strong hysteresis of the East Antarctic Ice Sheet once it has grown to continental dimensions. We also demonstrate that in the Neogene with low CO2 levels, algal carbon concentrating mechanisms and spontaneous biocarbonate-CO2 conversions are likely to play a more important role in algal carbon fixation, which provides a potential bias to the alkenone-pCO2 method.

21 CFR 868.2500 - Cutaneous oxygen (PcO2) monitor.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cutaneous oxygen (PcO2) monitor. 868.2500 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2500 Cutaneous oxygen (PcO2) monitor. (a) Identification. A cutaneous oxygen (PcO2) monitor is a noninvasive, heated sensor (e.g., a...

21 CFR 868.2500 - Cutaneous oxygen (PcO 2) monitor.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Cutaneous oxygen (PcO 2) monitor. 868.2500 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2500 Cutaneous oxygen (PcO 2) monitor. (a) Identification. A cutaneous oxygen (PcO2) monitor is a noninvasive, heated sensor (e.g., a...

21 CFR 868.2500 - Cutaneous oxygen (PcO 2) monitor.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Cutaneous oxygen (PcO 2) monitor. 868.2500 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2500 Cutaneous oxygen (PcO 2) monitor. (a) Identification. A cutaneous oxygen (PcO2) monitor is a noninvasive, heated sensor (e.g., a...

21 CFR 868.2500 - Cutaneous oxygen (PcO2) monitor.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Cutaneous oxygen (PcO2) monitor. 868.2500 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2500 Cutaneous oxygen (PcO2) monitor. (a) Identification. A cutaneous oxygen (PcO2) monitor is a noninvasive, heated sensor (e.g., a...

21 CFR 868.2500 - Cutaneous oxygen (PcO2) monitor.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Cutaneous oxygen (PcO2) monitor. 868.2500 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2500 Cutaneous oxygen (PcO2) monitor. (a) Identification. A cutaneous oxygen (PcO2) monitor is a noninvasive, heated sensor (e.g., a...

Conditions of Mytilus edulis extracellular body fluids and shell composition in a pH-treatment experiment: Acid-base status, trace elements and δ11B

NASA Astrophysics Data System (ADS)

Heinemann, Agnes; Fietzke, Jan; Melzner, Frank; BöHm, Florian; Thomsen, JöRn; Garbe-SchöNberg, Dieter; Eisenhauer, Anton

2012-01-01

Mytilus edulis were cultured for 3 months under six different seawater pCO2 levels ranging from 380 to 4000 μatm. Specimen were taken from Kiel Fjord (Western Baltic Sea, Germany) which is a habitat with high and variable seawater pCO2 and related shifts in carbonate system speciation (e.g., low pH and low CaCO3 saturation state). Hemolymph (HL) and extrapallial fluid (EPF) samples were analyzed for pH and total dissolved inorganic carbon (CT) to calculate pCO2 and [HCO3-]. A second experiment was conducted for 2 months with three different pCO2 levels (380, 1400 and 4000 μatm). Boron isotopes (δ11B) were investigated by LA-MC-ICP-MS (Laser Ablation-Multicollector-Inductively Coupled Plasma-Mass Spectrometry) in shell portions precipitated during experimental treatment time. Additionally, elemental ratios (B/Ca, Mg/Ca and Sr/Ca) in the EPF of specimen from the second experiment were measured via ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometry). Extracellular pH was not significantly different in HL and EPF but systematically lower than ambient water pH. This is due to high extracellular pCO2 values, a prerequisite for metabolic CO2 excretion. No accumulation of extracellular [HCO3-] was measured. Elemental ratios (B/Ca, Mg/Ca and Sr/Ca) in the EPF increased slightly with pH which is in accordance with increasing growth and calcification rates at higher seawater pH values. Boron isotope ratios were highly variable between different individuals but also within single shells. This corresponds to a high individual variability in fluid B/Ca ratios and may be due to high boron concentrations in the organic parts of the shell. The mean δ11B value shows no trend with pH but appears to represent internal pH (EPF) rather than ambient water pH.

Time series pCO2 at a coastal mooring: Internal consistency, seasonal cycles, and interannual variability

NASA Astrophysics Data System (ADS)

Reimer, Janet J.; Cai, Wei-Jun; Xue, Liang; Vargas, Rodrigo; Noakes, Scott; Hu, Xinping; Signorini, Sergio R.; Mathis, Jeremy T.; Feely, Richard A.; Sutton, Adrienne J.; Sabine, Christopher; Musielewicz, Sylvia; Chen, Baoshan; Wanninkhof, Rik

2017-08-01

Marine carbonate system monitoring programs often consist of multiple observational methods that include underway cruise data, moored autonomous time series, and discrete water bottle samples. Monitored parameters include all, or some of the following: partial pressure of CO2 of the water (pCO2w) and air, dissolved inorganic carbon (DIC), total alkalinity (TA), and pH. Any combination of at least two of the aforementioned parameters can be used to calculate the others. In this study at the Gray's Reef (GR) mooring in the South Atlantic Bight (SAB) we: examine the internal consistency of pCO2w from underway cruise, moored autonomous time series, and calculated from bottle samples (DIC-TA pairing); describe the seasonal to interannual pCO2w time series variability and air-sea flux (FCO2), as well as describe the potential sources of pCO2w variability; and determine the source/sink for atmospheric pCO2. Over the 8.5 years of GR mooring time series, mooring-underway and mooring-bottle calculated-pCO2w strongly correlate with r-values > 0.90. pCO2w and FCO2 time series follow seasonal thermal patterns; however, seasonal non-thermal processes, such as terrestrial export, net biological production, and air-sea exchange also influence variability. The linear slope of time series pCO2w increases by 5.2 ± 1.4 μatm y-1 with FCO2 increasing 51-70 mmol m-2 y-1. The net FCO2 sign can switch interannually with the magnitude varying greatly. Non-thermal pCO2w is also increasing over the time series, likely indicating that terrestrial export and net biological processes drive the long term pCO2w increase.

Pressure signatures can influence tissue response for individuals supported on an alternating pressure mattress.

PubMed

Chai, C Y; Sadou, O; Worsley, P R; Bader, D L

2017-08-01

Prolonged mechanical loading can lead to the breakdown of skin and underlying tissues which can, in turn, develop into a pressure ulcer. The benefits of pressure relief and/or redistribution to minimise risk have been well documented. Manufacturers have developed alternating air pressure mattresses (APAMs) to provide periodic relief for individuals on prolonged bed-rest. The present study describes the development of a control system, termed Pneumatic Manager which can vary the signature of an APAM, namely its pressure amplitude, cell profile and cycle period. An experimental array was designed to investigate the effects of varying these parameters, particularly with respect to its ability to maintain skin viability in a group of five healthy volunteers lying in a supine position. Transcutaneous gas (T c PO 2 /T c PCO 2 ) tensions at the sacrum were monitored. In addition, pressures and microclimate parameters at the loaded support interface were also measured. In the majority of test conditions the alternating support produced sacral T c PO 2 values, which either remained relatively high or fluctuated in concert with cycle period providing adequate viability. However, in 46% of cases at the extreme pressure amplitude of 100/0 mmHg, there was compromise to the skin viability at the sacrum, as reflected in depressed T c PO 2 levels associated with an elevation of T c PCO 2 levels above the normal range. In all cases, both the humidity and temperature levels increased during the test period. It is interesting to note that interface pressures at the sacrum rarely exceeded 60 mmHg. Although such studies need to be extended to involve bed-bound individuals, the results provide a design template for the optimum pressure signatures of APAM systems to ensure maintenance of skin viability during pronged loading. Copyright © 2017 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.

Hyperventilation and blood acid-base balance in hypercapnia exposed red drum (Sciaenops ocellatus).

PubMed

Ern, Rasmus; Esbaugh, Andrew J

2016-05-01

Hyperventilation is a common response in fish exposed to elevated water CO2. It is believed to lessen the respiratory acidosis associated with hypercapnia by lowering arterial PCO2, but the contribution of hyperventilation to blood acid-base compensation has yet to be quantified. Hyperventilation may also increase the flux of irons across the gill epithelium and the cost of osmoregulation, owing to the osmo-respiratory compromise. Therefore, hypercapnia exposed fish may increase standard metabolic rate (SMR) leaving less energy for physiological functions such as foraging, migration, growth and reproduction. Here we show that gill ventilation, blood PCO2 and total blood [CO2] increased in red drum (Sciaenops ocellatus) exposed to 1000 and 5000 µatm water CO2, and that blood PCO2 and total blood [CO2] decrease in fish during hypoxia induced hyperventilation. Based on these results we estimate the ventilatory contributions to total acid-base compensation in 1000 and 5000 µatm water CO2. We find that S. ocellatus only utilize a portion of its ventilatory capacity to reduce the acid-base disturbance in 1000 µatm water CO2. SMR was unaffected by both salinity and hypercapnia exposure indicating that the cost of osmoregulation is small relative to SMR, and that the lack of increased ventilation in 1000 µatm water CO2 despite the capacity to do so is not due to an energetic tradeoff between acid-base balance and osmoregulation. Therefore, while ocean acidification may impact ventilatory parameters, there will be little impact on the overall energy budget of S. ocellatus.

Ocean acidification and fertilization in the antarctic sea urchin Sterechinus neumayeri: the importance of polyspermy.

PubMed

Sewell, Mary A; Millar, Russell B; Yu, Pauline C; Kapsenberg, Lydia; Hofmann, Gretchen E

2014-01-01

Ocean acidification (OA), the reduction of the seawater pH as a result of increasing levels of atmospheric CO2, is an important climate change stressor in the Southern Ocean and Antarctic. We examined the impact of OA on fertilization success in the Antarctic sea urchin Sterechinus neumayeri using pH treatment conditions reflective of the current and near-future "pH seascape" for this species: current (control: pH 8.052, 384.1 μatm of pCO2), a high CO2 treatment approximating the 0.2-0.3 unit decrease in pH predicted for 2100 (high CO2: pH 7.830, 666.0 μatm of pCO2), and an intermediate medium CO2 (pH 7.967, 473.4 μatm of pCO2). Using a fertilization kinetics approach and mixed-effect models, we observed significant variation in the OA response between individual male/female pairs (N = 7) and a significant population-level increase (70-100%) in tb (time for a complete block to polyspermy) at medium and high CO2, a mechanism that potentially explains the higher levels of abnormal development seen in OA conditions. However, two pairs showed higher fertilization success with CO2 treatment and a nonsignificant effect. Future studies should focus on the mechanisms and levels of interindividual variability in OA response, so that we can consider the potential for selection and adaptation of organisms to a future ocean.

PCO(2) in the large intestine of mice, rats, guinea pigs, and dogs and effects of the dietary substrate.

PubMed

Rasmussen, Henrik; Mirtaheri, Peyman; Dirven, Hubert; Johnsen, Helge; Kvarstein, Gunnvald; Tønnessen, Tor Inge; Midtvedt, Tore

2002-01-01

PCO(2) in the lumen and serosa of cecum and colon was measured in rats, guinea pigs, and dogs to examine the relationship between serosal PCO(2) and the incidence of intestinal necrotic lesions after administration of gas-carrier contrast agents in rodents. The effects of the dietary substrate were tested in a group of mice maintained on a diet based on glucose as the only carbohydrate source. The anesthetic used was a fentanyl-fluanison-midazolam mixture (rodents) and pentobarbital (dogs). PCO(2) was measured in vivo and postmortem, and the kinetics of the postmortem serosal PCO(2) [transmural CO(2) flux (J(CO(2)))] was calculated. PCO(2) in the cecal serosa and lumen, respectively, was 64 +/- 4 and 392 +/- 18 Torr in rats, 67 +/- 3 and 276 +/- 17 Torr in guinea pigs, and 73 +/- 6 and 137 +/- 7 Torr in mice on glucose-based diet. In the colon serosa and lumen of dogs, PCO(2) was 30 +/- 6 and 523 +/- 67 Torr, respectively. Serosal PCO(2) increased rapidly after death in rats and slower in guinea pigs and mice, and the slowest change was observed in dogs. Compared with dogs, serosal PCO(2) and J(CO(2)) of rats and guinea pigs were significantly higher. Serosal PCO(2) of guinea pigs was similar to that of rats, whereas the J(CO(2)) of guinea pigs was significantly lower. These data suggest a causal relationship between the ability of the cecal and colonic wall to act as a barrier to CO(2) diffusion and the presence of characteristic gas-carrier contrast agent-induced intestinal lesions in mice and rats and their absence in guinea pigs, dogs, and other species.

Species interactions can shift the response of a maerl bed community to ocean acidification and warming

NASA Astrophysics Data System (ADS)

Legrand, Erwann; Riera, Pascal; Lutier, Mathieu; Coudret, Jérôme; Grall, Jacques; Martin, Sophie

2017-11-01

Predicted ocean acidification and warming are likely to have major implications for marine organisms, especially marine calcifiers. However, little information is available on the response of marine benthic communities as a whole to predicted changes. Here, we experimentally examined the combined effects of temperature and partial pressure of carbon dioxide (pCO2) increases on the response of maerl bed assemblages, composed of living and dead thalli of the free-living coralline alga Lithothamnion corallioides, epiphytic fleshy algae, and grazer species. Two 3-month experiments were performed in the winter and summer seasons in mesocosms with four different combinations of pCO2 (ambient and high pCO2) and temperature (ambient and +3 °C). The response of maerl assemblages was assessed using metabolic measurements at the species and assemblage scales. This study suggests that seasonal variability represents an important driver influencing the magnitude and the direction of species and community response to climate change. Gross primary production and respiration of assemblages was enhanced by high pCO2 conditions in the summer. This positive effect was attributed to the increase in epiphyte biomass, which benefited from higher CO2 concentrations for growth and primary production. Conversely, high pCO2 drastically decreased the calcification rates in assemblages. This response can be attributed to the decline in calcification rates of living L. corallioides due to acidification and increased dissolution of dead L. corallioides. Future changes in pCO2 and temperature are likely to promote the development of non-calcifying algae to the detriment of the engineer species L. corallioides. The development of fleshy algae may be modulated by the ability of grazers to regulate epiphyte growth. However, our results suggest that predicted changes will negatively affect the metabolism of grazers and potentially their ability to control epiphyte abundance. We show here that the effects of pCO2 and temperature on maerl bed communities were weakened when these factors were combined. This underlines the importance of examining multi-factorial approaches and community-level processes, which integrate species interactions, to better understand the impact of global change on marine ecosystems.

Prevention of posterior capsular opacification through cyclooxygenase-2 inhibition

PubMed Central

Barden, Curtis A; Lu, Ping; Kusewitt, Donna F.; Colitz, Carmen M. H.

2007-01-01

Purpose To determine if cyclooxygenase-2 (COX-2) is upregulated when lens epithelial cells (LEC) in clinical samples of cataracts and posterior capsule opacification (PCO) undergo epithelial-mesenchymal transition (EMT)-like changes. We also wanted to learn if inhibition of the enzymatic activity of COX-2 could prevent PCO formation. Methods To ensure that EMT-like changes were occurring in LEC, real-time RT-PCR was used to examine expression of EMT markers. Clinical samples of canine cataracts and PCO were examined for COX-2 expression using immunohistochemistry, western blot analysis, and real-time RT-PCR. The COX-2 inhibitors, rofecoxib and celecoxib, were used in an ex vivo model of PCO formation, and the effects on cellular migration, proliferation, and apoptosis were analyzed using immunohistochemistry and western blots. Prostaglandin E2 (PGE2) expression was examined with ELISA. Results Markers of EMT, such as lumican, Snail, Slug, and COX-2 were expressed in LEC. In clinical samples of cataracts and PCO, there was overexpression of COX-2 protein and mRNA. Both rofecoxib and celecoxib were effective at inhibiting PCO formation in our ex vivo model. Prevention of PCO with the COX-2 inhibitors appeared to work through decreased migration and proliferation, and increased apoptosis. Neither of the drugs had a toxic effect on confluent LEC and appeared to inhibit PCO through their pharmacologic action. Synthesis of PGE2 was inhibiting in the capsules treated with the COX-2 inhibiting drugs. Conclusions Extracapsular phacoemulsification cataract surgery is the most common surgical procedure performed in human and veterinary ophthalmology. The most frequent postoperative complication is PCO. The LEC that remain adhered to the lens capsule undergo EMT-like changes, proliferate, and migrate across the posterior lens capsule causing opacities. We have shown that COX-2, a protein associated with EMT, is upregulated in canine cataracts and PCO. Inhibiting the enzymatic activity effectively prevented EMT of LEC in our ex vivo model of PCO through pharmacologic action, and not acute toxicity. These findings indicate that using COX-2 inhibitors in vivo may be an effective technique in preventing PCO. PMID:17563718

Impact of ocean acidification on the early development and escape behavior of marine medaka (Oryzias melastigma).

PubMed

Wang, Xiaojie; Song, Lulu; Chen, Yi; Ran, Haoyu; Song, Jiakun

2017-10-01

Ocean acidification is predicted to affect a wide diversity of marine organisms. However, no studies have reported the effects of ocean acidification on Indian Ocean fish. We have used the Indian Ocean medaka (Oryzias melastigma) as a model species for a marine fish that lives in coastal waters. We investigated the impact of ocean acidification on the embryonic development and the stereotyped escape behavior (mediated by the Mauthner cell) in newly hatched larvae. Newly fertilized eggs of medaka were reared in seawater at three different partial pressures of carbon dioxide (pCO 2 ): control at 450 μatm, moderate at 1160 μatm, and high at 1783 μatm. Hatch rates, embryonic duration, and larval malformation rates were compared and were not significantly different between the treatments and the control. In the high pCO 2 group, however, the yolks of larvae were significantly smaller than in the control group, and the newly hatched larvae were significantly longer than the larvae in the control. In the moderate pCO 2 group, the eye distance decreased significantly. No significantly negative growth effects were observed in the larvae when exposed to pCO 2 levels that are predicted as a result of ocean acidification in the next 100-200 years. Larvae reared under control conditions readily produced C-start escape behavior to mechanosensory stimuli; however, in the moderate and high pCO 2 experimental groups, the probabilities of C-start were significantly lower than those of the control group. Therefore, the sensory integration needed for the C-start escape behavior appears to be vulnerable to ocean acidification. Altered behavior in marine larval fish, particularly behaviors involved in escape from predation, could have potentially negative implications to fish populations, and, further, to the marine ecosystems at the levels of CO 2 projected for the future. Copyright © 2017 Elsevier Ltd. All rights reserved.

21 CFR 862.1120 - Blood gases (PCO2, PO2) and blood pH test system.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Blood gases (PCO2, PO2) and blood pH test system... Test Systems § 862.1120 Blood gases (PCO2, PO2) and blood pH test system. (a) Identification. A blood gases (PCO2, PO2) and blood pH test system is a device intended to measure certain gases in blood, serum...

Global sea-air CO 2 flux based on climatological surface ocean pCO 2, and seasonal biological and temperature effects

NASA Astrophysics Data System (ADS)

Takahashi, Taro; Sutherland, Stewart C.; Sweeney, Colm; Poisson, Alain; Metzl, Nicolas; Tilbrook, Bronte; Bates, Nicolas; Wanninkhof, Rik; Feely, Richard A.; Sabine, Christopher; Olafsson, Jon; Nojiri, Yukihiro

Based on about 940,000 measurements of surface-water pCO 2 obtained since the International Geophysical Year of 1956-59, the climatological, monthly distribution of pCO 2 in the global surface waters representing mean non-El Niño conditions has been obtained with a spatial resolution of 4°×5° for a reference year 1995. The monthly and annual net sea-air CO 2 flux has been computed using the NCEP/NCAR 41-year mean monthly wind speeds. An annual net uptake flux of CO 2 by the global oceans has been estimated to be 2.2 (+22% or -19%) Pg C yr -1 using the (wind speed) 2 dependence of the CO 2 gas transfer velocity of Wanninkhof (J. Geophys. Res. 97 (1992) 7373). The errors associated with the wind-speed variation have been estimated using one standard deviation (about±2 m s -1) from the mean monthly wind speed observed over each 4°×5° pixel area of the global oceans. The new global uptake flux obtained with the Wanninkhof (wind speed) 2 dependence is compared with those obtained previously using a smaller number of measurements, about 250,000 and 550,000, respectively, and are found to be consistent within±0.2 Pg C yr -1. This estimate for the global ocean uptake flux is consistent with the values of 2.0±0.6 Pg C yr -1 estimated on the basis of the observed changes in the atmospheric CO 2 and oxygen concentrations during the 1990s (Nature 381 (1996) 218; Science 287 (2000) 2467). However, if the (wind speed) 3 dependence of Wanninkhof and McGillis (Res. Lett. 26 (1999) 1889) is used instead, the annual ocean uptake as well as the sensitivity to wind-speed variability is increased by about 70%. A zone between 40° and 60° latitudes in both the northern and southern hemispheres is found to be a major sink for atmospheric CO 2. In these areas, poleward-flowing warm waters meet and mix with the cold subpolar waters rich in nutrients. The pCO 2 in the surface water is decreased by the cooling effect on warm waters and by the biological drawdown of pCO 2 in subpolar waters. High wind speeds over these low pCO 2 waters increase the CO 2 uptake rate by the ocean waters. The pCO 2 in surface waters of the global oceans varies seasonally over a wide range of about 60% above and below the current atmospheric pCO 2 level of about 360 μatm. A global map showing the seasonal amplitude of surface-water pCO 2 is presented. The effect of biological utilization of CO 2 is differentiated from that of seasonal temperature changes using seasonal temperature data. The seasonal amplitude of surface-water pCO 2 in high-latitude waters located poleward of about 40° latitude and in the equatorial zone is dominated by the biology effect, whereas that in the temperate gyre regions is dominated by the temperature effect. These effects are about 6 months out of phase. Accordingly, along the boundaries between these two regimes, they tend to cancel each other, forming a zone of small pCO 2 amplitude. In the oligotrophic waters of the northern and southern temperate gyres, the biology effect is about 35 μatm on average. This is consistent with the biological export flux estimated by Laws et al. (Glob. Biogeochem. Cycles 14 (2000) 1231). Small areas such as the northwestern Arabian Sea and the eastern equatorial Pacific, where seasonal upwelling occurs, exhibit intense seasonal changes in pCO 2 due to the biological drawdown of CO 2.

Dependence on glucose limitation of the pCO2 influences on CHO cell growth, metabolism and IgG production.

PubMed

Takuma, Shinya; Hirashima, Chikashi; Piret, James M

2007-08-15

The culture levels of glucose and CO(2) have been reported to independently have important influences on mammalian cell processes. In this work the combined effects of glucose limitation and CO(2) partial pressure (pCO(2)) on monoclonal antibody (IgG) producing Chinese Hamster Ovary cells were investigated in a perfusion reactor operated with controlled cell specific medium feed rate, pH and osmolality. Under high glucose conditions (14.3 +/- 0.8 mM), the apparent growth rate decreased (from 0.021 to 0.009 h(-1)) as the pCO(2) increased to approximately 220 mmHg, while the cell specific IgG productivity was almost unchanged. The lactate yield from glucose was not affected by pCO(2) up to approximately 220 mmHg and glucose was mainly converted to lactate. A feed medium modification from high (33 mM) to low (6 mM) glucose resulted in <0.1 mM glucose in the culture. As a result of apparently shifting metabolism towards the conversion of pyruvate to CO(2), both the ratio of lactate to glucose and the alanine production rate were lowered (1.51-1.14 and 17.7-0.56 nmol/10(6) cells h, respectively). Interestingly, when the pCO(2) was increased to approximately 140 mmHg, limiting glucose resulted in 1.7-fold higher growth rates, compared to high glucose conditions. However, at approximately 220 mmHg pCO(2) this beneficial effect of glucose limitation on these CHO cells was lost as the growth rate dropped dramatically to 0.008 h(-1) and the IgG productivity was lowered by 15% (P < 0.01) relative to the high glucose condition. The IgG galactosylation increased under glucose- limited compared to high-glucose conditions. (c) 2007 Wiley Periodicals, Inc.

Carbon dioxide partial pressure and 13C content of north temperate and boreal lakes at spring ice melt

USGS Publications Warehouse

Striegl, Robert G.; Kortelainen, Pirkko; Chanton, J.P.; Wickland, K.P.; Bugna, G.C.; Rantakari, M.

2001-01-01

Carbon dioxide (CO2) accumulates under lake ice in winter and degasses to the atmosphere after ice melt. This large springtime CO2 pulse is not typically considered in surface-atmosphere flux estimates, because most field studies have not sampled through ice during late winter. Measured CO2 partial pressure (pCO2) of lake surface water ranged from 8.6 to 4,290 Pa (85-4,230 ??atm) in 234 north temperate and boreal lakes prior to ice melt during 1998 and 1999. Only four lakes had surface pCO2 less than or equal to atmospheric pCO2, whereas 75% had pCO2 >5 times atmospheric. The ??13CDIC (DIC = ??CO2) of 142 of the lakes ranged from -26.28??? to +0.95.???. Lakes with the greatest pCO2 also had the lightest ??13CDIC, which indicates respiration as their primary CO2 source. Finnish lakes that received large amounts of dissolved organic carbon from surrounding peatlands had the greatest pCO2. Lakes set in noncarbonate till and bedrock in Minnesota and Wisconsin had the smallest pCO2 and the heaviest ??13CDIC, which indicates atmospheric and/or mineral sources of C for those lakes. Potential emissions for the period after ice melt were 2.36 ?? 1.44 mol CO2 m-2 for lakes with average pCO2 values and were as large as 13.7 ?? 8.4 mol CO2 m-2 for lakes with high pCO2 values.

Transgenerational exposure of North Atlantic bivalves to ocean acidification renders offspring more vulnerable to low pH and additional stressors.

PubMed

Griffith, Andrew W; Gobler, Christopher J

2017-09-12

While early life-stage marine bivalves are vulnerable to ocean acidification, effects over successive generations are poorly characterized. The objective of this work was to assess the transgenerational effects of ocean acidification on two species of North Atlantic bivalve shellfish, Mercenaria mercenaria and Argopecten irradians. Adults of both species were subjected to high and low pCO 2 conditions during gametogenesis. Resultant larvae were exposed to low and ambient pH conditions in addition to multiple, additional stressors including thermal stress, food-limitation, and exposure to a harmful alga. There were no indications of transgenerational acclimation to ocean acidification during experiments. Offspring of elevated pCO 2 -treatment adults were significantly more vulnerable to acidification as well as the additional stressors. Our results suggest that clams and scallops are unlikely to acclimate to ocean acidification over short time scales and that as coastal oceans continue to acidify, negative effects on these populations may become compounded and more severe.

Physiological responses to ocean acidification and warming synergistically reduce condition of the common cockle Cerastoderma edule.

PubMed

Ong, E Z; Briffa, M; Moens, T; Van Colen, C

2017-09-01

The combined effect of ocean acidification and warming on the common cockle Cerastoderma edule was investigated in a fully crossed laboratory experiment. Survival of the examined adult organisms remained high and was not affected by elevated temperature (+3 °C) or lowered pH (-0.3 units). However, the morphometric condition index of the cockles incubated under high pCO 2 conditions (i.e. combined warming and acidification) was significantly reduced after six weeks of incubation. Respiration rates increased significantly under low pH, with highest rates measured under combined warm and low pH conditions. Calcification decreased significantly under low pH while clearance rates increased significantly under warm conditions and were generally lower in low pH treatments. The observed physiological responses suggest that the reduced food intake under hypercapnia is insufficient to support the higher energy requirements to compensate for the higher costs for basal maintenance and growth in future high pCO 2 waters. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ocean acidification at high latitudes: potential effects on functioning of the Antarctic bivalve Laternula elliptica.

PubMed

Cummings, Vonda; Hewitt, Judi; Van Rooyen, Anthony; Currie, Kim; Beard, Samuel; Thrush, Simon; Norkko, Joanna; Barr, Neill; Heath, Philip; Halliday, N Jane; Sedcole, Richard; Gomez, Antony; McGraw, Christina; Metcalf, Victoria

2011-01-05

Ocean acidification is a well recognised threat to marine ecosystems. High latitude regions are predicted to be particularly affected due to cold waters and naturally low carbonate saturation levels. This is of concern for organisms utilising calcium carbonate (CaCO(3)) to generate shells or skeletons. Studies of potential effects of future levels of pCO(2) on high latitude calcifiers are at present limited, and there is little understanding of their potential to acclimate to these changes. We describe a laboratory experiment to compare physiological and metabolic responses of a key benthic bivalve, Laternula elliptica, at pCO(2) levels of their natural environment (430 µatm, pH 7.99; based on field measurements) with those predicted for 2100 (735 µatm, pH 7.78) and glacial levels (187 µatm, pH 8.32). Adult L. elliptica basal metabolism (oxygen consumption rates) and heat shock protein HSP70 gene expression levels increased in response both to lowering and elevation of pH. Expression of chitin synthase (CHS), a key enzyme involved in synthesis of bivalve shells, was significantly up-regulated in individuals at pH 7.78, indicating L. elliptica were working harder to calcify in seawater undersaturated in aragonite (Ω(Ar) = 0.71), the CaCO(3) polymorph of which their shells are comprised. The different response variables were influenced by pH in differing ways, highlighting the importance of assessing a variety of factors to determine the likely impact of pH change. In combination, the results indicate a negative effect of ocean acidification on whole-organism functioning of L. elliptica over relatively short terms (weeks-months) that may be energetically difficult to maintain over longer time periods. Importantly, however, the observed changes in L. elliptica CHS gene expression provides evidence for biological control over the shell formation process, which may enable some degree of adaptation or acclimation to future ocean acidification scenarios.

Lack of agreement between tonometric and gastric juice partial carbon dioxide tension

PubMed Central

Dubin, Arnaldo; Badie, Julio; Fernandez, Sofía; Estenssoro, Elisa; Canales, Héctor; Bordoli, Guillermo; Pálizas, Fernando

2000-01-01

Introduction: In recent years there has been growing interest in tonometric estimation of gastric intramucosal pH (pHi). More recently, attention has focused on the gradient between intraluminal and arterial PCO2. pHi appears to be a useful diagnostic and prognostic tool in critically ill patients, and may also be used as a therapeutic guide. However, intraluminal PCO2 is the parameter measured to calculate pHi, and it is assumed as equivalent to the PCO2 of the upper layers of the gastric mucosa. Direct measurement of PCO2 in gastric juice might offer advantages over tonometry. Tonometer costs could be saved, and equilibration time would no longer be necessary. Additionally, preanalytic factors that account for poor reproducibility, such as inadequate volume of saline in the tonometer, errors in the dwell time of the sample or in the technique used to aspirate saline, mixing of the sample with tonometer dead space and delay in analysis, could be prevented. Nevertheless, to our knowledge few experimental or clinical studies have examined PCO2 in gastric juice. Moreover, no comparison with simultaneous tonometric samples has been performed. Our goal was to compare simultaneous measurement of PCO2 in gastric juice and in saline samples from a tonometer. Data from the present study show that gastric juice PCO2 is systematically higher. Furthermore, differences widen at high PCO2 values, and data dispersion becomes even more striking. Therefore, tonometric PCO2 and gastric juice PCO2 are not interchangeable. Patients and methods: The present study was approved by the local ethics committee, and informed consent was obtained from the next of kin of each patient. We studied 15 consecutive mechanically ventilated patients from a medical/surgical intensive care unit, in whom tonometric monitoring was indicated by attending physicians. All patients were receiving 50 mg intravenous ranitidine every 8 h. Gastric tonometers were filled with saline, which was extracted after 90 min of equilibration time. At the same time, gastric juice was anaerobically extracted from the aspiration port of the tonometer. The initial 20 ml was discarded. PCO2 in both samples was measured using a blood gas analyzer (AVL 945; AVL List GMBH, Gratz, Austria). These measurements were taken at various time points in each patient, and under various haemodynamic and oxygen transport conditions, All measurements were performed with the patient fasted. Correlation between the two measurements was examined using the Bland-Altman technique. We also performed an in vitro study to quantify the precision and bias for the AVL 945. For this purpose, a stable PCO2 in saline solution was achieved by bubbling 5% carbon dioxide calibration gas. Results: We performed 112 pairs of measurements in 15 patients. Table 1 shows clinical data and the first values of arterial, tonometered and gastric juice PCO2 for each patient. Regression analysis demonstrated a significant correlation between both methods of measuring PCO2 (r 2 =0.43; gastric juice PCO2 = -28.79 + [2.55 × tonometric PCO2]; P < 0.0001; Fig. 1). However, the bias calculated as the mean difference of gastric juice and tonometric PCO2 was 51 mmHg. The 95% limits of agreement were 315 mmHg (Fig. 2). For mean PCO2 values lesser than 100 mmHg, the bias and the 95% limits of agreement were 19 and 102 mmHg, respectively. As mean PCO2 increased, the scattering of differences widened (r 2 =0.71; P < 0.0001). In an effort to prevent the bias related to multiple measurements per patient, we performed Bland-Altman analysis with the first measurement of each patient. After this the results remained similar (bias 55 mmHg, 95% limits of agreement 216 mmHg). The AVL 945 blood gas analyzer showed a negative bias of 0.97 mmHg and a precision of 2.13 mmHg. This bias was considered negligible, so no further correction was made to saline tonometric values. Discussion: The results of the present study show that tonometric PCO2 and gastric juice PCO2 are not interchangeable. Gastric juice PCO2 is systematically higher. At high PCO2 values the differences widen, and data dispersion becomes even more marked. There is no clear cause for these observations. A possible explanation might be that tonometric PCO2 is generated over a time interval, whereas gastric juice PCO2 might reflect rapid changes in mucosal metabolism. Different equilibrium time could also account for data dispersion, but not for the positive bias for gastric juice. Rapid changes should occur in both directions. Another potential confounding factor is the ability of blood gas analyzers to measure PCO2 in gastric juice. Measurement of PCO2 in 0.9% saline is an important source of error in the estimation of pHi. Variation in PCO2 values may occur with different PCO2 equilibration solutions. For example, bias is -66.5% when the Nova Stat Profile 7 blood gas analyzer (Nova Biomedical, Waltham, MA, USA) measures concentration of 1.95% of CO2 equilibrated in normal saline. However, bias changes to +45.4% when 1.95% CO2 is equilibrated in human albumin solution 4.5%. It would not be surprising if gastric juice components such as proteins, mucopolisaccharides and others interfere with CO2 solubility and its subsequent measurement by blood gas analyzers. In this way, intersubject and intrasubject variation in gastric juice composition could also account for data dispersion. Fiddian-Green et al [1] measured PCO2 in gastric contents of anaesthetized dogs. They isolated the stomach from the oesophagus and the duodenum with ligatures, and washed it through a catheter with saline. Then, they instilled 250 ml 0.9% saline and took samples to measure PCO2 and to estimate pHi. Simultaneously, mucosa pH was recorded with a microglass probe. They found a statistically significant correlation between both methods. However, data dispersion in the graph was considerable. We were able to exclude analyzer underestimation of PCO2 in saline as the cause for the present results. In vitro performance of the AVL 945 in blood was good. It showed a negative bias less than 1 mmHg and a precision of about 2 mmHg. We cannot infer from the present data the technique that should be the gold standard for measuring PCO2 in gastric mucosa. However, the studies that have established the normal values for pHi, prognostic changes and its uses as a therapeutic index have been performed with tonometry. Hence, more data are needed for the routine measurement of PCO2 in gastric juice. Figure 1 Correlation between gastric juice and tonometric PCO2. We performed 112 pairs of measurements of gastric juice and tonometric PCO2 in 15 critical care patients under different haemodynamic and oxygen transport conditions. The linear regression coefficient is significant. However, the slope value indicates systematic overestimation of gastric juice PCO2 in relation to saline PCO2. Figure 2 Bland-Altman analysis of the differences between gastric juice and tonometric PCO2. The bias calculated as the mean difference of gastric juice and tonometric PCO2 was 51 mmHg. The 95% limits of agreement were 315 mmHg. The bias and the scattering of differences widened as PCO2 increased. Table 1 Clinical characteristics and first value of arterial, tonometer and gastric juice PCO2 PCO2 (mmHg) Age Inotropes Gastric Patient Sex (years) Diagnosis (μg/kg per min) Outcome Arterial Tonometric juice 1 Female 53 Stroke, ARDS Dopamine 32 Survival 30 48 165 2 Female 73 Intestinal obstruction, septic shock Dopamine 40 Death 26 44 92 3 Male 37 Multiple trauma Survival 21 28 41 4 Male 56 Multiple trauma Survival 39 42 49 5 Female 64 Acute pancreatitis, shock, ARDS Dopamine 18 Death 30 34 80 6 Male 17 Multiple trauma Survival 43 60 60 7 Female 18 Fat liver of pregnancy Survival 30 40 44 8 Male 73 Necrotizing celulitis, septic shock, ARDS Epinephrine 1.2 Death 28 33 31 9 Male 64 Multiple trauma, pneumonia, ARDS Death 36 41 57 10 Male 65 Lung cancer postoperatively, ARDS Death 35 51 242 11 Male 65 Lung cancer postoperatively, ARDS Dopamine 20 Death 36 30 125 12 Female 22 Neutropenia, septic shock, ARDS Epinephrine 0.8 Death 50 69 81 13 Male 83 Perioperative shock Dopamine 25 Survival 23 28 34 14 Male 52 Ventilator-associated pneumonia Survival 43 43 126 15 Male 56 Colangitis, septic shock Dopamine 36 Survival 38 44 92 ARDS, acute respiratory distress syndrome. PMID:11056754

Historical patterns of acidification and increasing CO2 flux associated with Florida springs

USGS Publications Warehouse

Barrera, Kira E.; Robbins, Lisa L.

2017-01-01

Florida has one of the highest concentrations of springs in the world, with many discharging into rivers and predominantly into eastern Gulf of Mexico coast, and they likely influence the hydrochemistry of these adjacent waters; however, temporal and spatial trends have not been well studied. We present over 20 yr of hydrochemical, seasonally sampled data to identify temporal and spatial trends of pH, alkalinity, partial pressure of carbon dioxide (pCO2), and CO2flux from five first-order-magnitude (springs that discharge greater than 2.83 m3 s−1) coastal spring groups fed by the Floridan Aquifer System that ultimately discharge into the Gulf of Mexico. All spring groups had pCO2 levels (averages 3174.3–6773.2 μatm) that were much higher than atmospheric levels of CO2 and demonstrated statistically significant temporal decreases in pH and increases in CO2 flux, pCO2, and alkalinity. Total carbon flux emissions increased from each of the spring groups by between 3.48 × 107 and 2.856 × 108 kg C yr−1 over the time period. By 2013 the Springs Groups in total emitted more than 1.1739 × 109 kg C yr−1. Increases in alkalinity and pCO2 varied from 90.9 to 347.6 μmol kg−1 and 1262.3 to 2666.7 μatm, respectively. Coastal data show higher CO2 evasion than the open Gulf of Mexico, which suggests spring water influences nearshore waters. The results of this study have important implications for spring water quality, dissolution of the Florida carbonate platform, and identification of the effect and partitioning of carbon fluxes to and within coastal and marine ecosystems.

Central Chemoreceptors: Locations and Functions

PubMed Central

Nattie, Eugene; Li, Aihua

2016-01-01

Central chemoreception traditionally refers to a change in ventilation attributable to changes in CO2/H+ detected within the brain. Interest in central chemoreception has grown substantially since the previous Handbook of Physiology published in 1986. Initially, central chemoreception was localized to areas on the ventral medullary surface, a hypothesis complemented by the recent identification of neurons with specific phenotypes near one of these areas as putative chemoreceptor cells. However, there is substantial evidence that many sites participate in central chemoreception some located at a distance from the ventral medulla. Functionally, central chemoreception, via the sensing of brain interstitial fluid H+, serves to detect and integrate information on 1) alveolar ventilation (arterial PCO2), 2) brain blood flow and metabolism and 3) acid-base balance, and, in response, can affect breathing, airway resistance, blood pressure (sympathetic tone) and arousal. In addition, central chemoreception provides a tonic ‘drive’ (source of excitation) at the normal, baseline PCO2 level that maintains a degree of functional connectivity among brainstem respiratory neurons necessary to produce eupneic breathing. Central chemoreception responds to small variations in PCO2 to regulate normal gas exchange and to large changes in PCO2 to minimize acid-base changes. Central chemoreceptor sites vary in function with sex and with development. From an evolutionary perspective, central chemoreception grew out of the demands posed by air vs. water breathing, homeothermy, sleep, optimization of the work of breathing with the ‘ideal’ arterial PCO2, and the maintenance of the appropriate pH at 37°C for optimal protein structure and function. PMID:23728974

Effects of ocean acidification with pCO2 diurnal fluctuations on survival and larval shell formation of Ezo abalone, Haliotis discus hannai.

PubMed

Onitsuka, Toshihiro; Takami, Hideki; Muraoka, Daisuke; Matsumoto, Yukio; Nakatsubo, Ayumi; Kimura, Ryo; Ono, Tsuneo; Nojiri, Yukihiro

2018-03-01

This study assessed the effects of constant and diurnally fluctuating pCO 2 on development and shell formation of larval abalone Haliotis discus hannai. The larvae was exposed to different pCO 2 conditions; constant [450, 800, or 1200 μatm in the first experiment (Exp. I), 450 or 780 μatm in the second experiment (Exp. II)] or diurnally fluctuating pCO 2 (800 ± 400 or 1200 ± 400 μatm in Exp. I, 450 ± 80, 780 ± 200 or 780 ± 400 μatm in Exp. II). Mortality, malformation rates or shell length of larval abalone were not significantly different among the 450, 800, and 800 ± 400 μatm pCO 2 treatments. Meanwhile, significantly higher malformation rates and smaller shells were detected in the 1200 and 1200 ± 400 μatm pCO 2 treatments than in the 450 μatm pCO 2 treatment. The negative impacts were greater in the 1200 ± 400 μatm than in the 1200 μatm. Shell length and malformation rate of larval abalone were related with aragonite saturation state (Ω-aragonite) in experimental seawater, and greatly changed around 1.1 of Ω-aragonite which corresponded to 1000-1300 μatm pCO 2 . These results indicate that there is a pCO 2 threshold associated with Ω-aragonite in the seawater, and that pCO 2 fluctuations produce additional negative impacts on abalone when above the threshold. Clear relationships were detected between abalone fitness and the integrated pCO 2 value over the threshold, indicating that the effects of OA on development and shell formation of larval abalone can be determined by intensity and time of exposure to pCO 2 over the threshold. Copyright © 2017 Elsevier Ltd. All rights reserved.

A comparison of four different blood gas analysers.

PubMed

Kofstad, J

1981-06-01

Four automatic blood gas analysers from four different manufactures were evaluated and compared. The measurements were performed on blood representing respiratory acidosis and hypoxemia, normal conditions, and respiratory alkalosis and hyperoxemia. On each level nine complete runs were carried out, each run consisting of six replicates of each parameter (pH, Pco2 and Po2) on each instrument (six rounds). Only the directly measured parameters (pH, Pco2, Po2) were compared. The main conclusion is that the four instruments can be used alternatively, and that the differences between the values measured by the four instruments are of little clinical significance.

Carbon dioxide induced plasticity of branchial acid-base pathways in an estuarine teleost

PubMed Central

Allmon, Elizabeth B.; Esbaugh, Andrew J.

2017-01-01

Anthropogenic CO2 is expected to drive ocean pCO2 above 1,000 μatm by 2100 – inducing respiratory acidosis in fish that must be corrected through branchial ion transport. This study examined the time course and plasticity of branchial metabolic compensation in response to varying levels of CO2 in an estuarine fish, the red drum, which regularly encounters elevated CO2 and may therefore have intrinsic resilience. Under control conditions fish exhibited net base excretion; however, CO2 exposure resulted in a dose dependent increase in acid excretion during the initial 2 h. This returned to baseline levels during the second 2 h interval for exposures up to 5,000 μatm, but remained elevated for exposures above 15,000 μatm. Plasticity was assessed via gene expression in three CO2 treatments: environmentally realistic 1,000 and 6,000 μatm exposures, and a proof-of-principle 30,000 μatm exposure. Few differences were observed at 1,000 or 6,000 μatm; however, 30,000 μatm stimulated widespread up-regulation. Translocation of V-type ATPase after 1 h of exposure to 30,000 μatm was also assessed; however, no evidence of translocation was found. These results indicate that red drum can quickly compensate to environmentally relevant acid-base disturbances using baseline cellular machinery, yet are capable of plasticity in response to extreme acid-base challenges. PMID:28378831

Carbon dioxide induced plasticity of branchial acid-base pathways in an estuarine teleost

NASA Astrophysics Data System (ADS)

Allmon, Elizabeth B.; Esbaugh, Andrew J.

2017-04-01

Anthropogenic CO2 is expected to drive ocean pCO2 above 1,000 μatm by 2100 - inducing respiratory acidosis in fish that must be corrected through branchial ion transport. This study examined the time course and plasticity of branchial metabolic compensation in response to varying levels of CO2 in an estuarine fish, the red drum, which regularly encounters elevated CO2 and may therefore have intrinsic resilience. Under control conditions fish exhibited net base excretion; however, CO2 exposure resulted in a dose dependent increase in acid excretion during the initial 2 h. This returned to baseline levels during the second 2 h interval for exposures up to 5,000 μatm, but remained elevated for exposures above 15,000 μatm. Plasticity was assessed via gene expression in three CO2 treatments: environmentally realistic 1,000 and 6,000 μatm exposures, and a proof-of-principle 30,000 μatm exposure. Few differences were observed at 1,000 or 6,000 μatm however, 30,000 μatm stimulated widespread up-regulation. Translocation of V-type ATPase after 1 h of exposure to 30,000 μatm was also assessed; however, no evidence of translocation was found. These results indicate that red drum can quickly compensate to environmentally relevant acid-base disturbances using baseline cellular machinery, yet are capable of plasticity in response to extreme acid-base challenges.

Evolutionary differences in Δ13C detected between spore and seed bearing plants following exposure to a range of atmospheric O2:CO2 ratios; implications for paleoatmosphere reconstruction

NASA Astrophysics Data System (ADS)

Porter, Amanda S.; Yiotis, Charilaos; Montañez, Isabel P.; McElwain, Jennifer C.

2017-09-01

The stable carbon isotopes of fossil plants are a reflection of the atmosphere and environment in which they grew. Fossil plant remains have thus stored information about the isotopic composition and concentration of atmospheric carbon dioxide (pCO2) and possibly pO2 through time. Studies to date, utilizing extant plants, have linked changes in plant stable carbon isotopes (δ13Cp) or carbon isotope discrimination (Δ13C) to changes in pCO2 and/or pO2. These studies have relied heavily on angiosperm representatives, a phylogenetic group only present in the fossil record post-Early Cretaceous (∼140 million years ago (mya)), whereas gymnosperms, monilophytes and lycophytes dominated terrestrial ecosystems prior to this time. The aim of this study was to expand our understanding of carbon isotope discrimination in all vascular plant groups of C3 plants including lycophytes, monilophytes, gymnosperms and angiosperms, under elevated CO2 and sub-ambient O2 to explore their utility as paleo-atmospheric proxies. To achieve this goal, plants were grown in controlled environment chambers under a range of O2:CO2 ratio treatments. Results reveal a strong phylogenetic dependency on Δ13C, where spore-bearing (lycophytes and monilophytes) have significantly higher 13C discrimination than seed plants (gymnosperms and angiosperms) by ∼5‰. We attribute this strong phylogenetic signal to differences in Ci/Ca likely mediated by fundamental differences in how spore and seed bearing plants control stomatal aperture. Decreasing O2:CO2 ratio in general resulted in increased carbon isotope discrimination in all plant groups. Notably, while all plant groups respond unidirectionally to elevated atmospheric CO2 (1900 ppm and ambient O2), they do not respond equally to sub-ambient O2 (16%). We conclude that (1) Δ13C has a strong phylogenetic or 'reproductive grade' bias, whereby Δ13C of spore reproducing plants is significantly different to seed reproducing taxa. (2) Δ13C increases with decreasing O2:CO2 ratios (where significant) but is more likely a result of mechanistically uncoupled responses to elevated pCO2 and sub-ambient O2; and (3) due to this response we find δ13Ca cannot be calculated from δ13Cp unless environmental influences such as O2:CO2 ratio can be independently constrained. Therefore, interpretations of trends in fossil plant δ13Cp to reconstruct paleoatmospheric CO2 concentration should include cross calibration based on a nearest living relative, appropriate nearest living equivalent, or utilizing the phylogenetic corrections produced from this study.

Effects of elevated carbon dioxide (CO2) concentrations on early developmental stages of the marine copepod Calanus finmarchicus Gunnerus (Copepoda: Calanoidae).

PubMed

Pedersen, Sindre Andre; Våge, Vegard Thorset; Olsen, Anders Johny; Hammer, Karen Marie; Altin, Dag

2014-01-01

Ocean acidification poses an ongoing threat to marine organisms, and early life stages are believed to be particularly sensitive. The boreal calanoid copepod Calanus finmarchicus seasonally dominates the standing stock of zooplankton in the northern North Sea and North Atlantic, and due to its size and abundance is considered an ecological key species linking energy from primary producers to higher trophic levels. To examine whether the early stages of C. finmarchicus are particularly vulnerable to elevated levels of CO2, eggs and nauplii were subjected to different levels of CO2-acidified seawater for 1 wk. The first experiment, with eggs as the starting point, revealed no marked effect on hatching success, but a significant reduction in nauplii survival during incubation at 8800 ppm CO2. In addition, a significant decrease in ontogenetic development rate during incubation at 8800 ppm CO2 was observed in this experiment. In the second experiment, where third-stage nauplii represented the starting point, no significant effects on ontogenetic development and survival following exposure to pCO2 ≥ 7700 ppm were observed. Data suggest that the two first nauplii stages, which are fed endogenously, may be more vulnerable and therefore likely to represent the "bottleneck" for this species in a more acidic ocean. However, the absence of significant effects in the most sensitive stages during exposure to 2800 ppm CO2, a level that is well above worst-case scenario predictions for year 2300 (approximately 2000 ppm CO2), suggests that this species may be generally robust to direct effects of ocean acidification.

pCO2 and CO2 Exchange During High Bora Winds in the Northern Adriatic

DTIC Science & Technology

2013-03-05

coastal ocean , has not been adequately assessed. Here we show the response of surfacewater pCO2 and CO2 fluxes during high borawind in the Northern...m−2 day−1 day in thewinter cases and 29 mmol m−2 day−1 in the summer case) over themag- nitude of the mean annual value. Oceanic data measured...simultaneously to surface pCO2 measurements suggest that themost likely responsiblemechanisms for the observed pCO2 increaseswere oceanic verticalmixing and

Cardiorespiratory responses of the facultative air-breathing fish jeju, Hoplerythrinus unitaeniatus (Teleostei, Erythrinidae), exposed to graded ambient hypoxia.

PubMed

Oliveira, R D; Lopes, J M; Sanches, J R; Kalinin, A L; Glass, M L; Rantin, F T

2004-12-01

The jeju, Hoplerythrinus unitaeniatus, is equipped with a modified part of the swim bladder that allows aerial respiration. On this background, we have evaluated its respiratory and cardiovascular responses to aquatic hypoxia. Its aquatic O2 uptake (V(O2)) was maintained constant down to a critical P(O2) (P(cO2)) of 40 mm Hg, below which V(O2) declined linearly with further reductions of P(iO2). Just below P(cO2), the ventilatory tidal volume (V(T)) increased significantly along with gill ventilation (V(G)), while respiratory frequency changed little. Consequently, water convection requirement (V(G)/V(O2)) increased steeply. The same threshold applied to cardiovascular responses that included reflex bradycardia and elevated arterial blood pressure (P(a)). Aerial respiration was initiated at water P(O2) of 44 mm Hg and breathing episodes and time at the surface increased linearly with more severe hypoxia. At the lowest water P(O2) (20 mm Hg), the time spent at the surface accounted for 50% of total time. This response has a character of a temporary emergency behavior that may allow the animal to escape hypoxia.

Effects of Hypoxia and Hypercapnic Hypoxia on Oxygen Transport and Acid-Base Status in the Atlantic Blue Crab, Callinectes sapidus, During Exercise.

PubMed

Lehtonen, Mark P; Burnett, Louis E

2016-11-01

The responses of estuarine invertebrates to hypoxic conditions are well established. However, many studies have investigated hypoxia as an isolated condition despite its frequent co-occurrence with hypercapnia (elevated CO 2 ). Although many studies suggest deleterious effects, hypercapnia has been observed to improve blue crab walking performance in hypoxia. To investigate the physiological effects of combined hypercapnic hypoxia, we measured Po 2 , pH, [l-lactate], Pco 2 , and total O 2 in pre- and postbranchial hemolymph sampled from blue crabs during walking exercise. Crabs walked at 8 m min -1 on an aquatic treadmill in normoxic (100% air saturation), moderately hypoxic (50%), and severely hypoxic (20%) seawater with and without the addition of hypercapnia (about 2% CO 2 ). Respiration was almost completely aerobic in normoxic conditions, with little buildup of lactate. During exercise under severe hypoxia, lactate increased from 1.4 to 11.0 mM, indicating a heavy reliance on anaerobic respiration. The O 2 saturation of arterial hemocyanin was 47% in severe hypoxia after 120 min, significantly lower than in normoxia (80%). However, the addition of hypercapnia significantly increased the percentage saturation of arterial hemocyanin in severe hypoxia to 92% after 120 min of exercise, equivalent to normoxic levels. Hypercapnia in severe hypoxia also caused a marked increase in hemolymph Pco 2 (around 1.1 kPa), but caused only a minor decrease in pH of 0.1 units. We suggest that the improved O 2 saturation at the gills results from a specific effect of molecular CO 2 on hemocyanin oxygen binding affinity, which works independently of and counter to the effects of decreased pH. © 2016 Wiley Periodicals, Inc.

Symbiosis increases coral tolerance to ocean acidification

NASA Astrophysics Data System (ADS)

Ohki, S.; Irie, T.; Inoue, M.; Shinmen, K.; Kawahata, H.; Nakamura, T.; Kato, A.; Nojiri, Y.; Suzuki, A.; Sakai, K.; van Woesik, R.

2013-04-01

Increasing the acidity of ocean waters will directly threaten calcifying marine organisms such as reef-building scleractinian corals, and the myriad of species that rely on corals for protection and sustenance. Ocean pH has already decreased by around 0.1 pH units since the beginning of the industrial revolution, and is expected to decrease by another 0.2-0.4 pH units by 2100. This study mimicked the pre-industrial, present, and near-future levels of pCO2 using a precise control system (±5% pCO2), to assess the impact of ocean acidification on the calcification of recently-settled primary polyps of Acropora digitifera, both with and without symbionts, and adult fragments with symbionts. The increase in pCO2 of 100 μatm between the pre-industrial period and the present had more effect on the calcification rate of adult A. digitifera than the anticipated future increases of several hundreds of micro-atmospheres of pCO2. The primary polyps with symbionts showed higher calcification rates than primary polyps without symbionts, suggesting that (i) primary polyps housing symbionts are more tolerant to near-future ocean acidification than organisms without symbionts, and (ii) corals acquiring symbionts from the environment (i.e. broadcasting species) will be more vulnerable to ocean acidification than corals that maternally acquire symbionts.

Calcifying algae maintain settlement cues to larval abalone following algal exposure to extreme ocean acidification.

PubMed

O'Leary, Jennifer K; Barry, James P; Gabrielson, Paul W; Rogers-Bennett, Laura; Potts, Donald C; Palumbi, Stephen R; Micheli, Fiorenza

2017-07-18

Ocean acidification (OA) increasingly threatens marine systems, and is especially harmful to calcifying organisms. One important question is whether OA will alter species interactions. Crustose coralline algae (CCA) provide space and chemical cues for larval settlement. CCA have shown strongly negative responses to OA in previous studies, including disruption of settlement cues to corals. In California, CCA provide cues for seven species of harvested, threatened, and endangered abalone. We exposed four common CCA genera and a crustose calcifying red algae, Peyssonnelia (collectively CCRA) from California to three pCO 2 levels ranging from 419-2,013 µatm for four months. We then evaluated abalone (Haliotis rufescens) settlement under ambient conditions among the CCRA and non-algal controls that had been previously exposed to the pCO 2 treatments. Abalone settlement and metamorphosis increased from 11% in the absence of CCRA to 45-69% when CCRA were present, with minor variation among CCRA genera. Though all CCRA genera reduced growth during exposure to increased pCO 2 , abalone settlement was unaffected by prior CCRA exposure to increased pCO 2 . Thus, we find no impacts of OA exposure history on CCRA provision of settlement cues. Additionally, there appears to be functional redundancy in genera of CCRA providing cues to abalone, which may further buffer OA effects.

Brain Cell Swelling During Hypocapnia Increases with Hyperglycemia or Ketosis

PubMed Central

Glaser, Nicole; Bundros, Angeliki; Anderson, Steve; Tancredi, Daniel; Lo, Weei; Orgain, Myra; O'Donnell, Martha

2014-01-01

Severe hypocapnia increases the risk of DKA-related cerebral injury in children, but the reason for this association is unclear. To determine whether the effects of hypocapnia on the brain are altered during hyperglycemia or ketosis, we induced hypocapnia (pCO2 20 ± 3 mmHg) via mechanical ventilation in three groups of juvenile rats: 25 controls, 22 hyperglycemic rats (serum glucose 451± 78 mg/dL) and 15 ketotic rats (beta-hydroxy butyrate 3.0 ± 1.0 mmol/L). We used magnetic resonance imaging to measure cerebral blood flow (CBF) and apparent diffusion coefficient (ADC) values in these groups and in 17 ventilated rats with normal pCO2 (40±3 mmHg). In a subset (n=35), after 2 hrs of hypocapnia, pCO2 levels were normalized (40±3 mmHg) and ADC and CBF measurements repeated. Declines in CBF with hypocapnia occurred in all groups. Normalization of pCO2 after hypocapnia resulted in striatal hyperemia. These effects were not substantially altered by hyperglycemia or ketosis, however, declines in ADC during hypocapnia were greater during both hyperglycemia and ketosis. We conclude that brain cell swelling associated with hypocapnia is increased by both hyperglycemia and ketosis, suggesting that these metabolic conditions may make the brain more vulnerable to injury during hypocapnia. PMID:24443981

Atmospheric pCO2 Reconstructed across the Early Eocene Hyperthermals

NASA Astrophysics Data System (ADS)

Cui, Y.; Schubert, B.

2015-12-01

Negative carbon isotope excursions (CIEs) are commonly associated with extreme global warming. The Early Eocene is punctuated by five such CIEs, the Paleocene-Eocene thermal maximum (PETM, ca. 55.8 Ma), H1 (ca. 53.6 Ma), H2 (ca. 53.5 Ma), I1 (ca. 53.3 Ma), and I2 (ca. 53.2 Ma), each characterized by global warming. The negative CIEs are recognized in both marine and terrestrial substrates, but the terrestrial substrates exhibit a larger absolute magnitude CIE than the marine substrates. Here we reconcile the difference in CIE magnitude between the terrestrial and marine substrates for each of these events by accounting for the additional carbon isotope fractionation by C3 land plants in response to increased atmospheric pCO2. Our analysis yields background and peak pCO2 values for each of the events. Assuming a common mechanism for each event, we calculate that background pCO2 was not static across the Early Eocene, with the highest background pCO2 immediately prior to I2, the last of the five CIEs. Background pCO2 is dependent on the source used in our analysis with values ranging from 300 to 720 ppmv provided an injection of 13C-depleted carbon with δ13C value of -60‰ (e.g. biogenic methane). The peak pCO2 during each event scales according to the magnitude of CIE, and is therefore greatest during the PETM and smallest during H2. Both background and peak pCO2 are higher if we assume a mechanism of permafrost thawing (δ13C = -25‰). Our reconstruction of pCO2 across these events is consistent with trends in the δ18O value of deep-sea benthic foraminifera, suggesting a strong link between pCO2 and temperature during the Early Eocene.

Sympathetic innervation regulates macrophage activity in rats with polycystic ovary.

PubMed

Figueroa, Florencia; Mendoza, Gisela; Cardozo, Darío; Mohamed, Fabián; Oliveros, Liliana; Forneris, Myriam

2018-07-01

Polycystic ovarian syndrome (PCOS) is a low-grade inflammatory disease characterized by hyperandrogenism and ovarian hyperinnervation. The aim of this work is to investigate whether in vivo bilateral superior ovarian nerve (SON) section in adult rats with estradiol valerate-induced PCOS (PCO rats) affects macrophage spleen cells (MФ) and modifies the steroidogenic ability of their secretions. Culture media of MФ from PCO rats and PCO rats with SON section (PCO-SON rats) were used to stimulate in vitro intact ovaries. Compared with macrophages PCO, macrophages from PCO-SON rats released less tumor necrosis factor-α and nitric oxide, expressed lower Bax and Nfkb mRNA and showed reduced TUNEL staining. Also, in PCO rats, the SON section decreased kisspeptin and nerve growth factor mRNA expressions, without changes in Trka receptor mRNA levels. Macrophage secretions from PCO-SON rats decreased androstenedione and stimulated progesterone release in PCO ovaries, compared to macrophage secretions from PCO rats. No changes were observed in ovarian estradiol response. These findings emphasize the importance of the SON in spleen MΦ, since its manipulation leads to secondary modifications of immunological and neural mediators, which might influence ovarian steroidogenesis. In PCO ovaries, the reduction of androstenedione and the improvement of progesterone release induced by PCO-SON MΦ secretion, might be beneficial considering the hormonal anomalies characteristic of PCOS. We present functional evidence that modulation of the immune-endocrine function by peripheral sympathetic nervous system might have implications for understanding the pathophysiology of PCOS. © 2018 Society for Endocrinology.

Nonuniform ocean acidification and attenuation of the ocean carbon sink

NASA Astrophysics Data System (ADS)

Fassbender, Andrea J.; Sabine, Christopher L.; Palevsky, Hilary I.

2017-08-01

Surface ocean carbon chemistry is changing rapidly. Partial pressures of carbon dioxide gas (pCO2) are rising, pH levels are declining, and the ocean's buffer capacity is eroding. Regional differences in short-term pH trends primarily have been attributed to physical and biological processes; however, heterogeneous seawater carbonate chemistry may also be playing an important role. Here we use Surface Ocean CO2 Atlas Version 4 data to develop 12 month gridded climatologies of carbonate system variables and explore the coherent spatial patterns of ocean acidification and attenuation in the ocean carbon sink caused by rising atmospheric pCO2. High-latitude regions exhibit the highest pH and buffer capacity sensitivities to pCO2 increases, while the equatorial Pacific is uniquely insensitive due to a newly defined aqueous CO2 concentration effect. Importantly, dissimilar regional pH trends do not necessarily equate to dissimilar acidity ([H+]) trends, indicating that [H+] is a more useful metric of acidification.

Impacts of ocean acidification on early life-history stages and settlement of the coral-eating sea star Acanthaster planci.

PubMed

Uthicke, Sven; Pecorino, Danilo; Albright, Rebecca; Negri, Andrew Peter; Cantin, Neal; Liddy, Michelle; Dworjanyn, Symon; Kamya, Pamela; Byrne, Maria; Lamare, Miles

2013-01-01

Coral reefs are marine biodiversity hotspots, but their existence is threatened by global change and local pressures such as land-runoff and overfishing. Population explosions of coral-eating crown of thorns sea stars (COTS) are a major contributor to recent decline in coral cover on the Great Barrier Reef. Here, we investigate how projected near-future ocean acidification (OA) conditions can affect early life history stages of COTS, by investigating important milestones including sperm motility, fertilisation rates, and larval development and settlement. OA (increased pCO2 to 900-1200 µatm pCO2) significantly reduced sperm motility and, to a lesser extent, velocity, which strongly reduced fertilization rates at environmentally relevant sperm concentrations. Normal development of 10 d old larvae was significantly lower under elevated pCO2 but larval size was not significantly different between treatments. Settlement of COTS larvae was significantly reduced on crustose coralline algae (known settlement inducers of COTS) that had been exposed to OA conditions for 85 d prior to settlement assays. Effect size analyses illustrated that reduced settlement may be the largest bottleneck for overall juvenile production. Results indicate that reductions in fertilisation and settlement success alone would reduce COTS population replenishment by over 50%. However, it is unlikely that this effect is sufficient to provide respite for corals from other negative anthropogenic impacts and direct stress from OA and warming on corals.

Simultaneous shifts in elemental stoichiometry and fatty acids of Emiliania huxleyi in response to environmental changes

NASA Astrophysics Data System (ADS)

Bi, Rong; Ismar, Stefanie M. H.; Sommer, Ulrich; Zhao, Meixun

2018-02-01

Climate-driven changes in environmental conditions have significant and complex effects on marine ecosystems. Variability in phytoplankton elements and biochemicals can be important for global ocean biogeochemistry and ecological functions, while there is currently limited understanding on how elements and biochemicals respond to the changing environments in key coccolithophore species such as Emiliania huxleyi. We investigated responses of elemental stoichiometry and fatty acids (FAs) in a strain of E. huxleyi under three temperatures (12, 18 and 24 °C), three N : P supply ratios (molar ratios 10:1, 24:1 and 63:1) and two pCO2 levels (560 and 2400 µatm). Overall, C : N : P stoichiometry showed the most pronounced response to N : P supply ratios, with high ratios of particulate organic carbon vs. particulate organic nitrogen (POC : PON) and low ratios of PON vs. particulate organic phosphorus (PON : POP) in low-N media, and high POC : POP and PON : POP in low-P media. The ratio of particulate inorganic carbon vs. POC (PIC : POC) and polyunsaturated fatty acid proportions strongly responded to temperature and pCO2, both being lower under high pCO2 and higher with warming. We observed synergistic interactions between warming and nutrient deficiency (and high pCO2) on elemental cellular contents and docosahexaenoic acid (DHA) proportion in most cases, indicating the enhanced effect of warming under nutrient deficiency (and high pCO2). Our results suggest differential sensitivity of elements and FAs to the changes in temperature, nutrient availability and pCO2 in E. huxleyi, which is to some extent unique compared to non-calcifying algal classes. Thus, simultaneous changes of elements and FAs should be considered when predicting future roles of E. huxleyi in the biotic-mediated connection between biogeochemical cycles, ecological functions and climate change.

Acid-base responses to feeding and intestinal Cl- uptake in freshwater- and seawater-acclimated killifish, Fundulus heteroclitus, an agastric euryhaline teleost.

PubMed

Wood, Chris M; Bucking, Carol; Grosell, Martin

2010-08-01

Marine teleosts generally secrete basic equivalents (HCO(3)(-)) and take up Na(+) and Cl(-) in the intestine so as to promote absorption of H(2)O. However, neither the integration of these functions with feeding nor the potential role of the gut in ionoregulation and acid-base balance in freshwater have been well studied. The euryhaline killifish (Fundulus heteroclitus) is unusual in lacking both an acid-secreting stomach and a mechanism for Cl(-) uptake at the gills in freshwater. Responses to a satiation meal were evaluated in both freshwater- and seawater-acclimated killifish. In intact animals, there was no change in acid or base flux to the external water after the meal, in accord with the absence of any post-prandial alkaline tide in the blood. Indeed, freshwater animals exhibited a post-prandial metabolic acidosis ('acidic tide'), whereas seawater animals showed no change in blood acid-base status. In vitro gut sac experiments revealed a substantially higher rate of Cl(-) absorption by the intestine in freshwater killifish, which was greatest at 1-3 h after feeding. The Cl(-) concentration of the absorbate was higher in preparations from freshwater animals than from seawater killifish and increased with fasting. Surprisingly, net basic equivalent secretion rates were also much higher in preparations from freshwater animals, in accord with the 'acidic tide'; in seawater preparations, they were lowest after feeding and increased with fasting. Bafilomycin (1 micromol l(-1)) promoted an 80% increase in net base secretion rates, as well as in Cl(-) and fluid absorption, at 1-3 h post-feeding in seawater preparations only, explaining the difference between freshwater and seawater fish. Preparations from seawater animals at 1-3 h post-feeding also acidified the mucosal saline, and this effect was associated with a marked rise in P(CO(2)), which was attenuated by bafilomycin. Measurements of chyme pH from intact animals confirmed that intestinal fluid (chyme) pH and basic equivalent concentration were lowest after feeding in seawater killifish, whereas P(CO(2)) was greatly elevated (80-95 Torr) in chyme from both seawater and freshwater animals but declined to lower levels (13 Torr) after 1-2 weeks fasting. There were no differences in pH, P(CO(2)) or the concentrations of basic equivalents in intestinal fluid from seawater versus freshwater animals at 12-24 h or 1-2 weeks post-feeding. The results are interpreted in terms of the absence of gastric HCl secretion, the limitations of the gills for acid-base balance and Cl(-) transport, and therefore the need for intestinal Cl(-) uptake in freshwater killifish, and the potential for O(2) release from the mucosal blood flow by the high P(CO(2)) in the intestinal fluids. At least in seawater killifish, H(+)-ATPase running in parallel to HCO(3)(-):Cl(-) exchange in the apical membranes of teleost enterocytes might reduce net base secretion and explain the high P(CO(2)) in the chyme after feeding.

Passive aerobic treatment of net-alkaline, iron-laden drainage from a flooded underground anthracite mine, Pennsylvania, USA

USGS Publications Warehouse

Cravotta, C.A.

2007-01-01

This report evaluates the results of a continuous 4.5-day laboratory aeration experiment and the first year of passive, aerobic treatment of abandoned mine drainage (AMD) from a typical flooded underground anthracite mine in eastern Pennsylvania, USA. During 1991-2006, the AMD source, locally known as the Otto Discharge, had flows from 20 to 270 L/s (median 92 L/s) and water quality that was consistently suboxic (median 0.9 mg/L O2) and circumneutral (pH ??? 6.0; net alkalinity >10) with moderate concentrations of dissolved iron and manganese and low concentrations of dissolved aluminum (medians of 11, 2.2, and <0.2 mg/L, respectively). In 2001, the laboratory aeration experiment demonstrated rapid oxidation of ferrous iron (Fe 2+) without supplemental alkalinity; the initial Fe2+ concentration of 16.4 mg/L decreased to less than 0.5 mg/L within 24 h; pH values increased rapidly from 5.8 to 7.2, ultimately attaining a steady-state value of 7.5. The increased pH coincided with a rapid decrease in the partial pressure of carbon dioxide (PCO2) from an initial value of 10 -1.1atm to a steady-state value of 10-3.1atm. From these results, a staged aerobic treatment system was conceptualized consisting of a 2 m deep pond with innovative aeration and recirculation to promote rapid oxidation of Fe2+, two 0.3 m deep wetlands to facilitate iron solids removal, and a supplemental oxic limestone drain for dissolved manganese and trace-metal removal. The system was constructed, but without the aeration mechanism, and began operation in June 2005. During the first 12 months of operation, estimated detention times in the treatment system ranged from 9 to 38 h. However, in contrast with 80-100% removal of Fe2+ over similar elapsed times during the laboratory aeration experiment, the treatment system typically removed less than 35% of the influent Fe2+. Although concentrations of dissolved CO2 decreased progressively within the treatment system, the PCO2 values for treated effluent remained elevated (10-2.4 to 10-1.7atm). The elevated PCO 2 maintained the pH within the system at values less than 7 and hence slowed the rate of Fe2+ oxidation compared to the aeration experiment. Kinetic models of Fe2+ oxidation that consider effects of pH and dissolved O2 were incorporated in the geochemical computer program PHREEQC to evaluate the effects of detention time, pH, and other variables on Fe2+ oxidation and removal rates. These models and the laboratory aeration experiment indicate that performance of this and other aerobic wetlands for treatment of net-alkaline AMD could be improved by aggressive, continuous aeration in the initial stage to decrease PCO 2, increase pH, and accelerate Fe2+ oxidation. ?? 2007 Springer-Verlag.

Differential thermal response within inshore vs. offshore congeneric scleractinian coral species in Palau.

NASA Astrophysics Data System (ADS)

Hoadley, K. D.; Lewis, A.; Wham, D.; Pettay, D. T.; Kemp, D.; Warner, M.; Lajeunesse, T.

2016-02-01

The rock island reef habitats of Palau are an ideal location to study climate change effects to reefs, as corals there are exposed to average temperature and pCO2 conditions well above levels experienced at offshore reef locations. We examined the response of 6 coral species, Acropora muricata, Goniastrea sp, Porities rus, Cyphastrea sp, Porites cylindrical and Pachyseris sp, from both rock island and offshore habitats to high temperature (32 Celsius) for 15 days. With the exception of P. rus and P. cylindrica which harbored Symbiodinium C15 at both locations, other rock island corals harbored the thermally tolerant species Symbiodinium trenchii, whereas offshore colonies harbored clade C symbionts. A total of 15 separate host and symbiont physiological variables were utilized to assess thermal acclimation/stress response within each host/symbiont combination. Differences in photophysiology, algal cell volume and biochemical composition were observed for Symbiodinium trenchii within different host species, reflecting the importance of the host organism in mitigating the symbiont response. Similarly, the host thermal response was also dependent on symbiont type, with greater reductions in symbiont density occurring within the offshore colonies. Overall, prior exposure to warmer temperatures, elevated nutrient and pCO2 conditions, along with association with more robust symbionts allowed rock island corals to exhibit greater thermal tolerance toward high temperature. Importantly, the results herein for Symbiodinium trenchii physiological plasticity and thermal mitigation provides useful insight into the potential of scleractinian corals to acclimatize under future climate change scenarios.

Carbon Isotope Discrimination in C3 Land Plants is Independent of Atmospheric PCO2

NASA Astrophysics Data System (ADS)

Kohn, M. J.

2015-12-01

The δ13C of terrestrial C3 plant tissues and soil organic matter is important for understanding the carbon cycle, inferring past climatic and ecological conditions, and predicting responses of vegetation to future climate change. Plant δ13C depends on the δ13C of atmospheric CO2 and mean annual precipitation (MAP), but an unresolved decades-long debate centers on whether terrestrial C3 plant δ13C responds to pCO2. Here, the pCO2-dependence of C3 land plant δ13C was tested using isotopic records from low- and high-pCO2 times spanning historical through Eocene data. Historical data do not resolve a clear pCO2-effect (-1.2±1.0 to 0.59±0.34‰/100 ppmv), and organic carbon records of the Pleistocene-Holocene transition implicate changes in MAP and ecosystems, rather than pCO2, as the major driver of δ13C changes. Fossil collagen and tooth enamel data constrain pCO2-effects most tightly to -0.03±0.13 and -0.03±0.24‰/100 ppmv between 200 and 700 ppmv. Combining all constraints yields a preferred value of 0.0±0.2‰/100 ppmv (2 s.e.), i.e. there is effectively no pCO2 effect. Recent models of pCO2-dependence imply unrealistic MAP for Cenozoic records.

Air-ice CO2 fluxes and pCO2 dynamics in the Arctic coastal area (Amundsen Gulf, Canada)

NASA Astrophysics Data System (ADS)

Geilfus, Nicolas-Xavier; Tison, Jean Louis; Carnat, Gauthier; Else, Brent; Borges, Alberto V.; Thomas, Helmuth; Shadwick, Elizabeth; Delille, Bruno

2010-05-01

Sea ice covers about 7% of the Earth surface at its maximum seasonal extent. For decades sea ice was assumed to be an impermeable and inert barrier for air - sea exchange of CO2 so that global climate models do not include CO2 exchange between the oceans and the atmosphere in the polar regions. However, uptake of atmospheric CO2 by sea ice cover was recently reported raising the need to further investigate pCO2 dynamics in the marine cryosphere realm and related air-ice CO2 fluxes. In addition, budget of CO2 fluxes are poorly constrained in high latitudes continental shelves [Borges et al., 2006]. We report measurements of air-ice CO2 fluxes above the Canadian continental shelf and compare them to previous measurements carried out in Antarctica. We carried out measurements of pCO2 within brines and bulk ice, and related air-ice CO2 fluxes (chamber method) in Antarctic first year pack ice ("Sea Ice Mass Balance in Antarctica -SIMBA" drifting station experiment September - October 2007) and in Arctic first year land fast ice ("Circumpolar Flaw Lead" - CFL, April - June 2008). These 2 experiments were carried out in contrasted sites. SIMBA was carried out on sea ice in early spring while CFL was carried out in from the middle of the winter to the late spring while sea ice was melting. Both in Arctic and Antarctic, no air-ice CO2 fluxes were detected when sea ice interface was below -10°C. Slightly above -10°C, fluxes toward the atmosphere were observed. In contrast, at -7°C fluxes from the atmosphere to the ice were significant. The pCO2 of the brine exhibits a same trend in both hemispheres with a strong decrease of the pCO2 anti-correlated with the increase of sea ice temperature. The pCO2 shifted from a large over-saturation at low temperature to a marked under-saturation at high temperature. These air-ice CO2 fluxes are partly controlled by the permeability of the air-ice interface, which depends of the temperature of this one. Moreover, air-ice CO2 fluxes are driven by the air-ice pCO2 gradient. Hence, while the temperature is a leading factor in controlling magnitude of air-ice CO2 fluxes, pCO2 of the ice controls both magnitude and direction of fluxes. However, pCO2 in Arctic is significantly higher than in Antarctica. This difference could be due to a higher level of organic matter in Arctic. The degradation of this organic matter fuel CO2 efflux from the ice to the atmosphere in early spring. We observed evidence of CaCO3 precipitation, but only at the top of the ice. Implications in term of air-ice CO2 transfer of such CaCO3 precipitation will be discussed. In addition, salt-rich snow appears to strongly affect air-ice CO2 fluxes in the arctic. Borges, A. V., et al. (2006), Carbon dioxide in European coastal waters, Estuar. Coast. Shelf Sci., 70(3), 375-387.

Patency of the posterior communicating artery following treatment with the Pipeline Embolization Device.

PubMed

Daou, Badih; Valle-Giler, Edison P; Chalouhi, Nohra; Starke, Robert M; Tjoumakaris, Stavropoula; Hasan, David; Rosenwasser, Robert H; Hebert, Ryan; Jabbour, Pascal

2017-02-01

OBJECTIVE The Pipeline Embolization Device (PED) has become an effective treatment strategy for some cerebral aneurysms. Concerns regarding the patency of branch arteries have been raised. The objective of this study was to assess the patency of the posterior communicating artery (PCoA) following treatment of PCoA aneurysms using the PED. METHODS All patients with PCoA aneurysms treated with the PED who had angiographic follow-up were retrospectively identified. The patency of the PCoA at follow-up was evaluated by 2 authors who were not involved in the intervention. Univariate and multivariate analyses were performed to identify factors associated with the following: 1) PCoA patency versus no or diminished flow, and 2) PCoA patency and diminished flow versus PCoA occlusion. RESULTS Thirty patients with an angiographic follow-up of 6 months were included. Aneurysm obliteration was achieved in 25 patients (83.3%). The PCoA was patent in 7 patients (23.3%), had diminished flow in 7 patients (23.3%), and was occluded in 16 patients (53.3%). In the univariate analysis of outcome, there was a trend for aneurysms with incomplete occlusion, aneurysms not previously treated, those with presence of a fetal PCoA, and those with an artery coming from the aneurysm to have higher odds of the PCoA remaining patent. In univariate and multivariate analyses of factors associated with outcome, fetal PCoA and presence of an artery coming from the aneurysm were associated with the PCoA remaining open with or without diminished flow. No patients had symptoms related to PCoA occlusion. CONCLUSIONS Occlusion and diminished flow through the PCoA is common following PED treatment of PCoA aneurysms. However, it is clinically insignificant in most cases.

Ocean acidification increases the sensitivity of and variability in physiological responses of an intertidal limpet to thermal stress

NASA Astrophysics Data System (ADS)

Wang, Jie; Russell, Bayden D.; Ding, Meng-Wen; Dong, Yun-Wei

2018-05-01

Understanding physiological responses of organisms to warming and ocean acidification is the first step towards predicting the potential population- and community-level ecological impacts of these stressors. Increasingly, physiological plasticity is being recognized as important for organisms to adapt to the changing microclimates. Here, we evaluate the importance of physiological plasticity for coping with ocean acidification and elevated temperature, and its variability among individuals, of the intertidal limpet Cellana toreuma from the same population in Xiamen. Limpets were collected from shaded mid-intertidal rock surfaces. They were acclimated under combinations of different pCO2 concentrations (400 and 1000 ppm, corresponding to a pH of 8.1 and 7.8) and temperatures (20 and 24 °C) in a short-term period (7 days), with the control conditions (20 °C and 400 ppm) representing the average annual temperature and present-day pCO2 level at the collection site. Heart rates (as a proxy for metabolic performance) and expression of genes encoding inducible and constitutive heat-shock proteins (hsp70 and hsc70) at different heat-shock temperatures (26, 30, 34, and 38 °C) were measured. Hsp70 and Hsc70 play important roles in protecting cells from heat stresses, but have different expression patterns, with Hsp70 significantly increased in expression during stress and Hsc70 constitutively expressed and only mildly induced during stress. Analysis of heart rate showed significantly higher temperature coefficients (Q10 rates) for limpets at 20 °C than at 24 °C and post-acclimation thermal sensitivity of limpets at 400 ppm was lower than at 1000 ppm. Expression of hsp70 linearly increased with the increasing heat-shock temperatures, with the largest slope occurring in limpets acclimated under a future scenario (24 °C and 1000 ppm pCO2). These results suggested that limpets showed increased sensitivity and stress response under future conditions. Furthermore, the increased variation in physiological response under the future scenario indicated that some individuals have higher physiological plasticity to cope with these conditions. While short-term acclimation to reduced pH seawater decreases the ability of partial individuals against thermal stress, physiological plasticity and variability seem to be crucial in allowing some intertidal animals to survive in a rapidly changing environment.

Leaf Wax δ13C Varies with Elevation in the Peruvian Andes and Western Amazonia

NASA Astrophysics Data System (ADS)

Wu, M. S.; Feakins, S. J.; Ponton, C.; Peters, T.; West, A. J.; Galy, V.; Bentley, L. P.; Salinas, N.; Shenkin, A.; Martin, R.; Asner, G. P.; Malhi, Y.

2015-12-01

Plant leaf wax carbon isotopic composition (δ13Cwax) reflects the net isotopic effects associated with diffusion into the leaf, fixation of carbon by Rubisco and biosynthesis of individual leaf wax biochemicals. As declining pCO2 with elevation affects the first two fractionations, we expect to find an isotopic gradient in δ13Cwax, if the fractionation of leaf wax biosynthesis is constant. To test this, we report δ13Cwax values from 500 samples of leaves collected by tree-climbers from the upper canopy from 9 forest-inventory plots spanning a 3.5km elevation transect in the Peruvian Andes and western Amazonia during the CHAMBASA field campaign. These samples provide a unique opportunity to study the relationship between δ13Cwax and pCO2 in diverse species across this remote tropical montane forest and lowland rainforest. The very wet climate throughout (2-5 m rainfall per year) minimizes fractionation effects due to stomatal restrictions (i.e. water use efficiency) that may be an important factor elsewhere. Preliminary results show δ13Cwax values on average increase with elevation by ~1.5‰/km, a trend consistent with bulk plant δ13C in previous studies. The mean epsilon between bulk and C29 n-alkane is -7.3±2.2‰. Inter-sample differences are large on the order of 10‰. Shaded leaves and understory leaves are found to be depleted relative to sunlit leaves, presumably due to a lower photosynthetic rate and use of respired CO2 in the understory. C29 n-alkanes are on average ~2.5‰ more depleted than C30 n-alkanoic acids, indicating fractionation during selective decarboxylation. We further compare results from plants with soil and river sediments to provide insights into how leaf wax signals are archived in soils and exported from the landscape. We find a ~1.4‰/km gradient in forest soils similar to plants. We observe a ~2‰ offset between C29 n-alkane in plant leaves and in soils across the elevation profile, which is likely a signal of degradation. Suspended sediments from the Kosñipata and Madre de Dios Rivers draining this region show δ13Cwax values aligned with soils from the mean elevation of the catchment, suggesting soils as the sources of waxes exported in rivers, with ages on average 400-2,000 years revealed by compound specific radiocarbon analysis.

Incorporation of Mg, Sr, Ba, U, and B in High-Mg Calcite Benthic Foraminifers Cultured Under Controlled pCO2

NASA Astrophysics Data System (ADS)

Not, C.; Thibodeau, B.; Yokoyama, Y.

2018-01-01

Measurement of elemental ratios (E/Ca) has been performed in two symbiont-bearing species of high-Mg calcite benthic foraminifers (hyaline, Baculogypsina sphaerulata and porcelaneous, Amphisorus hemprichii), cultured under five pCO2 levels, representing preindustrial, modern, and three predicted future values. E/Ca ratios were analyzed by Laser Ablation coupled with Inductively Coupled Plasma Mass Spectrometer (LA-ICP-MS). We measured several E/Ca, such as Mg/Ca, Sr/Ca, Ba/Ca, U/Ca, and B/Ca simultaneously. We observed that high-Mg calcite benthic foraminifers possess higher E/Ca than low-Mg calcite foraminifers, irrespective of their calcification mode (hyaline or porcelaneous). In both modes of calcification, Mg, Sr, Ba, U, and B incorporation could be controlled by Rayleigh fractionation. However, more data are needed to validate and quantify the relative importance of this process and closely investigate the presence/absence of other mechanism. Therefore, it highlights the need for a multielemental approach when looking at trace element incorporation. Finally, no significant relationship was observed between the different ratios and the pCO2 of the water, suggesting that none of the Mg/Ca, Sr/Ca, Ba/Ca, U/Ca, and B/Ca is sensitive to bottom water pCO2 or pH for these species.

Spatio-temporal variations of carbon dioxide and its gross emission regulated by artificial operation in a typical hydropower reservoir in China.

PubMed

Li, Zhe; Zhang, Zengyu; Xiao, Yan; Guo, Jinsong; Wu, Shengjun; Liu, Jing

2014-05-01

Supersaturation and excess emission of greenhouse gases in freshwater reservoirs have received a great deal of attention in recent years. Although impoundment of reservoirs has been shown to contribute to the net emission of greenhouse gases, reservoir age, geographical distribution, submerged soil type and artificial regulation also have a great impact on their emissions. To examine how large scale reservoir operation impact the water column CO2 and its air-water interface flux, a field study was conducted in 2010 to evaluate potential ecological processes that regulate the partial pressure of CO2 (pCO2) in the water column in the Pengxi River backwater area (PBA), a typical tributary in the Three Gorges Reservoir, China. Measurements of total alkalinity (TA), pH and water temperature were applied to compute the pCO2. And this approach was also validated by calculation of pCO2 from the dissolved inorganic carbon data of samples. Partial least squares (PLS) regression was used to determine how the dynamics of the water pCO2 were related to the available variables. The estimated pCO2 in our sample ranged from 26 to 4,087 μatm in the surface water. During low water operation from July to early September, there was an obvious pCO2 stratification, and pCO2 in the surface was almost unsaturated. This phenomenon was also observed in the spring bloom during discharge period. Conversely, there was no significant pCO2 stratification and the entire water column was supersaturated during high water operation from November to the following February. Significant correlation was observed between the magnitude of pCO2, DO and chlorophyll a, suggesting that phytoplankton dynamics regulate pCO2 in the PBA. The average areal rate of CO2 emissions from the Pengxi River ranged from 18.06 to 48.09 mmol m(-2) day(-1), with an estimated gross CO2 emission from the water surface of 14-37 t day(-1) in this area in 2010. Photosynthesis and respiration rates by phytoplankton might be the dominant processes that regulated pCO2 in the water column. We conclude that pCO2 values in the surface water of Pengxi River could be regarded as potential sources of CO2 to the atmosphere were smaller or similar to those that have been reported for many other reservoirs to date.

Fate of metal resistance genes in arable soil after manure application in a microcosm study.

PubMed

Xiong, Wenguang; Zeng, Zhenling; Zhang, Yiming; Ding, Xueyao; Sun, Yongxue

2015-03-01

Manure application contributes to the spread and persistence of metal resistance genes (MRGs) in the environment. We investigated the fate of copper (Cu) and zinc (Zn) resistance genes (pcoA, pcoD and zntA) in arable soil after Cu/Zn-containing manure application. Manure with or without addition of metals (Cu/Zn) was added in a soil microcosm over 2 months. Soil samples were collected for analysis on day 0, 30 and 60. The abundances of all MRGs (pcoA, pcoD and zntA) in manure group were significantly higher than those in untreated soil and manure+metals groups. All MRGs dissipated 1.2-1.3 times faster in manure group (from -90 ± 8% to -93 ± 7%) than those in manure+metals group (from -68 ± 8% to -78 ± 5%). The results indicated that manure from healthy pigs contributed to the occurrence of metals (Cu/Zn) and MRGs (pcoA, pcoD and zntA) in arable soil. The significant effects of manure application on the accumulation of pcoA, pcoD and zntA lasted for 1-2 months. Cu/Zn can slow down the dissipation of pcoA, pcoD and zntA after manure application. This is the first report to investigate the fate of MRGs in soil after manure application. Copyright © 2014 Elsevier Inc. All rights reserved.

Acclimatization of the Crustose Coralline Alga Porolithon onkodes to Variable pCO2

PubMed Central

Johnson, Maggie D.; Moriarty, Vincent W.; Carpenter, Robert C.

2014-01-01

Ocean acidification (OA) has important implications for the persistence of coral reef ecosystems, due to potentially negative effects on biomineralization. Many coral reefs are dynamic with respect to carbonate chemistry, and experience fluctuations in pCO2 that exceed OA projections for the near future. To understand the influence of dynamic pCO2 on an important reef calcifier, we tested the response of the crustose coralline alga Porolithon onkodes to oscillating pCO2. Individuals were exposed to ambient (400 µatm), high (660 µatm), or variable pCO2 (oscillating between 400/660 µatm) treatments for 14 days. To explore the potential for coralline acclimatization, we collected individuals from low and high pCO2 variability sites (upstream and downstream respectively) on a back reef characterized by unidirectional water flow in Moorea, French Polynesia. We quantified the effects of treatment on algal calcification by measuring the change in buoyant weight, and on algal metabolism by conducting sealed incubations to measure rates of photosynthesis and respiration. Net photosynthesis was higher in the ambient treatment than the variable treatment, regardless of habitat origin, and there was no effect on respiration or gross photosynthesis. Exposure to high pCO2 decreased P. onkodes calcification by >70%, regardless of the original habitat. In the variable treatment, corallines from the high variability habitat calcified 42% more than corallines from the low variability habitat. The significance of the original habitat for the coralline calcification response to variable, high pCO2 indicates that individuals existing in dynamic pCO2 habitats may be acclimatized to OA within the scope of in situ variability. These results highlight the importance of accounting for natural pCO2 variability in OA manipulations, and provide insight into the potential for plasticity in habitat and species-specific responses to changing ocean chemistry. PMID:24505305

Evolutionary and functional mitogenomics associated with the genetic restoration of the Florida panther

USGS Publications Warehouse

Ochoa, Alexander; Onorato, David P.; Fitak, Robert R.; Roelke-Parker, Melody; Culver, Melanie

2017-01-01

Florida panthers are endangered pumas that currently persist in reduced patches of habitat in South Florida, USA. We performed mitogenome reference-based assemblies for most parental lines of the admixed Florida panthers that resulted from the introduction of female Texas pumas into South Florida in 1995. With the addition of 2 puma mitogenomes, we characterized 174 single nucleotide polymorphisms (SNPs) across 12 individuals. We defined 5 haplotypes (Pco1–Pco5), one of which (Pco1) had a geographic origin exclusive to Costa Rica and Panama and was possibly introduced into the Everglades National Park, Florida, prior to 1995. Haplotype Pco2 was native to Florida. Haplotypes Pco3 and Pco4 were exclusive to Texas, whereas haplotype Pco5 had an undetermined geographic origin. Phylogenetic inference suggests that haplotypes Pco1–Pco4 diverged ~202000 (95% HPDI = 83000–345000) years ago and that haplotypes Pco2–Pco4 diverged ~61000 (95% HPDI = 9000–127000) years ago. These results are congruent with a south-to-north continental expansion and with a recent North American colonization by pumas. Furthermore, pumas may have migrated from Texas to Florida no earlier than ~44000 (95% HPDI = 2000–98000) years ago. Synonymous mutations presented a greater mean substitution rate than other mitochondrial functional regions: nonsynonymous mutations, tRNAs, rRNAs, and control region. Similarly, all protein-coding genes were under predominant negative selection constraints. We directly and indirectly assessed the presence of potential deleterious SNPs in the ND2 and ND5 genes in Florida panthers prior to and as a consequence of the introduction of Texas pumas. Screenings for such variants are recommended in extant Florida panthers.

Effects of Mild Hypercapnia During Head-Down Bed Rest on Ocular Structures, Cerebral Blood Flow, aud Visual Acuity in Healthy Human Subjects

NASA Technical Reports Server (NTRS)

Laurie, S. S.; Taibbi, G.; Lee, S. M. C.; Martin, D. S.; Zanello, S.; Ploutz-Snyder, R.; Hu, X.; Stenger, M. B.; Vizzeri, G.

2014-01-01

The cephalad fluid shift induced by microgravity has been hypothesized to cause an elevation in intracranial pressure (ICP) and contribute to the development of the Visual Impairment/Intracranial Pressure (VIIP) syndrome, as experienced by some astronauts during long-duration space flight. Elevated ambient partial pressure of carbon dioxide (PCO2) on ISS may also raise ICP and contribute to VIIP development. We seek to determine if the combination of mild CO2 exposure, similar to that occurring on the International Space Station, with the cephalad fluid shift induced by head-down tilt, will induce ophthalmic and cerebral blood flow changes similar to those described in the VIIP syndrome. We hypothesize that mild hypercapnia in the head-down tilt position will increase choroidal blood volume and cerebral blood flow, raise intraocular pressure (IOP), and transiently reduce visual acuity as compared to the seated or the head-down tilt position without elevated CO2, respectively.

True posterior communicating artery aneurysms: are they more prone to rupture? A biomorphometric analysis.

PubMed

He, Wenzhuan; Hauptman, Jason; Pasupuleti, Latha; Setton, Avi; Farrow, Maria G; Kasper, Lydia; Karimi, Reza; Gandhi, Chirag D; Catrambone, Jeffrey E; Prestigiacomo, Charles J

2010-03-01

Posterior communicating artery (PCoA) aneurysms can occur at the junction with the internal carotid artery, posterior cerebral artery (PCA), or the proximal PCoA itself. Hemodynamic stressors contribute to aneurysm formation and may be associated with parent vessel size and aneurysm location. This study evaluates the correlation of various biomorphometric characteristics in 2 of the aforementioned types of PCoA aneurysms. Patients with PCoA aneurysms were analyzed using CT angiography. Source images and reconstructions were used to determine which aneurysms originated purely from the PCoA and those that originated from the internal carotid artery/PCoA junction. Morphometric analysis was performed on the aneurysm, the precommunicating segment of the PCA (P(1)), the ambient segment of the PCA (P(2)), and both PCoA arteries and were correlated to clinical presentation. Parametric and nonparametric analyses were performed to test for significance. A total of 77 PCoA aneurysms were analyzed, and 10 were found to be true PCoA aneurysms (13.0%). The ipsilateral PCoA/P(1) ratio (1.77 +/- 0.44 vs 0.82 +/- 0.46, p = 0.0001) and ipsilateral P(2)/P(1) ratio (1.73 +/- 0.40 vs 1.22 +/- 0.41, p = 0.0003) were significantly larger in true PCoA aneurysms. Interestingly, aneurysm size was statistically larger in the junctional aneurysms (0.14 +/- 0.1 vs 0.072 +/- 0.04 cm(3), p = 0.03). The prevalence of ruptured aneurysms was similar in both groups (approximately 80%, p value not significant). These data suggest that true PCoA aneurysms have a larger PCoA relative to the ipsilateral P(1) segment. To the authors' knowledge, this represents the first such biomorphometric comparison of these different types of PCoA aneurysms. Although statistically smaller in size, true PCoA aneurysms also have a similar prevalence of presenting as a ruptured aneurysm, suggesting that they might be more prone to rupture than a junctional aneurysms of similar size. Further analysis will be required to determine the biophysical factors affecting rupture rates.

Physiological responses of Daphnia pulex to acid stress

PubMed Central

Weber, Anna K; Pirow, Ralph

2009-01-01

Background Acidity exerts a determining influence on the composition and diversity of freshwater faunas. While the physiological implications of freshwater acidification have been intensively studied in teleost fish and crayfish, much less is known about the acid-stress physiology of ecologically important groups such as cladoceran zooplankton. This study analyzed the extracellular acid-base state and CO2 partial pressure (PCO2), circulation and ventilation, as well as the respiration rate of Daphnia pulex acclimated to acidic (pH 5.5 and 6.0) and circumneutral (pH 7.8) conditions. Results D. pulex had a remarkably high extracellular pH of 8.33 and extracellular PCO2 of 0.56 kPa under normal ambient conditions (pH 7.8 and normocapnia). The hemolymph had a high bicarbonate concentration of 20.9 mM and a total buffer value of 51.5 meq L-1 pH-1. Bicarbonate covered 93% of the total buffer value. Acidic conditions induced a slight acidosis (ΔpH = 0.16–0.23), a 30–65% bicarbonate loss, and elevated systemic activities (tachycardia, hyperventilation, hypermetabolism). pH 6.0 animals partly compensated the bicarbonate loss by increasing the non-bicarbonate buffer value from 2.0 to 5.1 meq L-1 pH-1. The extracellular PCO2 of pH 5.5 animals was significantly reduced to 0.33 kPa, and these animals showed the highest tolerance to a short-term exposure to severe acid stress. Conclusion Chronic exposure to acidic conditions had a pervasive impact on Daphnia's physiology including acid-base balance, extracellular PCO2, circulation and ventilation, and energy metabolism. Compensatory changes in extracellular non-bicarbonate buffering capacity and the improved tolerance to severe acid stress indicated the activation of defense mechanisms which may result from gene-expression mediated adjustments in hemolymph buffer proteins and in epithelial properties. Mechanistic analyses of the interdependence between extracellular acid-base balance and CO2 transport raised the question of whether a carbonic anhydrase (CA) is involved in the catalysis of the reaction, which led to the discovery of 31 CA-genes in the genome of D. pulex. PMID:19383148

CO2 time series patterns in contrasting headwater streams of North America

USGS Publications Warehouse

Crawford, John T.; Stanley, Emily H.; Dornblaser, Mark M.; Striegl, Robert G.

2017-01-01

We explored the underlying patterns of temporal stream CO2 partial pressure (pCO2) variability using highfrequency sensors in seven disparate headwater streams distributed across the northern hemisphere. We also compared this dataset of [40,000 pCO2 records with other published records from lotic systems. Individual stream sites exhibited relatively distinct pCO2 patterns over time with few consistent traits across sites. Some sites showed strong diel variability, some exhibited increasing pCO2 with increasing discharge, whereas other streams had reduced pCO2 with increasing discharge or no clear response to changes in flow. The only ‘‘universal’’ signature observed in headwater streams was a late summer pCO2 maxima that was likely driven by greatest rates of organic matter respiration due to highest annual temperatures. However, we did not observe this seasonal pattern in a southern hardwood forest site, likely because the region was transitioning from a severe drought. This work clearly illustrates the heterogeneous nature of headwater streams, and highlights the idiosyncratic nature of a non-conservative solute that is jointly influenced by physics, hydrology, and biology. We suggest that future researchers carefully select sensor locations (within and among streams) and provide additional contextual information when attempting to explain pCO2 patterns.

Ammonium excretion and oxygen respiration of tropical copepods and euphausiids exposed to oxygen minimum zone conditions

NASA Astrophysics Data System (ADS)

Kiko, Rainer; Hauss, Helena; Buchholz, Friedrich; Melzner, Frank

2016-04-01

Calanoid copepods and euphausiids are key components of marine zooplankton communities worldwide. Most euphausiids and several copepod species perform diel vertical migrations (DVMs) that contribute to the export of particulate and dissolved matter to midwater depths. In vast areas of the global ocean, and in particular in the eastern tropical Atlantic and Pacific, the daytime distribution depth of many migrating organisms corresponds to the core of the oxygen minimum zone (OMZ). At depth, the animals experience reduced temperature and oxygen partial pressure (pO2) and an increased carbon dioxide partial pressure (pCO2) compared to their near-surface nighttime habitat. Although it is well known that low oxygen levels can inhibit respiratory activity, the respiration response of tropical copepods and euphausiids to relevant pCO2, pO2, and temperature conditions remains poorly parameterized. Further, the regulation of ammonium excretion at OMZ conditions is generally not well understood. It was recently estimated that DVM-mediated ammonium supply could fuel bacterial anaerobic ammonium oxidation - a major loss process for fixed nitrogen in the ocean considerably. These estimates were based on the implicit assumption that hypoxia or anoxia in combination with hypercapnia (elevated pCO2) does not result in a down-regulation of ammonium excretion. We exposed calanoid copepods from the Eastern Tropical North Atlantic (ETNA; Undinula vulgaris and Pleuromamma abdominalis) and euphausiids from the Eastern Tropical South Pacific (ETSP; Euphausia mucronata) and the ETNA (Euphausia gibboides) to different temperatures, carbon dioxide and oxygen levels to study their survival, respiration and excretion rates at these conditions. An increase in temperature by 10 °C led to an approximately 2-fold increase of the respiration and excretion rates of U. vulgaris (Q10, respiration = 1.4; Q10, NH4-excretion = 1.6), P. abdominalis (Q10, respiration = 2.0; Q10, NH4-excretion = 2.4) and E. gibboides (Q10, respiration = 2.0; Q10, NH4-excretion = 2.4; E. mucronata not tested). Exposure to differing carbon dioxide levels had no overall significant impact on the respiration or excretion rates. Species from the ETNA were less tolerant to low oxygen levels than E. mucronata from the ETSP, which survived exposure to anoxia at 13 °C. Respiration and excretion rates were reduced upon exposure to low oxygen levels, albeit at different species-specific levels. Reduction of the excretion and respiration rates in ETNA species occurred at a pO2 of 0.6 (P. abdominalis) and 2.4 kPa (U. vulgaris and E. gibboides) at OMZ temperatures. Such low oxygen levels are normally not encountered by these species in the ETNA. E. mucronata however regularly migrates into the strongly hypoxic to anoxic core of the ETSP OMZ. Exposure to low oxygen levels led to a strong reduction of respiration and ammonium excretion in E. mucronata (pcrit respiration = 0.6, pcrit NH4-excretion = 0.73). A drastic reduction of respiratory activity was also observed by other authors for euphausiids, squat lobsters and calanoid copepods, but was not yet accounted for when calculating DVM-mediated active fluxes into the ETSP OMZ. Current estimates of DVM-mediated active export of carbon and nitrogen into the ETSP OMZ are therefore likely too high and future efforts to calculate these export rates should take the physiological responses of migratory species to OMZ conditions into account.

Investigations Regarding Anesthesia during Hypovolemic Conditions.

DTIC Science & Technology

1982-09-25

i / b ,- 18 For each level of hemoglobin, the equation was "normalized" to a pH of 7.400 for a BE of zero and a PCO of 40.0 torr, Orr et al. (171...the shifted BE values. Curve nomogram. Using the equations resulting from the above curve- fitting procedure, we calculated the relationship between pH...model for a given BE (i.e., pH = m i log PCO 2 + bi). Solve the following set of equations for pHind and log dX - 0 d(PHind) where X = (pHl - pHind) 2

Oysters and eelgrass: potential partners in a high pCO2 ocean.

PubMed

Groner, Maya L; Burge, Colleen A; Cox, Ruth; Rivlin, Natalie; Turner, Mo; Van Alstyne, Kathryn L; Wyllie-Echeverria, Sandy; Bucci, John; Staudigel, Philip; Friedman, Carolyn S

2018-05-25

Climate change is affecting the health and physiology of marine organisms and altering species interactions. Ocean acidification (OA) threatens calcifying organisms such as the Pacific oyster, Crassostrea gigas. In contrast, seagrasses, such as the eelgrass Zostera marina, can benefit from the increase in available carbon for photosynthesis found at a lower seawater pH. Seagrasses can remove dissolved inorganic carbon from OA environments, creating local daytime pH refugia. Pacific oysters may improve the health of eelgrass by filtering out pathogens such as Labyrinthula zosterae (LZ), which causes eelgrass wasting disease (EWD). We examined how co-culture of eelgrass ramets and juvenile oysters affected the health and growth of eelgrass and the mass of oysters under different pCO 2 exposures. In Phase I, each species was cultured alone or in co-culture at 12°C across ambient, medium, and high pCO 2 conditions, (656, 1158 and1606 μatm pCO 2 , respectively). Under high pCO 2 , eelgrass grew faster and had less severe EWD (contracted in the field prior to the experiment). Co-culture with oysters also reduced the severity of EWD. While the presence of eelgrass decreased daytime pCO 2 , this reduction was not substantial enough to ameliorate the negative impact of high pCO 2 on oyster mass. In Phase II, eelgrass alone or oysters and eelgrass in co-culture were held at 15°C under ambient and high pCO 2 conditions, (488 and 2013 μatm pCO 2 , respectively). Half of the replicates were challenged with cultured LZ. Concentrations of defensive compounds in eelgrass (total phenolics and tannins), were altered by LZ exposure and pCO 2 treatments. Greater pathogen loads and increased EWD severity were detected in LZ exposed eelgrass ramets; EWD severity was reduced at high relative to low pCO 2 . Oyster presence did not influence pathogen load or EWD severity; high LZ concentrations in experimental treatments may have masked the effect of this treatment. Collectively, these results indicate that, when exposed to natural concentrations of LZ under high pCO 2 conditions, eelgrass can benefit from co-culture with oysters. Further experimentation is necessary to quantify how oysters may benefit from co-culture with eelgrass, examine these interactions in the field and quantify context-dependency. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Pacific-wide contrast highlights resistance of reef calcifiers to ocean acidification.

PubMed

Comeau, S; Carpenter, R C; Nojiri, Y; Putnam, H M; Sakai, K; Edmunds, P J

2014-09-07

Ocean acidification (OA) and its associated decline in calcium carbonate saturation states is one of the major threats that tropical coral reefs face this century. Previous studies of the effect of OA on coral reef calcifiers have described a wide variety of outcomes for studies using comparable partial pressure of CO2 (pCO2) ranges, suggesting that key questions remain unresolved. One unresolved hypothesis posits that heterogeneity in the response of reef calcifiers to high pCO2 is a result of regional-scale variation in the responses to OA. To test this hypothesis, we incubated two coral taxa (Pocillopora damicornis and massive Porites) and two calcified algae (Porolithon onkodes and Halimeda macroloba) under 400, 700 and 1000 μatm pCO2 levels in experiments in Moorea (French Polynesia), Hawaii (USA) and Okinawa (Japan), where environmental conditions differ. Both corals and H. macroloba were insensitive to OA at all three locations, while the effects of OA on P. onkodes were location-specific. In Moorea and Hawaii, calcification of P. onkodes was depressed by high pCO2, but for specimens in Okinawa, there was no effect of OA. Using a study of large geographical scale, we show that resistance to OA of some reef species is a constitutive character expressed across the Pacific. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

The interacting effects of nutrient enrichment and ocean acidification on the growth and physiology of the macroalgae Ulva sp.

NASA Astrophysics Data System (ADS)

Reidenbach, L. B.; Hurd, C. L.; Kubler, J.; Fernandez, P. A.; Leal, P. P.; Noisette, F.; Revill, A. T.; McGraw, C. M.

2016-02-01

Ocean acidification, caused by the increased absorption of carbon dioxide in the ocean, changes the carbon chemistry in the seawater, decreases pH, and alters the chemical speciation of some nitrogenous compounds, such as ammonium. The green macroalgae Ulva spp. are intertidal species that occur worldwide. Ocean acidification may alter the growth response of Ulva sp. to increased nutrients by altering the photosynthetic and nutrient physiology of the algae as well as the bioavailability of nutrients. To determine if there is an interactive effect between ocean acidification and nutrient enrichment Ulva sp. were grown in the lab in a cross of three pCO2 levels under ambient and enriched ammonium concentrations. We predicted that the growth rates of Ulva sp. in ammonium enriched treatments would be enhanced by increased pCO2 relative to those in ambient ammonium concentrations. While growth rate, relative electron transport rates, and chlorophyll content were enhanced by enriched ammonium, there was no interactive effect of high pCO2 and ammonium enrichment. Ammonium uptake rates and ammonium pools were not affected by the pH and ammonium interaction, but nitrate reductase activity increased in the high pCO2, high ammonium treatments. Increased pCO2 has been found to increase Ulva sp. growth rates under some conditions, but this was not the case in this set of experiments. To make realistic predictions of Ulva sp. abundances into the future, based on better understanding of their physiology, ocean acidification experiments should include additional environmental variables such as light intensity and macronutrient supplies that may simultaneously be affected by climate change.

PCoD Lite - Using an Interim PCoD Protocol to Assess the Effects of Disturbance Associated with US Navy Exercises on Marine Mammal Populations

DTIC Science & Technology

2014-09-30

1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. PCoD Lite - Using an Interim PCoD Protocol to Assess...Skookum Tom Road Friday Harbor, WA, USA phone: 1-360-370-5493 email: jw@smrullc.com Award Number: N000141410406 http://www.smrumarine.com/ pcod ...DATE 30 SEP 2014 2. REPORT TYPE 3. DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE PCoD Lite - Using an Interim PCoD Protocol to

Towards better GNSS observations at the new IGS reference station BRUX: multipath mitigation and individual antenna calibration

NASA Astrophysics Data System (ADS)

Aerts, W.; Baire, Q.; Bruyninx, C.; Legrand, J.; Pottiaux, E.

2012-12-01

A new multi-GNSS IGS reference station, BRUX, has been installed at Brussels. It replaces the former IGS reference station BRUS, which had to be dismantled because of construction works. The antenna of BRUX is sited on top of a telescope dome. Although this might be an unfortunate choice from an electromagnetic point of view, the siting is very convenient for other reasons. Being close to the time lab hosting the atomic clocks, the cable length is within acceptable and affordable limits, both for cost and signal loss reasons. Moreover, the site offers open sky view, which can indeed be expected from a former telescope siting. The dome is entirely metal, hence shielding of the dome was required in order to mitigate multipath propagation. This was achieved using a metal shield topped with RF absorbing material and respecting a certain antenna-to-absorber spacing in order not to alter the antenna phase center offset (PCO) and variations (PCVs) too much. This would otherwise render the individual calibration of the antenna, in an anechoic chamber in the case of BRUX, invalid. But even taking all precautions, the PCO and PCVs of the calibration do not exactly equal those after installation. Moreover, different calibrations, in an anechoic chamber and by an outdoor robot, of the same antenna have shown to result in PCO and PCVs that differ up to several mm at certain azimuths and elevations. A test set-up with 6 such redundantly calibrated GNSS antennas revealed that the calibration differences can reach 8 mm on the ionosphere-free frequency, which amplifies the calibration differences by a factor three compared to L1 and L2 only. The use of different receiver antenna calibration models can impact position at almost the centimeter level. In an attempt to align the historical time series for BRUS with the (future) data for BRUX, the tie between the new station BRUX and the old IGS station BRUS was determined using terrestrial measurements as well as GPS. In the case of GPS, several L1, L2 and ionosphere-free baseline measurements were performed using state-of-the-art type-mean receiver antenna calibrations as well as individual calibrations. Differences between the different GPS measurements are several mm, while the differences between the terrestrial tie and the GPS ties reaches almost the cm-level. One contribution to the error budget is the absence of an individual calibration for the BRUS antenna, another one is the difference in PCO and PCVs on site, as opposed to at calibration, as already mentioned.

The penalty of a long, hot summer. Photosynthetic acclimation to high CO2 and continuous light in "living fossil" conifers.

PubMed

Osborne, Colin P; Beerling, David J

2003-10-01

Deciduous forests covered the ice-free polar regions 280 to 40 million years ago under warm "greenhouse" climates and high atmospheric pCO2. Their deciduous habit is frequently interpreted as an adaptation for minimizing carbon losses during winter, but experiments with "living fossils" in a simulated warm polar environment refute this explanation. Measured carbon losses through leaf abscission of deciduous trees are significantly greater than losses through winter respiration in evergreens, yet annual rates of primary productivity are similar in all species. Here, we investigate mechanisms underlying this apparent paradox by measuring the seasonal patterns of leaf photosynthesis (A) under pCO2 enrichment in the same trees. During spring, A increased significantly in coastal redwood (Sequoia sempervirens), dawn redwood (Metasequoia glyptostroboides), and swamp cypress (Taxodium distichum) at an elevated pCO2 of 80 Pa compared with controls at 40 Pa. However, strong acclimation in Rubisco carboxylation capacity (Vc,max) completely offset the CO2 response of A in all species by the end of 6 weeks of continuous illumination in the simulated polar summer. Further measurements demonstrated the temporary nature of acclimation, with increases in Vc,max during autumn restoring the CO2 sensitivity of A. Contrary to expectations, the acclimation of Vc,max was not always accompanied by accumulation of leaf carbohydrates, but was associated with a decline in leaf nitrogen in summer, suggesting an alteration of the balance in plant sources and sinks for carbon and nitrogen. Preliminary calculations using A indicated that winter carbon losses through deciduous leaf abscission and respiration were recovered by 10 to 25 d of canopy carbon fixation during summer, thereby explaining the productivity paradox.

The Penalty of a Long, Hot Summer. Photosynthetic Acclimation to High CO2 and Continuous Light in “Living Fossil” Conifers1

PubMed Central

Osborne, Colin P.; Beerling, David J.

2003-01-01

Deciduous forests covered the ice-free polar regions 280 to 40 million years ago under warm “greenhouse” climates and high atmospheric pCO2. Their deciduous habit is frequently interpreted as an adaptation for minimizing carbon losses during winter, but experiments with “living fossils” in a simulated warm polar environment refute this explanation. Measured carbon losses through leaf abscission of deciduous trees are significantly greater than losses through winter respiration in evergreens, yet annual rates of primary productivity are similar in all species. Here, we investigate mechanisms underlying this apparent paradox by measuring the seasonal patterns of leaf photosynthesis (A) under pCO2 enrichment in the same trees. During spring, A increased significantly in coastal redwood (Sequoia sempervirens), dawn redwood (Metasequoia glyptostroboides), and swamp cypress (Taxodium distichum) at an elevated pCO2 of 80 Pa compared with controls at 40 Pa. However, strong acclimation in Rubisco carboxylation capacity (Vc,max) completely offset the CO2 response of A in all species by the end of 6 weeks of continuous illumination in the simulated polar summer. Further measurements demonstrated the temporary nature of acclimation, with increases in Vc,max during autumn restoring the CO2 sensitivity of A. Contrary to expectations, the acclimation of Vc,max was not always accompanied by accumulation of leaf carbohydrates, but was associated with a decline in leaf nitrogen in summer, suggesting an alteration of the balance in plant sources and sinks for carbon and nitrogen. Preliminary calculations using A indicated that winter carbon losses through deciduous leaf abscission and respiration were recovered by 10 to 25 d of canopy carbon fixation during summer, thereby explaining the productivity paradox. PMID:12972654

Extending isotopic fractionation in phytoplankton for Phanerozoic pCO2 reconstruction

NASA Astrophysics Data System (ADS)

Witkowski, C. R.; Agostini, S.; Weijers, J.; Schouten, S.; S Sinninghe Damsté, J.

2017-12-01

The atmospheric concentration of carbon dioxide (pCO2) is a keystone in many earth system dynamics, including the biosphere, carbon cycle, and climate. In order to better understand the impact of today's exceptional increases in pCO2 on the future, we look to secular trends in pCO2. Photosynthetic carbon isotopic fractionation (Ɛp), calculated from the difference between the stable carbon isotopic composition (δ13C) of environmental CO2 and biomass, has some of the lowest uncertainty in estimation among CO2 proxies. However, Ɛp is generally applied to species-specific compounds which have an evolution-limited record (e.g. alkenones limited ca. 50 Ma). To extend the use of Ɛp, we explore the general phytoplankton biomarker phytane. As the fossilized side-chain of chlorophyll, phytane is spatially and temporally ubiquitous, with the potential to record pCO2 back to the earliest photoautotrophs in the geologic record. To develop and validate its potential as a pCO2 proxy, we explored phytane in modern environments, in a multi-proxy case study, and in a Phanerozoic reconstruction. As a proof-of-concept, the δ13C of phytane was tested in modern environments at naturally-occurring CO2 vents in Japan and Italy, which showed clear fractionation over the steep CO2 gradient. This was then further tested in a multi-proxy assessment in DSDP site 467 that spans the last 15 Ma, looking at both well-established (i.e. alkenones) and potential (i.e. phytane, steranes, hopanes) pCO2 proxies; phytane represented the average δ13C for these biomarkers. Finally, the δ13C of phytane data over the Phanerozoic was compiled, showing agreement with literature reconstructions of pCO2. Current pCO2 reconstructions are derived from many different types of proxies, which can create incongruities and inconsistencies throughout time, making this single well-constrained proxy that ubiquitously spans the geologic record a useful addition to the palaeo-detective's toolbox.

Surface Ocean pCO2 Seasonality and Sea-Air CO2 Flux Estimates for the North American East Coast

NASA Technical Reports Server (NTRS)

Signorini, Sergio; Mannino, Antonio; Najjar, Raymond G., Jr.; Friedrichs, Marjorie A. M.; Cai, Wei-Jun; Salisbury, Joe; Wang, Zhaohui Aleck; Thomas, Helmuth; Shadwick, Elizabeth

2013-01-01

Underway and in situ observations of surface ocean pCO2, combined with satellite data, were used to develop pCO2 regional algorithms to analyze the seasonal and interannual variability of surface ocean pCO2 and sea-air CO2 flux for five physically and biologically distinct regions of the eastern North American continental shelf: the South Atlantic Bight (SAB), the Mid-Atlantic Bight (MAB), the Gulf of Maine (GoM), Nantucket Shoals and Georges Bank (NS+GB), and the Scotian Shelf (SS). Temperature and dissolved inorganic carbon variability are the most influential factors driving the seasonality of pCO2. Estimates of the sea-air CO2 flux were derived from the available pCO2 data, as well as from the pCO2 reconstructed by the algorithm. Two different gas exchange parameterizations were used. The SS, GB+NS, MAB, and SAB regions are net sinks of atmospheric CO2 while the GoM is a weak source. The estimates vary depending on the use of surface ocean pCO2 from the data or algorithm, as well as with the use of the two different gas exchange parameterizations. Most of the regional estimates are in general agreement with previous studies when the range of uncertainty and interannual variability are taken into account. According to the algorithm, the average annual uptake of atmospheric CO2 by eastern North American continental shelf waters is found to be between 3.4 and 5.4 Tg C/yr (areal average of 0.7 to 1.0 mol CO2 /sq m/yr) over the period 2003-2010.

Late Triassic tropical climate of Pangea: Carbon isotopic and other insights into the rise of dinosaurs

NASA Astrophysics Data System (ADS)

Whiteside, J. H.; Lindström, S.; Irmis, R. B.; Glasspool, I.; Schaller, M. F.; Dunlavey, M.; Nesbitt, S. J.; Smith, N. D.; Turner, A. H.

2015-12-01

The rarity and species-poor nature of early dinosaurs and their relatives at low paleolatitudes persisted for 30 million years after their origin and 10-15 million years after they became abundant and speciose at higher latitudes. New environmental reconstructions from stable carbon isotope ratios of preserved organic matter (δ13Corg), atmospheric pCO2 data based on the δ13C of soil carbonate, palynological, and wildfire data from charcoal from early dinosaur-bearing strata at low paleolatitudes in western North America show that variations in δ13Corg and palynomorph ecotypes are tightly correlated, displaying large and high-frequency excursions. These variations occurred within an environment characterized by elevated and increasing atmospheric pCO2, pervasive wildfires, and rapidly fluctuating extreme climatic conditions. Whereas pseudosuchian archosaur-dominated communities were able to persist in these same regions until the end-Triassic, the large-bodied, fast-growing tachymetabolic dinosaurian herbivores were not. We hypothesize that the greater resources required by the herbivores made it difficult from them to adapt to the unstable conditions at low paleolatitudes in the Late Triassic.

Eutrophication and warming-driven green tides (Ulva rigida) are predicted to increase under future climate change scenarios.

PubMed

Gao, Guang; Clare, Anthony S; Rose, Craig; Caldwell, Gary S

2017-01-15

The incidence and severity of extraordinary macroalgae blooms (green tides) are increasing. Here, climate change (ocean warming and acidification) impacts on life history and biochemical responses of a causative green tide species, Ulva rigida, were investigated under combinations of pH (7.95, 7.55, corresponding to lower and higher pCO 2 ), temperature (14, 18°C) and nitrate availability (6 and 150μmolL -1 ). The higher temperature accelerated the onset and magnitude of gamete settlement. Any two factor combination promoted germination and accelerated growth in young plants. The higher temperature increased reproduction, which increased further in combination with elevated pCO 2 or nitrate. Reproductive success was highest (64.4±5.1%) when the upper limits of all three variables were combined. Biochemically, more protein and lipid but less carbohydrate were synthesized under higher temperature and nitrate conditions. These results suggest that climate change may cause more severe green tides, particularly when eutrophication cannot be effectively controlled. Copyright © 2016 Elsevier Ltd. All rights reserved.

History of blood gas analysis. II. pH and acid-base balance measurements.

PubMed

Severinghaus, J W; Astrup, P B

1985-10-01

Electrometric measurement of the hydrogen ion concentration was discovered by Wilhelm Ostwald in Leipzig about 1890 and described thermodynamically by his student Walther Nernst, using the van't Hoff concept of osmotic pressure as a kind of gas pressure, and the Arrhenius concept of ionization of acids, both of which had been formalized in 1887. Hasselbalch, after adapting the pH nomenclature of Sørensen to the carbonic-acid mass equation of Henderson, made the first actual blood pH measurements (with a hydrogen electrode) and proposed that metabolic acid-base imbalance be quantified as the "reduced" pH of blood after equilibration to a carbon dioxide tension (PCO2) of 40 mm Hg. This good idea, coming 40 years before simple blood pH measurements at 37 degrees C became widely available, was never adopted. Instead, Van Slyke developed a concept of acid-base chemistry that depended on measuring plasma CO2 content with his manometric apparatus, a standard method until the 1960s, when it was displaced by the three-electrode method of blood gas analysis. The 1952 polio epidemic in Copenhagen stimulated Astrup to develop a glass electrode in which pH could be measured in blood at 37 degrees C before and after equilibration with known PCO2. He introduced the interpolative measurement of PCO2 and bicarbonate level (later base excess) using only pH measurements and, with Siggaard-Andersen, developed clinical acid-base chemistry. Controversy arose when blood base excess was noted to be altered by acute changes in PCO2 and when abnormalities of base excess were called metabolic acidosis or alkalosis, even when they represented compensation for respiratory abnormalities in PCO2. In the 1970s it became clear that "in-vivo" or "extracellular fluid" base excess (measured at an average extracellular fluid hemoglobin concentration of 5 g) eliminated the error caused by acute changes in PCO2. Base excess is now almost universally used as the index of nonrespiratory acid-base imbalance.

Sea urchin fertilization in a warm, acidified and high pCO2 ocean across a range of sperm densities.

PubMed

Byrne, Maria; Soars, Natalie; Selvakumaraswamy, Paulina; Dworjanyn, Symon A; Davis, Andrew R

2010-05-01

Marine invertebrate gametes are being spawned into an ocean simultaneously warming, acidifying and increasing in pCO(2). Decreased pH/increased pCO(2) narcotizes sperm indicating that acidification may impair fertilization, exacerbating problems of sperm limitation, with dire implications for marine life. In contrast, increased temperature may have a stimulatory effect, enhancing fertilization. We investigated effects of ocean change on sea urchin fertilization across a range of sperm densities. We address two predictions: (1) low pH/increased pCO(2) reduces fertilization at low sperm density and (2) increased temperature enhances fertilization, buffering negative effects of acidification and increased pCO(2). Neither prediction was supported. Fertilization was only affected by sperm density. Increased acidification and pCO(2) did not reduce fertilization even at low sperm density and increased temperature did not enhance fertilization. It is important to identify where vulnerabilities lie across life histories and our results indicate that sea urchin fertilization is robust to climate change stressors. However, developmental stages may be vulnerable to ocean change. Copyright 2009 Elsevier Ltd. All rights reserved.

Assessment of acidification and eutrophication in the coastal waters of Bolinao, Pangasinan, Philippines

NASA Astrophysics Data System (ADS)

Lagumen, M. C. T.; San Diego-McGlone, M. L.

2014-12-01

Ocean acidification is becoming a global concern due to its potential effects on marine resources. In coastal areas, an emerging problem is ocean acidicification due to eutrophication resulting from human activities. The coastal water of Bolinao, Pangasinan, Philippines has become eutrophic due to increased nutrient loading from unconsumed fish feeds in fish cages. Mariculture is a big industry in Bolinao. In over a decade, the area has experienced decreased oxygen levels leading to hypoxia, fish kills, and algal blooms. The decomposition of organic matter from unconsumed fish feeds results not only to high nutrient buildup but also increased CO2 and acidity in the area. Nutrients (ammonia, nitrate, nitrite, phosphate and silicate), total alkalinity (TA), dissolved inorganic carbon (DIC), pH, dissolved oxygen (DO), aragonite saturation state (Ωarg) and partial pressure of carbon dioxide (pCO2) were measured to determine the combined effect of acidification and eutrophication in Bolinao. Monitoring results have shown an increase in nutrients by 30% to 70% in over a decade. Stratified water during rainy season have resulted in low DO (<5.5) and acidic water (<7.5) with high pCO2 level (>900 μatm). Shallow stations with poor water circulation have shown undersaturated aragonite state (< 2.0) and high pCO2 levels of 800 matm. The eutrophic and acidified coastal waters of Bolinao are already affecting the seagrass and coral reef ecosystems in the area.

Toxic effects of Pb2+ entering sperm through Ca2+ channels in the freshwater crab Sinopotamon henanense.

PubMed

Li, Na; Xu, Peng; Jing, Wei-Xin; Hwang, Jiang-Shiou; Wang, Lan

2017-11-01

Lead (Pb) is a heavy metal that can damage animal sperm. To study the effects of Pb on calcium homeostasis and calcium channel in the sperm of freshwater crab Sinopotamon henanense, the induction of acrosome reaction (AR) and acrosin activity were investigated when crabs were exposed to different Pb concentrations (0, 3.675, 7.35, 14.7, 29.4 and 58.8mg/L) for 3, 5 and 7 d separately. Fluorescent probe Fluo-3/AM was loaded into the sperm, and [Ca 2+ ] in the sperm was measured by fluorescence microscopy and using microplate reader. The calmodulin (CaM) concentration was measured by ELISA method. Verapamil (VRP), a calcium channel blocker, was used to evaluate whether Pb can enter the sperm through calcium channels leading to sperm damage. After sperm were exposed at 50μg/L VRP, 100μg/L Pb, 50μg/L VRP+100μg/L Pb, 1000μg/L Pb and 50μg/L VRP+1000μg/L Pb for 1h in vitro，sperm quality parameters (sperm survival and sperm DNA integrity) and levels of parameters indicating oxidative stress (protein carbonylation [PCO] and malondialdehyde [MDA]) were measured. Our data showed that Pb reduced the induction of acrosome reaction (AR), down-regulated the acrosin activity, decreased the intracellular concentration of Ca 2+ and elevated CaM concentration. Compared to controls, Pb alone induced significant stress, as reflected by decreasing sperm survival and sperm DNA integrity, and increasing PCO and MDA contents. In the presence of VRP, 100μg/L Pb-induced stresses were reduced, all the measured parameters in the sperm exposed at 100μg/L Pb returned to control levels. Our results indicate that Pb enters the sperm of the crab S. henanense through calcium channels, the inhibition of which blocks Pb-induced stresses such as sperm quality decline and oxidative damage. Copyright © 2017 Elsevier B.V. All rights reserved.

Efficient degradation of H2S over transition metal modified TiO2 under VUV irradiation: Performance and mechanism

NASA Astrophysics Data System (ADS)

Liu, Gaoyuan; Ji, Jian; Hu, Peng; Lin, Sixin; Huang, Haibao

2018-03-01

Odor pollution causes great harm to the atmospheric environment and human health. H2S, as an odor gas, is highly toxic and corrosive and thus requires removal efficiently. In this study, TiO2 catalysts modified by transition metals including Mn, Cu, Ni and Co, were prepared using a modified sol-gelatin method and tested under UV-PCO or VUV-PCO process. H2S degradation was great enhanced in VUV-PCO compared with conventional UV-PCO. Among the catalysts, 1 wt% Mn-TiO2 showed the highest removal efficiency of 89.9%, which is 30 times higher than that under 254 nm UV irradiation. Residual ozone in the outlet can be completely eliminated by Mn-TiO2. Photocatalytic oxidation, photolysis and ozone-assisted catalytic oxidation all involved in the VUV-PCO process and their contribution were determined by H2S removal efficiency.

Methane and Carbon Dioxide Concentrations and Fluxes in Amazon Floodplains

NASA Astrophysics Data System (ADS)

Melack, J. M.; MacIntyre, S.; Forsberg, B.; Barbosa, P.; Amaral, J. H.

2016-12-01

Field studies on the central Amazon floodplain in representative aquatic habitats (open water, flooded forests, floating macrophytes) combine measurements of methane and carbon dioxide concentrations and fluxes to the atmosphere over diel and seasonal times with deployment of meteorological sensors and high-resolution thermistors and dissolved oxygen sondes. A cavity ringdown spectrometer is used to determine gas concentrations, and floating chambers and bubble collectors are used to measure fluxes. To further understand fluxes, we measured turbulence as rate of dissipation of turbulent kinetic energy based on microstructure profiling. These results allow calculations of vertical mixing within the water column and of air-water exchanges using surface renewal models. Methane and carbon dioxide fluxes varied as a function of season, habitat and water depth. High CO2 fluxes at high water are related to high pCO2; low pCO2 levels at low water result from increased phytoplankton uptake. CO2 fluxes are highest at turbulent open water sites, and pCO2 is highest in macrophyte beds. Fluxes and pCH4 are high in macrophyte beds.

Low pCO2 under sea-ice melt in the Canada Basin of the western Arctic Ocean

NASA Astrophysics Data System (ADS)

Kosugi, Naohiro; Sasano, Daisuke; Ishii, Masao; Nishino, Shigeto; Uchida, Hiroshi; Yoshikawa-Inoue, Hisayuki

2017-12-01

In September 2013, we observed an expanse of surface water with low CO2 partial pressure (pCO2sea) (< 200 µatm) in the Chukchi Sea of the western Arctic Ocean. The large undersaturation of CO2 in this region was the result of massive primary production after the sea-ice retreat in June and July. In the surface of the Canada Basin, salinity was low (< 27) and pCO2sea was closer to the air-sea CO2 equilibrium (˜ 360 µatm). From the relationships between salinity and total alkalinity, we confirmed that the low salinity in the Canada Basin was due to the larger fraction of meltwater input (˜ 0.16) rather than the riverine discharge (˜ 0.1). Such an increase in pCO2sea was not so clear in the coastal region near Point Barrow, where the fraction of riverine discharge was larger than that of sea-ice melt. We also identified low pCO2sea (< 250 µatm) in the depth of 30-50 m under the halocline of the Canada Basin. This subsurface low pCO2sea was attributed to the advection of Pacific-origin water, in which dissolved inorganic carbon is relatively low, through the Chukchi Sea where net primary production is high. Oxygen supersaturation (> 20 µmol kg-1) in the subsurface low pCO2sea layer in the Canada Basin indicated significant net primary production undersea and/or in preformed condition. If these low pCO2sea layers surface by wind mixing, they will act as additional CO2 sinks; however, this is unlikely because intensification of stratification by sea-ice melt inhibits mixing across the halocline.

Water bicarbonate modulates the response of the shore crab Carcinus maenas to ocean acidification.

PubMed

Maus, Bastian; Bock, Christian; Pörtner, Hans-O

2018-05-23

Ocean acidification causes an accumulation of CO 2 in marine organisms and leads to shifts in acid-base parameters. Acid-base regulation in gill breathers involves a net increase of internal bicarbonate levels through transmembrane ion exchange with the surrounding water. Successful maintenance of body fluid pH depends on the functional capacity of ion-exchange mechanisms and associated energy budget. For a detailed understanding of the dependence of acid-base regulation on water parameters, we investigated the physiological responses of the shore crab Carcinus maenas to 4 weeks of ocean acidification [OA, P(CO 2 ) w  = 1800 µatm], at variable water bicarbonate levels, paralleled by changes in water pH. Cardiovascular performance was determined together with extra-(pH e ) and intracellular pH (pH i ), oxygen consumption, haemolymph CO 2 parameters, and ion composition. High water P(CO 2 ) caused haemolymph P(CO 2 ) to rise, but pH e and pH i remained constant due to increased haemolymph and cellular [HCO 3 - ]. This process was effective even under reduced seawater pH and bicarbonate concentrations. While extracellular cation concentrations increased throughout, anion levels remained constant or decreased. Despite similar levels of haemolymph pH and ion concentrations under OA, metabolic rates, and haemolymph flow were significantly depressed by 40 and 30%, respectively, when OA was combined with reduced seawater [HCO 3 - ] and pH. Our findings suggest an influence of water bicarbonate levels on metabolic rates as well as on correlations between blood flow and pH e . This previously unknown phenomenon should direct attention to pathways of acid-base regulation and their potential feedback on whole-animal energy demand, in relation with changing seawater carbonate parameters.

Impact of Ocean Acidification on Energy Metabolism of Oyster, Crassostrea gigas—Changes in Metabolic Pathways and Thermal Response

PubMed Central

Lannig, Gisela; Eilers, Silke; Pörtner, Hans O.; Sokolova, Inna M.; Bock, Christian

2010-01-01

Climate change with increasing temperature and ocean acidification (OA) poses risks for marine ecosystems. According to Pörtner and Farrell [1], synergistic effects of elevated temperature and CO2-induced OA on energy metabolism will narrow the thermal tolerance window of marine ectothermal animals. To test this hypothesis, we investigated the effect of an acute temperature rise on energy metabolism of the oyster, Crassostrea gigas chronically exposed to elevated CO2 levels (partial pressure of CO2 in the seawater ~0.15 kPa, seawater pH ~ 7.7). Within one month of incubation at elevated Pco2 and 15 °C hemolymph pH fell (pHe = 7.1 ± 0.2 (CO2-group) vs. 7.6 ± 0.1 (control)) and Peco2 values in hemolymph increased (0.5 ± 0.2 kPa (CO2-group) vs. 0.2 ± 0.04 kPa (control)). Slightly but significantly elevated bicarbonate concentrations in the hemolymph of CO2-incubated oysters ([HCO− 3]e = 1.8 ± 0.3 mM (CO2-group) vs. 1.3 ± 0.1 mM (control)) indicate only minimal regulation of extracellular acid-base status. At the acclimation temperature of 15 °C the OA-induced decrease in pHe did not lead to metabolic depression in oysters as standard metabolism rates (SMR) of CO2-exposed oysters were similar to controls. Upon acute warming SMR rose in both groups, but displayed a stronger increase in the CO2-incubated group. Investigation in isolated gill cells revealed a similar temperaturedependence of respiration between groups. Furthermore, the fraction of cellular energy demand for ion regulation via Na+/K+-ATPase was not affected by chronic hypercapnia or temperature. Metabolic profiling using 1H-NMR spectroscopy revealed substantial changes in some tissues following OA exposure at 15 °C. In mantle tissue alanine and ATP levels decreased significantly whereas an increase in succinate levels was observed in gill tissue. These findings suggest shifts in metabolic pathways following OA-exposure. Our study confirms that OA affects energy metabolism in oysters and suggests that climate change may affect populations of sessile coastal invertebrates such as mollusks. PMID:20948910

Impact of global warming and rising CO2 levels on coral reef fishes: what hope for the future?

PubMed

Munday, Philip L; McCormick, Mark I; Nilsson, Göran E

2012-11-15

Average sea-surface temperature and the amount of CO(2) dissolved in the ocean are rising as a result of increasing concentrations of atmospheric CO(2). Many coral reef fishes appear to be living close to their thermal optimum, and for some of them, even relatively moderate increases in temperature (2-4°C) lead to significant reductions in aerobic scope. Reduced aerobic capacity could affect population sustainability because less energy can be devoted to feeding and reproduction. Coral reef fishes seem to have limited capacity to acclimate to elevated temperature as adults, but recent research shows that developmental and transgenerational plasticity occur, which might enable some species to adjust to rising ocean temperatures. Predicted increases in P(CO(2)), and associated ocean acidification, can also influence the aerobic scope of coral reef fishes, although there is considerable interspecific variation, with some species exhibiting a decline and others an increase in aerobic scope at near-future CO(2) levels. As with thermal effects, there are transgenerational changes in response to elevated CO(2) that could mitigate impacts of high CO(2) on the growth and survival of reef fishes. An unexpected discovery is that elevated CO(2) has a dramatic effect on a wide range of behaviours and sensory responses of reef fishes, with consequences for the timing of settlement, habitat selection, predator avoidance and individual fitness. The underlying physiological mechanism appears to be the interference of acid-base regulatory processes with brain neurotransmitter function. Differences in the sensitivity of species and populations to global warming and rising CO(2) have been identified that will lead to changes in fish community structure as the oceans warm and becomes more acidic; however, the prospect for acclimation and adaptation of populations to these threats also needs to be considered. Ultimately, it will be the capacity for species to adjust to environmental change over coming decades that will determine the impact of climate change on marine ecosystems.

21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Indwelling blood carbon dioxide partial pressure....1150 Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. (a) Identification. An indwelling blood carbon dioxide partial pressure PCO2 analyzer is a device that consists of a catheter-tip...

21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Indwelling blood carbon dioxide partial pressure....1150 Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. (a) Identification. An indwelling blood carbon dioxide partial pressure PCO2 analyzer is a device that consists of a catheter-tip...

21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Indwelling blood carbon dioxide partial pressure....1150 Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. (a) Identification. An indwelling blood carbon dioxide partial pressure PCO2 analyzer is a device that consists of a catheter-tip...

21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Indwelling blood carbon dioxide partial pressure....1150 Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. (a) Identification. An indwelling blood carbon dioxide partial pressure PCO2 analyzer is a device that consists of a catheter-tip...

Southern Ocean carbon-wind stress feedback

NASA Astrophysics Data System (ADS)

Bronselaer, Ben; Zanna, Laure; Munday, David R.; Lowe, Jason

2018-02-01

The Southern Ocean is the largest sink of anthropogenic carbon in the present-day climate. Here, Southern Ocean pCO2 and its dependence on wind forcing are investigated using an equilibrium mixed layer carbon budget. This budget is used to derive an expression for Southern Ocean pCO2 sensitivity to wind stress. Southern Ocean pCO2 is found to vary as the square root of area-mean wind stress, arising from the dominance of vertical mixing over other processes such as lateral Ekman transport. The expression for pCO2 is validated using idealised coarse-resolution ocean numerical experiments. Additionally, we show that increased (decreased) stratification through surface warming reduces (increases) the sensitivity of the Southern Ocean pCO2 to wind stress. The scaling is then used to estimate the wind-stress induced changes of atmospheric pCO_2 in CMIP5 models using only a handful of parameters. The scaling is further used to model the anthropogenic carbon sink, showing a long-term reversal of the Southern Ocean sink for large wind stress strength.

Effects of Co-Varying Diel-Cycling Hypoxia and pH on Growth in the Juvenile Eastern Oyster, Crassostrea virginica

PubMed Central

Keppel, Andrew G.; Breitburg, Denise L.; Burrell, Rebecca B.

2016-01-01

Shallow water provides important habitat for many species, but also exposes these organisms to daily fluctuations in dissolved oxygen (DO) and pH caused by cycles in the balance between photosynthesis and respiration that can contribute to repeated, brief periods of hypoxia and low pH (caused by elevated pCO2). The amplitude of these cycles, and the severity and duration of hypoxia and hypercapnia that result, can be increased by eutrophication, and are predicted to worsen with climate change. We conducted laboratory experiments to test the effects of both diel-cycling and constant low DO and pH (elevated pCO2) on growth of the juvenile eastern oyster (Crassostrea virginica), an economically and ecologically important estuarine species. Severe diel-cycling hypoxia (to 0.5 mg O2 L-1) reduced shell growth in juvenile oysters, as did constant hypoxia (1.2 and 2.0 mg O2 L-1), although effects varied among experiments, oyster ages, and exposure durations. Diel-cycling pH reduced growth only in experiments in which calcite saturation state cycled to ≤0.10 and only during the initial weeks of these experiments. In other cases, cycling pH sometimes led to increased growth rates. Comparisons of treatment effects across multiple weeks of exposure, and during a longer post-experiment field deployment, indicated that juvenile oysters can acclimate to, and in some cases compensate for initial reductions in growth. As a result, some ecosystem services dependent on juvenile oyster growth rates may be preserved even under severe cycling hypoxia and pH. PMID:27548256

Influence of pressurized carbon dioxide on ketoprofen-incorporated hot-melt extruded low molecular weight hydroxypropylcellulose.

PubMed

A Ashour, Eman; Kulkarni, Vijay; Almutairy, Bjad; Park, Jun-Bom; Shah, Sejal P; Majumdar, Soumyajit; Lian, Zhuoyang; Pinto, Elanor; Bi, Vivian; Durig, Thomas; Martin, Scott T; Repka, Michael A

2016-01-01

The aim of the current research project was to investigate the effect of pressurized carbon dioxide (P-CO 2 ) on the physico-mechanical properties of ketoprofen (KTP)-incorporated hydroxypropylcellulose (HPC) (Klucel™ ELF, EF, and LF) produced using hot-melt extrusion (HME) techniques and to assess the plasticization effect of P-CO 2 on the various polymers tested. The physico-mechanical properties of extrudates with and without injection of P-CO 2 were examined and compared with extrudates with the addition of 5% liquid plasticizer of propylene glycol (PG). The extrudates were milled and compressed into tablets. Tablet characteristics of the extrudates with and without injection of P-CO 2 were evaluated. P-CO 2 acted as a plasticizer for tested polymers, which allowed for the reduction in extrusion processing temperature. The microscopic morphology of the extrudates was changed to a foam-like structure due to the expansion of the CO 2 at the extrusion die. The foamy extrudates demonstrated enhanced KTP release compared with the extrudates processed without P-CO 2 due to the increase of porosity and surface area of those extrudates. Furthermore, the hardness of the tablets prepared by foamy extrudates was increased and the percent friability was decreased. Thus, the good binding properties and compressibility of the extrudates were positively influenced by utilizing P-CO 2 processing.

Influence of Pressurized Carbon Dioxide on Ketoprofen-Incorporated Hot-Melt Extruded Low Molecular Weight Hydroxypropylcellulose

PubMed Central

Ashour, Eman A.; Kulkarni, Vijay; Almutairy, Bjad; Park, Jun-Bom; Shah, Sejal; Majumdar, Soumyajit; Lian, Zhuoyang; Pinto, Elanor; Bi, Yunxia; Durig, Thomas; Martin, Scott T.; Repka, Michael A.

2017-01-01

Objectives The aim of the current research project was to investigate the effect of pressurized carbon dioxide (P-CO2) on the physico-mechanical properties of Ketoprofen (KTP)-incorporated hydroxypropylcellulose (HPC) (Klucel™ ELF, EF and LF) produced using hot melt extrusion (HME) techniques and to assess the plasticization effect of P-CO2 on the various polymers tested. Methods The physico-mechanical properties of extrudates with and without injection of P-CO2 were examined and compared to extrudates with the addition of 5% liquid plasticizer of propylene glycol (PG). The extrudates were milled and compressed into tablets. Tablet characteristics of the extrudates with and without injection of P-CO2 were evaluated. Results & conclusion P-CO2 acted as a plasticizer for tested polymers, which allowed for the reduction in extrusion processing temperature. The microscopic morphology of the extrudates were changed to a foam-like structure due to expansion of the CO2 at the extrusion die. The foamy extrudates demonstrated enhanced KTP release compared to the extrudates processed without P-CO2 due to the increase of porosity and surface area of those extrudates. Furthermore, the hardness of the tablets prepared by foamy extrudates was increased and the percent friability was decreased. Thus, the good binding properties and compressibility of the extrudates were positively influenced by utilizing P-CO2 processing. PMID:25997363

Effects of elevated dissolved carbon dioxide and perfluorooctane sulfonic acid, given singly and in combination, on steroidogenic and biotransformation pathways of Atlantic cod.

PubMed

Preus-Olsen, Gunnhild; Olufsen, Marianne O; Pedersen, Sindre Andre; Letcher, Robert J; Arukwe, Augustine

2014-10-01

In the aquatic environments, the predicted changes in water temperature, pO2 and pCO2 could result in hypercapnic and hypoxic conditions for aquatic animals. These conditions are thought to affect several basic cellular and physiological mechanisms. Yet, possible adverse effects of elevated CO2 (hypercapnia) on teleost fish, as well as combined effects with emerging and legacy environmental contaminants are poorly investigated. In this study, juvenile Atlantic cod (Gadus morhua) were divided into groups and exposed to three different water bath PFOS exposure regimes (0 (control), 100 and 200 μg L(-1)) for 5 days at 1h/day, followed by three different CO2-levels (normocapnia, moderate (0.3%) and high (0.9%)). The moderate CO2 level is the predicted near future (within year 2300) level, while 0.9% represent severe hypercapnia. Tissue samples were collected at 3, 6 and 9 days after initiated CO2 exposure. Effects on the endocrine and biotransformation systems were examined by analyzing levels of sex steroid hormones (E2, T, 11-KT) and transcript expression of estrogen responsive genes (ERα, Vtg-α, Vtg-β, ZP2 and ZP3). In addition, transcripts for genes encoding xenobiotic metabolizing enzymes (cyp1a and cyp3a) and hypoxia-inducible factor (HIF-1α) were analyzed. Hypercapnia alone produced increased levels of sex steroid hormones (E2, T, 11-KT) with concomitant mRNA level increase of estrogen responsive genes, while PFOS produced weak and time-dependent effects on E2-inducible gene transcription. Combined PFOS and hypercapnia exposure produced increased effects on sex steroid levels as compared to hypercapnia alone, with transcript expression patterns that are indicative of time-dependent interactive effects. Exposure to hypercapnia singly or in combination with PFOS produced modulations of the biotransformation and hypoxic responses that were apparently concentration- and time-dependent. Loading plots of principal component analysis (PCA) produced a significant grouping of individual scores according to the exposure scenarios at day 6 and 9. Overall, the PCA analysis produced a unique clustering of variables that signifies a positive correlation between exposure to high PFOS concentration and mRNA expression of E2 responsive genes. Notably, this pattern was not evident for individuals exposed to PFOS concentrations in combination with elevated CO2 scenarios. To our knowledge, the present study is the first of its kind, to evaluate such effects using combined exposure to a perfluoroalkyl sulfonate and elevated levels of CO2 saturation, representative of future oceanic climate change, in any fish species or lower vertebrate. Copyright © 2014 Elsevier B.V. All rights reserved.

Alkenone and boron-based Pliocene pCO 2 records

NASA Astrophysics Data System (ADS)

Seki, Osamu; Foster, Gavin L.; Schmidt, Daniela N.; Mackensen, Andreas; Kawamura, Kimitaka; Pancost, Richard D.

2010-03-01

The Pliocene period is the most recent time when the Earth was globally significantly (˜ 3 °C) warmer than today. However, the existing pCO 2 data for the Pliocene are sparse and there is little agreement between the various techniques used to reconstruct palaeo- pCO 2. This disagreement, coupled with the general low temporal resolution of the published records, does not allow a robust assessment of the role of declining pCO 2 in the intensification of the Northern Hemisphere Glaciation (INHG) and a direct comparison to other proxy records are lacking. For the first time, we use a combination of foraminiferal ( δ11B) and organic biomarker (alkenone-derived carbon isotopes) proxies to determine the concentration of atmospheric CO 2 over the past 5 Ma. Both proxy records show that during the warm Pliocene pCO 2 was between 330 and 400 ppm, i.e. similar to today. The decrease to values similar to pre-industrial times (275-285 ppm) occurred between 3.2 Ma and 2.8 Ma — coincident with the INHG and affirming the link between global climate, the cryosphere and pCO 2.

A 20 million year record of planktic foraminiferal B/Ca ratios: Systematics and uncertainties in pCO 2 reconstructions

NASA Astrophysics Data System (ADS)

Tripati, Aradhna K.; Roberts, Christopher D.; Eagle, Robert A.; Li, Gaojun

2011-05-01

We use new and published data representing a 20 million long record to discuss the systematics of interpreting planktic foraminiferal B/Ca ratios. B/Ca-based reconstructions of seawater carbonate chemistry and atmospheric pCO 2 assume that the incorporation of boron into foraminiferal tests can be empirically described by an apparent partition coefficient, KD={B/Ca}/{B(OH4-/HCO)} ( Hemming and Hanson, 1992). It has also been proposed that there is a species-specific relationship between K D and temperature ( Yu et al., 2007). As we discuss, although these relationships may be robust, there remain significant uncertainties over the controls on boron incorporation into foraminifera. It is difficult to be certain that the empirically defined correlation between temperature and K D is not simply a result of covariance of temperature and other hydrographic variables in the ocean, including carbonate system parameters. There is also some evidence that K D may be affected by solution [HCO3-]/[CO32-] ratios (i.e., pH), or by [CO32-]. In addition, the theoretical basis for the definition of K D and for a temperature control on K D is of debate. We also discuss the sensitivity of pCO 2 reconstructions to different K D-temperature calibrations and seawater B/Ca. If a K D-temperature calibration is estimated using ice core pCO 2 values between 0 and 200 ka, B/Ca ratios can be used to reasonably approximate atmospheric pCO 2 between 200 and 800 ka; however, the absolute values of pCO 2 calculated are sensitive to the choice of K D-temperature relationship. For older time periods, the absolute values of pCO 2 are also dependent on the evolution of seawater B concentrations. However, we find that over the last 20 Ma, reconstructed changes in declining pCO 2 across the Mid-Pleistocene Transition, Pliocene glacial intensification, and the Middle Miocene Climate Transition are supported by the B/Ca record even if a constant coretop K D is used, or different K D-temperature calibrations and models of seawater B evolution are applied to the data. The inferred influence of temperature on K D from coretop data therefore cannot itself explain the structure of a published pCO 2 reconstruction ( Tripati et al., 2009). We conclude the raw B/Ca data supports a coupling between pCO 2 and climate over the past 20 Ma. Finally, we explore possible implications of B/Ca-based pCO 2 estimates for the interpretation of other marine pCO 2 proxies.

Calculating the balance between atmospheric CO2 drawdown and organic carbon oxidation in subglacial hydrochemical systems

NASA Astrophysics Data System (ADS)

Graly, Joseph A.; Drever, James I.; Humphrey, Neil F.

2017-04-01

In order to constrain CO2 fluxes from biogeochemical processes in subglacial environments, we model the evolution of pH and alkalinity over a range of subglacial weathering conditions. We show that subglacial waters reach or exceed atmospheric pCO2 levels when atmospheric gases are able to partially access the subglacial environment. Subsequently, closed system oxidation of sulfides is capable of producing pCO2 levels well in excess of atmosphere levels without any input from the decay of organic matter. We compared this model to published pH and alkalinity measurements from 21 glaciers and ice sheets. Most subglacial waters are near atmospheric pCO2 values. The assumption of an initial period of open system weathering requires substantial organic carbon oxidation in only 4 of the 21 analyzed ice bodies. If the subglacial environment is assumed to be closed from any input of atmospheric gas, large organic carbon inputs are required in nearly all cases. These closed system assumptions imply that order of 10 g m-2 y-1 of organic carbon are removed from a typical subglacial environment—a rate too high to represent soil carbon built up over previous interglacial periods and far in excess of fluxes of surface deposited organic carbon. Partial open system input of atmospheric gases is therefore likely in most subglacial environments. The decay of organic carbon is still important to subglacial inorganic chemistry where substantial reserves of ancient organic carbon are found in bedrock. In glaciers and ice sheets on silicate bedrock, substantial long-term drawdown of atmospheric CO2 occurs.

Microanatomical bases for intraoperative division of the posterior communicating artery.

PubMed

Gabrovsky, N

2002-11-01

Micro-anatomical parameters of the hypoplastic posterior communicating artery (PCoA) are assessed and compared with the micro-anatomical parameters of the adult type PCoA. Based on the results obtained, the safest place is proposed for PCoA division during basilar tip aneurysm surgery via the pterional route. In 35 human cadaver brains, red coloured latex was injected and micro-anatomical dissection was performed. Seventy PCoA were found. Adult type PCoA was found in 29 cases (41.43%) with mean length 12.58 mm. Reduction of the PCoA diameter from its anterior to its posterior third by up to 20% was found in 27% and by more than 20% in 10% of the cases. The mean perforating vessel number was 8.17, distributed in each third: 3.48, 2.90 and 1.79, respectively. A hypoplastic PCoA was found in 33 cases (47.14%) with mean length 16.09 mm. The PCoA's diameter reduction by up to 20% was found in 24% and by more in 27% of the cases. In 6% of the cases an extreme reduction by up to 70% was observed. The mean perforating vessel (PV) number was 8.82, distributed in each third: 3.18, 3.36 and 2.27, respectively. Hypoplastic PCoA tends to be longer and with a more distinct diameter reduction from the anterior to the posterior third than the adult type PCoA. The PV anatomical parameters are similar for both groups. The posterior third of the PCoA seems to be the area where the risk of perforating vessel damage is the least when performing intra-operative PCoA division.

Calculating surface ocean pCO2 from biogeochemical Argo floats equipped with pH: An uncertainty analysis

NASA Astrophysics Data System (ADS)

Williams, N. L.; Juranek, L. W.; Feely, R. A.; Johnson, K. S.; Sarmiento, J. L.; Talley, L. D.; Dickson, A. G.; Gray, A. R.; Wanninkhof, R.; Russell, J. L.; Riser, S. C.; Takeshita, Y.

2017-03-01

More than 74 biogeochemical profiling floats that measure water column pH, oxygen, nitrate, fluorescence, and backscattering at 10 day intervals have been deployed throughout the Southern Ocean. Calculating the surface ocean partial pressure of carbon dioxide (pCO2sw) from float pH has uncertainty contributions from the pH sensor, the alkalinity estimate, and carbonate system equilibrium constants, resulting in a relative standard uncertainty in pCO2sw of 2.7% (or 11 µatm at pCO2sw of 400 µatm). The calculated pCO2sw from several floats spanning a range of oceanographic regimes are compared to existing climatologies. In some locations, such as the subantarctic zone, the float data closely match the climatologies, but in the polar Antarctic zone significantly higher pCO2sw are calculated in the wintertime implying a greater air-sea CO2 efflux estimate. Our results based on four representative floats suggest that despite their uncertainty relative to direct measurements, the float data can be used to improve estimates for air-sea carbon flux, as well as to increase knowledge of spatial, seasonal, and interannual variability in this flux.

[Changes in PCO2 and pH gradients in a canine model of experimental acute hemorrhage].

PubMed

Rabanal, J M; Mons, R; Galindo, M; Solares, G; Seco, I; García-Castrillo, L

1999-01-01

To study changes in arterial-venous PCO2 pressures (Da-vPCO2) and in pH (Da-vpH) in an experimental dog model of acute bleeding. To emphasize the utility of monitoring these variables in situations of acute bleeding. ANIMALS AND METHOD: Eighteen dogs were anesthesized and monitored while being subjected to gradual bleeding. Gasometric and hemodynamic variables were recorded at the following moments: baseline, stage I (15% of volemic loss), stage Ib (20%), stage II (25%), stage IIb (30%) and stage III (35%). No significant differences in pH or PCO2 in either arterial or mixed venous blood were found. Bleeding induced a constant and progressive increase in Da-vPCO2 that correlated with changes in volume (r = -0.56, p < 0.001), SvO2 (r = 0.71; p < 0.001), Da-vO2 gradient (r = 0.62; p < 0.001) and cardiac output (r = 0.63; p < 0.001). Gradual bleeding caused a constant and significant increase of Da-vPCO2. Monitoring such changes in states of circulatory insufficiency may be useful for evaluating tissue ischemia.

Estimating surface pCO2 in the northern Gulf of Mexico: Which remote sensing model to use?

NASA Astrophysics Data System (ADS)

Chen, Shuangling; Hu, Chuanmin; Cai, Wei-Jun; Yang, Bo

2017-12-01

Various approaches and models have been proposed to remotely estimate surface pCO2 in the ocean, with variable performance as they were designed for different environments. Among these, a recently developed mechanistic semi-analytical approach (MeSAA) has shown its advantage for its explicit inclusion of physical and biological forcing in the model, yet its general applicability is unknown. Here, with extensive in situ measurements of surface pCO2, the MeSAA, originally developed for the summertime East China Sea, was tested in the northern Gulf of Mexico (GOM) where river plumes dominate water's biogeochemical properties during summer. Specifically, the MeSAA-predicted surface pCO2 was estimated by combining the dominating effects of thermodynamics, river-ocean mixing and biological activities on surface pCO2. Firstly, effects of thermodynamics and river-ocean mixing (pCO2@Hmixing) were estimated with a two-endmember mixing model, assuming conservative mixing. Secondly, pCO2 variations caused by biological activities (ΔpCO2@bio) was determined through an empirical relationship between sea surface temperature (SST)-normalized pCO2 and MODIS (Moderate Resolution Imaging Spectroradiometer) 8-day composite chlorophyll concentration (CHL). The MeSAA-modeled pCO2 (sum of pCO2@Hmixing and ΔpCO2@bio) was compared with the field-measured pCO2. The Root Mean Square Error (RMSE) was 22.94 μatm (5.91%), with coefficient of determination (R2) of 0.25, mean bias (MB) of - 0.23 μatm and mean ratio (MR) of 1.001, for pCO2 ranging between 316 and 452 μatm. To improve the model performance, a locally tuned MeSAA was developed through the use of a locally tuned ΔpCO2@bio term. A multi-variate empirical regression model was also developed using the same dataset. Both the locally tuned MeSAA and the regression models showed improved performance comparing to the original MeSAA, with R2 of 0.78 and 0.84, RMSE of 12.36 μatm (3.14%) and 10.66 μatm (2.68%), MB of 0.00 μatm and - 0.10 μatm, MR of 1.001 and 1.000, respectively. A sensitivity analysis was conducted to study the uncertainties in the predicted pCO2 as a result of the uncertainties in the input variables of each model. Although the MeSAA was more sensitive to variations in SST and CHL than in sea surface salinity (SSS), and the locally tuned MeSAA and the empirical regression models were more sensitive to changes in SST and SSS than in CHL, generally for these three models the bias induced by the uncertainties in the empirically derived parameters (river endmember total alkalinity (TA) and dissolved inorganic carbon (DIC), biological coefficient of the MeSAA and locally tuned MeSAA models) and environmental variables (SST, SSS, CHL) was within or close to the uncertainty of each model. While all these three models showed that surface pCO2 was positively correlated to SST, the MeSAA showed negative correlation between surface pCO2 and SSS and CHL but the locally tuned MeSAA and the empirical regression showed the opposite. These results suggest that the locally tuned MeSAA worked better in the river-dominated northern GOM than the original MeSAA, with slightly worse statistics but more meaningful physical and biogeochemical interpretations than the empirical regression model. Because data from abnormal upwelling were not used to train the models, they are not applicable for waters with strong upwelling, yet the empirical regression approach showed ability to be further tuned to adapt to such cases.

Fiber-optic microsensor for high resolution pCO2 sensing in marine environment.

PubMed

Neurauter, G; Klimant, I; Wolfbeis, O S

2000-03-01

A fast responding fiber-optic microsensor for sensing pCO2 in marine sediments with high spatial resolution is presented. The tip diameter varies typically between 20 and 50 microm. In order to make the pH-indicator 8-hydroxypyrene-1,3,6-trisulfonate soluble in the ethyl cellulose matrix, it was lipophilized with tetraoctylammonium as the counterion [HPTS-(TOA)4]. The microsensor was tuned to sense very low levels of dissolved carbon dioxide which are typically present in marine systems. The detection limit is 0.04 hPa pCO2 which corresponds to 60 ppb CO2 of dissolved carbon dioxide. A soluble Teflon derivative with an extraordinarily high gas permeability was chosen as a protective coating to eliminate interferences by ionic species like chloride or pH. Response times of less than 1 min were observed. The performance of the new microsensor is described with respect to reproducibility of the calibration curves, dynamic range, temperature behavior, long term stability and storage stability. The effect of hydrogen sulfide as an interferent, which is frequently present in anaerobic sediment layers, was studied in detail.

Validating and comparing GNSS antenna calibrations

NASA Astrophysics Data System (ADS)

Kallio, Ulla; Koivula, Hannu; Lahtinen, Sonja; Nikkonen, Ville; Poutanen, Markku

2018-03-01

GNSS antennas have no fixed electrical reference point. The variation of the phase centre is modelled and tabulated in antenna calibration tables, which include the offset vector (PCO) and phase centre variation (PCV) for each frequency according to the elevations and azimuths of the incoming signal. Used together, PCV and PCO reduce the phase observations to the antenna reference point. The remaining biases, called the residual offsets, can be revealed by circulating and rotating the antennas on pillars. The residual offsets are estimated as additional parameters when combining the daily GNSS network solutions with full covariance matrix. We present a procedure for validating the antenna calibration tables. The dedicated test field, called Revolver, was constructed at Metsähovi. We used the procedure to validate the calibration tables of 17 antennas. Tables from the IGS and three different calibration institutions were used. The tests show that we were able to separate the residual offsets at the millimetre level. We also investigated the influence of the calibration tables from the different institutions on site coordinates by performing kinematic double-difference baseline processing of the data from one site with different antenna tables. We found small but significant differences between the tables.

The effects of thermal and high-CO2 stresses on the metabolism and surrounding microenvironment of the coral Galaxea fascicularis.

PubMed

Agostini, Sylvain; Fujimura, Hiroyuki; Higuchi, Tomihiko; Yuyama, Ikuko; Casareto, Beatriz E; Suzuki, Yoshimi; Nakano, Yoshikatsu

2013-08-01

The effects of elevated temperature and high pCO2 on the metabolism of Galaxea fascicularis were studied with oxygen and pH microsensors. Photosynthesis and respiration rates were evaluated from the oxygen fluxes from and to the coral polyps. High-temperature alone lowered both photosynthetic and respiration rates. High pCO2 alone did not significantly affect either photosynthesis or respiration rates. Under a combination of high-temperature and high-CO2, the photosynthetic rate increased to values close to those of the controls. The same pH in the diffusion boundary layer was observed under light in both (400 and 750 ppm) CO2 treatments, but decreased significantly in the dark as a result of increased CO2. The ATP contents decreased with increasing temperature. The effects of temperature on the metabolism of corals were stronger than the effects of increased CO2. The effects of acidification were minimal without combined temperature stress. However, acidification combined with higher temperature may affect coral metabolism due to the amplification of diel variations in the microenvironment surrounding the coral and the decrease in ATP contents. Copyright © 2013 Académie des sciences. Published by Elsevier SAS. All rights reserved.

Microsurgical clipping for the true posterior communicating artery aneurysm in the distal portion of the posterior communicating artery

PubMed Central

Takeda, Masaru; Kashimura, Hiroshi; Chida, Kohei; Murakami, Toshiyuki

2015-01-01

Background: Aneurysms arising from the posterior communicating artery (PCoA) itself are rare in which aneurysms usually located in the proximal portion of the PCoA. The authors report a case of the true PCoA ruptured aneurysm in the distal portion of the PCoA. Case Description: The patient was an 83-year-old man who suffered subarachnoid hemorrhage. Cerebral angiography revealed a saccular aneurysm arising on the fetal type right PCoA itself in the distal portion of the PCoA. 2 days after the onset of symptoms, the patient underwent right interfascial pterional craniotomy, with anterior temporal approach. The aneurysm was successfully clipped with the preservation of both the PCoA and the thalamoperforating artery. Conclusion: We speculated that blood flow into the PCoA gradually increased after occlusion of the left vertebral artery, which induced tortuosity of the PCoA. As a result, hemodynamic stress might increase near the curvature and cause aneurysm formation. PMID:26110082

Microsurgical clipping for the true posterior communicating artery aneurysm in the distal portion of the posterior communicating artery.

PubMed

Takeda, Masaru; Kashimura, Hiroshi; Chida, Kohei; Murakami, Toshiyuki

2015-01-01

Aneurysms arising from the posterior communicating artery (PCoA) itself are rare in which aneurysms usually located in the proximal portion of the PCoA. The authors report a case of the true PCoA ruptured aneurysm in the distal portion of the PCoA. The patient was an 83-year-old man who suffered subarachnoid hemorrhage. Cerebral angiography revealed a saccular aneurysm arising on the fetal type right PCoA itself in the distal portion of the PCoA. 2 days after the onset of symptoms, the patient underwent right interfascial pterional craniotomy, with anterior temporal approach. The aneurysm was successfully clipped with the preservation of both the PCoA and the thalamoperforating artery. We speculated that blood flow into the PCoA gradually increased after occlusion of the left vertebral artery, which induced tortuosity of the PCoA. As a result, hemodynamic stress might increase near the curvature and cause aneurysm formation.

Weight-correction of carbon dioxide diffusion coefficient (DCO2 ) reduces its inter-individual variability and improves its correlation with blood carbon dioxide levels in neonates receiving high-frequency oscillatory ventilation.

PubMed

Belteki, Gusztav; Lin, Benjamin; Morley, Colin J

2017-10-01

Carbon-dioxide elimination during high-frequency oscillatory ventilation (HFOV) is thought to be proportional to the carbon dioxide diffusion coefficient (DCO 2 ) which is calculated as frequency x (tidal volume) 2 . DCO 2 can be used to as an indicator of CO 2 elimination but values obtained in different patients cannot be directly compared. To analyze the relationship between DCO 2 , the weight-corrected DCO 2 (DCO 2 corr) and blood gas PCO 2 values obtained from infants receiving HFOV. DCO 2 data were obtained from 14 infants at 1/s sampling rate and the mean DCO 2 was determined over 10 min periods preceding the time of the blood gas. DCO 2 corr was calculated by dividing the DCO 2 by the square of the body weight in kg. Weight-correction significantly reduced the inter-individual variability of DCO 2 . When data from all the babies were combined, standard DCO 2 showed no correlation with PCO 2 but DCO 2 corr showed a weak but statistically significant inverse correlation. The correlation was better when the endotracheal leak was <10%. There was significant inverse but weaker correlation between the HFOV tidal volume (VThf) and the PCO 2 . In any baby, DCO 2 corr >50 mL 2 /sec/kg 2 or VThf > 2.5 mL/kg was rarely needed to avoid hypercapnia. Weight-correction of DCO 2 values improved its comparability between patients. Weight-corrected DCO 2 correlated better with PCO 2 than uncorrected DCO 2 but the correlation was weak. © 2017 Wiley Periodicals, Inc.

Low haemoglobin concentration in Tibetan males is associated with greater high-altitude exercise capacity.

PubMed

Simonson, T S; Wei, G; Wagner, H E; Wuren, T; Qin, G; Yan, M; Wagner, P D; Ge, R L

2015-07-15

Tibetans living at high altitude have adapted genetically such that many display a low erythropoietic response, resulting in near sea-level haemoglobin (Hb) concentration. We hypothesized that absence of the erythropoietic response would be associated with greater exercise capacity compared to those with high [Hb] as a result of beneficial changes in oxygen transport. We measured, in 21 Tibetan males with [Hb] ranging from 15.2 g dl(-1) to 22.9 g dl(-1) (9.4 mmol l(-1) to 14.2 mmol l(-1) ), [Hb], ventilation, volumes of O2 and CO2 utilized at peak exercise (V̇O2 and V̇CO2), heart rate, cardiac output and arterial blood gas variables at peak exercise on a cycle ergometer at ∼4200 m. Lung and muscle O2 diffusional conductances were computed from these measurements. [Hb] was related (negatively) to V̇O2 kg(-1) (r = -0.45, P< 0.05), cardiac output kg(-1) (QT kg(-1) , r = -0.54, P < 0.02), and O2 diffusion capacity in muscle (DM kg(-1) , r = -0.44, P<0.05), but was unrelated to ventilation, arterial partial pressure of O2 (PaO2) or pulmonary diffusing capacity. Using multiple linear regression, variance in peak V̇O2 kg(-1) was primarily attributed to QT, DM, and PCO2 (R(2) = 0.88). However, variance in pulmonary gas exchange played essentially no role in determining peak V̇O2. These results (1) show higher exercise capacity in Tibetans without the erythropoietic response, supported mostly by cardiac and muscle O2 transport capacity and ventilation rather than pulmonary adaptations, and (2) support the emerging hypothesis that the polycythaemia of altitude, normally a beneficial response to low cellular PO2, may become maladaptive if excessively elevated under chronic hypoxia. The cause and effect relationships among [Hb], QT, DM, and PCO2 remain to be elucidated. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

Fenestrations and Various Duplications of the Posterior Communicating Artery in the Prenatal and Postnatal Periods.

PubMed

Trandafilović, Milena; Vasović, Ljiljana; Vlajković, Slobodan; Đorđević, Gordana; Stojanović, Borisav; Mladenović, Marija

2016-07-01

The 2 paired arteries-the posterior communicating arteries (PCoAs) and the precommunicating parts of the posterior cerebral arteries-form the so-called posterior segment of the cerebral arterial circle on the base of the brain. A number of (ab)normal morphologic features were described in the literature (e.g., unusual kinking, or extreme elongations, hypoplasia, duplications, fenestrations, the infundibular widening, or aplasia of the PCoA in the prenatal and/or postnatal periods). The aim of this study was to analyze an incidence of various fenestrations and duplications of the PCoA, and describe their general features and their association with other vascular abnormalities. The research was performed on the brains of 200 human fetuses and 377 adult cadavers of both genders and different ages using microdissection and macrodissection methods. There were 0.34% cases with PCoA fenestrations and 3.12% cases with various PCoA duplications. Their morphologic features were described and compared with the similar PCoA abnormalities recorded in the scientific literature. There was no association between the PCoA and either duplication or aneurysm in adult cases. After thorough examination, the fenestrations and duplications of the PCoA are distinguished as 2 special forms of vascular abnormalities, and the PCoA duplications are characterized as partial and total. Furthermore, whereas the low incidence of a fenestration of the PCoA suggests it to be a sufficiently rare phenomenon, the duplications of the PCoA trunk are fairly frequent, especially concerning its terminal segment. Copyright © 2016 Elsevier Inc. All rights reserved.

Mussel byssus attachment weakened by ocean acidification

NASA Astrophysics Data System (ADS)

O'Donnell, Michael J.; George, Matthew N.; Carrington, Emily

2013-06-01

Biomaterials connect organisms to their environments. Their function depends on biological, chemical and environmental factors, both at the time of creation and throughout the life of the material. Shifts in the chemistry of the oceans driven by anthropogenic CO2 (termed ocean acidification) have profound implications for the function of critical materials formed under these altered conditions. Most ocean acidification studies have focused on one biomaterial (secreted calcium carbonate), frequently using a single assay (net rate of calcification) to quantify whether reductions in environmental pH alter how organisms create biomaterials. Here, we examine biological structures critical for the success of ecologically and economically important bivalve molluscs. One non-calcified material, the proteinaceous byssal threads that anchor mytilid mussels to hard substrates, exhibited reduced mechanical performance when secreted under elevated pCO2 conditions, whereas shell and tissue growth were unaffected. Threads made under high pCO2 (>1,200μatm) were weaker and less extensible owing to compromised attachment to the substratum. According to a mathematical model, this reduced byssal fibre performance, decreasing individual tenacity by 40%. In the face of ocean acidification, weakened attachment presents a potential challenge for suspension-culture mussel farms and for intertidal communities anchored by mussel beds.

Distributions and Relationships of CO2, O2, and Dimethylsulfide in the Changjiang (Yangtze) Estuary and Its Adjacent Waters in Summer

NASA Astrophysics Data System (ADS)

Wu, Xi; Tan, Tingting; Liu, Chunying; Li, Tie; Liu, Xiaoshou; Yang, Guipeng

2018-04-01

The distributions and relationships of O2, CO2, and dimethylsulfide (DMS) in the Changjiang (Yangtze) Estuary and its adjacent waters were investigated in June 2014. In surface water, mean O2 saturation level, partial pressure of CO2 (pCO2), and DMS concentrations (and ranges) were 110% (89%-167%), 374 μatm (91-640 μatm), and 8.53 nmol L-1 (1.10-27.50 nmol L-1), respectively. The sea-to-air fluxes (and ranges) of DMS and CO2 were 8.24 μmol m-2 d-1 (0.26-62.77 μmol m-2 d-1), and -4.7 mmol m-2 d-1 (-110.8-31.7 mmol m-2 d-1), respectively. Dissolved O2 was oversaturated, DMS concentrations were relatively high, and this region served as a sink of atmospheric CO2. The pCO2 was significantly and negatively correlated with the O2 saturation level, while the DMS concentration showed different positive relationships with the O2 saturation level in different water masses. In vertical profiles, a hypoxic zone existed below 20 m at a longitude of 123°E. The stratification of temperature and salinity caused by the Taiwan Warm Current suppressed seawater exchange between upper and lower layers, resulting in the formation of a hypoxic zone. Oxidative decomposition of organic detritus carried by the Changjiang River Diluted Water (CRDW) consumed abundant O2 and produced additional CO2. The DMS concentrations decreased because of low phytoplankton biomass in the hypoxic zone. Strong correlations appeared between the O2 saturation level, pCO2 and DMS concentrations in vertical profiles. Our results strongly suggested that CRDW played an important role in the distributions and relationships of O2, CO2, and DMS.

The internal consistency of the North Sea carbonate system

NASA Astrophysics Data System (ADS)

Salt, Lesley A.; Thomas, Helmuth; Bozec, Yann; Borges, Alberto V.; de Baar, Hein J. W.

2016-05-01

In 2002 (February) and 2005 (August), the full suite of carbonate system parameters (total alkalinity (AT), dissolved inorganic carbon (DIC), pH, and partial pressure of CO2 (pCO2) were measured on two re-occupations of the entire North Sea basin, with three parameters (AT, DIC, pCO2) measured on four additional re-occupations, covering all four seasons, allowing an assessment of the internal consistency of the carbonate system. For most of the year, there is a similar level of internal consistency, with AT being calculated to within ± 6 μmol kg- 1 using DIC and pH, DIC to ± 6 μmol kg- 1 using AT and pH, pH to ± 0.008 using AT and pCO2, and pCO2 to ± 8 μatm using DIC and pH, with the dissociation constants of Millero et al. (2006). In spring, however, we observe a significant decline in the ability to accurately calculate the carbonate system. Lower consistency is observed with an increasing fraction of Baltic Sea water, caused by the high contribution of organic alkalinity in this water mass, not accounted for in the carbonate system calculations. Attempts to improve the internal consistency by accounting for the unconventional salinity-borate relationships in freshwater and the Baltic Sea, and through application of the new North Atlantic salinity-boron relationship (Lee et al., 2010), resulted in no significant difference in the internal consistency.

Impact of posterior communicating artery on basilar artery steno-occlusive disease.

PubMed

Hong, J M; Choi, J Y; Lee, J H; Yong, S W; Bang, O Y; Joo, I S; Huh, K

2009-12-01

Acute brainstem infarction with basilar artery (BA) occlusive disease is the most fatal type of all ischaemic strokes. This report investigates the prognostic impact of the posterior communicating artery (PcoA) and whether its anatomy is a safeguard or not. Consecutive patients who had acute brainstem infarction with at least 50% stenosis of BA upon CT angiography (CTA) were studied. The configuration of PcoA was divided into two groups upon CTA: "textbook" group (invisible PcoA with good P1 and P2 segment) and "fetal-variant of PcoA" group (only visible PcoA with absent P1 segment). Baseline demographics, radiological findings and stroke mechanisms were analysed. A multiple regression analysis was performed to predict clinical outcome at 30 days (modified Rankin disability Scale (mRS