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Sample records for abiotic environmental variables

  1. Maternal, social and abiotic environmental effects on growth vary across life stages in a cooperative mammal.

    PubMed

    English, Sinead; Bateman, Andrew W; Mares, Rafael; Ozgul, Arpat; Clutton-Brock, Tim H

    2014-03-01

    Resource availability plays a key role in driving variation in somatic growth and body condition, and the factors determining access to resources vary considerably across life stages. Parents and carers may exert important influences in early life, when individuals are nutritionally dependent, with abiotic environmental effects having stronger influences later in development as individuals forage independently. Most studies have measured specific factors influencing growth across development or have compared relative influences of different factors within specific life stages. Such studies may not capture whether early-life factors continue to have delayed effects at later stages, or whether social factors change when individuals become nutritionally independent and adults become competitors for, rather than providers of, food. Here, we examined variation in the influence of the abiotic, social and maternal environment on growth across life stages in a wild population of cooperatively breeding meerkats. Cooperatively breeding vertebrates are ideal for investigating environmental influences on growth. In addition to experiencing highly variable abiotic conditions, cooperative breeders are typified by heterogeneity both among breeders, with mothers varying in age and social status, and in the number of carers present. Recent rainfall had a consistently marked effect on growth across life stages, yet other seasonal terms only influenced growth during stages when individuals were growing fastest. Group size and maternal dominance status had positive effects on growth during the period of nutritional dependence on carers, but did not influence mass at emergence (at 1 month) or growth at independent stages (>4 months). Pups born to older mothers were lighter at 1 month of age and subsequently grew faster as subadults. Males grew faster than females during the juvenile and subadult stage only. Our findings demonstrate the complex ways in which the external environment

  2. Assessing Utilization and Environmental Risks of Important Genes in Plant Abiotic Stress Tolerance

    PubMed Central

    Khan, Mohammad S.; Khan, Muhammad A.; Ahmad, Dawood

    2016-01-01

    Transgenic plants with improved salt and drought stress tolerance have been developed with a large number of abiotic stress-related genes. Among these, the most extensively used genes are the glycine betaine biosynthetic codA, the DREB transcription factors, and vacuolar membrane Na+/H+ antiporters. The use of codA, DREBs, and Na+/H+ antiporters in transgenic plants has conferred stress tolerance and improved plant phenotype. However, the future deployment and commercialization of these plants depend on their safety to the environment. Addressing environmental risk assessment is challenging since mechanisms governing abiotic stress tolerance are much more complex than that of insect resistance and herbicide tolerance traits, which have been considered to date. Therefore, questions arise, whether abiotic stress tolerance genes need additional considerations and new measurements in risk assessment and, whether these genes would have effects on weediness and invasiveness potential of transgenic plants? While considering these concerns, the environmental risk assessment of abiotic stress tolerance genes would need to focus on the magnitude of stress tolerance, plant phenotype and characteristics of the potential receiving environment. In the present review, we discuss environmental concerns and likelihood of concerns associated with the use of abiotic stress tolerance genes. Based on our analysis, we conclude that the uses of these genes in domesticated crop plants are safe for the environment. Risk assessment, however, should be carefully conducted on biofeedstocks and perennial plants taking into account plant phenotype and the potential receiving environment. PMID:27446095

  3. Phytoplankton dynamics of a subtropical reservoir controlled by the complex interplay among hydrological, abiotic, and biotic variables.

    PubMed

    Kuo, Yi-Ming; Wu, Jiunn-Tzong

    2016-12-01

    This study was conducted to identify the key factors related to the spatiotemporal variations in phytoplankton abundance in a subtropical reservoir from 2006 to 2010 and to assist in developing strategies for water quality management. Dynamic factor analysis (DFA), a dimension-reduction technique, was used to identify interactions between explanatory variables (i.e., environmental variables) and abundance (biovolume) of predominant phytoplankton classes. The optimal DFA model significantly described the dynamic changes in abundances of predominant phytoplankton groups (including dinoflagellates, diatoms, and green algae) at five monitoring sites. Water temperature, electrical conductivity, water level, nutrients (total phosphorus, NO3-N, and NH3-N), macro-zooplankton, and zooplankton were the key factors affecting the dynamics of aforementioned phytoplankton. Therefore, transformations of nutrients and reactions between water quality variables and aforementioned processes altered by hydrological conditions may also control the abundance dynamics of phytoplankton, which may represent common trends in the DFA model. The meandering shape of Shihmen Reservoir and its surrounding rivers caused a complex interplay between hydrological conditions and abiotic and biotic variables, resulting in phytoplankton abundance that could not be estimated using certain variables. Additional water quality and hydrological variables at surrounding rivers and monitoring plans should be executed a few days before and after reservoir operations and heavy storm, which would assist in developing site-specific preventive strategies to control phytoplankton abundance.

  4. Fitting response models of benthic community structure to abiotic variables in a polluted estuarine system

    NASA Astrophysics Data System (ADS)

    González-Oreja, José Antonio; Saiz-Salinas, José Ignacio

    1999-07-01

    Models of the macrozoobenthic community responses to abiotic variables measured in the polluted Bilbao estuary were obtained by multiple linear regression analyses. Total, Oligochaeta and Nematoda abundance and biomass were considered as dependent variables. Intertidal level, dissolved oxygen at the bottom of the water column (DOXB) and organic content of the sediment were selected by the analyses as the three principal explanatory variables. Goodness-of-fit of the models was high ( overlinex=71.3% ). Total abundance and biomass increased as a linear function of DOXB. The principal outcome of the vast sewage scheme currently in progress in the study area is an important contributor of increasing DOXB levels. The models exposed in this paper will serve as a tool to evaluate the expected changes in the near future.

  5. Abiotic variables affect STX concentration in a meso-oligotrophic subtropical coastal lake dominated by Cylindrospermopsis raciborskii (Cyanophyceae).

    PubMed

    Brentano, Débora Monteiro; Giehl, Eduardo L Hettwer; Petrucio, Maurício Mello

    2016-06-01

    The cyanobacterium Cylindrospermopsis raciborskii is capable of producing toxins including saxitoxin (STX). Few studies have verified the influence of environmental variables on the production of STX and most have only been studied in the laboratory. The goal of this work was to identify the abiotic variables related to STX concentration in situ. The relationship among STX concentration and the physical variables, nutrients and chlorophyll-a (chl-a) concentration was examined in a meso-oligotrophic subtropical coastal lake dominated by C. raciborskii. A generalized linear model was developed, incorporating all variables measured monthly over a 45-month monitoring period. Conductivity and dissolved inorganic nitrogen (DIN) concentration provided the greatest explanatory power for STX concentration in situ. Previous studies suggested that C. raciborskii cells exposed to stress associated with higher ionic concentrations appear to activate the biosynthesis of STX suggesting that STX can elicit changes cell permeability and may contribute to the homeostasis of this organism. An increase of DIN concentration results in a higher concentration of STX which may be related to a reduced metabolic demand, since the uptake of inorganic nitrogen requires less energy than N2-fixation. Thus, increased DIN can favor the growth of C. raciborskii population or improve cellular homeostasis, both potentially increasing STX concentration in the aquatic system, which was observed through a delayed response pattern. The developed model, while providing only a moderate predictive power, can assist in the understanding of the environmental variables associated with increases in STX concentration, and in monitoring and minimizing the risks of toxic blooms.

  6. Influence of abiotic variables on culturable yeast diversity in two distinct Alpine glaciers.

    PubMed

    Turchetti, Benedetta; Goretti, Marta; Branda, Eva; Diolaiuti, Guglielmina; D'Agata, Carlo; Smiraglia, Claudio; Onofri, Andrea; Buzzini, Pietro

    2013-11-01

    The influence of some abiotic variables (pH, dry weight, organic carbon, nitrogen and phosphorous) on culturable yeast diversity in two distinct, but adjacent Alpine glaciers (Glacier du Géant, France, and Miage Glacier, Italy) was investigated. In all, 682 yeast strains were isolated and identified by D1/D2 and ITS sequencing as belonging to species of the genera Aureobasidium, Candida, Bulleromyces, Cryptococcus, Cystofilobasidium, Dioszegia, Guehomyces, Holtermanniella, Leucosporidiella, Mrakia, Mrakiella, Rhodotorula, Sporidiobolus, Sporobolomyces and Udenyomyces. Overall, the most represented genera were Cryptococcus (55% of isolates), Rhodotorula (17%) and Mrakia (10%). About 10% of strains, presumably belonging to new species (yet to be described), were preliminarily identified at the genus level. Principal component analysis (PCA) revealed that organic carbon, nitrogen and phosphorous are apparently mostly related to culturable yeast abundance and diversity. In this context, the hypothesis that the frequency of isolation of certain species may be correlated with some organic nutrients (with special emphasis for phosphorous) is discussed.

  7. Influence of intraspecific variability and abiotic factors on mycotoxin production in Penicillium roqueforti.

    PubMed

    Fontaine, Kévin; Hymery, Nolwenn; Lacroix, Marlène Z; Puel, Sylvie; Puel, Olivier; Rigalma, Karim; Gaydou, Vincent; Coton, Emmanuel; Mounier, Jérôme

    2015-12-23

    Penicillium roqueforti has the ability to produce secondary metabolites, including roquefortine C (ROQC) and mycophenolic acid (MPA). In a previous study, the presence of these mycotoxins, alone or in co-occurrence, has been reported in blue-veined cheese. A high variability of mycotoxin content has also been observed, although the majority of samples exhibited relatively low concentrations. The observed variability raises the question of the factors impacting ROQC and MPA production. In this context, the mycotoxigenic potential of 96 P. roqueforti strains (biotic factor) and the effect of some abiotic factors (pH, temperature, NaCl and O2 contents, and C/N ratio) on mycotoxin production were evaluated. A high intraspecific diversity, established via genotypic (RAPD) and phenotypic (FTIR) approaches, was observed. It was associated with mycotoxigenic potential variability and may thus explain part of the observed variability in mycotoxin content of blue-veined cheese. Moreover, a significant decrease of ROQC and MPA production was observed for conditions (temperature, C/N ratio, O2 and NaCl concentrations) encountered during cheese-making compared with optimal growth conditions. The results also highlighted that there was no significant effect of addition of ROQC amino-acid precursor on the production of both mycotoxins whereas a pH increase from 4.5 to 6.5 slightly reduced MPA but not ROQC production.

  8. A comparative study of fatty acid profile and formation of biofilm in Geobacillus gargensis exposed to variable abiotic stress.

    PubMed

    Al-Beloshei, Noor Essa; Al-Awadhi, Husain; Al-Khalaf, Rania A; Afzal, Mohammad

    2015-01-01

    Understanding bacterial fatty acid (FA) profile has a great taxonomic significance as well as clinical importance for diagnosis issues. Both the composition and nature of membrane FAs change under different nutritional, biotic and (or) abiotic stresses, and environmental stress. Bacteria produce both odd-carbon as well as branched-chain fatty acids (BCFAs). This study was designed to examine the effect of abiotic pressure, including salinity, temperature, pH, and oxinic stress on the growth, development, and FA profile in thermophilic Geobacillus gargensis. Under these stresses, 3 parametric ratios, 2-methyl fatty acids/3-methyl fatty acids (iso-/anteiso-FAs), BCFAs/straight-chain saturated fatty acids (SCSFA), and SCSFAs/straight-chain unsaturated fatty acids (SCUFA), in addition to total lipids affected by variable stresses were measured. Our results indicate that the ratio of total iso-/anteiso-FAs increased at the acidic pH range of 4.1-5.2 and decreased with increasing pH. The reverse was true for salt stress when iso-/anteiso-FAs ratio increased with salt concentration. The BCFAs/SCSFAs and SCSFAs/SCUFAs ratios increased at neutral and alkaline pH and high salt concentration, reduced incubation time, and comparatively high temperature (55-65 °C) of the growth medium. The bacterial total lipid percentage deceased with increasing salt concentration, incubation period, but it increased with temperature. The formation of extracellular polymeric substances was observed under all stress conditions and with the addition of sodium dodecyl sulfate (2 and 5 mmol/L) to the growth medium. The membrane phospholipid composition of the bacterium was analyzed by thin-layer chromatography.

  9. Environmental Association Analyses Identify Candidates for Abiotic Stress Tolerance in Glycine soja, the Wild Progenitor of Cultivated Soybeans

    PubMed Central

    Anderson, Justin E.; Kono, Thomas J. Y.; Stupar, Robert M.; Kantar, Michael B.; Morrell, Peter L.

    2016-01-01

    Natural populations across a species range demonstrate population structure owing to neutral processes such as localized origins of mutations and migration limitations. Selection also acts on a subset of loci, contributing to local adaptation. An understanding of the genetic basis of adaptation to local environmental conditions is a fundamental goal in basic biological research. When applied to crop wild relatives, this same research provides the opportunity to identify adaptive genetic variation that may be used to breed for crops better adapted to novel or changing environments. The present study explores an ex situ conservation collection, the USDA germplasm collection, genotyped at 32,416 SNPs to identify population structure and test for associations with bioclimatic and biophysical variables in Glycine soja, the wild progenitor of Glycine max (soybean). Candidate loci were detected that putatively contribute to adaptation to abiotic stresses. The identification of potentially adaptive variants in this ex situ collection may permit a more targeted use of germplasm collections. PMID:26818076

  10. Environmental Association Analyses Identify Candidates for Abiotic Stress Tolerance in Glycine soja, the Wild Progenitor of Cultivated Soybeans.

    PubMed

    Anderson, Justin E; Kono, Thomas J Y; Stupar, Robert M; Kantar, Michael B; Morrell, Peter L

    2016-04-07

    Natural populations across a species range demonstrate population structure owing to neutral processes such as localized origins of mutations and migration limitations. Selection also acts on a subset of loci, contributing to local adaptation. An understanding of the genetic basis of adaptation to local environmental conditions is a fundamental goal in basic biological research. When applied to crop wild relatives, this same research provides the opportunity to identify adaptive genetic variation that may be used to breed for crops better adapted to novel or changing environments. The present study explores an ex situ conservation collection, the USDA germplasm collection, genotyped at 32,416 SNPs to identify population structure and test for associations with bioclimatic and biophysical variables in Glycine soja, the wild progenitor of Glycine max (soybean). Candidate loci were detected that putatively contribute to adaptation to abiotic stresses. The identification of potentially adaptive variants in this ex situ collection may permit a more targeted use of germplasm collections.

  11. Developing standards for environmental toxicants: the need to consider abiotic environmental factors and microbe-mediated ecologic processes.

    PubMed Central

    Babich, H; Stotzky, G

    1983-01-01

    This article suggests and discusses two novel aspects for the formulation of standards for environmental toxicants. First, uniform national standards for each pollutant will be underprotective for some ecosystems and overprotective for others, inasmuch as the toxicity of a pollutant to the indigenous biota is dependent on the physicochemical properties of the recipient environment. As the number of chemicals that need regulation is immense and as microbes appear to respond similarly to pollutant-abiotic factor interactions as do plants and animals, it is suggested that microbial assays be used initially to identify those abiotic factors that most influence the toxicity of specific pollutants. Thereafter, additional studies using plants and animals can focus on these pollutant-abiotic factor interactions, and more meaningful standards can then be formulated more rapidly and inexpensively. Second, it is suggested that the response to pollutants of microbe-mediated ecologic processes be used to quantitate the sensitivity of different ecosystems to various toxicants. Such a quantification, expressed in terms of an "ecological dose 50%" (EcD50), could be easily incorporated into the methodologies currently used to set water quality criteria and would also be applicable to setting criteria for terrestrial ecosystems. PMID:6339225

  12. Environmental Selenium Transformations: Distinguishing Abiotic and Biotic Factors Influencing Se Redox Transformations

    NASA Astrophysics Data System (ADS)

    Rosenfeld, C.; Kenyon, J.; James, B. R.; Santelli, C. M.

    2014-12-01

    Worldwide, selenium (Se) is proving to be a significant environmental concern, with many anthropogenic activities (e.g. coal mining and combustion, phosphate mining and agricultural irrigation) releasing potentially hazardous concentrations into surface and subsurface ecosystems. The US EPA is currently considering aquatic Se regulations, however no guidelines exist for excess soil Se, despite its ability to act as a persistent Se source. Various abiotic and biological processes mediate Se oxidation/reduction (redox) transformations in soils, thus influencing its solubility and bioavailability. In this research we assess (1) the ability of metal-transforming fungal species to aerobically reduce Se (Se (IV and/or VI) to Se(0)), and (2) the relative contribution of biotic and abiotic pathways for aerobic Se transformation. The primary objective of this research is to determine what abiotic and biotic factors enhance or restrict Se bioavailability. Results indicate that fungal-mediated Se reduction may be quite widespread, with at least 7 out of 10 species of known Mn(II)-oxidizing fungi isolated from metal impacted environments also identified as capable of aerobically reducing Se(IV) and/or Se(VI) to Se(0). Increasing concentrations of selenite (SeO32-; Se(IV)) and selenate (SeO42-; Se(VI)) generally reduced fungal growth rates, although selenate was more likely to inhibit fungal growth than selenite. To study oxidation, Se(0) was combined with Mn(III/IV) (hydr)oxides (henceforth referred to as Mn oxides), Se-transforming fungi (Alternaria alternata), and oxalic acid to mimic Se biogeochemistry at the plant-soil interface. Increased pH in the presence of fungi (7.2 with fungi, 6.8 without fungi after 24 days) was observed. Additionally, a slight decrease in redox potential was measured for incubations without Mn oxides (236 mV with Mn oxides, 205 mV without Mn oxides after 24 days), indicating that Mn oxides may enhance Se oxidation. Elemental Se oxidation rates to

  13. Connecting RNA Processing to Abiotic Environmental Response in Arabidopsis: the role of a polyadenylation factor

    NASA Astrophysics Data System (ADS)

    Li, Q. Q.; Xu, R.; Hunt, A. G.; Falcone, D. L.

    Plants are constantly challenged by numerous environmental stresses both biotic and abiotic It is clear that plants have evolved to counter these stresses using all but limited means We recently discovered the potential role of a messenger RNA processing factor namely the Arabidopsis cleavage and polyadenylation specificity factor 30 kDa subunit AtCPSF30 when a mutant deficient in this factor displayed altered responses to an array of abiotic stresses This AtCPSF30 mutant named oxt6 exhibited an elevated tolerance to oxidative stress Microarray experiments of oxt6 and its complemented lines revealed an altered gene expression profile among which were antioxidative defense genes Interestingly the same gene encoding AtCPSF30 can also be transcribed into a large transcript that codes for a potential splicing factor Both protein products have a domain for RNA binding and a calmodulin binding domain activities of which have been confirmed by biochemical assays Surprisingly binding of AtCPSF30 to calmodulin inhibits the RNA-binding activity of the protein Mutational analysis shows that a small part of the protein is responsible for calmodulin binding and point mutations in this region abolished both RNA binding activity and the inhibition of this activity by calmodulin Analyses of the potential splicing factor are on going and the results will be presented The interesting possibilities for both the interplay between splicing and polyadenylation and the regulation of these processes by stimuli that act through

  14. Spatial variability of biotic and abiotic tree establishment constraints across a treeline ecotone in the Alaska Range

    USGS Publications Warehouse

    Stueve, K.M.; Isaacs, R.E.; Tyrrell, L.E.; Densmore, R.V.

    2011-01-01

    Throughout interior Alaska (USA), a gradual warming trend in mean monthly temperatures occurred over the last few decades (;2-48C). The accompanying increases in woody vegetation at many alpine treeline (hereafter treeline) locations provided an opportunity to examine how biotic and abiotic local site conditions interact to control tree establishment patterns during warming. We devised a landscape ecological approach to investigate these relationships at an undisturbed treeline in the Alaska Range. We identified treeline changes between 1953 (aerial photography) and 2005 (satellite imagery) in a geographic information system (GIS) and linked them with corresponding local site conditions derived from digital terrain data, ancillary climate data, and distance to 1953 trees. Logistic regressions enabled us to rank the importance of local site conditions in controlling tree establishment. We discovered a spatial transition in the importance of tree establishment controls. The biotic variable (proximity to 1953 trees) was the most important tree establishment predictor below the upper tree limit, providing evidence of response lags with the abiotic setting and suggesting that tree establishment is rarely in equilibrium with the physical environment or responding directly to warming. Elevation and winter sun exposure were important predictors of tree establishment at the upper tree limit, but proximity to trees persisted as an important tertiary predictor, indicating that tree establishment may achieve equilibrium with the physical environment. However, even here, influences from the biotic variable may obscure unequivocal correlations with the abiotic setting (including temperature). Future treeline expansion will likely be patchy and challenging to predict without considering the spatial variability of influences from biotic and abiotic local site conditions. ?? 2011 by the Ecological Society of America.

  15. The role of abiotic environmental conditions and herbivory in shaping bacterial community composition in floral nectar.

    PubMed

    Samuni-Blank, Michal; Izhaki, Ido; Laviad, Sivan; Bar-Massada, Avi; Gerchman, Yoram; Halpern, Malka

    2014-01-01

    Identifying the processes that drive community assembly has long been a central theme in ecology. For microorganisms, a traditional prevailing hypothesis states that "everything is everywhere, but the environment selects". Although the bacterial community in floral nectar may be affected by both atmosphere (air-borne bacteria) and animals as dispersal vectors, the environmental and geographic factors that shape microbial communities in floral nectar are unknown. We studied culturable bacterial communities in Asphodelus aestivus floral nectar and in its typical herbivorous bug Capsodes infuscatus, along an aridity gradient. Bacteria were sampled from floral nectar and bugs at four sites, spanning a geographical range of 200 km from Mediterranean to semi-arid conditions, under open and bagged flower treatments. In agreement with the niche assembly hypothesis, the differences in bacterial community compositions were explained by differences in abiotic environmental conditions. These results suggest that microbial model systems are useful for addressing macro-ecological questions. In addition, similar bacterial communities were found in the nectar and on the surface of the bugs that were documented visiting the flowers. These similarities imply that floral nectar bacteria dispersal is shaped not only by air borne bacteria and nectar consumers as previously reported, but also by visiting vectors like the mirid bugs.

  16. Abiotic and biotic controls of soil moisture spatiotemporal variability and the occurrence of hysteresis

    NASA Astrophysics Data System (ADS)

    Fatichi, Simone; Katul, Gabriel G.; Ivanov, Valeriy Y.; Pappas, Christoforos; Paschalis, Athanasios; Consolo, Ada; Kim, Jongho; Burlando, Paolo

    2015-05-01

    An expression that separates biotic and abiotic controls on the temporal dynamics of the soil moisture spatial coefficient of variation Cv(θ) was explored via numerical simulations using a mechanistic ecohydrological model, Tethys-Chloris. Continuous soil moisture spatiotemporal dynamics at an exemplary hillslope domain were computed for six case studies characterized by different climate and vegetation cover and for three configurations of soil properties. It was shown that abiotic controls largely exceed their biotic counterparts in wet climates. Biotic controls on Cv(θ) were found to be more pronounced in Mediterranean climates. The relation between Cv(θ) and spatial mean soil moisture θ¯ was found to be unique in wet locations, regardless of the soil properties. For the case of homogeneous soil texture, hysteretic cycles between Cv(θ) and θ¯ were observed in all Mediterranean climate locations considered here and to a lesser extent in a deciduous temperate forest. Heterogeneity in soil properties increased Cv(θ) to values commensurate with field observations and weakened signatures of hysteresis at all of the studied locations. This finding highlights the role of site-specific heterogeneities in hiding or even eliminating the signature of climatic and biotic controls on Cv(θ), thereby offering a new perspective on causes of confounding results reported across field experiments.

  17. Biotic and abiotic variables influencing plant litter breakdown in streams: a global study.

    PubMed

    Boyero, Luz; Pearson, Richard G; Hui, Cang; Gessner, Mark O; Pérez, Javier; Alexandrou, Markos A; Graça, Manuel A S; Cardinale, Bradley J; Albariño, Ricardo J; Arunachalam, Muthukumarasamy; Barmuta, Leon A; Boulton, Andrew J; Bruder, Andreas; Callisto, Marcos; Chauvet, Eric; Death, Russell G; Dudgeon, David; Encalada, Andrea C; Ferreira, Verónica; Figueroa, Ricardo; Flecker, Alexander S; Gonçalves, José F; Helson, Julie; Iwata, Tomoya; Jinggut, Tajang; Mathooko, Jude; Mathuriau, Catherine; M'Erimba, Charles; Moretti, Marcelo S; Pringle, Catherine M; Ramírez, Alonso; Ratnarajah, Lavenia; Rincon, José; Yule, Catherine M

    2016-04-27

    Plant litter breakdown is a key ecological process in terrestrial and freshwater ecosystems. Streams and rivers, in particular, contribute substantially to global carbon fluxes. However, there is little information available on the relative roles of different drivers of plant litter breakdown in fresh waters, particularly at large scales. We present a global-scale study of litter breakdown in streams to compare the roles of biotic, climatic and other environmental factors on breakdown rates. We conducted an experiment in 24 streams encompassing latitudes from 47.8° N to 42.8° S, using litter mixtures of local species differing in quality and phylogenetic diversity (PD), and alder (Alnus glutinosa) to control for variation in litter traits. Our models revealed that breakdown of alder was driven by climate, with some influence of pH, whereas variation in breakdown of litter mixtures was explained mainly by litter quality and PD. Effects of litter quality and PD and stream pH were more positive at higher temperatures, indicating that different mechanisms may operate at different latitudes. These results reflect global variability caused by multiple factors, but unexplained variance points to the need for expanded global-scale comparisons.

  18. Robust RNA silencing-mediated resistance to Plum pox virus under variable abiotic and biotic conditions.

    PubMed

    Di Nicola, Elisa; Tavazza, Mario; Lucioli, Alessandra; Salandri, Laura; Ilardi, Vincenza

    2014-10-01

    Some abiotic and biotic conditions are known to have a negative impact on post-transcriptional gene silencing (PTGS), thus representing a potential concern for the production of stable engineered virus resistance traits. However, depending on the strategy followed to achieve PTGS of the transgene, different responses to external conditions can be expected. In the present study, we utilized the Nicotiana benthamiana–Plum pox virus (PPV) pathosystem to evaluate in detail the stability of intron-hairpin(ihp)-mediated virus resistance under conditions known to adversely affect PTGS. The ihp plants grown at low or high temperatures were fully resistant to multiple PPV challenges, different PPV inoculum concentrations and even to a PPV isolate differing from the ihp construct by more than 28% at the nucleotide level. In addition, infections of ihp plants with viruses belonging to Cucumovirus, Potyvirus or Tombusvirus, all known to affect PTGS at different steps, were not able to defeat PPV resistance. Low temperatures did not affect the accumulation of transgenic small interfering RNAs (siRNAs), whereas a clear increase in the amount of siRNAs was observed during infections sustained by Cucumber mosaic virus and Potato virus Y. Our results show that the above stress factors do not represent an important concern for the production,through ihp-PTGS technology, of transgenic plants having robust virus resistance traits.

  19. Environmental Variables as Predictors of Academic Performance.

    ERIC Educational Resources Information Center

    Henderson, Ronald W.

    This project used six environmental variables identified by Dave (1963) and Wolf (1964) and three additional variables (identification with models, range of social interaction, and perception of practical value of education) to predict academic achievement in six-year-old Mexican-American children from an economically depressed area. The children…

  20. Henipavirus susceptibility to environmental variables.

    PubMed

    Fogarty, Rhys; Halpin, Kim; Hyatt, Alex D; Daszak, Peter; Mungall, Bruce A

    2008-03-01

    The routes of henipavirus transmission between hosts are poorly understood. The purpose of this study was to measure the persistence of henipaviruses under various environmental conditions and thereby gain an insight into likely mechanisms of transmission. Henipaviruses survived for more than 4 days at 22 degrees C in pH-neutral fruit bat urine but were sensitive to higher temperatures and pH changes. On mango flesh, survival time varied depending on temperature and fruit pH, ranging from 2h to more than 2 days. Desiccation of viruses substantially reduced survival time to less than 2h. The sensitivity of henipaviruses to pH, temperature and desiccation indicates a need for close contact between hosts for transmission to occur, although under ideal conditions henipaviruses can persist for extended periods facilitating vehicle-borne transmission.

  1. The effects of abiotic and biotic environmental components on the microbial mineralization of selected xenobiotic compounds in soils

    SciTech Connect

    Knaebel, D.B.

    1990-01-01

    This research investigated the effects of environmental components on the microbial mineralization of xenobiotic compounds in soils. The soils' chemical and physical characteristics, microbial community structure, organic and inorganic components, and other associated biota (plants) were examined for their effects on the biodegradation process. The biodegradation of {sup 14}C foreign, synthetic ({double bond} xenobiotic) compounds was measured by quantifying {sup 14} CO{sub 2} production over time. Mineralization kinetics were estimated by first-order and 3/2 order mineralization models. The compounds displayed different mineralization kinetics in the different soils, which were due to nature of the xenobiotic chemical and to abiotic and biotic soil characteristics. Specific soil components (montmorillonite, humic acids and fulvic acids) inhibited mineralization. Other soil components (sand, illite, kaolinite) had less effect on the biodegradation process. Modified soil microbial communities mineralized the compounds differently. Bacteria-enhanced soils metabolized the compounds to greater extents than the fungi-enhanced soils, which both mineralized the compounds more than actinomycete-enhanced soils. However, the rates of mineralization were only significantly different between the bacteria-enhanced soils and the actinomycete-enhanced soil. Plants significantly increased soil microbial biomass and activity, and stimulated the rate of microbial mineralization of xenobiotic compounds. However, they had no effect on the total amounts of mineralization. In summary, these diverse abiotic and biotic environmental components exerted tremendous influences on the microbial turnover of xenobiotic compounds in soils. Therefore, these components should be considered when modeling the fate of xenobiotic chemicals in the environment.

  2. Abiotic variability among different aquatic systems of the central Amazon floodplain during drought and flood events.

    PubMed

    Affonso, A G; Queiroz, H L; Novo, E M L M

    2015-11-01

    This paper examines water properties from lakes, (depression lakes, sensu Junk et al., 2012), channels (scroll lakes with high connectivity, sensu Junk et al., 2012) and paleo-channels (scroll lakes with low connectivity-sensu Junk et al., 2012, locally called ressacas) located in Mamirauá Sustainable Development Reserve, in Central Amazon floodplain, Amazonas, Brazil. We analysed surface temperature, conductivity, pH, dissolved oxygen, turbidity, transparency, suspended inorganic and organic matter, chlorophyll-a, pheophytin, total nitrogen, total phosphorus, organic and inorganic carbon in 2009 high water phase, 2009 and 2010 low water phases. Multivariate statistical analyses of 24 aquatic systems (6 ressacas, 12 lakes and 6 channels, 142 samples) were applied to the variables in order to: 1) quantify differences among aquatic system types; 2) assess how those differences are affected in the different phases of the hydrological year. First, we analysed the entire set of variables to test for differences among phases of the hydrological year and types of aquatic systems using a PERMANOVA two-way crossed design. The results showed that the all measured limnological variables are distinct regarding both factors: types of aquatic systems and hydrological phases. In general, the magnitude and amplitude of all variables were higher in the low water phase than in the high water phase, except for water transparency in all aquatic system's types. PERMANOVA showed that the differences between aquatic system's types and hydrological phases of all variables were highly significant for both main factors (type and phase) and for the type x phase interaction. Limnological patterns of Amazon floodplain aquatic systems are highly dynamic, dependent on the surrounding environment, flood pulse, main river input and system type. These patterns show how undisturbed systems respond to natural variability in such a diverse environment, and how distinct are those aquatic systems

  3. Differential kinetics and temperature dependence of abiotic and biotic processes controlling the environmental fate of TNT in simulated marine systems.

    PubMed

    Chappell, Mark A; Porter, Beth E; Price, Cynthia L; Pettway, Brad A; George, Robert D

    2011-08-01

    This work seeks to understand how the balance of abiotic and biotic kinetic processes in sediments control the residual concentration of TNT in marine systems after release from ocean-dumped source. Kinetics of TNT disappearance were followed using marine sediments at different temperatures and under both biotic and presumably abiotic conditions (through sodium azide addition). Sediments exhibiting the highest rate of TNT disappearance under biotic conditions also exhibited the highest sorption affinity for TNT under abiotic conditions. Significant temperature dependence in the abiotic processes was observed in the diffusion coefficient of TNT and not sediment sorption affinity. At higher temperature, kinetics of biotic processes outpaced abiotic processes, but at low temperature, kinetics of abiotic processes were much more significant. We concluded that the differential influence of temperature on the kinetics of abiotic and biotic processes could provide distinguishing predictions for the potential residual concentration of TNT contamination in marine-sediment systems.

  4. Inversion analysis of estimating interannual variability and its uncertainties in biotic and abiotic parameters of a parsimonious physiologically based model after wind disturbance

    NASA Astrophysics Data System (ADS)

    Toda, M.; Yokozawa, M.; Richardson, A. D.; Kohyama, T.

    2011-12-01

    The effects of wind disturbance on interannual variability in ecosystem CO2 exchange have been assessed in two forests in northern Japan, i.e., a young, even-aged, monocultured, deciduous forest and an uneven-aged mixed forest of evergreen and deciduous trees, including some over 200 years old using eddy covariance (EC) measurements during 2004-2008. The EC measurements have indicated that photosynthetic recovery of trees after a huge typhoon occurred during early September in 2004 activated annual carbon uptake of both forests due to changes in physiological response of tree leaves during their growth stages. However, little have been resolved about what biotic and abiotic factors regulated interannual variability in heat, water and carbon exchange between an atmosphere and forests. In recent years, an inverse modeling analysis has been utilized as a powerful tool to estimate biotic and abiotic parameters that might affect heat, water and CO2 exchange between the atmosphere and forest of a parsimonious physiologically based model. We conducted the Bayesian inverse model analysis for the model with the EC measurements. The preliminary result showed that the above model-derived NEE values were consistent with observed ones on the hourly basis with optimized parameters by Baysian inversion. In the presentation, we would examine interannual variability in biotic and abiotic parameters related to heat, water and carbon exchange between the atmosphere and forests after disturbance by typhoon.

  5. Interactions of biotic and abiotic environmental factors in an ectomycorrhizal symbiosis, and the potential for selection mosaics

    PubMed Central

    Piculell, Bridget J; Hoeksema, Jason D; Thompson, John N

    2008-01-01

    Background Geographic selection mosaics, in which species exert different evolutionary impacts on each other in different environments, may drive diversification in coevolving species. We studied the potential for geographic selection mosaics in plant-mycorrhizal interactions by testing whether the interaction between bishop pine (Pinus muricata D. Don) and one of its common ectomycorrhizal fungi (Rhizopogon occidentalis Zeller and Dodge) varies in outcome, when different combinations of plant and fungal genotypes are tested under a range of different abiotic and biotic conditions. Results We used a 2 × 2 × 2 × 2 factorial experiment to test the main and interactive effects of plant lineage (two maternal seed families), fungal lineage (two spore collections), soil type (lab mix or field soil), and non-mycorrhizal microbes (with or without) on the performance of plants and fungi. Ecological outcomes, as assessed by plant and fungal performance, varied widely across experimental environments, including interactions between plant or fungal lineages and soil environmental factors. Conclusion These results show the potential for selection mosaics in plant-mycorrhizal interactions, and indicate that these interactions are likely to coevolve in different ways in different environments, even when initially the genotypes of the interacting species are the same across all environments. Hence, selection mosaics may be equally as effective as genetic differences among populations in driving divergent coevolution among populations of interacting species. PMID:18507825

  6. Mechanisms and Dynamics of Abiotic and Biotic Interactions at Environmental Interfaces

    SciTech Connect

    Roso, Kevin M.

    2006-06-01

    The Stanford EMSI (SEMSI) was established in 2004 through joint funding by the National Science Foundation and the OBER-ERSD. It encompasses a number of universities and national laboratories. The PNNL component of the SEMSI is funded by ERSD and is the focus of this report. This component has the objective of providing theory support to the SEMSI by bringing computational capabilities and expertise to bear on important electron transfer problems at mineral/water and mineral/microbe interfaces. PNNL staff member Dr. Kevin Rosso, who is also ''matrixed'' into the Environmental Molecular Sciences Laboratory (EMSL) at PNNL, is a co-PI on the SEMSI project and the PNNL lead. The EMSL computational facilities being applied to the SEMSI project include the 11.8 teraflop massively-parallel supercomputer. Science goals of this EMSL/SEMSI partnership include advancing our understanding of: (1) The kinetics of U(VI) and Cr(VI) reduction by aqueous and solid-phase Fe(II), (2) The structure of mineral surfaces in equilibrium with solution, and (3) Mechanisms of bacterial electron transfer to iron oxide surfaces via outer-membrane cytochromes.

  7. Responses to abiotic environmental stresses among phylloplane and soil isolates of Beauveria bassiana from two holm oak ecosystems.

    PubMed

    Fernández-Bravo, María; Garrido-Jurado, Inmaculada; Valverde-García, Pablo; Enkerli, Jürg; Quesada-Moraga, Enrique

    2016-11-01

    The response of entomopathogenic mitosporic ascomycete (EMAs) to abiotic stresses might be adapted to the microhabitats in which they inhabit. In phylloplane, these organisms are more exposed to such stresses than they are in soil, which may have led to adaptation to this environment. In the present work, we investigate whether Beauveria bassiana genotype or isolation habitat, i.e., soil or phylloplane, within the same geographic area influences their responses to key environmental stresses, such as temperature, moisture and ultraviolet radiation (UV-B), which can affect their successful use in microbial control. Twenty isolates of B. bassiana obtained from the soil and phylloplane in two ecosystems from southern Spain (holm oak dehesa and a reforested area) were selected to study the population distribution of these isolates and evaluate their thermal, humidity and UV-B requirements. Molecular characterization was conducted by using elongation factor-1α (EF-1α), the intergenic nuclear region Bloc and 15 microsatellite primers. The cluster analysis based on concatenated EF-1α and Bloc sequences grouped the 20 isolates into five clades within B. basiana, with Clades a, b, d and e containing both soil and phylloplane isolates and Clade c including three phylloplane isolates. The dendrogram and the minimal spanning network generated from the genetic distances among multilocus genotypes showed four divergent groups corresponding to the five clades obtained based on the sequence data (Clades b and d were represented in the same group), with a high degree of shared alleles within groups and few alleles shared among groups. Although no relationship was found between MLG and the habitat (soil or phylloplane) of isolation, isolates grouped into Clade c, all of which were collected from phylloplane, formed a separate group of MLGs. To investigate our hypothesis, the responses to temperature (germination and colony growth evaluated in the range 15-35°C), water activity

  8. Environmentally relevant impacts of nano-TiO2 on abiotic degradation of bisphenol A under sunlight irradiation.

    PubMed

    Wu, Wei; Shan, Guoqiang; Wang, Shanfeng; Zhu, Lingyan; Yue, Longfei; Xiang, Qian; Zhang, Yinqing; Li, Zhuo

    2016-09-01

    Understanding the effects of nano-TiO2 particles on the environmental behaviors of organic pollutants in natural aquatic environments is of paramount importance considering that large amount of nano-TiO2 is being released in the environment. In this study, the effect of nano-TiO2 on the degradation of bisphenol A (BPA) in water was investigated under simulated solar light irradiation. The results indicated that nano-TiO2 at environmentally relevant concentration (1 mg/L) could significantly facilitate the abiotic degradation of BPA (also at low concentration) under mild solar light irradiation, with the pseudo first-order rate constant (kobs) for BPA degradation raised by 1-2 orders of magnitude. As reflected by the inhibition experiments, hydroxyl radicals (OHs) and superoxide radical species were the predominant active species responsible for BPA degradation. The reaction was affected by water pH, and the degradation rate was higher at acidic or alkaline conditions than that at neutral condition. Humic acid (HA) also affected the reaction rate, depending on its concentration. At lower concentration (the mass ratio of HA/nano-TiO2 was 0.1:1), HA improved the dispersion and stability of nano-TiO2 in aquatic environment. As a result, the yield of OHs by nano-TiO2 under sunlight irradiation increased and BPA degradation was facilitated. When the HA concentration increased, a coating of HA formed on the surface of nano-TiO2. Although nano-TiO2 became more stable, the light absorption by nano-TiO2 was significantly reduced due to the strong light absorption of the HA coated on the surface. As a consequence, the yield of OH decreased and BPA degradation was depressed. The results imply that nano-TiO2 at low concentration may distinctly mediate BPA degradation, and can contribute to the natural attenuation of some organic pollutants in aquatic environment with low level of HA. However, this process would be significantly reduced in the presence of high level of HA.

  9. Environmental variability and child growth in Nepal.

    PubMed

    Shively, Gerald; Sununtnasuk, Celeste; Brown, Molly

    2015-09-01

    Data from the 2011 Nepal Demographic Health Survey are combined with satellite remotely sensed Normalized Difference Vegetation Index (NDVI) data to evaluate whether interannual variability in weather is associated with child health. For stunting, we focus on children older than 24 months of age. NDVI anomaly averages during cropping months are evaluated during the year before birth, the year of birth, and the second year after birth. For wasting, we assess children under 59 months of age and relate growth to NDVI averages for the current and most recent growing periods. Correlations between short-run indicators of child growth and intensity of green vegetation are generally positive. Regressions that control for a range of child-, mother- and household-specific characteristics produce mixed evidence regarding the role of NDVI anomalies during critical periods in a child's early life and the subsequent probability of stunting and wasting. Overall findings suggest that the relationship between environmental conditions and child growth are heterogeneous across the landscape in Nepal and, in many cases, highly non-linear and sensitive to departures from normality.

  10. Individual Cell Based Traits Obtained by Scanning Flow-Cytometry Show Selection by Biotic and Abiotic Environmental Factors during a Phytoplankton Spring Bloom

    PubMed Central

    Pomati, Francesco; Kraft, Nathan J. B.; Posch, Thomas; Eugster, Bettina; Jokela, Jukka; Ibelings, Bas W.

    2013-01-01

    In ecology and evolution, the primary challenge in understanding the processes that shape biodiversity is to assess the relationship between the phenotypic traits of organisms and the environment. Here we tested for selection on physio-morphological traits measured by scanning flow-cytometry at the individual level in phytoplankton communities under a temporally changing biotic and abiotic environment. Our aim was to study how high-frequency temporal changes in the environment influence biodiversity dynamics in a natural community. We focused on a spring bloom in Lake Zurich (Switzerland), characterized by rapid changes in phytoplankton, water conditions, nutrients and grazing (mainly mediated by herbivore ciliates). We described bloom dynamics in terms of taxonomic and trait-based diversity and found that diversity dynamics of trait-based groups were more pronounced than those of identified phytoplankton taxa. We characterized the linkage between measured phytoplankton traits, abiotic environmental factors and abundance of the main grazers and observed weak but significant correlations between changing abiotic and biotic conditions and measured size-related and fluorescence-related traits. We tested for deviations in observed community-wide distributions of focal traits from random patterns and found evidence for both clustering and even spacing of traits, occurring sporadically over the time series. Patterns were consistent with environmental filtering and phenotypic divergence under herbivore pressure, respectively. Size-related traits showed significant even spacing during the peak of herbivore abundance, suggesting that morphology-related traits were under selection from grazing. Pigment distribution within cells and colonies appeared instead to be associated with acclimation to temperature and water chemistry. We found support for trade-offs among grazing resistance and environmental tolerance traits, as well as for substantial periods of dynamics in which

  11. Environmental stochasticity controls soil erosion variability

    PubMed Central

    Kim, Jongho; Ivanov, Valeriy Y.; Fatichi, Simone

    2016-01-01

    Understanding soil erosion by water is essential for a range of research areas but the predictive skill of prognostic models has been repeatedly questioned because of scale limitations of empirical data and the high variability of soil loss across space and time scales. Improved understanding of the underlying processes and their interactions are needed to infer scaling properties of soil loss and better inform predictive methods. This study uses data from multiple environments to highlight temporal-scale dependency of soil loss: erosion variability decreases at larger scales but the reduction rate varies with environment. The reduction of variability of the geomorphic response is attributed to a ‘compensation effect’: temporal alternation of events that exhibit either source-limited or transport-limited regimes. The rate of reduction is related to environment stochasticity and a novel index is derived to reflect the level of variability of intra- and inter-event hydrometeorologic conditions. A higher stochasticity index implies a larger reduction of soil loss variability (enhanced predictability at the aggregated temporal scales) with respect to the mean hydrologic forcing, offering a promising indicator for estimating the degree of uncertainty of erosion assessments. PMID:26925542

  12. Environmental stochasticity controls soil erosion variability

    NASA Astrophysics Data System (ADS)

    Kim, Jongho; Ivanov, Valeriy Y.; Fatichi, Simone

    2016-03-01

    Understanding soil erosion by water is essential for a range of research areas but the predictive skill of prognostic models has been repeatedly questioned because of scale limitations of empirical data and the high variability of soil loss across space and time scales. Improved understanding of the underlying processes and their interactions are needed to infer scaling properties of soil loss and better inform predictive methods. This study uses data from multiple environments to highlight temporal-scale dependency of soil loss: erosion variability decreases at larger scales but the reduction rate varies with environment. The reduction of variability of the geomorphic response is attributed to a ‘compensation effect’: temporal alternation of events that exhibit either source-limited or transport-limited regimes. The rate of reduction is related to environment stochasticity and a novel index is derived to reflect the level of variability of intra- and inter-event hydrometeorologic conditions. A higher stochasticity index implies a larger reduction of soil loss variability (enhanced predictability at the aggregated temporal scales) with respect to the mean hydrologic forcing, offering a promising indicator for estimating the degree of uncertainty of erosion assessments.

  13. Review of Microbial Responses to Abiotic Environmental Factors in the Context of the Proposed Yucca Mountain Repository

    SciTech Connect

    Meike, A.; Stroes-Gascoyne, S.

    2000-08-01

    A workshop on Microbial Activities at Yucca Mountain (May 1995, Lafayette, CA) was held with the intention to compile information on all pertinent aspects of microbial activity for application to a potential repository at Yucca Mountain. The findings of this workshop set off a number of efforts intended to eventually incorporate the impacts of microbial behavior into performance assessment models. One effort was to expand an existing modeling approach to include the distinctive characteristics of a repository at Yucca Mountain (e.g., unsaturated conditions and a significant thermal load). At the same time, a number of experimental studies were initiated as well as a compilation of relevant literature to more thoroughly study the physical, chemical and biological parameters that would affect microbial activity under Yucca Mountain-like conditions. This literature search (completed in 1996) is the subject of the present document. The collected literature can be divided into four categories: (1) abiotic factors, (2) community dynamics and in-situ considerations, (3) nutrient considerations and (4) transport of radionuclides. The complete bibliography represents a considerable resource, but is too large to be discussed in one document. Therefore, the present report focuses on the first category, abiotic factors, and a discussion of these factors in order to facilitate the development of a model for Yucca Mountain.

  14. Matching Environmental Variability and Organizational Design.

    ERIC Educational Resources Information Center

    Neves, Joao S.

    1990-01-01

    Describes an experiential exercise designed to demonstrate how a good match between environmental characteristics and organizational solutions is critical for the performance of an organization. Use of the game by students and practitioners in production and operations management is explained, and adaptation of the game to other applications is…

  15. Comparing Selections of Environmental Variables for Ecological Studies: A Focus on Terrain Attributes

    PubMed Central

    Brown, Craig J.; Devillers, Rodolphe; Lucieer, Vanessa L.; Edinger, Evan N.

    2016-01-01

    Selecting appropriate environmental variables is a key step in ecology. Terrain attributes (e.g. slope, rugosity) are routinely used as abiotic surrogates of species distribution and to produce habitat maps that can be used in decision-making for conservation or management. Selecting appropriate terrain attributes for ecological studies may be a challenging process that can lead users to select a subjective, potentially sub-optimal combination of attributes for their applications. The objective of this paper is to assess the impacts of subjectively selecting terrain attributes for ecological applications by comparing the performance of different combinations of terrain attributes in the production of habitat maps and species distribution models. Seven different selections of terrain attributes, alone or in combination with other environmental variables, were used to map benthic habitats of German Bank (off Nova Scotia, Canada). 29 maps of potential habitats based on unsupervised classifications of biophysical characteristics of German Bank were produced, and 29 species distribution models of sea scallops were generated using MaxEnt. The performances of the 58 maps were quantified and compared to evaluate the effectiveness of the various combinations of environmental variables. One of the combinations of terrain attributes–recommended in a related study and that includes a measure of relative position, slope, two measures of orientation, topographic mean and a measure of rugosity–yielded better results than the other selections for both methodologies, confirming that they together best describe terrain properties. Important differences in performance (up to 47% in accuracy measurement) and spatial outputs (up to 58% in spatial distribution of habitats) highlighted the importance of carefully selecting variables for ecological applications. This paper demonstrates that making a subjective choice of variables may reduce map accuracy and produce maps that do not

  16. Integrated biomarker responses of the invasive species Corbicula fluminea in relation to environmental abiotic conditions: a potential indicator of the likelihood of clam's summer mortality syndrome.

    PubMed

    Oliveira, Cristiana; Vilares, Pedro; Guilhermino, Lúcia

    2015-04-01

    The aim of this study was to investigate the variation of several biomarkers in wild populations of Corbicula fluminea in relation to abiotic condition changes to identify environmental factors associated with increased stress in this species potentially leading to massive mortality events. The study was carried out from July to October in the freshwater tidal areas of the estuaries of Minho and Lima Rivers (NW Iberian Peninsula). Monthly, 7 biomarkers (biotransformation, energy production, anti-oxidant defenses and lipid peroxidation damages) were determined in C. fluminea and 17 abiotic parameters were determined in water or sediments in 4 sampling sites: M1, M2 and M3 in Minho (up=> downstream); and L in Lima estuaries. The results of biomarkers were integrated using the Integrated Biomarker Response (IBR), Index and also analysed in relation to environmental parameters by Redundancy Analysis (RDA). Overall, the findings of the present study indicate that July and August are particularly stressful months for the studied C. fluminea populations, especially at downstream sites; the increase of nutrients and ammonium water concentrations, water temperature and conductivity are major contributors for this increased stress; the biomarkers indicated that in July/August C. fluminea is exposed to oxidative stress inducers, environmental chemical contaminants biotransformed by esterases and glutathione S-transferase enzymes, and that organisms need additional energy to cope with the chemical and/or thermally-induced stress. The findings of the present study stress the importance of biomonitoring the health condition of C. fluminea because it may allow determining the likelihood of summer/post summer mortality syndrome in this species.

  17. A review of selection-based tests of abiotic surrogates for species representation.

    PubMed

    Beier, Paul; Sutcliffe, Patricia; Hjort, Jan; Faith, Daniel P; Pressey, Robert L; Albuquerque, Fabio

    2015-06-01

    Because conservation planners typically lack data on where species occur, environmental surrogates--including geophysical settings and climate types--have been used to prioritize sites within a planning area. We reviewed 622 evaluations of the effectiveness of abiotic surrogates in representing species in 19 study areas. Sites selected using abiotic surrogates represented more species than an equal number of randomly selected sites in 43% of tests (55% for plants) and on average improved on random selection of sites by about 8% (21% for plants). Environmental diversity (ED) (42% median improvement on random selection) and biotically informed clusters showed promising results and merit additional testing. We suggest 4 ways to improve performance of abiotic surrogates. First, analysts should consider a broad spectrum of candidate variables to define surrogates, including rarely used variables related to geographic separation, distance from coast, hydrology, and within-site abiotic diversity. Second, abiotic surrogates should be defined at fine thematic resolution. Third, sites (the landscape units prioritized within a planning area) should be small enough to ensure that surrogates reflect species' environments and to produce prioritizations that match the spatial resolution of conservation decisions. Fourth, if species inventories are available for some planning units, planners should define surrogates based on the abiotic variables that most influence species turnover in the planning area. Although species inventories increase the cost of using abiotic surrogates, a modest number of inventories could provide the data needed to select variables and evaluate surrogates. Additional tests of nonclimate abiotic surrogates are needed to evaluate the utility of conserving nature's stage as a strategy for conservation planning in the face of climate change.

  18. Constraining the role of iron in environmental nitrogen transformations: Dual stable isotope systematics of abiotic NO2- reduction by Fe(II) and its production of N2O

    NASA Astrophysics Data System (ADS)

    Buchwald, Carolyn; Grabb, Kalina; Hansel, Colleen M.; Wankel, Scott D.

    2016-08-01

    Despite mounting evidence for biogeochemical interactions between iron and nitrogen, our understanding of their environmental importance remains limited. Here we present an investigation of abiotic nitrite (NO2-) reduction by Fe(II) or 'chemodenitrification', and its relevance to the production of nitrous oxide (N2O), specifically focusing on dual (N and O) isotope systematics under a variety of environmental conditions. We observe a range of kinetic isotope effects that are regulated by reaction rates, with faster rates at higher pH (∼8), higher concentrations of Fe(II) and in the presence of mineral surfaces. A clear non-linear relationship between rate constant and kinetic isotope effects of NO2- reduction was evident (with larger isotope effects at slower rates) and is interpreted as reflecting the dynamics of Fe(II)-N reaction intermediates. N and O isotopic composition of product N2O also suggests a complex network of parallel and/or competing pathways. Our findings suggest that NO2- reduction by Fe(II) may represent an important abiotic source of environmental N2O, especially in iron-rich environments experiencing dynamic redox variations. This study provides a multi-compound, multi-isotope framework for evaluating the environmental occurrence of abiotic NO2- reduction and N2O formation, helping future studies constrain the relative roles of abiotic and biological N2O production pathways.

  19. Modeling the role of environmental variables on the population dynamics of the malaria vector Anopheles gambiae sensu stricto

    PubMed Central

    2012-01-01

    Background The impact of weather and climate on malaria transmission has attracted considerable attention in recent years, yet uncertainties around future disease trends under climate change remain. Mathematical models provide powerful tools for addressing such questions and understanding the implications for interventions and eradication strategies, but these require realistic modeling of the vector population dynamics and its response to environmental variables. Methods Published and unpublished field and experimental data are used to develop new formulations for modeling the relationships between key aspects of vector ecology and environmental variables. These relationships are integrated within a validated deterministic model of Anopheles gambiae s.s. population dynamics to provide a valuable tool for understanding vector response to biotic and abiotic variables. Results A novel, parsimonious framework for assessing the effects of rainfall, cloudiness, wind speed, desiccation, temperature, relative humidity and density-dependence on vector abundance is developed, allowing ease of construction, analysis, and integration into malaria transmission models. Model validation shows good agreement with longitudinal vector abundance data from Tanzania, suggesting that recent malaria reductions in certain areas of Africa could be due to changing environmental conditions affecting vector populations. Conclusions Mathematical models provide a powerful, explanatory means of understanding the role of environmental variables on mosquito populations and hence for predicting future malaria transmission under global change. The framework developed provides a valuable advance in this respect, but also highlights key research gaps that need to be resolved if we are to better understand future malaria risk in vulnerable communities. PMID:22877154

  20. Sparse modeling of spatial environmental variables associated with asthma.

    PubMed

    Chang, Timothy S; Gangnon, Ronald E; David Page, C; Buckingham, William R; Tandias, Aman; Cowan, Kelly J; Tomasallo, Carrie D; Arndt, Brian G; Hanrahan, Lawrence P; Guilbert, Theresa W

    2015-02-01

    Geographically distributed environmental factors influence the burden of diseases such as asthma. Our objective was to identify sparse environmental variables associated with asthma diagnosis gathered from a large electronic health record (EHR) dataset while controlling for spatial variation. An EHR dataset from the University of Wisconsin's Family Medicine, Internal Medicine and Pediatrics Departments was obtained for 199,220 patients aged 5-50years over a three-year period. Each patient's home address was geocoded to one of 3456 geographic census block groups. Over one thousand block group variables were obtained from a commercial database. We developed a Sparse Spatial Environmental Analysis (SASEA). Using this method, the environmental variables were first dimensionally reduced with sparse principal component analysis. Logistic thin plate regression spline modeling was then used to identify block group variables associated with asthma from sparse principal components. The addresses of patients from the EHR dataset were distributed throughout the majority of Wisconsin's geography. Logistic thin plate regression spline modeling captured spatial variation of asthma. Four sparse principal components identified via model selection consisted of food at home, dog ownership, household size, and disposable income variables. In rural areas, dog ownership and renter occupied housing units from significant sparse principal components were associated with asthma. Our main contribution is the incorporation of sparsity in spatial modeling. SASEA sequentially added sparse principal components to Logistic thin plate regression spline modeling. This method allowed association of geographically distributed environmental factors with asthma using EHR and environmental datasets. SASEA can be applied to other diseases with environmental risk factors.

  1. Controlling for exogenous environmental variables when using data envelopment analysis for regional environmental assessments.

    PubMed

    Macpherson, Alexander J; Principe, Peter P; Shao, Yang

    2013-04-15

    Researchers are increasingly using data envelopment analysis (DEA) to examine the efficiency of environmental policies and resource allocations. An assumption of the basic DEA model is that decisionmakers operate within homogeneous environments. But, this assumption is not valid when environmental performance is influenced by variables beyond managerial control. Understanding the influence of these variables is important to distinguish between characterizing environmental conditions and identifying opportunities to improve environmental performance. While environmental assessments often focus on characterizing conditions, the point of using DEA is to identify opportunities to improve environmental performance and thereby prevent (or rectify) an inefficient allocation of resources. We examine the role of exogenous variables such as climate, hydrology, and topography in producing environmental impacts such as deposition, runoff, invasive species, and forest fragmentation within the United States Mid-Atlantic region. We apply a four-stage procedure to adjust environmental impacts in a DEA model that seeks to minimize environmental impacts while obtaining given levels of socioeconomic outcomes. The approach creates a performance index that bundles multiple indicators while adjusting for variables that are outside management control, offering numerous advantages for environmental assessment.

  2. Dynamics and spatio-temporal variability of environmental factors in Eastern Australia using functional principal component analysis

    USGS Publications Warehouse

    Szabo, J.K.; Fedriani, E.M.; Segovia-Gonzalez, M. M.; Astheimer, L.B.; Hooper, M.J.

    2010-01-01

    This paper introduces a new technique in ecology to analyze spatial and temporal variability in environmental variables. By using simple statistics, we explore the relations between abiotic and biotic variables that influence animal distributions. However, spatial and temporal variability in rainfall, a key variable in ecological studies, can cause difficulties to any basic model including time evolution. The study was of a landscape scale (three million square kilometers in eastern Australia), mainly over the period of 19982004. We simultaneously considered qualitative spatial (soil and habitat types) and quantitative temporal (rainfall) variables in a Geographical Information System environment. In addition to some techniques commonly used in ecology, we applied a new method, Functional Principal Component Analysis, which proved to be very suitable for this case, as it explained more than 97% of the total variance of the rainfall data, providing us with substitute variables that are easier to manage and are even able to explain rainfall patterns. The main variable came from a habitat classification that showed strong correlations with rainfall values and soil types. ?? 2010 World Scientific Publishing Company.

  3. Environmental Concern and Sociodemographic Variables: A Study of Statistical Models

    ERIC Educational Resources Information Center

    Xiao, Chenyang; McCright, Aaron M.

    2007-01-01

    Studies of the social bases of environmental concern over the past 30 years have produced somewhat inconsistent results regarding the effects of sociodemographic variables, such as gender, income, and place of residence. The authors argue that model specification errors resulting from violation of two statistical assumptions (interval-level…

  4. Environmental Disturbances Decrease the Variability of Microbial Populations within Periphyton

    PubMed Central

    Webert, Kyle C.; McMahon, Katherine D.

    2016-01-01

    ABSTRACT A central pursuit of microbial ecology is to accurately model changes in microbial community composition in response to environmental factors. This goal requires a thorough understanding of the drivers of variability in microbial populations. However, most microbial ecology studies focus on the effects of environmental factors on mean population abundances, rather than on population variability. Here, we imposed several experimental disturbances upon periphyton communities and analyzed the variability of populations within disturbed communities compared with those in undisturbed communities. We analyzed both the bacterial and the diatom communities in the periphyton under nine different disturbance regimes, including regimes that contained multiple disturbances. We found several similarities in the responses of the two communities to disturbance; all significant treatment effects showed that populations became less variable as the result of environmental disturbances. Furthermore, multiple disturbances to these communities were often interactive, meaning that the effects of two disturbances could not have been predicted from studying single disturbances in isolation. These results suggest that environmental factors had repeatable effects on populations within microbial communities, thereby creating communities that were more similar as a result of disturbances. These experiments add to the predictive framework of microbial ecology by quantifying variability in microbial populations and by demonstrating that disturbances can place consistent constraints on the abundance of microbial populations. Although models will never be fully predictive due to stochastic forces, these results indicate that environmental stressors may increase the ability of models to capture microbial community dynamics because of their consistent effects on microbial populations. IMPORTANCE There are many reasons why microbial community composition is difficult to model. For example

  5. Using Simple Environmental Variables to Estimate Biomass Disturbance

    DTIC Science & Technology

    2014-08-01

    ecology • tracking of nutrient cycling and energy flow as system alternatives to quantification of biomass • use of geospatial science and remote...Estimate Biomass Disturbance Co ns tr uc tio n En gi ne er in g R es ea rc h La bo ra to ry Natalie Myers, Daniel Koch, Andrew Fulton, Anne...Uses (OPAL) ERDC/CERL TR-14-13 August 2014 Using Simple Environmental Variables to Estimate Biomass Disturbance Natalie Myers, Daniel Koch

  6. Analysis of 3-D Propagation Effects Due to Environmental Variability

    DTIC Science & Technology

    2014-09-30

    presence of 3-D environmental variations, especially shelf break canyons . Work was also performed in support of 2-D propagation in shallow water to...propagation in the Monterey Bay Canyon . This was motivated by observations of highly variable directional features in measured acoustic vector data...Rev. 8-98) Prescribed by ANSI Std Z39-18 2 the Monterey Bay Canyon were used as inputs to the model, and broadband calculations were performed

  7. Effect of environmental variables on body size evolution of crinoids between periods of mass extinctions

    NASA Astrophysics Data System (ADS)

    Jani, T.; Heim, N. A.; Payne, J.

    2013-12-01

    Body size plays a major role in determining whether or not an organism can sustain in its local environment. The ecosystem of an animal has a major effect on the fitness of organisms, and it would be interesting to note the degree to which various environmental factors alter body size. In my project, I identify three environmental factors that seem to affect body size of crinoids, marine invertebrates from phylum Echinodermata, and explore how these variables play out in the intervals between the five mass extinctions. The particular factors I study include atmospheric CO2 concentration (proxy for temperature), O2 concentration, and sea level. Although the r and p values for all of these factors were statistically insignificant to definitively make any correlation, there was a visual correlation. For O2, I noted a generally positive correlation with body size over time. CO2 trends suggested a negative correlation until the K-T boundary, but a positive correlation afterwards. Correlation with sea level was a little more complicated: correlation was positive from the start of the Phanerozoic to the Permian extinction; it turned negative until the Cretaceous-Tertiary boundary; afterwards, it again became positive. However, for all three variables, statistical values are too low to say definitively mark any correlation. Out of all three factors, CO2 levels had the highest correlation and lowest p-values in the most time intervals: from the start of the Phanerozoic to Ordovician-Silurian Extinction, from the Late Devonian to the Permian Extinction, and from the Cretaceous-Tertiary boundary to the present. When considering first differences, CO2 levels also had the highest correlation from the Permian Extinction to Triassic-Jurassic Extinction and from the Triassic-Jurassic Extinction to Cretaceous-Tertiary Extinction. Using PaleoTS, I found that body size evolution patterns either seemed to follow either an unbiased random walk (URW) or stasis in the intervals between

  8. Constraining the role of iron in environmental nitrogen transformations. Dual stable isotope systematics of abiotic NO2- reduction by Fe(II) and its production of N2O

    SciTech Connect

    Johnston, David; Wankel, Scott David; Buchwald, Carolyn; Hansel, Colleen

    2015-09-16

    Redox reactions involving nitrogen and iron have been shown to have important implications for mobilization of priority contaminants. Thus, an understanding of the linkages between their biogeochemical cycling is critical for predicting subsurface mobilization of radionuclides such as uranium. Despite mounting evidence for biogeochemical interactions between iron and nitrogen, our understanding of their environmental importance remains limited. Here we present an investigation of abiotic nitrite (NO2-) reduction by Fe(II) or ‘chemodenitrification,’ and its relevance to the production of nitrous oxide (N2O), specifically focusing on dual (N and O) isotope systematics under a variety of environmentally relevant conditions. We observe a range of kinetic isotope effects that are regulated by reaction rates, with faster rates at higher pH (~8), higher concentrations of Fe(II) and in the presence of mineral surfaces. A clear non-linear relationship between rate constant and kinetic isotope effects of NO2- reduction was evident (with larger isotope effects at slower rates) and is interpreted as reflecting the dynamics of Fe(II)-N reaction intermediates. N and O isotopic composition of product N2O also suggests a complex network of parallel and/or competing pathways. Our findings suggest that NO2- reduction by Fe(II) may represent an important abiotic source of environmental N2O, especially in iron-rich environments experiencing dynamic redox variations. This study provides a multi-compound, multi-isotope framework for evaluating the environmental occurrence of abiotic NO2- reduction and N2O formation, helping future studies constrain the relative roles of abiotic and biological N2O production pathways.

  9. Recent changes in aquatic biota in subarctic Fennoscandia - the role of global and local environmental variables

    NASA Astrophysics Data System (ADS)

    Weckström, Jan; Leppänen, Jaakko; Sorvari, Sanna; Kaukolehto, Marjut; Weckström, Kaarina; Korhola, Atte

    2013-04-01

    The Arctic, representing a fifth of the earth's surface, is highly sensitive to the predicted future warming and it has indeed been warming up faster than most other regions. This makes the region critically important and highlights the need to investigate the earliest signals of global warming and its impacts on the arctic and subarctic aquatic ecosystems and their biota. It has been demonstrated that many Arctic freshwater ecosystems have already experienced dramatic and unpreceded regime shifts during the last ca. 150 years, primarily driven by climate warming. However, despite the indisputable impact of climate-related variables on freshwater ecosystems other, especially local-scale catchment related variables (e.g. geology, vegetation, human activities) may override the climate signal and become the primary factor in shaping the structure of aquatic ecosystems. Although many studies have contributed to an improved understanding of limnological and hydrobiological features of Artic and subarctic lakes, much information is still needed especially on the interaction between the biotic and abiotic components, i.e. on factors controlling the food web dynamics in these sensitive aquatic ecosystems. This is of special importance as these lakes are of great value in water storage, flood prevention, and maintenance of biodiversity, in addition to which they are vital resources for settlement patterns, food production, recreation, and tourism. In this study we compare the pre-industrial sediment assemblages of primary producers (diatoms and Pediastrum) and primary consumers (cladoceran and chironomids) with their modern assemblages (a top-bottom approach) from 50 subarctic Fennoscandian lakes. We will evaluate the recent regional pattern of changes in aquatic assemblages, and assess how coherent the lakes' responses are across the subarctic area. Moreover, the impact of global (e.g. climate, precipitation) and local (e.g. lake and its catchment characteristics) scale

  10. Degradation of the tricyclic antipsychotic drug chlorpromazine under environmental conditions, identification of its main aquatic biotic and abiotic transformation products by LC-MSn and their effects on environmental bacteria.

    PubMed

    Trautwein, Christoph; Kümmerer, Klaus

    2012-03-15

    The search for environmental transformation products of organic pollutants (like drugs) is a difficult task and usually only few compounds are detected. This might be due to effective degradation but could also be a result of analytical deficits dealing with complex matrices. Especially transformation products of very low concentrations in sludge were difficult to identify so far. Additionally, the use of standard separation techniques might lead to the loss of isomeric compounds, which possess identical spectroscopic and spectrometric properties. To date no complete study investigating the environmental fate of any tricyclic antipsychotic drug has been reported. Therefore, this study investigated the popular neuroleptic drug chlorpromazine and its potential transformation by all main environmental pathways: aerobic and anaerobic biodegradation as well as abiotic photolytic degradation by sunlight. Analysis of test samples by high performance liquid chromatography coupled to multiple stage mass-spectrometry (HPLC-MS(n)) allowed the detection of numerous compounds. Further, the use of a special software allowed distinguishing between transformation products of small intensities and background "noise" caused by sludge or matrix. Three aerobic tests of different bacterial density (the Closed Bottle test, OECD 301D; the Manometric Respiratory test, OECD 301F; the modified Zahn-Wellens test, 302B; one anaerobic test (a modified anaerobic degradation test according to ISO 11734) as well as a photodegradation test were performed in the present study. According to the individual test guidelines, chlorpromazine had to be classified as not biodegradable in all of the biodegradation tests. However, a special chromatographic column and gradient along with mass spectrometric fragmentation experiments of higher order uncovered the presence of a total of 61 abiotic and biotic transformation products which where formed during the course of the tests. The structures of three

  11. Weekly periodicity of environmental variables in Phoenix, Arizona

    NASA Astrophysics Data System (ADS)

    Shutters, Shade T.; Balling, Robert C.

    Though there is no known meteorological cause for weekly cycling of environmental variables, weekly cycles have been discovered at local to global scales, particularly in areas affected by human urbanization. To uncover such cycles in Phoenix, AZ, and to highlight possible mechanisms for their existence, data from several public domain sources were collected and analyzed for cycles in three categories of variables: meteorological, pollution, and human activity measured as vehicle traffic flows. Results indicated that many meteorological and pollution variables do exhibit weekly periodicity and that these cycles are likely due to the weekly pattern of human traffic flows. Atmospheric concentrations of O 3 and NO X gases exhibit a high degree of negative correlation, supporting recent research that suggests anthropogenic NO X gases are effective scavengers of ozone in urban cores. Results further suggest that vehicle-generated NO X gases may be a significant generator of atmospheric nitrate particulates. Finally, both traffic flow and NO X gas concentrations display a strong correlation with wind speed in the urban core, though this study does not speculate on a mechanism for this relationship.

  12. Climate variability and change impacts on coastal environmental variables in British Columbia Canada

    NASA Astrophysics Data System (ADS)

    Abeysirigunawardena, Dilumie Saumedaka

    The research presented in this dissertation attempted to determine whether climate variability is critical to sea level changes in coastal BC. To that end, a number of statistical models were proposed to clarify the relationships between five climate variability indices representing large-scale atmospheric circulation regimes and sea levels, storm surges, extreme winds and storm track variability in coastal BC. The research findings demonstrate that decadal to inter decadal climatic variability is fundamental to explaining the changing frequency and intensity of extreme atmospheric and oceanic environmental variables in coastal BC. The trends revealed by these analyses suggest that coastal flooding risks are certain to increase in this region during the next few decades, especially if the global sea-levels continue to rise as predicted. The out come of this study emphasis the need to look beyond climatic means when completing climate impact assessments, by clearly showing that climate extremes are currently causing the majority of weather-related damage along coastal BC. The findings highlight the need to derive knowledge on climate variability and change effects relevant at regional to local scales to enable useful adaptation strategies. The major findings of this research resulted in five independent manuscripts: (i) Sea level responses to climatic variability and change in Northern BC. The Manuscript (MC) is published in the Journal of atmospheric and oceans (AO 46 (3), 277-296); (ii) Extreme sea-level recurrences in the south coast of BC with climate considerations. This MC is in review with the Asia Pacific Journal of Climate Change (APJCC); (iii) Extreme sea-surge responses to climate variability in coastal BC. This MC is currently in review in the Annals of the AAG (AN-2009-0098); (iv) Extreme wind regime responses to climate variability and change in the inner-south-coast of BC. This MC is published in the Journal of Atmosphere and Oceans (AO 47 (1), 41

  13. Environmental variability and heavy metal concentrations from five lagoons in the Ionian Sea (Amvrakikos Gulf, W Greece)

    PubMed Central

    Pavloudi, Christina; Kalantzi, Ioanna; Apostolaki, Eugenia T.; Chatzigeorgiou, Giorgos; Chatzinikolaou, Eva; Pafilis, Evangelos; Papageorgiou, Nafsika; Fanini, Lucia; Konstas, Spyridon; Fragopoulou, Nina; Arvanitidis, Christos

    2016-01-01

    Abstract Background Coastal lagoons are ecosystems of major importance as they host a number of species tolerant to disturbances and they are highly productive. Therefore, these ecosystems should be protected to ensure stability and resilience. The lagoons of Amvrakikos Gulf form one of the most important lagoonal complexes in Greece. The optimal ecological status of these lagoons is crucial for the well-being of the biodiversity and the economic prosperity of the local communities. Thus, monitoring of the area is necessary to detect possible sources of disturbance and restore stability. New information The environmental variables and heavy metals concentrations, from five lagoons of Amvrakikos Gulf were measured from seasonal samplings and compared to the findings of previous studies in the area, in order to check for possible sources of disturbance. The analysis, showed that i) the values of the abiotic parameters vary with time (season), space (lagoon) and with space over time; ii) the variability of the environmental factors and enrichment in certain elements is naturally induced and no source of contamination is detected in the lagoons. PMID:27932906

  14. Influence of environmental variables on Baylisascaris procyonis infection in raccoons.

    PubMed

    Samson, Amanda; Dubay, Shelli A; Huspeni, Todd C; Cyr, Amanda

    2012-12-01

    Baylisascaris procyonis is a zoonotic nematode commonly found in raccoons (Procyon lotor). Human-altered landscapes can support dense populations of raccoons, increasing the potential for interaction between humans and these animals. We used raccoon feces provided by licensed fur trappers to investigate environmental variables that influence prevalence of B. procyonis at 2 sites in Wisconsin. Trappers submitted raccoon feces to us, along with information on sex, age (juvenile and adult), and approximate trap location for each animal. We used zinc sulfate (1.18 specific gravity) flotation to detect B. procyonis eggs in approximately 1 g of fecal matter from each host. We used ArcView software to determine the distance of each trap location to an urban area as determined by the U.S. Census Bureau in 2000. We compared the habitat components in buffered home ranges (0.805 km around trap locations) of infected animals with those from uninfected animals using Mann-Whitney U-tests (P < 0.05). Variables investigated were human population, road density, housing units per census block, and land cover, including area of agriculture, forest, developed, shrubland, water, and grassland. We positively identified eggs in 64.9% of the animals sampled. Raccoons infected with B. procyonis had significantly larger area of agricultural habitats and significantly smaller areas of forested habitats in buffered home ranges than uninfected individuals. We found that raccoons near Madison and Milwaukee, Wisconsin, are commonly infected with B. procyonis , indicating that public education regarding protection from disease is warranted.

  15. Abiotic tooth enamel

    NASA Astrophysics Data System (ADS)

    Yeom, Bongjun; Sain, Trisha; Lacevic, Naida; Bukharina, Daria; Cha, Sang-Ho; Waas, Anthony M.; Arruda, Ellen M.; Kotov, Nicholas A.

    2017-03-01

    Tooth enamel comprises parallel microscale and nanoscale ceramic columns or prisms interlaced with a soft protein matrix. This structural motif is unusually consistent across all species from all geological eras. Such invariability—especially when juxtaposed with the diversity of other tissues—suggests the existence of a functional basis. Here we performed ex vivo replication of enamel-inspired columnar nanocomposites by sequential growth of zinc oxide nanowire carpets followed by layer-by-layer deposition of a polymeric matrix around these. We show that the mechanical properties of these nanocomposites, including hardness, are comparable to those of enamel despite the nanocomposites having a smaller hard-phase content. Our abiotic enamels have viscoelastic figures of merit (VFOM) and weight-adjusted VFOM that are similar to, or higher than, those of natural tooth enamels—we achieve values that exceed the traditional materials limits of 0.6 and 0.8, respectively. VFOM values describe resistance to vibrational damage, and our columnar composites demonstrate that light-weight materials of unusually high resistance to structural damage from shocks, environmental vibrations and oscillatory stress can be made using biomimetic design. The previously inaccessible combinations of high stiffness, damping and light weight that we achieve in these layer-by-layer composites are attributed to efficient energy dissipation in the interfacial portion of the organic phase. The in vivo contribution of this interfacial portion to macroscale deformations along the tooth’s normal is maximized when the architecture is columnar, suggesting an evolutionary advantage of the columnar motif in the enamel of living species. We expect our findings to apply to all columnar composites and to lead to the development of high-performance load-bearing materials.

  16. Abiotic tooth enamel.

    PubMed

    Yeom, Bongjun; Sain, Trisha; Lacevic, Naida; Bukharina, Daria; Cha, Sang-Ho; Waas, Anthony M; Arruda, Ellen M; Kotov, Nicholas A

    2017-03-01

    Tooth enamel comprises parallel microscale and nanoscale ceramic columns or prisms interlaced with a soft protein matrix. This structural motif is unusually consistent across all species from all geological eras. Such invariability-especially when juxtaposed with the diversity of other tissues-suggests the existence of a functional basis. Here we performed ex vivo replication of enamel-inspired columnar nanocomposites by sequential growth of zinc oxide nanowire carpets followed by layer-by-layer deposition of a polymeric matrix around these. We show that the mechanical properties of these nanocomposites, including hardness, are comparable to those of enamel despite the nanocomposites having a smaller hard-phase content. Our abiotic enamels have viscoelastic figures of merit (VFOM) and weight-adjusted VFOM that are similar to, or higher than, those of natural tooth enamels-we achieve values that exceed the traditional materials limits of 0.6 and 0.8, respectively. VFOM values describe resistance to vibrational damage, and our columnar composites demonstrate that light-weight materials of unusually high resistance to structural damage from shocks, environmental vibrations and oscillatory stress can be made using biomimetic design. The previously inaccessible combinations of high stiffness, damping and light weight that we achieve in these layer-by-layer composites are attributed to efficient energy dissipation in the interfacial portion of the organic phase. The in vivo contribution of this interfacial portion to macroscale deformations along the tooth's normal is maximized when the architecture is columnar, suggesting an evolutionary advantage of the columnar motif in the enamel of living species. We expect our findings to apply to all columnar composites and to lead to the development of high-performance load-bearing materials.

  17. Soil abiotic factors influence interactions between belowground herbivores and plant roots.

    PubMed

    Erb, Matthias; Lu, Jing

    2013-03-01

    Root herbivores are important ecosystem drivers and agricultural pests, and, possibly as a consequence, plants protect their roots using a variety of defensive strategies. One aspect that distinguishes belowground from aboveground plant-insect interactions is that roots are constantly exposed to a set of soil-specific abiotic factors. These factors can profoundly influence root resistance, and, consequently, the outcome of the interaction with belowground feeders. In this review, we synthesize the current literature on the impact of soil moisture, nutrients, and texture on root-herbivore interactions. We show that soil abiotic factors influence the interaction by modulating herbivore abundance and behaviour, root growth and resistance, beneficial microorganisms, as well as natural enemies of the herbivores. We suggest that abiotic heterogeneity may explain the high variability that is often encountered in root-herbivore systems. We also propose that under abiotic stress, the relative fitness value of the roots and the potential negative impact of herbivory increases, which may lead to a higher defensive investment and an increased recruitment of beneficial microorganisms by the plant. At the same time, both root-feeding herbivores and natural enemies are likely to decrease in abundance under extreme environmental conditions, leading to a context- and species-specific impact on plant fitness. Only by using tightly controlled experiments that include soil abiotic heterogeneity will it be possible to understand the impact of root feeders on an ecosystem scale and to develop predictive models for pest occurrence and impact.

  18. The Importance of Biotic vs. Abiotic Drivers of Local Plant Community Composition Along Regional Bioclimatic Gradients.

    PubMed

    Klanderud, Kari; Vandvik, Vigdis; Goldberg, Deborah

    2015-01-01

    We assessed if the relative importance of biotic and abiotic factors for plant community composition differs along environmental gradients and between functional groups, and asked which implications this may have in a warmer and wetter future. The study location is a unique grid of sites spanning regional-scale temperature and precipitation gradients in boreal and alpine grasslands in southern Norway. Within each site we sampled vegetation and associated biotic and abiotic factors, and combined broad- and fine-scale ordination analyses to assess the relative explanatory power of these factors for species composition. Although the community responses to biotic and abiotic factors did not consistently change as predicted along the bioclimatic gradients, abiotic variables tended to explain a larger proportion of the variation in species composition towards colder sites, whereas biotic variables explained more towards warmer sites, supporting the stress gradient hypothesis. Significant interactions with precipitation suggest that biotic variables explained more towards wetter climates in the sub alpine and boreal sites, but more towards drier climates in the colder alpine. Thus, we predict that biotic interactions may become more important in alpine and boreal grasslands in a warmer future, although more winter precipitation may counteract this trend in oceanic alpine climates. Our results show that both local and regional scales analyses are needed to disentangle the local vegetation-environment relationships and their regional-scale drivers, and biotic interactions and precipitation must be included when predicting future species assemblages.

  19. Environmental Literacy in Madeira Island (Portugal): The Influence of Demographic Variables

    ERIC Educational Resources Information Center

    Spinola, Hélder

    2016-01-01

    Demographic factors are among those that influence environmental literacy and, particularly, environmentally responsible behaviours, either directly or due to an aggregation effect dependent on other types of variables. Present study evaluates a set of demographic variables as predictors for environmental literacy among 9th grade students from…

  20. Acute exposure to environmental tobacco smoke and heart rate variability.

    PubMed Central

    Pope, C A; Eatough, D J; Gold, D R; Pang, Y; Nielsen, K R; Nath, P; Verrier, R L; Kanner, R E

    2001-01-01

    Environmental tobacco smoke (ETS) has been associated with cardiovascular mortality. Pathophysiologic pathways leading from ETS exposure to cardiopulmonary disease are still being explored. Reduced cardiac autonomic function, as measured by heart rate variability (HRV), has been associated with cardiac vulnerability and may represent an important pathophysiologic mechanism linking ETS and risk of cardiac mortality. In this study we evaluated acute ETS exposure in a commercial airport with changes in HRV in 16 adult nonsmokers. We conducted ambulatory electrocardiographic (ECG) monitoring for 8-hr periods while participants alternated 2 hr in nonsmoking and smoking areas. Nicotine and respirable suspended particle concentrations and participants' blood oxygen saturation were also monitored. We calculated time and frequency domain measures of HRV for periods in and out of the smoking area, and we evaluated associations with ETS using comparative statistics and regression modeling. ETS exposure was negatively associated with all measures of HRV. During exposure periods, we observed an average decrement of approximately 12% in the standard deviation of all normal-to-normal heart beat intervals (an estimate of overall HRV). ETS exposures were not associated with mean heart rate or blood oxygen saturation. Altered cardiac autonomic function, assessed by decrements in HRV, is associated with acute exposure to ETS and may be part of the pathophysiologic mechanisms linking ETS exposure and increased cardiac vulnerability. PMID:11485870

  1. Diagnosing Abiotic Degradation

    EPA Science Inventory

    The abiotic degradation of chlorinated solvents in ground water can be difficult to diagnose. Under current practice, most of the “evidence” is negative; specifically the apparent disappearance of chlorinated solvents with an accumulation of vinyl chloride, ethane, ethylene, or ...

  2. THE ROLE OF INDIVIDUAL VARIABILITY IN POPULATION DYNAMICS UNDER CHANGING ENVIRONMENTAL CONDITIONS

    EPA Science Inventory

    Environmental variability can influence species distributions through changes in
    survival, fecundity, behavior, and metabolic activities. As worldwide coastal populations rise, the associated deforestation and development can increase both quantities and variability in runoff...

  3. Variability in Shipboard Morbidity Rates: Environmental and Occupational Influences.

    DTIC Science & Technology

    1976-09-01

    relate significantly to illness rates during overseas deployments. 1 ,2 ,3 *From the Environmental and Social Medicine Division, Naval Health Research...Center, San Diego, California 92152. iHead, Environmental and Social Medicine Division. 2Psychology Technician, Fleet Medicine Branch, Environmental and... Social Medicine Division. 0 k W4 ~~;’:r4 ,: ,l cl :-on Important questions remain concerning environmental and occupational determi- nants of

  4. Guaranteeing robustness of structural condition monitoring to environmental variability

    NASA Astrophysics Data System (ADS)

    Van Buren, Kendra; Reilly, Jack; Neal, Kyle; Edwards, Harry; Hemez, François

    2017-01-01

    Advances in sensor deployment and computational modeling have allowed significant strides to be recently made in the field of Structural Health Monitoring (SHM). One widely used SHM strategy is to perform a vibration analysis where a model of the structure's pristine (undamaged) condition is compared with vibration response data collected from the physical structure. Discrepancies between model predictions and monitoring data can be interpreted as structural damage. Unfortunately, multiple sources of uncertainty must also be considered in the analysis, including environmental variability, unknown model functional forms, and unknown values of model parameters. Not accounting for these sources of uncertainty can lead to false-positives or false-negatives in the structural condition assessment. To manage the uncertainty, we propose a robust SHM methodology that combines three technologies. A time series algorithm is trained using "baseline" data to predict the vibration response, compare predictions to actual measurements collected on a potentially damaged structure, and calculate a user-defined damage indicator. The second technology handles the uncertainty present in the problem. An analysis of robustness is performed to propagate this uncertainty through the time series algorithm and obtain the corresponding bounds of variation of the damage indicator. The uncertainty description and robustness analysis are both inspired by the theory of info-gap decision-making. Lastly, an appropriate "size" of the uncertainty space is determined through physical experiments performed in laboratory conditions. Our hypothesis is that examining how the uncertainty space changes throughout time might lead to superior diagnostics of structural damage as compared to only monitoring the damage indicator. This methodology is applied to a portal frame structure to assess if the strategy holds promise for robust SHM. (Publication approved for unlimited, public release on October-28

  5. Abiotic origin of biopolymers

    NASA Technical Reports Server (NTRS)

    Oro, J.; Stephen-Sherwood, E.

    1976-01-01

    A variety of methods have been investigated in different laboratories for the polymerization of amino acids and nucleotides under abiotic conditions. They include (1) thermal polymerization; (2) direct polymerization of certain amino acid nitriles, amides, or esters; (3) polymerization using polyphosphate esters; (4) polymerization under aqueous or drying conditions at moderate temperatures using a variety of simple catalysts or condensing agents like cyanamide, dicyandiamide, or imidazole; and (5) polymerization under similar mild conditions but employing activated monomers or abiotically synthesized high-energy compounds such as adenosine 5'-triphosphate (ATP). The role and significance of these methods for the synthesis of oligopeptides and oligonucleotides under possible primitive-earth conditions is evaluated. It is concluded that the more recent approach involving chemical processes similar to those used by contemporary living organisms appears to offer a reasonable solution to the prebiotic synthesis of these biopolymers.

  6. Influence of environmental and prey variables on low tide shorebird habitat use within the Robbins Passage wetlands, Northwest Tasmania

    NASA Astrophysics Data System (ADS)

    Spruzen, Fiona L.; Richardson, Alastair M. M.; Woehler, Eric J.

    2008-06-01

    Shorebirds feed primarily on tidal flats, and their distribution over these flats is influenced by their prey and abiotic factors. These factors act by influencing the distribution and abundance of the prey, or the shorebirds ability to exploit it. The aims of this study were to investigate the low tide foraging distribution of shorebirds at four sites within the Robbins Passage wetlands, and the environmental and invertebrate factors that may influence their distribution. The greatest densities and number of shorebirds were found at Shipwreck Point and East Inlet. The shorebirds within-site distribution was also non-random, with the shorebirds present in greatest densities at the water's edge and low intertidal stratum, although this varied among species. Generally, on a small spatial scale, invertebrate diversity was positively correlated, and seagrass leaf mass was negatively correlated, with shorebird feeding density. On a large spatial scale, invertebrate biomass and seagrass root mass were positively correlated with shorebird feeding density. Invertebrate biomass and seagrass root mass explained 71% of the variance in total shorebird feeding density on the tidal flats. The variation in shorebird feeding density and diversity was therefore partly explained by invertebrate diversity and biomass, as well as the environmental factors seagrass roots and leaf mass and tidal flat area, although the strength of these relationships was influenced by the two different spatial scales of the study. The strength of the relationships between shorebird feeding density and the invertebrate and environmental variables was stronger on a large spatial scale. The presence of seagrass may have influenced shorebird-feeding density by affecting the invertebrate abundance and composition or the shorebirds ability to detect and capture their prey. The area of the tidal flat had opposing effects on the shorebird species. These results can be used to assist in the development of

  7. Environmental variability and population dynamics: Do European and North American ducks play by the same rules?

    USGS Publications Warehouse

    Pöysä, Hannu; Rintala, Jukka; Johnson, Douglas H.; Kauppinen, Jukka; Lammi, Esa; Nudds, Thomas D.; Väänänen, Veli-Matti

    2016-01-01

    Density dependence, population regulation, and variability in population size are fundamental population processes, the manifestation and interrelationships of which are affected by environmental variability. However, there are surprisingly few empirical studies that distinguish the effect of environmental variability from the effects of population processes. We took advantage of a unique system, in which populations of the same duck species or close ecological counterparts live in highly variable (north American prairies) and in stable (north European lakes) environments, to distinguish the relative contributions of environmental variability (measured as between-year fluctuations in wetland numbers) and intraspecific interactions (density dependence) in driving population dynamics. We tested whether populations living in stable environments (in northern Europe) were more strongly governed by density dependence than populations living in variable environments (in North America). We also addressed whether relative population dynamical responses to environmental variability versus density corresponded to differences in life history strategies between dabbling (relatively “fast species” and governed by environmental variability) and diving (relatively “slow species” and governed by density) ducks. As expected, the variance component of population fluctuations caused by changes in breeding environments was greater in North America than in Europe. Contrary to expectations, however, populations in more stable environments were not less variable nor clearly more strongly density dependent than populations in highly variable environments. Also, contrary to expectations, populations of diving ducks were neither more stable nor stronger density dependent than populations of dabbling ducks, and the effect of environmental variability on population dynamics was greater in diving than in dabbling ducks. In general, irrespective of continent and species life history

  8. Terrestrial Environmental Variables Derived From EOS Platform Sensors

    NASA Technical Reports Server (NTRS)

    Stadler, Stephen J.; Czajkowski, Kevin P.; Goward, Samuel N.; Xue, Yongkang

    2001-01-01

    The three main objectives of the overall project were: 1. Adaptation of environmental constraint methods to take advantage of EOS sensors, specifically, MODIS, ASTER, and Landsat-7, in addition to the PM AVHRR observations 2. Refinement of environmental constraint methods based on fundamental scientific knowledge. 3. Assessment of spatial scaling patterns in environmental constraint measurements to evaluate the potential biases and errors that occur when estimating regional and global-scale NPP patterns with moderate to coarse satellite observations. These goals were modified because, on one hand, MODIS data did not become available until after the first year of the project and because of project staffing issues at the University of Maryland., The OSU portion of the project contained a modest amount of funding and responsibility compared to the University of Maryland and the University of Toledo.

  9. RBM25 Mediates Abiotic Responses in Plants

    PubMed Central

    Cheng, Chunhong; Wang, Zhijuan; Yuan, Bingjian; Li, Xia

    2017-01-01

    Alternative splicing (AS) of pre-mRNAs is one of the most important post-transcriptional regulations that enable a single gene to code for multiple proteins resulting in the biodiversity of proteins in eukaryotes. Recently, we have shown that an Arabidopsis thaliana RNA recognition motif-containing protein RBM25 is a novel splicing factor to modulate plant response to ABA during seed germination and post-germination through regulating HAB1 pre-mRNA AS. Here, we show that RBM25 is preferentially expressed in stomata and vascular tissues in Arabidopsis and is induced by ABA and abiotic stresses. Loss-of-function mutant is highly tolerant to drought and sensitive to salt stress. Bioinformatic analysis and expression assays reveal that Arabidopsis RBM25 is induced by multiple abiotic stresses, suggesting a crucial role of RBM25 in Arabidopsis responses to adverse environmental conditions. Furthermore, we provide a comprehensive characterization of the homologous genes of Arabidopsis RBM25 based on the latest plant genome sequences and public microarray databases. Fourteen homologous genes are identified in different plant species which show similar structure in gene and protein. Notably, the promoter analysis reveals that RBM25 homologs are likely controlled by the regulators involved in multiple plant growth and abiotic stresses, such as drought and unfavorable temperature. The comparative analysis of general and unique cis regulatory elements of the RBM25 homologs highlights the conserved and unique molecular processes that modulate plant response to abiotic stresses through RBM25-mediated alternative splicing. PMID:28344583

  10. RBM25 Mediates Abiotic Responses in Plants.

    PubMed

    Cheng, Chunhong; Wang, Zhijuan; Yuan, Bingjian; Li, Xia

    2017-01-01

    Alternative splicing (AS) of pre-mRNAs is one of the most important post-transcriptional regulations that enable a single gene to code for multiple proteins resulting in the biodiversity of proteins in eukaryotes. Recently, we have shown that an Arabidopsis thaliana RNA recognition motif-containing protein RBM25 is a novel splicing factor to modulate plant response to ABA during seed germination and post-germination through regulating HAB1 pre-mRNA AS. Here, we show that RBM25 is preferentially expressed in stomata and vascular tissues in Arabidopsis and is induced by ABA and abiotic stresses. Loss-of-function mutant is highly tolerant to drought and sensitive to salt stress. Bioinformatic analysis and expression assays reveal that Arabidopsis RBM25 is induced by multiple abiotic stresses, suggesting a crucial role of RBM25 in Arabidopsis responses to adverse environmental conditions. Furthermore, we provide a comprehensive characterization of the homologous genes of Arabidopsis RBM25 based on the latest plant genome sequences and public microarray databases. Fourteen homologous genes are identified in different plant species which show similar structure in gene and protein. Notably, the promoter analysis reveals that RBM25 homologs are likely controlled by the regulators involved in multiple plant growth and abiotic stresses, such as drought and unfavorable temperature. The comparative analysis of general and unique cis regulatory elements of the RBM25 homologs highlights the conserved and unique molecular processes that modulate plant response to abiotic stresses through RBM25-mediated alternative splicing.

  11. The whole relationship between environmental variables and firm performance: competitive advantage and firm resources as mediator variables.

    PubMed

    López-Gamero, María D; Molina-Azorín, José F; Claver-Cortés, Enrique

    2009-07-01

    The examination of the possible direct link between environmental protection and firm performance in the literature has generally produced mixed results. The present paper contributes to the literature by using the resource-based view as a mediating process in this relationship. The study specifically tests whether or not the resource-based view of the firm mediates the positive relationships of proactive environmental management and improved environmental performance with competitive advantage, which also has consequences for financial performance. We also check the possible link between the adoption of a pioneering approach and good environmental management practices. Our findings support that early investment timing and intensity in environmental issues impact on the adoption of a proactive environmental management, which in turn helps to improve environmental performance. The findings also show that a firm's resources and competitive advantage act as mediator variables for a positive relationship between environmental protection and financial performance. This contribution is original because the present paper develops a comprehensive whole picture of this path process, which has previously only been partially discussed in the literature. In addition, this study clarifies a relevant point in the literature, namely that the effect of environmental protection on firm performance is not direct and can vary depending on the sector considered. Whereas competitive advantage in relation to costs influences financial performance in the IPPC law sector, the relevant influence in the hotel sector comes from competitive advantage through differentiation.

  12. A VARIABLE REACTIVITY MODEL FOR ION BINDING TO ENVIRONMENTAL SORBENTS

    EPA Science Inventory

    The conceptual and mathematical basis for a new general-composite modeling approach for ion binding to environmental sorbents is presented. The work extends the Simple Metal Sorption (SiMS) model previously presented for metal and proton binding to humic substances. A surface com...

  13. Regional variability of environmental effects of energy crop rotations

    NASA Astrophysics Data System (ADS)

    Prescher, Anne-Katrin; Peter, Christiane; Specka, Xenia; Willms, Matthias; Glemnitz, Michael

    2014-05-01

    The use of energy crops for bioenergy production is increasingly promoted by different frameworks and policies (ECCP, UNFCCC). Energy cropping decreases greenhouse gas emissions by replacing the use of fossil fuel. However, despite this, growing in monocultures energy crop rotations has low environmental benefit. It is broadly accepted consensus that sustainable energy cropping is only realizable by crop rotations which include several energy crop species. Four crop rotations consisting of species mixtures of C3, C4 and leguminous plants and their crop positions were tested to identify the environmental effect of energy cropping systems. The experimental design included four replicates per crop rotation each covering four cultivation years. The study took place at five sites across Germany covering a considerable range of soil types (loamy sand to silt loam), temperatures (7.5 ° C - 10.0 ° C) and precipitation (559 mm - 807 mm) which allow a regional comparison of crop rotation performance. Four indicators were used to characterize the environmental conditions: (1) greenhouse gas (GHG) emissions from the management actions; (2) change in humus carbon (Chum); (3) groundwater recharge (RGW) and (4) nitrogen dynamics. The indicators were derived by balance, by an empirical model and by a dynamic model, respectively, all based and calibrated on measured values. The results show that the crop rotation impact on environmental indicators varied between plant species mixtures and the crop positions, between sites and climate. Crop rotations with 100 % energy crops (including C4 plants) had negative influence on Chum, GHG emissions per area and RGW in comparison to the rotation of 50 % energy crops and 50 % cash crops, which were mainly due to the remaining straw on the field. However, the biogas yield of the latter rotation was smaller, thus GHG emissions per product were higher, pointing out the importance to distinguish between GHG emissions per product and per area

  14. Recent Molecular Advances on Downstream Plant Responses to Abiotic Stress

    PubMed Central

    dos Reis, Sávio Pinho; Lima, Aline Medeiros; de Souza, Cláudia Regina Batista

    2012-01-01

    Abiotic stresses such as extremes of temperature and pH, high salinity and drought, comprise some of the major factors causing extensive losses to crop production worldwide. Understanding how plants respond and adapt at cellular and molecular levels to continuous environmental changes is a pre-requisite for the generation of resistant or tolerant plants to abiotic stresses. In this review we aimed to present the recent advances on mechanisms of downstream plant responses to abiotic stresses and the use of stress-related genes in the development of genetically engineered crops. PMID:22942725

  15. Circadian regulation of abiotic stress tolerance in plants

    PubMed Central

    Grundy, Jack; Stoker, Claire; Carré, Isabelle A.

    2015-01-01

    Extremes of temperatures, drought and salinity cause widespread crop losses throughout the world and impose severe limitations on the amount of land that can be used for agricultural purposes. Hence, there is an urgent need to develop crops that perform better under such abiotic stress conditions. Here, we discuss intriguing, recent evidence that circadian clock contributes to plants’ ability to tolerate different types of environmental stress, and to acclimate to them. The clock controls expression of a large fraction of abiotic stress-responsive genes, as well as biosynthesis and signaling downstream of stress response hormones. Conversely, abiotic stress results in altered expression and differential splicing of the clock genes, leading to altered oscillations of downstream stress-response pathways. We propose a range of mechanisms by which this intimate coupling between the circadian clock and environmental stress-response pathways may contribute to plant growth and survival under abiotic stress. PMID:26379680

  16. Environmental Variability at Site Alfa during the Broadband-87 Exercise

    DTIC Science & Technology

    1989-08-01

    temporally sampled XBT data set was taken aboard Lynch during tlie exercise for the purpose of assessing the effects of internal wave activity and...Variability at Site Alfa during tine Broadband-87 Exercise 6. Author(s). Paul J. Bucca and Roger W. Meredith 5. Funding Numbers. Program Element No...Directorate IMaval Ocean Research and Development Activity Stennis Space Center, Mississippi 39529-5004 8. Performing Organization Report Number

  17. Abiotic degradation of plastic films

    NASA Astrophysics Data System (ADS)

    Ángeles-López, Y. G.; Gutiérrez-Mayen, A. M.; Velasco-Pérez, M.; Beltrán-Villavicencio, M.; Vázquez-Morillas, A.; Cano-Blanco, M.

    2017-01-01

    Degradable plastics have been promoted as an option to mitigate the environmental impacts of plastic waste. However, there is no certainty about its degradability under different environmental conditions. The effect of accelerated weathering (AW), natural weathering (NW) and thermal oxidation (TO) on different plastics (high density polyethylene, HDPE; oxodegradable high density polyethylene, HDPE-oxo; compostable plastic, Ecovio ® metalized polypropylene, PP; and oxodegradable metalized polypropylene, PP-oxo) was studied. Plastics films were exposed to AW per 110 hours; to NW per 90 days; and to TO per 30 days. Plastic films exposed to AW and NW showed a general loss on mechanical properties. The highest reduction in elongation at break on AW occurred to HDPE-oxo (from 400.4% to 20.9%) and was higher than 90% for HDPE, HDPE-oxo, Ecovio ® and PP-oxo in NW. No substantial evidence of degradation was found on plastics exposed to TO. Oxo-plastics showed higher degradation rates than their conventional counterparts, and the compostable plastic was resistant to degradation in the studied abiotic conditions. This study shows that degradation of plastics in real life conditions will vary depending in both, their composition and the environment.

  18. Variability and specificity associated with environmental methamphetamine sampling and analysis.

    PubMed

    Van Dyke, Mike V; Serrano, Kate A; Kofford, Shalece; Contreras, John; Martyny, John W

    2011-11-01

    This study was designed to explore the efficacy of the use of wipe sampling to determine methamphetamine contamination associated with the clandestine manufacture of methamphetamine. Three laboratories were utilized to analyze wipe samples to investigate variability in reported methamphetamine concentration among samples spiked with known amounts of methamphetamine. Different sampling media, surfaces, and solvents were also utilized to determine potential differences in measured methamphetamine concentration due to different wipes, wipe solvents, and wipe contaminants. This study examined rate of false positive detection among blank samples and whether interference with common household substances would create a false positive detection of methamphetamine. Variability between the three labs-using liquid chromatography with mass spectrometry or gas chromatography with mass spectrometry for detection of a known concentration of methamphetamine-resulted in percent differences of 3-30%. Results from wipe sample analysis for methamphetamine, using methanol or isopropanol, showed no significant difference in methamphetamine contamination recovery. Dust and paint contamination on methamphetamine wipe samples with known methamphetamine spike amounts did not affect methamphetamine wipe sample recovery. This study confirmed that either methanol or isopropanol is an appropriate solvent for use in methamphetamine wipe sampling. Dust and paint contamination on wipe samples will not interfere with the wipe sample analysis for methamphetamine. False positive detection for methamphetamine was not observed in any of the blank wipe samples submitted for the study. Finally, this study determined that methamphetamine will not be detected in structures that are truly methamphetamine free at current laboratory limits of quantification.

  19. Investigation of High School Students' Environmental Attitudes in Terms of Some Demographic Variables

    ERIC Educational Resources Information Center

    Koruoglu, Nergiz; Ugulu, Ilker; Yorek, Nurettin

    2015-01-01

    Studying individuals and students' attitudes towards environment and factors affecting students to be responsible individuals towards their environment may provide help towards the solution of environmental problems. In this study, it is aimed to evaluate environmental attitudes of high school students in terms of some variables. The sample of the…

  20. Natural variation in abiotic stress responsive gene expression and local adaptation to climate in Arabidopsis thaliana.

    PubMed

    Lasky, Jesse R; Des Marais, David L; Lowry, David B; Povolotskaya, Inna; McKay, John K; Richards, James H; Keitt, Timothy H; Juenger, Thomas E

    2014-09-01

    Gene expression varies widely in natural populations, yet the proximate and ultimate causes of this variation are poorly known. Understanding how variation in gene expression affects abiotic stress tolerance, fitness, and adaptation is central to the field of evolutionary genetics. We tested the hypothesis that genes with natural genetic variation in their expression responses to abiotic stress are likely to be involved in local adaptation to climate in Arabidopsis thaliana. Specifically, we compared genes with consistent expression responses to environmental stress (expression stress responsive, "eSR") to genes with genetically variable responses to abiotic stress (expression genotype-by-environment interaction, "eGEI"). We found that on average genes that exhibited eGEI in response to drought or cold had greater polymorphism in promoter regions and stronger associations with climate than those of eSR genes or genomic controls. We also found that transcription factor binding sites known to respond to environmental stressors, especially abscisic acid responsive elements, showed significantly higher polymorphism in drought eGEI genes in comparison to eSR genes. By contrast, eSR genes tended to exhibit relatively greater pairwise haplotype sharing, lower promoter diversity, and fewer nonsynonymous polymorphisms, suggesting purifying selection or selective sweeps. Our results indicate that cis-regulatory evolution and genetic variation in stress responsive gene expression may be important mechanisms of local adaptation to climatic selective gradients.

  1. Environmental effects on the recruitment variability of nursery species

    NASA Astrophysics Data System (ADS)

    Martinho, F.; Dolbeth, M.; Viegas, I.; Teixeira, C. M.; Cabral, H. N.; Pardal, M. A.

    2009-08-01

    The recruitment variability of the marine fish species Dicentrarchus labrax, Platichthys flesus and Solea solea was evaluated in the Mondego estuary (Portugal) from 2003 to 2007. The relationships between sea surface temperature, NAO index, coastal wind speed and direction, precipitation and river runoff prior to the estuarine colonization and the abundance of 0-group fish were evaluated using gamma-based Generalized Linear Models. Dicentrarchus labrax and P. flesus 0-group decreased in abundance towards the end of the study period, while S. solea, despite low abundance in 2004, increased in abundance in 2007. For D. labrax, river runoff, precipitation and east-west wind were significant; for P. flesus, precipitation, river runoff and both north-south and east-west wind components were significant parameters, while for S. solea only river runoff was important. Results were compared with recent projections for climate change scenarios, to evaluate their effects on future recruitment levels.

  2. Bioaccumulation of photoprotective compounds in copepods: environmental triggers and sources of intra-specific variability

    NASA Astrophysics Data System (ADS)

    Zagarese, H. E.; García, P.; Diéguez, M. D.; Ferraro, M. A.

    2012-12-01

    Ultraviolet radiation (UVR) and temperature are two globally important abiotic factors affecting freshwater ecosystems. Planktonic organisms have developed a battery of counteracting mechanisms to minimize the risk of being damaged by UVR, which respond to three basic principles: avoid, protect, repair. Copepods are among the most successful zooplankton groups. They are highly adaptable animals, capable of displaying flexible behaviors, physiologies, and life strategies. In particular, they are well equipped to cope with harmful UVR. Their arsenal includes vertical migration, accumulation of photoprotective compounds, and photorepair. The preference for a particular strategy is affected by a plethora of environmental (extrinsic) parameters, such as the existence of a depth refuge, the risk of visual predation, and temperature. Temperature modifies the environment (e.g. the lake thermal structure), and animal metabolism (e.g., swimming speed, bioaccumulation of photoprotective compounds). In addition, the relative weight of UVR-coping strategies is also influenced by the organism (intrinsic) characteristics (e.g., inter- and intra-specific variability). The UV absorbing compounds, mycosporine-like amino acids (MAAs), are widely distributed among freshwater copepods. Animals are unable to synthesize MAAs, and therefore depend on external sources for accumulating these compounds. Although copepods may acquire MAAs from their food, for the few centropagic species investigated so far, the main source of MAAs are microbial (most likely prokaryotic) organisms living in close association with the copepods. Boeckella gracilipes is a common centropagic copepod in Patagonian lakes. We suspected that its occurrence in different types of lakes, hydrologically unconnected, but within close geographical proximity, could have resulted in different microbial-copepod associations (i.e., different MAAs sources) that could translate into intra-specific differences in the accumulation

  3. Consideration of environmental and operational variability for damage diagnosis

    SciTech Connect

    Sohn, H.; Worden, K.; Farrar, C. R.

    2002-01-01

    Damage diagnosis is a problem that can be addressed at many levels. Stated in its most basic form, the objective is to ascertain simply if damage is present or not. In a statistical pattern recognition paradigm of this problem, the philosophy is to collect baseline signatures from a system to be monitored and to compare subsequent data to see if the new 'pattern' deviates significantly from the baseline data. Unfortunately, matters are seldom as simple as this. In reality, structures will be subjected to changing environmental and operational conditions that will affect measured signals. In this case, there may be a wide range of normal conditions, and it is clearly undesirable to signal damage simply because of a change in the environment. In this paper, a unique combination of time series analysis, neural networks, and statistical inference techniques is developed for damage classification explicitly taking into account these natural variations of the system in order to minimize false positive indication of true system changes.

  4. Pre-exposure of Arabidopsis to the abiotic or biotic environmental stimuli “chilling” or “insect eggs” exhibits different transcriptomic responses to herbivory

    PubMed Central

    Firtzlaff, Vivien; Oberländer, Jana; Geiselhardt, Sven; Hilker, Monika; Kunze, Reinhard

    2016-01-01

    Plants can retain information about environmental stress and thus, prepare themselves for impending stress. In nature, it happens that environmental stimuli like ‘cold’ and ‘insect egg deposition’ precede insect herbivory. Both these stimuli are known to elicit transcriptomic changes in Arabidposis thaliana. It is unknown, however, whether they affect the plant’s anti-herbivore defence and feeding-induced transcriptome when they end prior to herbivory. Here we investigated the transcriptomic response of Arabidopsis to feeding by Pieris brassicae larvae after prior exposure to cold or oviposition. The transcriptome of plants that experienced a five-day-chilling period (4 °C) was not fully reset to the pre-chilling state after deacclimation (20 °C) for one day and responded differently to herbivory than that of chilling-inexperienced plants. In contrast, when after a five-day-lasting oviposition period the eggs were removed, one day later the transcriptome and, consistently, also its response to herbivory resembled that of egg-free plants. Larval performance was unaffected by previous exposure of plants to cold and to eggs, thus indicating P. brassicae tolerance to cold-mediated plant transcriptomic changes. Our results show strong differences in the persistence of the plant’s transcriptomic state after removal of different environmental cues, and consequently differential effects on the transcriptomic response to later herbivory. PMID:27329974

  5. Design of a WSN for the Sampling of Environmental Variability in Complex Terrain

    PubMed Central

    Martín-Tardío, Miguel A.; Felicísimo, Ángel M.

    2014-01-01

    In-situ environmental parameter measurements using sensor systems connected to a wireless network have become widespread, but the problem of monitoring large and mountainous areas by means of a wireless sensor network (WSN) is not well resolved. The main reasons for this are: (1) the environmental variability distribution is unknown in the field; (2) without this knowledge, a huge number of sensors would be necessary to ensure the complete coverage of the environmental variability and (3) WSN design requirements, for example, effective connectivity (intervisibility), limiting distances and controlled redundancy, are usually solved by trial and error. Using temperature as the target environmental variable, we propose: (1) a method to determine the homogeneous environmental classes to be sampled using the digital elevation model (DEM) and geometric simulations and (2) a procedure to determine an effective WSN design in complex terrain in terms of the number of sensors, redundancy, cost and spatial distribution. The proposed methodology, based on geographic information systems and binary integer programming can be easily adapted to a wide range of applications that need exhaustive and continuous environmental monitoring with high spatial resolution. The results show that the WSN design is perfectly suited to the topography and the technical specifications of the sensors, and provides a complete coverage of the environmental variability in terms of Sun exposure. However these results still need be validated in the field and the proposed procedure must be refined. PMID:25412218

  6. The impact of environmental variability on Atlantic mackerel Scomber scombrus larval abundance to the west of the British Isles

    NASA Astrophysics Data System (ADS)

    Pitois, Sophie G.; Jansen, Teunis; Pinnegar, John

    2015-05-01

    The value of the Continuous Plankton Recorder (CPR) fish larvae dataset, with its extensive spatio-temporal coverage, has been recently demonstrated with studies on long-term changes over decadal scales in the abundance and distribution of fish larvae in relation to physical and biological factors in the North Sea. We used a similar approach in the west and southwest area of the UK shelf and applied a principal component analysis (PCA) using 7 biotic and abiotic parameters, combined with Hierarchical Cluster Analysis (HCA), to investigate the impact of environmental changes in the west and southwest area of the UK shelf on mackerel larvae during the period 1960-2004. The analysis revealed 3 main periods of time (1960-1968; 1969-1994; 1995-2004) reflecting 3 different ecosystem states. The results suggest a transition from an ecosystem characterized by low temperature, high salinity, high abundances of zooplankton and the larger phytoplankton groups, to a system characterized by higher temperature, lower salinities, lower abundances of zooplankton and larger phytoplankton and higher abundances of the small phytoplankton species. Analysis revealed a very weak positive correlation between the Second principal component and mackerel larvae yearly abundance, attributed to the North Atlantic Oscillation (NAO). The results presented here are in broad accord with recent investigations that link climatic variability and dynamics of mackerel reproduction. However, the growing body of literature that documents statistical correlations between environment and mackerel needs to be supplemented by local process studies, to gain more insight and to be able to predict mackerel response to climate change scenarios. Utilising the strength of the CPR dataset, namely its unique temporal coverage, in an analysis where other data (such as egg surveys) are drawn in to compensate for the spatial issues could prove to be the way forward.

  7. Abiotic stress responses in plant roots: a proteomics perspective

    PubMed Central

    Ghosh, Dipanjana; Xu, Jian

    2014-01-01

    Abiotic stress conditions adversely affect plant growth, resulting in significant decline in crop productivity. To mitigate and recover from the damaging effects of such adverse environmental conditions, plants have evolved various adaptive strategies at cellular and metabolic levels. Most of these strategies involve dynamic changes in protein abundance that can be best explored through proteomics. This review summarizes comparative proteomic studies conducted with roots of various plant species subjected to different abiotic stresses especially drought, salinity, flood, and cold. The main purpose of this article is to highlight and classify the protein level changes in abiotic stress response pathways specifically in plant roots. Shared as well as stressor-specific proteome signatures and adaptive mechanism(s) are simultaneously described. Such a comprehensive account will facilitate the design of genetic engineering strategies that enable the development of broad-spectrum abiotic stress-tolerant crops. PMID:24478786

  8. Abiotic stresses and endophyte effects

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Abiotic stresses consist of nonorganismal, nonpathogenic factors that inhibit plant function. Tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] is widely symbiotic with a naturally occurring endophytic fungus [Neotyphodium coenophialum (Morgan-Jones and Gams) Glenn, Bacon, and Hanlin], which con...

  9. Common trends in German Bight benthic macrofaunal communities: Assessing temporal variability and the relative importance of environmental variables

    NASA Astrophysics Data System (ADS)

    Ghodrati Shojaei, Mehdi; Gutow, Lars; Dannheim, Jennifer; Rachor, Eike; Schröder, Alexander; Brey, Thomas

    2016-01-01

    We examined long-term variability in the abundance of German Bight soft bottom macro-zoobenthos together with major environmental factors (sea surface temperature, winter NAO index, salinity, phosphate, nitrate and silicate) using one of the most comprehensive ecological long-term data sets in the North Sea (1981-2011). Two techniques, Min/Max Autocorrelation Factor Analysis (MAFA) and Dynamic Factor Analysis (DFA) were used to identify underlying common trends in the macrofaunal time series and the relationships between this series and environmental variables. These methods are particularly suitable for relatively short (> 15-25 years), non-stationary multivariate data series. Both MAFA and DFA identify a common trend in German Bight macrofaunal abundance i.e. a slight decrease (1981-mid-1990s) followed by a sharp trough in the late 1990s. Subsequently, scores increased again towards 2011. Our analysis indicates that winter temperature and North Atlantic Oscillation were the predominant environmental drivers of temporal variation in German Bight macrofaunal abundance. The techniques applied here are suitable tools to describe temporal fluctuations in complex and noisy multiple time series data and can detect distinct shifts and trends within such time series.

  10. Plant–insect interactions from Middle Triassic (late Ladinian) of Monte Agnello (Dolomites, N-Italy)—initial pattern and response to abiotic environmental perturbations

    PubMed Central

    Kustatscher, Evelyn; Dellantonio, Elio

    2015-01-01

    The Paleozoic–Mesozoic transition is characterized by the most massive extinction of the Phanerozoic. Nevertheless, an impressive adaptive radiation of herbivorous insects occurred on gymnosperm-dominated floras not earlier than during the Middle to Late Triassic, penecontemporaneous with similar events worldwide, all which exhibit parallel expansions of generalized and mostly specialized insect herbivory on plants, expressed as insect damage on a various plant organs and tissues. The flora from Monte Agnello is distinctive, due to its preservation in subaerially deposited pyroclastic layers with exceptionally preserved details. Thus, the para-autochthonous assemblage provides insights into environmental disturbances, caused by volcanic activity, and how they profoundly affected the structure and composition of herbivory patterns. These diverse Middle Triassic biota supply extensive evidence for insect herbivore colonization, resulting in specific and complex herbivory patterns involving the frequency and diversity of 20 distinctive damage types (DTs). These DT patterns show that external foliage feeders, piercer-and-suckers, leaf miners, gallers, and oviposition culprits were intricately using almost all tissue types from the dominant host plants of voltzialean conifers (e.g., Voltzia), horsetails, ferns (e.g., Neuropteridium, Phlebopteris, Cladophlebis and Thaumatopteris), seed ferns (e.g., Scytophyllum), and cycadophytes (e.g., Bjuvia and Nilssonia). PMID:25945313

  11. Environmental variability uncovers disruptive effects of species' interactions on population dynamics.

    PubMed

    Gudmundson, Sara; Eklöf, Anna; Wennergren, Uno

    2015-08-07

    How species respond to changes in environmental variability has been shown for single species, but the question remains whether these results are transferable to species when incorporated in ecological communities. Here, we address this issue by analysing the same species exposed to a range of environmental variabilities when (i) isolated or (ii) embedded in a food web. We find that all species in food webs exposed to temporally uncorrelated environments (white noise) show the same type of dynamics as isolated species, whereas species in food webs exposed to positively autocorrelated environments (red noise) can respond completely differently compared with isolated species. This is owing to species following their equilibrium densities in a positively autocorrelated environment that in turn enables species-species interactions to come into play. Our results give new insights into species' response to environmental variation. They especially highlight the importance of considering both species' interactions and environmental autocorrelation when studying population dynamics in a fluctuating environment.

  12. Environmental variability uncovers disruptive effects of species' interactions on population dynamics

    PubMed Central

    Gudmundson, Sara; Eklöf, Anna; Wennergren, Uno

    2015-01-01

    How species respond to changes in environmental variability has been shown for single species, but the question remains whether these results are transferable to species when incorporated in ecological communities. Here, we address this issue by analysing the same species exposed to a range of environmental variabilities when (i) isolated or (ii) embedded in a food web. We find that all species in food webs exposed to temporally uncorrelated environments (white noise) show the same type of dynamics as isolated species, whereas species in food webs exposed to positively autocorrelated environments (red noise) can respond completely differently compared with isolated species. This is owing to species following their equilibrium densities in a positively autocorrelated environment that in turn enables species–species interactions to come into play. Our results give new insights into species' response to environmental variation. They especially highlight the importance of considering both species' interactions and environmental autocorrelation when studying population dynamics in a fluctuating environment. PMID:26224705

  13. Environmental variability drives shifts in the foraging behaviour and reproductive success of an inshore seabird.

    PubMed

    Kowalczyk, Nicole D; Reina, Richard D; Preston, Tiana J; Chiaradia, André

    2015-08-01

    Marine animals forage in areas that aggregate prey to maximize their energy intake. However, these foraging 'hot spots' experience environmental variability, which can substantially alter prey availability. To survive and reproduce animals need to modify their foraging in response to these prey shifts. By monitoring their inter-annual foraging behaviours, we can understand which environmental variables affect their foraging efficiency, and can assess how they respond to environmental variability. Here, we monitored the foraging behaviour and isotopic niche of little penguins (Eudyptula minor), over 3 years (2008, 2011, and 2012) of climatic and prey variability within Port Phillip Bay, Australia. During drought (2008), penguins foraged in close proximity to the Yarra River outlet on a predominantly anchovy-based diet. In periods of heavy rainfall, when water depth in the largest tributary into the bay (Yarra River) was high, the total distance travelled, maximum distance travelled, distance to core-range, and size of core- and home-ranges of penguins increased significantly. This larger foraging range was associated with broad dietary diversity and high reproductive success. These results suggest the increased foraging range and dietary diversity of penguins were a means to maximize resource acquisition rather than a strategy to overcome local depletions in prey. Our results demonstrate the significance of the Yarra River in structuring predator-prey interactions in this enclosed bay, as well as the flexible foraging strategies of penguins in response to environmental variability. This plasticity is central to the survival of this small-ranging, resident seabird species.

  14. Environmental variables measured at multiple spatial scales exert uneven influence on fish assemblages of floodplain lakes

    USGS Publications Warehouse

    Dembkowski, Daniel J.; Miranda, Leandro E.

    2014-01-01

    We examined the interaction between environmental variables measured at three different scales (i.e., landscape, lake, and in-lake) and fish assemblage descriptors across a range of over 50 floodplain lakes in the Mississippi Alluvial Valley of Mississippi and Arkansas. Our goal was to identify important local- and landscape-level determinants of fish assemblage structure. Relationships between fish assemblage structure and variables measured at broader scales (i.e., landscape-level and lake-level) were hypothesized to be stronger than relationships with variables measured at finer scales (i.e., in-lake variables). Results suggest that fish assemblage structure in floodplain lakes was influenced by variables operating on three different scales. However, and contrary to expectations, canonical correlations between in-lake environmental characteristics and fish assemblage structure were generally stronger than correlations between landscape-level and lake-level variables and fish assemblage structure, suggesting a hierarchy of influence. From a resource management perspective, our study suggests that landscape-level and lake-level variables may be manipulated for conservation or restoration purposes, and in-lake variables and fish assemblage structure may be used to monitor the success of such efforts.

  15. Spatiotemporal variability of dimethylsulphoniopropionate on a fringing coral reef: the role of reefal carbonate chemistry and environmental variability.

    PubMed

    Burdett, Heidi L; Donohue, Penelope J C; Hatton, Angela D; Alwany, Magdy A; Kamenos, Nicholas A

    2013-01-01

    Oceanic pH is projected to decrease by up to 0.5 units by 2100 (a process known as ocean acidification, OA), reducing the calcium carbonate saturation state of the oceans. The coastal ocean is expected to experience periods of even lower carbonate saturation state because of the inherent natural variability of coastal habitats. Thus, in order to accurately project the impact of OA on the coastal ocean, we must first understand its natural variability. The production of dimethylsulphoniopropionate (DMSP) by marine algae and the release of DMSP's breakdown product dimethylsulphide (DMS) are often related to environmental stress. This study investigated the spatiotemporal response of tropical macroalgae (Padina sp., Amphiroa sp. and Turbinaria sp.) and the overlying water column to natural changes in reefal carbonate chemistry. We compared macroalgal intracellular DMSP and water column DMSP+DMS concentrations between the environmentally stable reef crest and environmentally variable reef flat of the fringing Suleman Reef, Egypt, over 45-hour sampling periods. Similar diel patterns were observed throughout: maximum intracellular DMSP and water column DMS/P concentrations were observed at night, coinciding with the time of lowest carbonate saturation state. Spatially, water column DMS/P concentrations were highest over areas dominated by seagrass and macroalgae (dissolved DMS/P) and phytoplankton (particulate DMS/P) rather than corals. This research suggests that macroalgae may use DMSP to maintain metabolic function during periods of low carbonate saturation state. In the reef system, seagrass and macroalgae may be more important benthic producers of dissolved DMS/P than corals. An increase in DMS/P concentrations during periods of low carbonate saturation state may become ecologically important in the future under an OA regime, impacting larval settlement and increasing atmospheric emissions of DMS.

  16. Environmental variability and acoustic signals: a multi-level approach in songbirds.

    PubMed

    Medina, Iliana; Francis, Clinton D

    2012-12-23

    Among songbirds, growing evidence suggests that acoustic adaptation of song traits occurs in response to habitat features. Despite extensive study, most research supporting acoustic adaptation has only considered acoustic traits averaged for species or populations, overlooking intraindividual variation of song traits, which may facilitate effective communication in heterogeneous and variable environments. Fewer studies have explicitly incorporated sexual selection, which, if strong, may favour variation across environments. Here, we evaluate the prevalence of acoustic adaptation among 44 species of songbirds by determining how environmental variability and sexual selection intensity are associated with song variability (intraindividual and intraspecific) and short-term song complexity. We show that variability in precipitation can explain short-term song complexity among taxonomically diverse songbirds, and that precipitation seasonality and the intensity of sexual selection are related to intraindividual song variation. Our results link song complexity to environmental variability, something previously found for mockingbirds (Family Mimidae). Perhaps more importantly, our results illustrate that individual variation in song traits may be shaped by both environmental variability and strength of sexual selection.

  17. Influence of environmental variables on bioaccumulation of mercury. Environmental effects of dredging. Technical note

    SciTech Connect

    Clarkks, J.; Lutz, C.; McFarland, V.

    1988-12-01

    The purpose of this note examines the effects of environmental factors on the bioavailability of mercury from sediment and describes results of a laboratory experiment to assess the influence of temperature, salinity, and suspended sediment on bioaccumulation of mercury in estuarine clams and killifish.

  18. An omics approach to understand the plant abiotic stress.

    PubMed

    Debnath, Mousumi; Pandey, Mukeshwar; Bisen, P S

    2011-11-01

    Abiotic stress can lead to changes in development, productivity, and severe stress and may even threaten survival of plants. Several environmental stresses cause drastic changes in the growth, physiology, and metabolism of plants leading to the increased accumulation of secondary metabolites. As medicinal plants are important sources of drugs, steps are taken to understand the effect of stress on the physiology, biochemistry, genomic, proteomic, and metabolic levels. The molecular responses of plants to abiotic stress are often considered as a complex process. They are mainly based on the modulation of transcriptional activity of stress-related genes. Many genes have been induced under stress conditions. The products of stress-inducible genes protecting against these stresses includes the enzymes responsible for the synthesis of various osmoprotectants. Genetic engineering of tolerance to abiotic stresses help in molecular understanding of pathways induced in response to one or more of the abiotic stresses. Systems biology and virtual experiments allow visualizing and understanding how plants work to overcome abiotic stress. This review discusses the omic approach to understand the plant response to abiotic stress with special emphasis on medicinal plant.

  19. Spatio-temporal analysis of preterm birth in Portugal and its relation with environmental variables

    NASA Astrophysics Data System (ADS)

    Oliveira, M.; Teodoro, Ana C.; Freitas, A.; Bernardes, J.; Gonçalves, H.

    2016-10-01

    Preterm birth (PTB), one of the major concerns in obstetrics, is conventionally defined as the delivery of a live infant before 37 completed weeks of gestation, and one of its causes may be environmental factors. Remote sensing is a valuable approach for monitoring environmental variables, including in health sciences. In this work, remote sensing data were used to explore the relation of the environment with PTB. Time-series with monthly rates of male/female ratio and PTB were obtained from Portugal in 2000-2014. The environmental variables included in this study were monthly mean temperatures (T), relative humidity (RH), NDVI, concentrations of NO2 and PM10 in 2003-2008. A temporal and spatial analysis of each health-related and environmental variable was performed, as well as their correlation. PTB has been increasing over time, from below 5% in 2000 to around 7% in 2014, with predominance of higher rates in districts with larger population. From 2003 to 2008, T and PM10 decreased significantly. A positive and significant correlation was found between male/female ratio and NO2 and RH, and to a lesser extent with PM10 and NDVI. PTB was also positively and significantly correlated with NO2 and T, and to a lesser extent with RH and PM10. These preliminary results suggest an association of PTB with most of the environmental variables studied, showing that more polluted and populated districts have higher rates of PTB. Further studies are warranted to explore interaction between the considered environmental factors and other variables related with risk for PTB.

  20. [Environmental and demographic variables associated with psychiatric morbidity in former prisoners of war].

    PubMed

    Dethienne, F; Donnay, J M

    1976-01-01

    In this study, present psychiatric morbidity of 100 former prisoners of war is related to 28 environmental and demographic variables grouped in 3 periods: before, during and after WW2. With the exception of the invalidity percentage, all statistically significant relations concern variables of the first two periods. The present results are discussed at the light of former publications by the authors. It appears among others that the age variable has to be taken in consideration in the explanation of psychiatric sequels of captivity, and that the condition "invalid of war" poorly reflects the degree of psychiatric morbidity.

  1. Environmental variability counteracts priority effects to facilitate species coexistence: evidence from nectar microbes

    PubMed Central

    Tucker, Caroline M.; Fukami, Tadashi

    2014-01-01

    The order of species arrival during community assembly can greatly affect species coexistence, but the strength of these effects, known as priority effects, appears highly variable across species and ecosystems. Furthermore, the causes of this variation remain unclear despite their fundamental importance in understanding species coexistence. Here, we show that one potential cause is environmental variability. In laboratory experiments using nectar-inhabiting microorganisms as a model system, we manipulated spatial and temporal variability of temperature, and examined consequences for priority effects. If species arrived sequentially, multiple species coexisted under variable temperature, but not under constant temperature. Temperature variability prevented extinction of late-arriving species that would have been excluded owing to priority effects if temperature had been constant. By contrast, if species arrived simultaneously, species coexisted under both variable and constant temperatures. We propose possible mechanisms underlying these results using a mathematical model that incorporates contrasting effects of microbial species on nectar pH and amino acids. Overall, our findings suggest that understanding consequences of priority effects for species coexistence requires explicit consideration of environmental variability. PMID:24430846

  2. Near-global freshwater-specific environmental variables for biodiversity analyses in 1 km resolution.

    PubMed

    Domisch, Sami; Amatulli, Giuseppe; Jetz, Walter

    2015-12-08

    The lack of freshwater-specific environmental information at sufficiently fine spatial grain hampers broad-scale analyses in aquatic biology, biogeography, conservation, and ecology. Here we present a near-global, spatially continuous, and freshwater-specific set of environmental variables in a standardized 1 km grid. We delineate the sub-catchment for each grid cell along the HydroSHEDS river network and summarize the upstream climate, topography, land cover, surface geology and soil to each grid cell using various metrics (average, minimum, maximum, range, sum, inverse distance-weighted average and sum). All variables were subsequently averaged across single lakes and reservoirs of the Global lakes and Wetlands Database that are connected to the river network. Monthly climate variables were summarized into 19 long-term climatic variables following the 'bioclim' framework. This new set of variables provides a basis for spatial ecological and biodiversity analyses in freshwater ecosystems at near global extent, yet fine spatial grain. To facilitate the generation of freshwater variables for custom study areas and spatial grains, we provide the 'r.stream.watersheds' and 'r.stream.variables' add-ons for the GRASS GIS software.

  3. Variable selection with random forest: Balancing stability, performance, and interpretation in ecological and environmental modeling

    EPA Science Inventory

    Random forest (RF) is popular in ecological and environmental modeling, in part, because of its insensitivity to correlated predictors and resistance to overfitting. Although variable selection has been proposed to improve both performance and interpretation of RF models, it is u...

  4. Relationships between environmental conditions and the morphological variability of planktonic testate amoeba in four neotropical floodplains.

    PubMed

    Arrieira, Rodrigo Leite; Schwind, Leilane Talita Fatoreto; Joko, Ciro Yoshio; Alves, Geziele Mucio; Velho, Luiz Felipe Machado; Lansac-Tôha, Fábio Amodêo

    2016-10-01

    Planktonic testate amoebae in floodplains exhibit a broad-range of morphological variability. The variation size is already known, but it is necessary to know how this is for morphological variables. This study aimed to identify the relationships between testate amoebae morphology and environmental factors in four neotropical floodplains. We conducted detailed morphometric analyses on 27 common species of planktonic testate amoebae from genera Arcella, Centropyxis, Cucurbitella, Suiadifflugia, Difflugia, Lesquereusia and Netzelia. We sampled subsurface water from each lake in 72 lakes in four Brazilian floodplain lakes. Our goals were to assess: (1) the range of their morphological variability (a) over space within each floodplain, and (b) among the four floodplains, and (c) over time, and (2) which environmental factors explained this variation. Mean shell height and breadth varied considerably among the different floodplain lakes, especially in the Pantanal and Amazonian floodplains. The morphological variability of testate amoeba was correlated to environmental conditions (ammonia, nitrate, phosphate, chlorophyll-a, turbidity, temperature, and depth). Thus, understanding the morphological variation of the testate amoeba species can elucidate many questions involving the ecology of these organisms. Furthermore, could help molecular studies, bioindicator role of these organisations, environmental reconstruction, among others.

  5. Temporal Variability and Environmental Drivers of Harmful Algal Blooms (HABs) in Western Lake Erie

    NASA Astrophysics Data System (ADS)

    Liang, S.; Tian, D.; Xie, G.; Tian, J.; Tseng, K. S.; Shum, C. K.; Lee, J.

    2014-12-01

    Understanding temporal variability and environmental drivers of harmful algal blooms (HABs) is important for guiding HABs impact mitigation plans in Lake Erie. The objective of this study is to characterize temporal variability and explore environmental driving factors of chlorophyll a (Chl-a) and phycocyanin (PC), which are determinants of HABs, in western Lake Erie. Ten years' (2002 to 2012) biweekly estimates of Chl-a and PC over western Lake Erie were retrieved from remote sensing-based measurements of water color with Medium Resolution Imaging Spectrometer ( MERIS). Nine environmental factors, including water quality and hydrometeorological variables, for the same period were also collected. While Chl-a and PC showed different predictabilities and differences in importance of environmental drivers at different locations and seasons using the Multivariate Adaptive Regression Splines (MARS) with the Variance Inflation Factor (VIF) method, hydrometeorological variables consistently showed great influences on Chl-a and PC in all four seasons. For Chl-a, the most significant environmental drivers are solar radiation and wind speed (spring); water temperature, solar radiation, and total Kjeldahl nitrogen concentration (summer); wind speed (fall); and water temperature and streamflow (winter). For PC, the most important environmental drivers are solar radiation and wind speed (spring); precipitation, water temperature, wind speed, and total Kjeldahl nitrogen concentration (summer); wind speed (fall); precipitation, water temperature, and streamflow ( winter). Wavelet analysis suggested that Chl-a and PC showed strong seasonal and inter-annual pattern - the 0.5- and 1-year periods are the dominant modes for both Chl-a and PC series. These findings offer insights into possible mechanisms underlying the dynamics of the HABs.

  6. The influence of environmental variables on platelet concentration in horse platelet-rich plasma.

    PubMed

    Rinnovati, Riccardo; Romagnoli, Noemi; Gentilini, Fabio; Lambertini, Carlotta; Spadari, Alessandro

    2016-07-04

    Platelet-rich plasma (PRP) commonly refers to blood products which contain a higher platelet (PLT) concentration as compared to normal plasma. Autologous PRP has been shown to be safe and effective in promoting the natural processes of soft tissue healing or reconstruction in humans and horses. Variability in PLT concentration has been observed in practice between PRP preparations from different patients or from the same individual under different conditions. A change in PLT concentration could modify PRP efficacy in routine applications. The aim of this study was to test the influence of environmental, individual and agonistic variables on the PLT concentration of PRP in horses. Six healthy Standardbred mares were exposed to six different variables with a one-week washout period between variables, and PRP was subsequently obtained from each horse. The variables were time of withdrawal during the day (morning/evening), hydration status (overhydration/dehydration) treatment with anti-inflammatory drugs and training periods on a treadmill. The platelet concentration was significantly higher in horses treated with a non-steroidal anti-inflammatory drug (P = 0.03). The leukocyte concentration increased 2-9 fold with respect to whole blood in the PRP which was obtained after exposure to all the variable considered. Environmental variation in platelet concentration should be taken into consideration during PRP preparation.

  7. Addressing Human Variability in Next-Generation Human Health Risk Assessments of Environmental Chemicals

    PubMed Central

    Bois, Frederic Y.; Chiu, Weihsueh A.; Hattis, Dale; Rusyn, Ivan; Guyton, Kathryn Z.

    2012-01-01

    Background: Characterizing variability in the extent and nature of responses to environmental exposures is a critical aspect of human health risk assessment. Objective: Our goal was to explore how next-generation human health risk assessments may better characterize variability in the context of the conceptual framework for the source-to-outcome continuum. Methods: This review was informed by a National Research Council workshop titled “Biological Factors that Underlie Individual Susceptibility to Environmental Stressors and Their Implications for Decision-Making.” We considered current experimental and in silico approaches, and emerging data streams (such as genetically defined human cells lines, genetically diverse rodent models, human omic profiling, and genome-wide association studies) that are providing new types of information and models relevant for assessing interindividual variability for application to human health risk assessments of environmental chemicals. Discussion: One challenge for characterizing variability is the wide range of sources of inherent biological variability (e.g., genetic and epigenetic variants) among individuals. A second challenge is that each particular pair of health outcomes and chemical exposures involves combinations of these sources, which may be further compounded by extrinsic factors (e.g., diet, psychosocial stressors, other exogenous chemical exposures). A third challenge is that different decision contexts present distinct needs regarding the identification—and extent of characterization—of interindividual variability in the human population. Conclusions: Despite these inherent challenges, opportunities exist to incorporate evidence from emerging data streams for addressing interindividual variability in a range of decision-making contexts. PMID:23086705

  8. Responses of terrestrial ecosystems and carbon budgets to current and future environmental variability

    PubMed Central

    Medvigy, David; Wofsy, Steven C.; Munger, J. William; Moorcroft, Paul R.

    2010-01-01

    We assess the significance of high-frequency variability of environmental parameters (sunlight, precipitation, temperature) for the structure and function of terrestrial ecosystems under current and future climate. We examine the influence of hourly, daily, and monthly variance using the Ecosystem Demography model version 2 in conjunction with the long-term record of carbon fluxes measured at Harvard Forest. We find that fluctuations of sunlight and precipitation are strongly and nonlinearly coupled to ecosystem function, with effects that accumulate through annual and decadal timescales. Increasing variability in sunlight and precipitation leads to lower rates of carbon sequestration and favors broad-leaved deciduous trees over conifers. Temperature variability has only minor impacts by comparison. We also find that projected changes in sunlight and precipitation variability have important implications for carbon storage and ecosystem structure and composition. Based on Intergovernmental Panel on Climate Change model estimates for changes in high-frequency meteorological variability over the next 100 years, we expect that terrestrial ecosystems will be affected by changes in variability almost as much as by changes in mean climate. We conclude that terrestrial ecosystems are highly sensitive to high-frequency meteorological variability, and that accurate knowledge of the statistics of this variability is essential for realistic predictions of ecosystem structure and functioning. PMID:20404190

  9. Relations of fish community composition to environmental variables in streams of central Nebraska, USA

    USGS Publications Warehouse

    Frenzel, S.A.; Swanson, R.B.

    1996-01-01

    Nine sites on streams in the Platte River Basin in central Nebraska were sampled as part of the US Geological Survey's National Water Quality Assessment Program during 1993-1994. A combination of canonical correspondence analysis and an index of biotic integrity determined from fish community data produced complementary evaluations of water quality conditions. Results of the canonical correspondence analysis were useful in showing which environmental variables were significant in differentiating fish communities at the nine sites. Five environmental variables were statistically significant in the analysis. Median specific conductance of water samples collected at a site accounted for the largest amount of variability in the species data. Although the percentage of the basin as cropland was not the first variable chosen in a forward selection process, it was the most strongly correlated with the first ordination axis. A rangeland- dominated site was distinguished from all others along that axis. Median orthophosphate concentration of samples collected in the year up to the time of fish sampling was most strongly correlated with the second ordination axis. The index of biotic integrity produced results that could be interpreted in terms of the relative water quality between sites. Sites draining nearly 100% cropland had the lowest scores for two individual metrics of the index of biotic integrity that were related to species tolerance. Effective monitoring of water quality could be achieved by coupling methods that address both the ecological components of fish communities and their statistical relationships to environmental factors.

  10. Fish functional traits correlated with environmental variables in a temperate biodiversity hotspot.

    PubMed

    Keck, Benjamin P; Marion, Zachary H; Martin, Derek J; Kaufman, Jason C; Harden, Carol P; Schwartz, John S; Strange, Richard J

    2014-01-01

    The global biodiversity crisis has invigorated the search for generalized patterns in most disciplines within the natural sciences. Studies based on organismal functional traits attempt to broaden implications of results by identifying the response of functional traits, instead of taxonomic units, to environmental variables. Determining the functional trait responses enables more direct comparisons with, or predictions for, communities of different taxonomic composition. The North American freshwater fish fauna is both diverse and increasingly imperiled through human mediated disturbances, including climate change. The Tennessee River, USA, contains one of the most diverse assemblages of freshwater fish in North America and has more imperiled species than other rivers, but there has been no trait-based study of community structure in the system. We identified 211 localities in the upper Tennessee River that were sampled by the Tennessee Valley Authority between 2009 and 2011 and compiled fish functional traits for the observed species and environmental variables for each locality. Using fourth corner analysis, we identified significant correlations between many fish functional traits and environmental variables. Functional traits associated with an opportunistic life history strategy were correlated with localities subject to greater land use disturbance and less flow regulation, while functional traits associated with a periodic life history strategy were correlated with localities subject to regular disturbance and regulated flow. These are patterns observed at the continental scale, highlighting the generalizability of trait-based methods. Contrary to studies that found no community structure differences when considering riparian buffer zones, we found that fish functional traits were correlated with different environmental variables between analyses with buffer zones vs. entire catchment area land cover proportions. Using existing databases and fourth corner

  11. Fish Functional Traits Correlated with Environmental Variables in a Temperate Biodiversity Hotspot

    PubMed Central

    Keck, Benjamin P.; Marion, Zachary H.; Martin, Derek J.; Kaufman, Jason C.; Harden, Carol P.; Schwartz, John S.; Strange, Richard J.

    2014-01-01

    The global biodiversity crisis has invigorated the search for generalized patterns in most disciplines within the natural sciences. Studies based on organismal functional traits attempt to broaden implications of results by identifying the response of functional traits, instead of taxonomic units, to environmental variables. Determining the functional trait responses enables more direct comparisons with, or predictions for, communities of different taxonomic composition. The North American freshwater fish fauna is both diverse and increasingly imperiled through human mediated disturbances, including climate change. The Tennessee River, USA, contains one of the most diverse assemblages of freshwater fish in North America and has more imperiled species than other rivers, but there has been no trait-based study of community structure in the system. We identified 211 localities in the upper Tennessee River that were sampled by the Tennessee Valley Authority between 2009 and 2011 and compiled fish functional traits for the observed species and environmental variables for each locality. Using fourth corner analysis, we identified significant correlations between many fish functional traits and environmental variables. Functional traits associated with an opportunistic life history strategy were correlated with localities subject to greater land use disturbance and less flow regulation, while functional traits associated with a periodic life history strategy were correlated with localities subject to regular disturbance and regulated flow. These are patterns observed at the continental scale, highlighting the generalizability of trait-based methods. Contrary to studies that found no community structure differences when considering riparian buffer zones, we found that fish functional traits were correlated with different environmental variables between analyses with buffer zones vs. entire catchment area land cover proportions. Using existing databases and fourth corner

  12. What is environmental stress? Insights from fish living in a variable environment.

    PubMed

    Schulte, Patricia M

    2014-01-01

    Although the term environmental stress is used across multiple fields in biology, the inherent ambiguity associated with its definition has caused confusion when attempting to understand organismal responses to environmental change. Here I provide a brief summary of existing definitions of the term stress, and the related concepts of homeostasis and allostasis, and attempt to unify them to develop a general framework for understanding how organisms respond to environmental stressors. I suggest that viewing stressors as environmental changes that cause reductions in performance or fitness provides the broadest and most useful conception of the phenomenon of stress. I examine this framework in the context of animals that have evolved in highly variable environments, using the Atlantic killifish, Fundulus heteroclitus, as a case study. Consistent with the extreme environmental variation that they experience in their salt marsh habitats, killifish have substantial capacity for both short-term resistance and long-term plasticity in the face of changing temperature, salinity and oxygenation. There is inter-population variation in the sensitivity of killifish to environmental stressors, and in their ability to acclimate, suggesting that local adaptation can shape the stress response even in organisms that are broadly tolerant and highly plastic. Whole-organism differences between populations in stressor sensitivity and phenotypic plasticity are reflected at the biochemical and molecular levels in killifish, emphasizing the integrative nature of the response to environmental stressors. Examination of this empirical example highlights the utility of using an evolutionary perspective on stressors, stress and stress responses.

  13. Restoration impact of an uncontrolled phosphogypsum dump site on the seasonal distribution of abiotic variables, phytoplankton and zooplankton along the near shore of the south-western Mediterranean coast.

    PubMed

    Rekik, Amira; Maalej, Sami; Ayadi, Habib; Aleya, Lotfi

    2013-06-01

    'In connection with the Taparura Project, we studied the distribution of phytoplankton and zooplankton communities in relation to environmental variables at 18 stations sampled during four coastal cruises conducted between October 2009 and July 2010 on the north coast of Sfax (Tunisia, western Mediterranean Sea). The inshore location was largely dominated by diatoms (66 %) represented essentially by members of the genera Navicula, Grammatophora, and Licmophora. Dinophyceae were numerically the second largest group and showed an enhanced species richness. Cyanobacteriae developed in association with an important proliferation of colonial Trichodesmium erythraeum, contributing 39.4 % of total phytoplankton abundances. The results suggest that phytoplankters are generally adapted to specific environmental conditions. Copepods were the most abundant zooplankton group (82 %) of total zooplankton. A total of 21 copepod species were identified in all stations, with an overwhelming abundance of Oithona similis in autumn and summer, Euterpina acutifrons in winter, and Oncaea conifera in spring. The phosphogypsum restoration had been acutely necessary allowing dominant zooplankton species to exploit a wide range of food resources including phytoplankton and thus improving water quality.

  14. Genetic and environmental sources of fibrinogen variability in Israeli families: the Kibbutzim Family Study.

    PubMed Central

    Friedlander, Y; Elkana, Y; Sinnreich, R; Kark, J D

    1995-01-01

    Genetic and environmental determinants of plasma fibrinogen were investigated in a sample of 82 kindreds residing in kibbutz settlements in Israel. The sample included 223 males and 229 females ages 15-97 years. Fibrinogen levels were first adjusted for variability in sex and age. There was a significant familial aggregation of adjusted fibrinogen levels, as indicated by inter- and intraclass correlation coefficients significantly different from zero. Commingling analysis implied that in this population a mixture of two normal distributions fit the adjusted fibrinogen levels better than did a single normal distribution. Complex segregation analysis was first applied to these sex- and age-adjusted data. Heterogeneous etiologies for individual differences were suggested. There was evidence for a nontransmitted environmental major factor in addition to polygenic genes that explained the mixture of distributions. In parallel, a single recessive locus with a major effect that explained the adjusted variation in fibrinogen could not be rejected. However, when the regression model for sex and age allowed coefficients to be ousiotype (class)-specific, the recessive genetic model was rejected and the mixed environmental one was not. These results suggested that particular ousiotypes determined by the major environmental factor are associated with a steeper increase of fibrinogen with age. While at the age of 20 years, the major environmental factor contributed 10% to fibrinogen variability, and 48% was explained by polygenic loci, at 80 years of age, the major factor explained 64% and only approximately 20% was explained by polygenic factors. PMID:7726177

  15. Variable filtered photographic film as a radiation detector for environmental radiation monitoring

    NASA Astrophysics Data System (ADS)

    Majid, Zafri Azran Abdul; Junet, Laila Kalidah; Hazali, Norazlanshah; Abdullah, Abdul Adam; Hanafiah, Megat Ahmad Kamal Megat

    2013-05-01

    Environmental radiation is an ionising radiation that present in the natural environment which mostly originates from cosmic rays and radionuclide agents in the environment. This may lead the population to be exposed to the radiation. Therefore, the environmental radiation needs to be observed cautiously to minimize the impact of radiation. However, there is no specific or proper monitoring device that provides an outdoor environmental radiation monitoring. Hence, a new outdoor environmental radiation monitoring device was developed. A photographic film has been chosen as a dosimeter. The purpose of this study was to prove the covered photographic film attached with variable filter can be used to develop environmental radiation monitoring device to detect the ionising radiation. The filter used was variable thickness of plastic, aluminium (Al) and lead (Pb). The result from the study showed that the mean optical density (OD) values for medium speed film are in the range 0.41 to 0.73, and for fast speed film the OD values are in the range 0.51 to 1.35. The OD values decreased when the filter was attached. This has proven that the photographic film can be used to detect radiation and fast speed film was more sensitive compared to medium speed film.

  16. Nitric oxide signaling in plant responses to abiotic stresses.

    PubMed

    Qiao, Weihua; Fan, Liu-Min

    2008-10-01

    Nitric oxide (NO) plays important roles in diverse physiological processes in plants. NO can provoke both beneficial and harmful effects, which depend on the concentration and location of NO in plant cells. This review is focused on NO synthesis and the functions of NO in plant responses to abiotic environmental stresses. Abiotic stresses mostly induce NO production in plants. NO alleviates the harmfulness of reactive oxygen species, and reacts with other target molecules, and regulates the expression of stress responsive genes under various stress conditions.

  17. Starch as a determinant of plant fitness under abiotic stress.

    PubMed

    Thalmann, Matthias; Santelia, Diana

    2017-03-09

    I. II. III. IV. V. VI. References SUMMARY: Abiotic stresses, such as drought, high salinity and extreme temperatures, pose one of the most important constraints to plant growth and productivity in many regions of the world. A number of investigations have shown that plants, including several important crops, remobilize their starch reserve to release energy, sugars and derived metabolites to help mitigate the stress. This is an essential process for plant fitness with important implications for plant productivity under challenging environmental conditions. In this Tansley insight, we evaluate the current literature on starch metabolism in response to abiotic stresses, and discuss the key enzymes involved and how they are regulated.

  18. Polyamines and abiotic stress in plants: a complex relationship1

    PubMed Central

    Minocha, Rakesh; Majumdar, Rajtilak; Minocha, Subhash C.

    2014-01-01

    The physiological relationship between abiotic stress in plants and polyamines was reported more than 40 years ago. Ever since there has been a debate as to whether increased polyamines protect plants against abiotic stress (e.g., due to their ability to deal with oxidative radicals) or cause damage to them (perhaps due to hydrogen peroxide produced by their catabolism). The observation that cellular polyamines are typically elevated in plants under both short-term as well as long-term abiotic stress conditions is consistent with the possibility of their dual effects, i.e., being protectors from as well as perpetrators of stress damage to the cells. The observed increase in tolerance of plants to abiotic stress when their cellular contents are elevated by either exogenous treatment with polyamines or through genetic engineering with genes encoding polyamine biosynthetic enzymes is indicative of a protective role for them. However, through their catabolic production of hydrogen peroxide and acrolein, both strong oxidizers, they can potentially be the cause of cellular harm during stress. In fact, somewhat enigmatic but strong positive relationship between abiotic stress and foliar polyamines has been proposed as a potential biochemical marker of persistent environmental stress in forest trees in which phenotypic symptoms of stress are not yet visible. Such markers may help forewarn forest managers to undertake amelioration strategies before the appearance of visual symptoms of stress and damage at which stage it is often too late for implementing strategies for stress remediation and reversal of damage. This review provides a comprehensive and critical evaluation of the published literature on interactions between abiotic stress and polyamines in plants, and examines the experimental strategies used to understand the functional significance of this relationship with the aim of improving plant productivity, especially under conditions of abiotic stress. PMID:24847338

  19. Oxylipins and plant abiotic stress resistance.

    PubMed

    Savchenko, T V; Zastrijnaja, O M; Klimov, V V

    2014-04-01

    Oxylipins are signaling molecules formed enzymatically or spontaneously from unsaturated fatty acids in all aerobic organisms. Oxylipins regulate growth, development, and responses to environmental stimuli of organisms. The oxylipin biosynthesis pathway in plants includes a few parallel branches named after first enzyme of the corresponding branch as allene oxide synthase, hydroperoxide lyase, divinyl ether synthase, peroxygenase, epoxy alcohol synthase, and others in which various biologically active metabolites are produced. Oxylipins can be formed non-enzymatically as a result of oxygenation of fatty acids by free radicals and reactive oxygen species. Spontaneously formed oxylipins are called phytoprostanes. The role of oxylipins in biotic stress responses has been described in many published works. The role of oxylipins in plant adaptation to abiotic stress conditions is less studied; there is also obvious lack of available data compilation and analysis in this area of research. In this work we analyze data on oxylipins functions in plant adaptation to abiotic stress conditions, such as wounding, suboptimal light and temperature, dehydration and osmotic stress, and effects of ozone and heavy metals. Modern research articles elucidating the molecular mechanisms of oxylipins action by the methods of biochemistry, molecular biology, and genetics are reviewed here. Data on the role of oxylipins in stress signal transduction, stress-inducible gene expression regulation, and interaction of these metabolites with other signal transduction pathways in cells are described. In this review the general oxylipin-mediated mechanisms that help plants to adjust to a broad spectrum of stress factors are considered, followed by analysis of more specific responses regulated by oxylipins only under certain stress conditions. New approaches to improvement of plant resistance to abiotic stresses based on the induction of oxylipin-mediated processes are discussed.

  20. Influence of environmental variability on phylogenetic diversity and trait diversity within Calligonum communities.

    PubMed

    Wang, Jian-Cheng; Yang, Hong-Lan; Wang, Xi-Yong; Shi, Wei; Pan, Bo-Rong

    2014-01-01

    Since phylogenetic data provide the evolutionary history of the species and traits are the result of adaptation to the environmental conditions, joint analysis of these two aspects and ecological data may illuminate that how ecological processes affect the evolution of species and assembly of communities. In this study, we compared the community structure of sibling communities in order to illuminate the influence of environmental variability. We chose different Calligonum communities as research subjects which grow in active sand dunes and stabilized sand fields. Our results show that species which co-occurred in C. rubicundum community have greater phylogenetic evenness compared to species in other communities where co-occurring plants had similar traits. Soil variability might legitimately explain this result. Based on the similarity between the pattern of trait diversity and the pattern of phylogenetic diversity, we inferred that the evolution of traits is conservative and species of all but C. rubicundum communities are under more intense selection pressure.

  1. Risk factors for malnutrition in Brazilian children: the role of social and environmental variables

    PubMed Central

    Victora, Cesar G.; Vaughan, J. Patrick; Kirkwood, Betty R.; Martines, José Carlos; Barcelos, Lucio B.

    1986-01-01

    The article reports the effects of several socioeconomic and environmental indicators on the nutritional status (stunting, underweight, and wasting) of a sample of 802 children aged 12-35.9 months in urban and rural areas of southern Brazil. Of the social variables studied, family income and father's education level were the two risk factors that showed the strongest associations with nutritional status. The mother's education level, employment status of the head of the family, number of siblings, and family's ethnic background also showed some degree of association, but these were less significant when family income was included in the analysis. Environmental variables, particularly the type of housing, degree of crowding, and type of sewage disposal, were also strongly associated with malnutrition. The effects of having access to piped or treated water were only apparent on stunting and wasting. PMID:3488846

  2. The impact of abiotic factors on cellulose synthesis.

    PubMed

    Wang, Ting; McFarlane, Heather E; Persson, Staffan

    2016-01-01

    As sessile organisms, plants require mechanisms to sense and respond to changes in their environment, including both biotic and abiotic factors. One of the most common plant adaptations to environmental changes is differential regulation of growth, which results in growth either away from adverse conditions or towards more favorable conditions. As cell walls shape plant growth, this differential growth response must be accompanied by alterations to the plant cell wall. Here, we review the impact of four abiotic factors (osmotic conditions, ionic stress, light, and temperature) on the synthesis of cellulose, an important component of the plant cell wall. Understanding how different abiotic factors influence cellulose production and addressing key questions that remain in this field can provide crucial information to cope with the need for increased crop production under the mounting pressures of a growing world population and global climate change.

  3. Integrated metabolomics for abiotic stress responses in plants.

    PubMed

    Nakabayashi, Ryo; Saito, Kazuki

    2015-04-01

    Plants are considered to biosynthesize specialized (traditionally called secondary) metabolites to adapt to environmental stresses such as biotic and abiotic stresses. The majority of specialized metabolites induced by abiotic stress characteristically exhibit antioxidative activity in vitro, but their function in vivo is largely yet to be experimentally confirmed. In this review, we highlight recent advances in the identification of the role of abiotic stress-responsive specialized metabolites with an emphasis on flavonoids. Integrated 'omics' analysis, centered on metabolomics with a series of plant resources differing in their flavonoid accumulation, showed experimentally that flavonoids play a major role in antioxidation in vivo. In addition, the results also suggest the role of flavonoids in the vacuole. To obtain more in-depth insights, chemical and biological challenges need to be addressed for the identification of unknown specialized metabolites and their in vivo functions.

  4. Environmental life cycle assessment of grain maize production: An analysis of factors causing variability.

    PubMed

    Boone, Lieselot; Van Linden, Veerle; De Meester, Steven; Vandecasteele, Bart; Muylle, Hilde; Roldán-Ruiz, Isabel; Nemecek, Thomas; Dewulf, Jo

    2016-05-15

    To meet the growing demand, high yielding, but environmentally sustainable agricultural plant production systems are desired. Today, life cycle assessment (LCA) is increasingly used to assess the environmental impact of these agricultural systems. However, the impact results are very diverse due to management decisions or local natural conditions. The impact of grain maize is often generalized and an average is taken. Therefore, we studied variation in production systems. Four types of drivers for variability are distinguished: policy, farm management, year-to-year weather variation and innovation. For each driver, scenarios are elaborated using ReCiPe and CEENE (Cumulative Exergy Extraction from the Natural Environment) to assess the environmental footprint. Policy limits fertilisation levels in a soil-specific way. The resource consumption is lower for non-sandy soils than for sandy soils, but entails however more eutrophication. Farm management seems to have less influence on the environmental impact when considering the CEENE only. But farm management choices such as fertiliser type have a large effect on emission-related problems (e.g. eutrophication and acidification). In contrast, year-to-year weather variation results in large differences in the environmental footprint. The difference in impact results between favourable and poor environmental conditions amounts to 19% and 17% in terms of resources and emissions respectively, and irrigation clearly is an unfavourable environmental process. The best environmental performance is obtained by innovation as plant breeding results in a steadily increasing yield over 25 years. Finally, a comparison is made between grain maize production in Flanders and a generically applied dataset, based on Swiss practices. These very different results endorse the importance of using local data to conduct LCA of plant production systems. The results of this study show decision makers and farmers how they can improve the

  5. ROS Regulation During Abiotic Stress Responses in Crop Plants.

    PubMed

    You, Jun; Chan, Zhulong

    2015-01-01

    Abiotic stresses such as drought, cold, salt and heat cause reduction of plant growth and loss of crop yield worldwide. Reactive oxygen species (ROS) including hydrogen peroxide (H2O2), superoxide anions (O2 (•-)), hydroxyl radical (OH•) and singlet oxygen ((1)O2) are by-products of physiological metabolisms, and are precisely controlled by enzymatic and non-enzymatic antioxidant defense systems. ROS are significantly accumulated under abiotic stress conditions, which cause oxidative damage and eventually resulting in cell death. Recently, ROS have been also recognized as key players in the complex signaling network of plants stress responses. The involvement of ROS in signal transduction implies that there must be coordinated function of regulation networks to maintain ROS at non-toxic levels in a delicate balancing act between ROS production, involving ROS generating enzymes and the unavoidable production of ROS during basic cellular metabolism, and ROS-scavenging pathways. Increasing evidence showed that ROS play crucial roles in abiotic stress responses of crop plants for the activation of stress-response and defense pathways. More importantly, manipulating ROS levels provides an opportunity to enhance stress tolerances of crop plants under a variety of unfavorable environmental conditions. This review presents an overview of current knowledge about homeostasis regulation of ROS in crop plants. In particular, we summarize the essential proteins that are involved in abiotic stress tolerance of crop plants through ROS regulation. Finally, the challenges toward the improvement of abiotic stress tolerance through ROS regulation in crops are discussed.

  6. ROS Regulation During Abiotic Stress Responses in Crop Plants

    PubMed Central

    You, Jun; Chan, Zhulong

    2015-01-01

    Abiotic stresses such as drought, cold, salt and heat cause reduction of plant growth and loss of crop yield worldwide. Reactive oxygen species (ROS) including hydrogen peroxide (H2O2), superoxide anions (O2•-), hydroxyl radical (OH•) and singlet oxygen (1O2) are by-products of physiological metabolisms, and are precisely controlled by enzymatic and non-enzymatic antioxidant defense systems. ROS are significantly accumulated under abiotic stress conditions, which cause oxidative damage and eventually resulting in cell death. Recently, ROS have been also recognized as key players in the complex signaling network of plants stress responses. The involvement of ROS in signal transduction implies that there must be coordinated function of regulation networks to maintain ROS at non-toxic levels in a delicate balancing act between ROS production, involving ROS generating enzymes and the unavoidable production of ROS during basic cellular metabolism, and ROS-scavenging pathways. Increasing evidence showed that ROS play crucial roles in abiotic stress responses of crop plants for the activation of stress-response and defense pathways. More importantly, manipulating ROS levels provides an opportunity to enhance stress tolerances of crop plants under a variety of unfavorable environmental conditions. This review presents an overview of current knowledge about homeostasis regulation of ROS in crop plants. In particular, we summarize the essential proteins that are involved in abiotic stress tolerance of crop plants through ROS regulation. Finally, the challenges toward the improvement of abiotic stress tolerance through ROS regulation in crops are discussed. PMID:26697045

  7. Consistent patterns of variation in macrobenthic assemblages and environmental variables over multiple spatial scales using taxonomic and functional approaches.

    PubMed

    Veiga, Puri; Torres, Ana Catarina; Aneiros, Fernando; Sousa-Pinto, Isabel; Troncoso, Jesús S; Rubal, Marcos

    2016-09-01

    Spatial variability of environmental factors and macrobenthos, using species and functional groups, was examined over the same scales (100s of cm to >100 km) in intertidal sediments of two transitional water systems. The objectives were to test if functional groups were a good species surrogate and explore the relationship between environmental variables and macrobenthos. Environmental variables, diversity and the multivariate assemblage structure showed the highest variability at the scale of 10s of km. However, abundance was more variable at 10s of m. Consistent patterns were achieved using species and functional groups therefore, these may be a good species surrogate. Total carbon, salinity and silt/clay were the strongest correlated with macrobenthic assemblages. Results are valuable for design and interpretation of future monitoring programs including detection of anthropogenic disturbances in transitional systems and propose improvements in environmental variable sampling to refine the assessment of their relationship with biological data across spatial scales.

  8. Environmental variables associated with immature stage habitats of culicidae collected in aboriginal villages in Pahang, Malaysia.

    PubMed

    Ali, Wan Najdah Wan Mohamad; Ahmad, Rohani; Nor, Zurainee Mohamed; Ismail, Zamree; Ibrahim, Mohd Noor; Hadi, Azahari Abdul; Hassan, Rahimi; Lim, Lee Han

    2012-11-01

    Many of the most widely spread vector-borne diseases are water related, in that the mosquito vectors concerned breed or pass part of their lifecycle in or close to water. A major reason for the study of mosquito larval ecology is to gather information on environmental variables that may determine the species of mosquitoes and the distribution of larvae in the breeding habitats. Larval surveillance studies were conducted six times between May 2008 and October 2009 in Pos Lenjang, Kuala Lipis, Pahang. Twelve environmental variables were recorded for each sampling site, and samples of mosquito larvae were collected. Larval survey studies showed that anopheline and culicine larvae were collected from 79 and 67 breeding sites, respectively. All breeding sites were classified into nine habitat groups. Culicine larvae were found in all habitat groups, suggesting that they are very versatile and highly adaptable to different types of environment. Rock pools or water pockets with clear water formed on the bank of rivers and waterfalls were the most common habitats associated with An. maculatus. Environmental variables influence the suitability of aquatic habitats for anopheline and culicine larvae, but not significantly associated with the occurrence of both larvae genera (p>0.05). This study provides information on mosquito ecology in relation to breeding habitats that will be useful in designing and implementing larval control operations.

  9. Persistence of Selected Spartina alterniflora Rhizoplane Diazotrophs Exposed to Natural and Manipulated Environmental Variability

    PubMed Central

    Bagwell, Christopher E.; Lovell, Charles R.

    2000-01-01

    Rhizoplane-rhizosphere nitrogen-fixing microorganisms (diazotrophs) are thought to provide a major source of biologically available nitrogen in salt marshes dominated by Spartina alterniflora. Compositional and functional stability has been demonstrated for this important functional group; however, the quantitative responses of specific diazotroph populations to environmental variability have not been assessed. Changes in the relative abundances of selected rhizoplane diazotrophs in response to long-term fertilization were monitored quantitatively by reverse sample genome probing. Fertilization stimulated Spartina, with plant height nearly tripling after 1 year. Fertilization also resulted in significant changes in interstitial porewater parameters. Diazotrophic activity (acetylene reduction assay) was sensitive to the fertilization treatments and was inhibited in some plots on several sampling dates. However, inhibition was never consistent across all of the replicates within a treatment and activity always recovered. The rhizoplane diazotrophs were quite responsive to environmental variability and to experimental treatments, but none were displaced by either environmental variability or experimental treatments. All strains were detected consistently throughout this study, and extensive spatial heterogeneity in the distribution patterns of these organisms was observed. The physiological traits that differentiate the diazotroph populations presumably support competitiveness and niche specialization, resulting in the observed resilience of the diazotroph populations in the rhizosphere. PMID:11055903

  10. Flexible Control of Safety Margins for Action Based on Environmental Variability

    PubMed Central

    Hadjiosif, Alkis M.

    2015-01-01

    To reduce the risk of slip, grip force (GF) control includes a safety margin above the force level ordinarily sufficient for the expected load force (LF) dynamics. The current view is that this safety margin is based on the expected LF dynamics, amounting to a static safety factor like that often used in engineering design. More efficient control could be achieved, however, if the motor system reduces the safety margin when LF variability is low and increases it when this variability is high. Here we show that this is indeed the case by demonstrating that the human motor system sizes the GF safety margin in proportion to an internal estimate of LF variability to maintain a fixed statistical confidence against slip. In contrast to current models of GF control that neglect the variability of LF dynamics, we demonstrate that GF is threefold more sensitive to the SD than the expected value of LF dynamics, in line with the maintenance of a 3-sigma confidence level. We then show that a computational model of GF control that includes a variability-driven safety margin predicts highly asymmetric GF adaptation between increases versus decreases in load. We find clear experimental evidence for this asymmetry and show that it explains previously reported differences in how rapidly GFs and manipulatory forces adapt. This model further predicts bizarre nonmonotonic shapes for GF learning curves, which are faithfully borne out in our experimental data. Our findings establish a new role for environmental variability in the control of action. PMID:26085634

  11. The role of environmental variables on Aedes albopictus biology and chikungunya epidemiology

    PubMed Central

    Waldock, Joanna; Chandra, Nastassya L; Lelieveld, Jos; Proestos, Yiannis; Michael, Edwin; Christophides, George; Parham, Paul E

    2013-01-01

    Aedes albopictus is a vector of dengue and chikungunya viruses in the field, along with around 24 additional arboviruses under laboratory conditions. As an invasive mosquito species, Ae. albopictus has been expanding in geographical range over the past 20 years, although the poleward extent of mosquito populations is limited by winter temperatures. Nonetheless, population densities depend on environmental conditions and since global climate change projections indicate increasing temperatures and altered patterns of rainfall, geographic distributions of previously tropical mosquito species may change. Although mathematical models can provide explanatory insight into observed patterns of disease prevalence in terms of epidemiological and entomological processes, understanding how environmental variables affect transmission is possible only with reliable model parameterisation, which, in turn, is obtained only through a thorough understanding of the relationship between mosquito biology and environmental variables. Thus, in order to assess the impact of climate change on mosquito population distribution and regions threatened by vector-borne disease, a detailed understanding (through a synthesis of current knowledge) of the relationship between climate, mosquito biology, and disease transmission is required, but this process has not yet been undertaken for Ae. albopictus. In this review, the impact of temperature, rainfall, and relative humidity on Ae. albopictus development and survival are considered. Existing Ae. albopictus populations across Europe are mapped with current climatic conditions, considering whether estimates of climatic cutoffs for Ae. albopictus are accurate, and suggesting that environmental thresholds must be calibrated according to the scale and resolution of climate model outputs and mosquito presence data. PMID:23916332

  12. Spatiotemporal patterns provoked by environmental variability in a predator-prey model.

    PubMed

    Fras, Maja; Gosak, Marko

    2013-12-01

    The emergence of spatiotemporal patterns in the distribution of species is one of the most striking phenomena in ecology and nonlinear science. Since it is known that spatial inhomogeneities can significantly affect the dynamics of ecological populations, in the present paper we investigate the impact of environmental variability on the formation of patterns in a spatially extended predator-prey model. In particular, we utilize a predator-prey system with a Holling III functional response and introduce random spatial variations of the kinetic parameter signifying the intrinsic growth rate of the prey, reflecting the impact of a heterogeneous environment. Our results reveal that in the proximity of the Hopf bifurcation environmental variability is able to provoke pattern formation, whereby the coherence of the patterns exhibits a resonance-like dependence on the variability strength. Furthermore, we show that the phenomenon can only be observed if the spatial heterogeneities exhibit large enough regions with high growth rates of the prey. Our findings thus indicate that variability could be an essential pattern formation mechanism of the populations.

  13. Polyamines and abiotic stress tolerance in plants

    PubMed Central

    Gill, Sarvajeet Singh

    2010-01-01

    Environmental stresses including climate change, especially global warming, are severely affecting plant growth and productivity worldwide. It has been estimated that two-thirds of the yield potential of major crops are routinely lost due to the unfavorable environmental factors. On the other hand, the world population is estimated to reach about 10 billion by 2050, which will witness serious food shortages. Therefore, crops with enhanced vigour and high tolerance to various environmental factors should be developed to feed the increasing world population. Maintaining crop yields under adverse environmental stresses is probably the major challenge facing modern agriculture where polyamines can play important role. Polyamines (PAs)(putrescine, spermidine and spermine) are group of phytohormone-like aliphatic amine natural compounds with aliphatic nitrogen structure and present in almost all living organisms including plants. Evidences showed that polyamines are involved in many physiological processes, such as cell growth and development and respond to stress tolerance to various environmental factors. In many cases the relationship of plant stress tolerance was noted with the production of conjugated and bound polyamines as well as stimulation of polyamine oxidation. Therefore, genetic manipulation of crop plants with genes encoding enzymes of polyamine biosynthetic pathways may provide better stress tolerance to crop plants. Furthermore, the exogenous application of PAs is also another option for increasing the stress tolerance potential in plants. Here, we have described the synthesis and role of various polyamines in abiotic stress tolerance in plants. PMID:20592804

  14. The Use of Chemical Probes for the Characterization of the Predominant Abiotic Reductants in Anaerobic Sediments

    EPA Science Inventory

    Identifying the predominant chemical reductants and pathways for electron transfer in anaerobic systems is paramount to the development of environmental fate models that incorporate pathways for abiotic reductive transformations. Currently, such models do not exist. In this chapt...

  15. ANALYSIS OF BIOTIC AND ABIOTIC FACTORS INFLUENCING THE OCCURRENCE OF WEST NILE VIRUS INFECTION IN TUNISIA.

    PubMed

    Ben Hassine, Th; Calistri, P; Ippoliti, C; Conte, A; Danzetta, M L; Bruno, R; Lelli, R; Bejaoui, M; Hammami, S

    2014-01-01

    Eco-climatic conditions are often associated with the occurrence of West Nile Disease (WND) cases. Among the complex set of biotic and abiotic factors influencing the emergence and spread of this vector-borne disease, two main variables have been considered to have a great influence on the probability of West Nile Virus (WNV) introduction and circulation in Tunisia: the presence of susceptible bird populations and the existence of geographical areas where the environmental and climatic conditions are more favourable to mosquito multiplications. The aim of this study was to identify and classify the climatic and environmental variables possibly associated with the occurrence of WNVhuman cases in Tunisia. The following environmental and climatic variables have been considered: wetlands and humid areas, Normalised Difference Vegetation Index (NDVI), temperatures and elevation. A preliminary analysis for the characterization of main variables associated with areas with a history of WNV human cases in Tunisia between 1997 and 2011 has been made. This preliminary analysis clearly indicates the closeness to marshes ecosystem, where migratory bird populations are located, as an important risk factor for WNV infection. On the contrary the temperature absolute seems to be not a significant factor in Tunisian epidemiological situation. In relation to NDVI values, more complex considerations should be made.

  16. Environmental and economic benefits of variable rate nitrogen fertilization in a nitrate vulnerable zone.

    PubMed

    Basso, Bruno; Dumont, Benjamin; Cammarano, Davide; Pezzuolo, Andrea; Marinello, Francesco; Sartori, Luigi

    2016-03-01

    Agronomic input and management practices have traditionally been applied uniformly on agricultural fields despite the presence of spatial variability of soil properties and landscape position. When spatial variability is ignored, uniform agronomic management can be both economically and environmentally inefficient. The objectives of this study were to: i) identify optimal N fertilizer rates using an integrated spatio-temporal analysis of yield and site-specific N rate response; ii) test the sensitivity of site specific N management to nitrate leaching in response to different N rates; and iii) demonstrate the environmental benefits of variable rate N fertilizer in a Nitrate Vulnerable Zone. This study was carried out on a 13.6 ha field near the Venice Lagoon, northeast Italy over four years (2005-2008). We utilized a validated crop simulation model to evaluate crop response to different N rates at specific zones in the field based on localized soil and landscape properties under rainfed conditions. The simulated rates were: 50 kg N ha(-1) applied at sowing for the entire study area and increasing fractions, ranging from 150 to 350 kg N ha(-1) applied at V6 stage. Based on the analysis of yield maps from previous harvests and soil electrical resistivity data, three management zones were defined. Two N rates were applied in each of these zones, one suggested by our simulation analysis and the other with uniform N fertilization as normally applied by the producer. N leaching was lower and net revenue was higher in the zones where variable rates of N were applied when compared to uniform N fertilization. This demonstrates the efficacy of using crop models to determine variable rates of N fertilization within a field and the application of variable rate N fertilizer to achieve higher profit and reduce nitrate leaching.

  17. Non-Random Variability in Functional Composition of Coral Reef Fish Communities along an Environmental Gradient.

    PubMed

    Plass-Johnson, Jeremiah G; Taylor, Marc H; Husain, Aidah A A; Teichberg, Mirta C; Ferse, Sebastian C A

    2016-01-01

    Changes in the coral reef complex can affect predator-prey relationships, resource availability and niche utilisation in the associated fish community, which may be reflected in decreased stability of the functional traits present in a community. This is because particular traits may be favoured by a changing environment, or by habitat degradation. Furthermore, other traits can be selected against because degradation can relax the association between fishes and benthic habitat. We characterised six important ecological traits for fish species occurring at seven sites across a disturbed coral reef archipelago in Indonesia, where reefs have been exposed to eutrophication and destructive fishing practices for decades. Functional diversity was assessed using two complementary indices (FRic and RaoQ) and correlated to important environmental factors (live coral cover and rugosity, representing local reef health, and distance from shore, representing a cross-shelf environmental gradient). Indices were examined for both a change in their mean, as well as temporal (short-term; hours) and spatial (cross-shelf) variability, to assess whether fish-habitat association became relaxed along with habitat degradation. Furthermore, variability in individual traits was examined to identify the traits that are most affected by habitat change. Increases in the general reef health indicators, live coral cover and rugosity (correlated with distance from the mainland), were associated with decreases in the variability of functional diversity and with community-level changes in the abundance of several traits (notably home range size, maximum length, microalgae, detritus and small invertebrate feeding and reproductive turnover). A decrease in coral cover increased variability of RaoQ while rugosity and distance both inversely affected variability of FRic; however, averages for these indices did not reveal patterns associated with the environment. These results suggest that increased

  18. Non-Random Variability in Functional Composition of Coral Reef Fish Communities along an Environmental Gradient

    PubMed Central

    Plass-Johnson, Jeremiah G.; Taylor, Marc H.; Husain, Aidah A. A.; Teichberg, Mirta C.; Ferse, Sebastian C. A.

    2016-01-01

    Changes in the coral reef complex can affect predator-prey relationships, resource availability and niche utilisation in the associated fish community, which may be reflected in decreased stability of the functional traits present in a community. This is because particular traits may be favoured by a changing environment, or by habitat degradation. Furthermore, other traits can be selected against because degradation can relax the association between fishes and benthic habitat. We characterised six important ecological traits for fish species occurring at seven sites across a disturbed coral reef archipelago in Indonesia, where reefs have been exposed to eutrophication and destructive fishing practices for decades. Functional diversity was assessed using two complementary indices (FRic and RaoQ) and correlated to important environmental factors (live coral cover and rugosity, representing local reef health, and distance from shore, representing a cross-shelf environmental gradient). Indices were examined for both a change in their mean, as well as temporal (short-term; hours) and spatial (cross-shelf) variability, to assess whether fish-habitat association became relaxed along with habitat degradation. Furthermore, variability in individual traits was examined to identify the traits that are most affected by habitat change. Increases in the general reef health indicators, live coral cover and rugosity (correlated with distance from the mainland), were associated with decreases in the variability of functional diversity and with community-level changes in the abundance of several traits (notably home range size, maximum length, microalgae, detritus and small invertebrate feeding and reproductive turnover). A decrease in coral cover increased variability of RaoQ while rugosity and distance both inversely affected variability of FRic; however, averages for these indices did not reveal patterns associated with the environment. These results suggest that increased

  19. Mud, Macrofauna and Microbes: An ode to benthic organism-abiotic interactions at varying scales

    EPA Science Inventory

    Benthic environments are dynamic habitats, subject to variable sources and rates of sediment delivery, reworking from the abiotic and biotic processes, and complex biogeochemistry. These activities do not occur in a vacuum, and interact synergistically to influence food webs, bi...

  20. Hundred Years of Environmental Change and Phytoplankton Ecophysiological Variability Archived in Coastal Sediments

    PubMed Central

    Ribeiro, Sofia; Berge, Terje; Lundholm, Nina; Ellegaard, Marianne

    2013-01-01

    Marine protist species have been used for several decades as environmental indicators under the assumption that their ecological requirements have remained more or less stable through time. However, a growing body of evidence suggests that marine protists, including several phytoplankton species, are in fact highly diverse and may quickly respond to changes in the environment. Predicting how future climate will impact phytoplankton populations is important, but this task has been challenged by a lack of time-series of ecophysiological parameters at time-scales relevant for climate studies (i.e. at least decadal). Here, we report on ecophysiological variability in a marine dinoflagellate over a 100-year period of well-documented environmental change, by using the sedimentary archive of living cysts from a Scandinavian fjord (Koljö Fjord, Sweden). During the past century, Koljö Fjord has experienced important changes in salinity linked to the North Atlantic Oscillation (NAO). We revived resting cysts of Pentapharsodinium dalei preserved in the fjord sediments and determined growth rates for 18 strains obtained from 3 sediment core layers at salinity 15 and 30, which represent extreme sea-surface conditions during periods of predominantly negative and positive NAO phases, respectively. Upper pH tolerance limits for growth were also tested. In general, P. dalei grew at a higher rate in salinity 30 than 15 for all layers, but there were significant differences among strains. When accounting for inter-strain variability, cyst age had no effect on growth performance or upper pH tolerance limits for this species, indicating a stable growth response over the 100-year period in spite of environmental fluctuations. Our findings give some support for the use of morphospecies in environmental studies, particularly at decadal to century scales. Furthermore, the high intra-specific variability found down to sediment layers dated as ca. 50 years-old indicates that cyst-beds of P

  1. Testing the Effectiveness of Environmental Variables to Explain European Terrestrial Vertebrate Species Richness across Biogeographical Scales

    PubMed Central

    Mouchet, Maud; Levers, Christian; Zupan, Laure; Kuemmerle, Tobias; Plutzar, Christoph; Erb, Karlheinz; Lavorel, Sandra; Thuiller, Wilfried; Haberl, Helmut

    2015-01-01

    We compared the effectiveness of environmental variables, and in particular of land-use indicators, to explain species richness patterns across taxonomic groups and biogeographical scales (i.e. overall pan-Europe and ecoregions within pan-Europe). Using boosted regression trees that handle non-linear relationships, we compared the relative influence (as a measure of effectiveness) of environmental variables related to climate, landscape (or habitat heterogeneity), land-use intensity or energy availability to explain European vertebrate species richness (birds, amphibians, and mammals) at the continental and ecoregion scales. We found that dominant land cover and actual evapotranspiration that relate to energy availability were the main correlates of vertebrate species richness over Europe. At the ecoregion scale, we identified four distinct groups of ecoregions where species richness was essentially associated to (i) seasonality of temperature, (ii) actual evapotranspiration and/or mean annual temperature, (iii) seasonality of precipitation, actual evapotranspiration and land cover) and (iv) and an even combination of the environmental variables. This typology of ecoregions remained valid for total vertebrate richness and the three vertebrate groups taken separately. Despite the overwhelming influence of land cover and actual evapotranspiration to explain vertebrate species richness patterns at European scale, the ranking of the main correlates of species richness varied between regions. Interestingly, landscape and land-use indicators did not stand out at the continental scale but their influence greatly increased in southern ecoregions, revealing the long-lasting human footprint on land-use–land-cover changes. Our study provides one of the first multi-scale descriptions of the variability in the ranking of correlates across several taxa. PMID:26161981

  2. Testing the Effectiveness of Environmental Variables to Explain European Terrestrial Vertebrate Species Richness across Biogeographical Scales.

    PubMed

    Mouchet, Maud; Levers, Christian; Zupan, Laure; Kuemmerle, Tobias; Plutzar, Christoph; Erb, Karlheinz; Lavorel, Sandra; Thuiller, Wilfried; Haberl, Helmut

    2015-01-01

    We compared the effectiveness of environmental variables, and in particular of land-use indicators, to explain species richness patterns across taxonomic groups and biogeographical scales (i.e. overall pan-Europe and ecoregions within pan-Europe). Using boosted regression trees that handle non-linear relationships, we compared the relative influence (as a measure of effectiveness) of environmental variables related to climate, landscape (or habitat heterogeneity), land-use intensity or energy availability to explain European vertebrate species richness (birds, amphibians, and mammals) at the continental and ecoregion scales. We found that dominant land cover and actual evapotranspiration that relate to energy availability were the main correlates of vertebrate species richness over Europe. At the ecoregion scale, we identified four distinct groups of ecoregions where species richness was essentially associated to (i) seasonality of temperature, (ii) actual evapotranspiration and/or mean annual temperature, (iii) seasonality of precipitation, actual evapotranspiration and land cover) and (iv) and an even combination of the environmental variables. This typology of ecoregions remained valid for total vertebrate richness and the three vertebrate groups taken separately. Despite the overwhelming influence of land cover and actual evapotranspiration to explain vertebrate species richness patterns at European scale, the ranking of the main correlates of species richness varied between regions. Interestingly, landscape and land-use indicators did not stand out at the continental scale but their influence greatly increased in southern ecoregions, revealing the long-lasting human footprint on land-use-land-cover changes. Our study provides one of the first multi-scale descriptions of the variability in the ranking of correlates across several taxa.

  3. Estimating switchgrass productivity in the Great Plains using satellite vegetation index and site environmental variables

    USGS Publications Warehouse

    Gu, Yingxin; Wylie, Bruce K.; Howard, Daniel M.

    2015-01-01

    Switchgrass is being evaluated as a potential feedstock source for cellulosic biofuels and is being cultivated in several regions of the United States. The recent availability of switchgrass land cover maps derived from the National Agricultural Statistics Service cropland data layer for the conterminous United States provides an opportunity to assess the environmental conditions of switchgrass over large areas and across different geographic locations. The main goal of this study is to develop a data-driven multiple regression switchgrass productivity model and identify the optimal climate and environment conditions for the highly productive switchgrass in the Great Plains (GP). Environmental and climate variables used in the study include elevation, soil organic carbon, available water capacity, climate, and seasonal weather. Satellite-derived growing season averaged Normalized Difference Vegetation Index (GSN) was used as a proxy for switchgrass productivity. Multiple regression analyses indicate that there are strong correlations between site environmental variables and switchgrass productivity (r = 0.95). Sufficient precipitation and suitable temperature during the growing season (i.e., not too hot or too cold) are favorable for switchgrass growth. Elevation and soil characteristics (e.g., soil available water capacity) are also an important factor impacting switchgrass productivity. An anticipated switchgrass biomass productivity map for the entire GP based on site environmental and climate conditions and switchgrass productivity model was generated. Highly productive switchgrass areas are mainly located in the eastern part of the GP. Results from this study can help land managers and biofuel plant investors better understand the general environmental and climate conditions influencing switchgrass growth and make optimal land use decisions regarding switchgrass development in the GP.

  4. Environmental and management influences on temporal variability of near saturated soil hydraulic properties.

    PubMed

    Bodner, G; Scholl, P; Loiskandl, W; Kaul, H-P

    2013-08-01

    Structural porosity is a decisive property for soil productivity and soil environmental functions. Hydraulic properties in the structural range vary over time in response to management and environmental influences. Although this is widely recognized, there are few field studies that determine dominant driving forces underlying hydraulic property dynamics. During a three year field experiment we measured temporal variability of soil hydraulic properties by tension infiltrometry. Soil properties were characterized by hydraulic conductivity, effective macroporosity and Kosugi's lognormal pore size distribution model. Management related influences comprised three soil cover treatment (mustard and rye vs. fallow) and an initial mechanical soil disturbance with a rotary harrow. Environmental driving forces were derived from meteorological and soil moisture data. Soil hydraulic parameters varied over time by around one order of magnitude. The coefficient of variation of soil hydraulic conductivity K(h) decreased from 69.5% at saturation to 42.1% in the more unsaturated range (- 10 cm pressure head). A slight increase in the Kosugi parameter showing pore heterogeneity was observed under the rye cover crop, reflecting an enhanced structural porosity. The other hydraulic parameters were not significantly influenced by the soil cover treatments. Seedbed preparation with a rotary harrow resulted in a fourfold increase in macroporosity and hydraulic conductivity next to saturation, and homogenized the pore radius distribution. Re-consolidation after mechanical loosening lasted over 18 months until the soil returned to its initial state. The post-tillage trend of soil settlement could be approximated by an exponential decay function. Among environmental factors, wetting-drying cycles were identified as dominant driving force explaining short term hydraulic property changes within the season (r(2) = 0.43 to 0.59). Our results suggested that beside considering average

  5. Abiotic formation of oligonucleotides on basalt surfaces

    NASA Astrophysics Data System (ADS)

    Otroshchenko, V. A.; Vasilyeva, N. V.; Kopilov, A. M.

    1985-06-01

    The complication and further evolution of abiotic syntheses products occurred under environmental influences at the prebiological stage. From this point of view, the influence of some types of irradiation on the organic molecules adsorbed on the surfaces of volcanic rocks, appeared to be of great importance. In this connection, the effect of gamma rays on the AMP molecules adsorbed on mineral surfaces such as cinders and ashes has been studied. It has been shown that they can polymerize with the formation of oligonucleotides. The treatment of oligomers obtained by venom phosphodiesterase has shown that a polymeric product has mainly 3' 5' and 2' 5' bonds between nucleotides. The results obtained have been discussed from the evolutionary aspect.

  6. Fish communities and their associations with environmental variables, lower San Joaquin River drainage, California

    USGS Publications Warehouse

    Brown, L.R.

    2000-01-01

    Twenty sites in the lower San Joaquin River drainage, California, were sampled from 1993 to 1995 to characterize fish communities and their associations with measures of water quality and habitat quality. The feasibility of developing an Index of Biotic Integrity was assessed by evaluating four fish community metrics, including percentages of native fish, omnivorous fish, fish intolerant of environmental degradation, and fish with external anomalies. Of the thirty-one taxa of fish captured during the study, only 10 taxa were native to the drainage. Multivariate analyses of percentage data identified four site groups characterized by different groups of species. The distributions of fish species were related to specific conductance, gradient, and mean depth; however, specific conductance acted as a surrogate variable for a large group of correlated variables. Two of the fish community metrics - percentage of introduced fish and percentage of intolerant fish - appeared to be responsive to environmental quality but the responses of the other two metrics - percentage of omnivorous fish and percentage of fish with anomalies - were less direct. The conclusion of the study is that fish communities are responsive to environmental conditions, including conditions associated with human-caused disturbances, particularly agriculture and water development. The results suggest that changes in water management and water quality could result in changes in species distributions. Balancing the costs and benefits of such changes poses a considerable challenge to resource managers.

  7. Assemblages of fishes and their associations with environmental variables, lower San Joaquin River drainage, California

    USGS Publications Warehouse

    Brown, Larry R.

    1998-01-01

    Twenty sites in the lower San Joaquin River drainage, California, were sampled from 1993 to 1995 to characterize fish assemblages and their associations with measures of water quality and habitat quality. In addition, four fish community metrics were assessed, including percentages of native fish, omnivorous fish, fish intolerant of environmental degradation, and fish with external anomalies. Of the 31 taxa of fish captured during the study, only 10 taxa were native to the drainage. Multivariate analyses of percentage data identified four site groups characterized by characterized by different groups of species. The distributions of fish species were related to specific conductance, gradient, and mean depth; however, specific conductance acted as a surrogate variable for a large group of correlated variables. Two of the fish community metrics--percentage of introduced fish and percentage of intolerant fish--appeared to be responsive to environmental quality but the responses of the other two metrics--percentage of omnivorous fish and percentage of fish with anomalies--were less direct. The conclusion of the study is that fish assemblages are responsive to environmental conditions, including conditions associated with human-caused disturbances, particularly agriculture and water development. The results suggest that changes in water management and water quality could result in changes in species distributions. Balancing the costs and benefits of such changes poses a considerable challenge to resource managers. different groups of species.

  8. Tracing fecal pollution sources in karst groundwater by Bacteroidales genetic biomarkers, bacterial indicators, and environmental variables.

    PubMed

    Zhang, Ya; Kelly, Walton R; Panno, Samuel V; Liu, Wen-Tso

    2014-08-15

    Fecal contamination in Midwestern karst regions was evaluated by simultaneously measuring traditional bacterial indicators (coliforms and Escherichia coli), Bacteroidales-based biomarkers, and environmental variables. Water samples from springs and wells were collected from karst regions in Illinois (IL), Wisconsin (WI), Kentucky (KY), and Missouri (MO). Quantitative PCR (Q-PCR) with seven primer sets targeting different members of Bacteroidales was used to determine the origin of fecal contamination (i.e., from human waste, livestock waste, or both). Most samples were contaminated by both human and animal waste, with a few samples showing pollution solely by one or the other. Spring water tended to have higher levels of contamination than well water, and higher concentrations of fecal biomarkers were detected in urban springs compared to rural spring systems. However, there were discrepancies on contamination profile determined by Bacteroidales-based biomarkers and by traditional bacterial indicators. Among all the environmental parameters examined, E. coli, sulfate, total dissolved solids (TDS), and silicon were significantly correlated (p<0.05) with the level of Bacteroidales-based fecal indicators. A rapid screening method using total nitrogen (TN) and chloride (Cl(-)) concentrations to determine fecal contamination was shown to be effective and correlated well with Bacteroidales-based MST. The results suggest that human and livestock feces co-contaminated a large portion of karst groundwater systems in Midwestern regions, and the inclusion of traditional bacterial indicators, environmental variables, and Bacteroidales-based MST is an effective approach for identifying fecal contamination in karst regions.

  9. Natural sequence variants of yeast environmental sensors confer cell-to-cell expression variability.

    PubMed

    Fehrmann, Steffen; Bottin-Duplus, Hélène; Leonidou, Andri; Mollereau, Esther; Barthelaix, Audrey; Wei, Wu; Steinmetz, Lars M; Yvert, Gaël

    2013-10-08

    Living systems may have evolved probabilistic bet hedging strategies that generate cell-to-cell phenotypic diversity in anticipation of environmental catastrophes, as opposed to adaptation via a deterministic response to environmental changes. Evolution of bet hedging assumes that genotypes segregating in natural populations modulate the level of intraclonal diversity, which so far has largely remained hypothetical. Using a fluorescent P(met17)-GFP reporter, we mapped four genetic loci conferring to a wild yeast strain an elevated cell-to-cell variability in the expression of MET17, a gene regulated by the methionine pathway. A frameshift mutation in the Erc1p transmembrane transporter, probably resulting from a release of laboratory strains from negative selection, reduced P(met17)-GFP expression variability. At a second locus, cis-regulatory polymorphisms increased mean expression of the Mup1p methionine permease, causing increased expression variability in trans. These results demonstrate that an expression quantitative trait locus (eQTL) can simultaneously have a deterministic effect in cis and a probabilistic effect in trans. Our observations indicate that the evolution of transmembrane transporter genes can tune intraclonal variation and may therefore be implicated in both reactive and anticipatory strategies of adaptation.

  10. Timing and Variability of Galactose Metabolic Gene Activation Depend on the Rate of Environmental Change.

    PubMed

    Nguyen-Huu, Truong D; Gupta, Chinmaya; Ma, Bo; Ott, William; Josić, Krešimir; Bennett, Matthew R

    2015-07-01

    Modulation of gene network activity allows cells to respond to changes in environmental conditions. For example, the galactose utilization network in Saccharomyces cerevisiae is activated by the presence of galactose but repressed by glucose. If both sugars are present, the yeast will first metabolize glucose, depleting it from the extracellular environment. Upon depletion of glucose, the genes encoding galactose metabolic proteins will activate. Here, we show that the rate at which glucose levels are depleted determines the timing and variability of galactose gene activation. Paradoxically, we find that Gal1p, an enzyme needed for galactose metabolism, accumulates more quickly if glucose is depleted slowly rather than taken away quickly. Furthermore, the variability of induction times in individual cells depends non-monotonically on the rate of glucose depletion and exhibits a minimum at intermediate depletion rates. Our mathematical modeling suggests that the dynamics of the metabolic transition from glucose to galactose are responsible for the variability in galactose gene activation. These findings demonstrate that environmental dynamics can determine the phenotypic outcome at both the single-cell and population levels.

  11. Environmental Variables That Influence Patient Satisfaction: A Review of the Literature.

    PubMed

    MacAllister, Lorissa; Zimring, Craig; Ryherd, Erica

    2016-10-01

    Patient's perception of care-referred to as patient satisfaction-is of great interest in the healthcare industry, as it becomes more directly tied to the revenue of the health system providers. The perception of care has now become important in addition to the actual health outcome of the patient. The known influencers for the patient perception of care are the patient's own characteristics as well as the quality of service received. In patient surveys, the physical environment is noted as important for being clean and quiet but is not considered a critical part of patient satisfaction or other health outcomes. Patient perception of care is currently measured as patient satisfaction, a systematic collection of perceptions of social interactions from an individual person as well as their interaction with the environment. This exploration of the literature intends to explore the rigorous, statistically tested research conducted that has a spatial predictor variable and a health or behavior outcome, with the intent to begin to further test the relationships of these variables in the future studies. This literature review uses the patient satisfaction framework of components of influence and identifies at least 10 known spatial environmental variables that have been shown to have a direct connection to the health and behavior outcome of a patient. The results show that there are certain features of the spatial layout and environmental design in hospital or work settings that influence outcomes and should be noted in the future research.

  12. Effect of flow rate on environmental variables and phytoplankton dynamics: results from field enclosures

    NASA Astrophysics Data System (ADS)

    Zhang, Haiping; Chen, Ruihong; Li, Feipeng; Chen, Ling

    2015-03-01

    To investigate the effects of flow rate on phytoplankton dynamics and related environment variables, a set of enclosure experiments with different flow rates were conducted in an artificial lake. We monitored nutrients, temperature, dissolved oxygen, pH, conductivity, turbidity, chlorophyll- a and phytoplankton levels. The lower biomass in all flowing enclosures showed that flow rate significantly inhibited the growth of phytoplankton. A critical flow rate occurred near 0.06 m/s, which was the lowest relative inhibitory rate. Changes in flow conditions affected algal competition for light, resulting in a dramatic shift in phytoplankton composition, from blue-green algae in still waters to green algae in flowing conditions. These findings indicate that critical flow rate can be useful in developing methods to reduce algal bloom occurrence. However, flow rate significantly enhanced the inter-relationships among environmental variables, in particular by inducing higher water turbidity and vegetative reproduction of periphyton ( Spirogyra). These changes were accompanied by a decrease in underwater light intensity, which consequently inhibited the photosynthetic intensity of phytoplankton. These results warn that a universal critical flow rate might not exist, because the effect of flow rate on phytoplankton is interlinked with many other environmental variables.

  13. Strategies to ameliorate abiotic stress-induced plant senescence.

    PubMed

    Gepstein, Shimon; Glick, Bernard R

    2013-08-01

    The plant senescence syndrome resembles, in many molecular and phenotypic aspects, plant responses to abiotic stresses. Both processes have an enormous negative global agro-economic impact and endanger food security worldwide. Premature plant senescence is the main cause of losses in grain filling and biomass yield due to leaf yellowing and deteriorated photosynthesis, and is also responsible for the losses resulting from the short shelf life of many vegetables and fruits. Under abiotic stress conditions the yield losses are often even greater. The primary challenge in agricultural sciences today is to develop technologies that will increase food production and sustainability of agriculture especially under environmentally limiting conditions. In this chapter, some of the mechanisms involved in abiotic stress-induced plant senescence are discussed. Recent studies have shown that crop yield and nutritional values can be altered as well as plant stress tolerance through manipulating the timing of senescence. It is often difficult to separate the effects of age-dependent senescence from stress-induced senescence since both share many biochemical processes and ultimately result in plant death. The focus of this review is on abiotic stress-induced senescence. Here, a number of the major approaches that have been developed to ameliorate some of the effects of abiotic stress-induced plant senescence are considered and discussed. Some approaches mimic the mechanisms already used by some plants and soil bacteria whereas others are based on development of new improved transgenic plants. While there may not be one simple strategy that can effectively decrease all losses of crop yield that accrue as a consequence of abiotic stress-induced plant senescence, some of the strategies that are discussed already show great promise.

  14. Influence of Different Environmental Variables on Energy and Carbon Fluxes in a Mediterranean Maquis Site

    NASA Astrophysics Data System (ADS)

    Bellucco, V.; Marras, S.; Sirca, C.; Duce, P.; Spano, D.

    2015-12-01

    Recent studies show that, in the Mediterranean area, global climate changes are likely causing an increase in frequency and intensity of drought periods as well as in the number of warmer days and nights. Mediterranean maquis (schlerophyll species) is a typical evergreen ecosystem consisting of short shrubs with leathery leaves sparsely distributed. It is adapted to live in a semi-arid climate as that of Mediterranean coasts and can survive to these environmental stress condition, being able to recover after autumn rainfall. However, increased environmental stress condition may determine changes in vegetation behavior in the long period. The aim of this study is to show the seasonal variability of sensible and latent heat, and CO2 exchanges measured, with the Eddy Covariance (EC) technique, over a Mediterranean Maquis site. It is located, about 600 m far from the sea, in the Capo Caccia peninsula (municipal district of Alghero (SS), Italy) within a natural reserve called "Le Prigionette", also known as Arca di Noé, in the North-West Sardinia coast (40.61° N, 8.15° E, 74 m asl). Due to this proximity of the EC tower to the sea, the ecosystem vertical exchanges and their footprint may be differently affected by sea and land breeze during days and nights, respectively. A four-component net radiometer, a quantum sensor, and a meteorological station were also set up for ancillary measurements as well as four heat plates in four different positions to account for under canopy and bare soil conditions in the Maquis ecosystem. Therefore, the influence of different environmental variables, such as soil/air temperature, atmospheric conditions and soil moisture content, on energy and carbon fluxes will be investigated and their effect on the seasonal and inter-annual variability of surface fluxes will be analyzed.

  15. Pan-Svalbard growth rate variability and environmental regulation in the Arctic bivalve Serripes groenlandicus

    NASA Astrophysics Data System (ADS)

    Carroll, Michael L.; Ambrose, William G.; Levin, Benjamin S.; Locke V, William L.; Henkes, Gregory A.; Hop, Haakon; Renaud, Paul E.

    2011-11-01

    Growth histories contained in the shells of bivalves provide continuous records of environmental and biological information over lifetimes spanning decades to centuries, thereby linking ecosystem responses to both natural and anthropogenic climatic variations over a range of scales. We examined growth rates and temporal growth patterns of 260 individuals of the circumpolar Greenland Smooth Cockle ( Serripes groenlandicus) collected between 1997 and 2009 from 11 sites around the Svalbard Archipelago. These sites encompass a range of oceanographic and environmental conditions, from strongly Atlantic-influenced conditions on the west coast to high-Arctic conditions in northeast Svalbard. Absolute growth was up to three times greater at the most strongly Atlantic-influenced locations compared to the most Arctic-influenced areas, and growth performance was highest at sites closest to the West Spitsbergen Current. We also developed growth chronologies up to 34 years in length extending back to 1974. Standardized growth indices (SGI) exhibited substantial inter-site variability, but there were also common temporal features including steadily increasing growth from the late 1980's to the mid-1990's followed by a marked shift from relatively greater to poorer growth in the mid-1990's and from 2004 to 2008. This pattern was consistent with phase-shifts in large-scale climatic drivers. Interannual variability in SGI was also related to local manifestations of the large-scale drivers, including sea temperature and sea ice extent. The temporal growth pattern at Rijpfjorden, on northeast Svalbard, was broadly representative (R = 0.81) of the entire dataset. While there were site-related differences in the specific relationships between growth and environmental parameters, the aggregated dataset indicated an overriding regional driver of bivalve growth: the Arctic Climate Regime Index (ACRI). These results demonstrate that sclerochronological proxies can be useful retrospective

  16. Phytoplankton community structure defined by key environmental variables in Tagus estuary, Portugal.

    PubMed

    Brogueira, Maria José; Oliveira, Maria do Rosário; Cabeçadas, Graça

    2007-12-01

    In this work, we analyze environmental (physical and chemical) and biological (phytoplankton) data obtained along Tagus estuary during three surveys, carried out in productive period (May/June/July) at ebb tide. The main objective of this study was to identify the key environmental factors affecting phytoplankton structure in the estuary. BIOENV analysis revealed that, in study period, temperature, salinity, silicate and total phosphorus were the variables that best explained the phytoplankton spatial pattern in the estuary (Spearman correlation, rho=0.803). A generalized linear model (GLM) also identified salinity, silicate and phosphate as having a high explanatory power (63%) of phytoplankton abundance. These selected nutrients appear to be consistent with the requirements of the dominant phytoplankton group, Baccilariophyceae. Apparently, phytoplankton community is adapted to fluctuations in light intensity, as suspended particulate matter did not come out as a key factor in shaping phytoplankton structure along Tagus estuary.

  17. Climate variability and environmental stress in the Sudan-Sahel zone of West Africa.

    PubMed

    Mertz, Ole; D'haen, Sarah; Maiga, Abdou; Moussa, Ibrahim Bouzou; Barbier, Bruno; Diouf, Awa; Diallo, Drissa; Da, Evariste Dapola; Dabi, Daniel

    2012-06-01

    Environmental change in the Sudan-Sahel region of West Africa (SSWA) has been much debated since the droughts of the 1970s. In this article we assess climate variability and environmental stress in the region. Households in Senegal, Mali, Burkina Faso, Niger, and Nigeria were asked about climatic changes and their perceptions were compared across north-south and west-east rainfall gradients. More than 80% of all households found that rainfall had decreased, especially in the wettest areas. Increases in wind speeds and temperature were perceived by an overall 60-80% of households. Contrary to household perceptions, observed rainfall patterns showed an increasing trend over the past 20 years. However, August rainfall declined, and could therefore potentially explain the contrasting negative household perceptions of rainfall trends. Most households reported degradation of soils, water resources, vegetation, and fauna, but more so in the 500-900 mm zones. Adaptation measures to counter environmental degradation included use of manure, reforestation, soil and water conservation, and protection of fauna and vegetation. The results raise concerns for future environmental management in the region, especially in the 500-900 mm zones and the western part of SSWA.

  18. Environmental drivers of mesozooplankton biomass variability in the North Pacific Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    Valencia, Bellineth; Landry, Michael R.; Décima, Moira; Hannides, Cecelia C. S.

    2016-12-01

    The environmental drivers of zooplankton variability are poorly explored for the central subtropical Pacific, where a direct bottom-up food-web connection is suggested by increasing trends in primary production and mesozooplankton biomass at station ALOHA (A Long-term Oligotrophic Habitat Assessment) over the past 20 years (1994-2013). Here we use generalized additive models (GAMs) to investigate how these trends relate to the major modes of North Pacific climate variability. A GAM based on monthly mean data explains 43% of the temporal variability in mesozooplankton biomass with significant influences from primary productivity (PP), sea surface temperature (SST), North Pacific Gyre Oscillation (NPGO), and El Niño. This result mainly reflects the seasonal plankton cycle at station ALOHA, in which increasing light and SST lead to enhanced nitrogen fixation, productivity, and zooplankton biomass during summertime. Based on annual mean data, GAMs for two variables suggest that PP and 3-4 year lagged NPGO individually account for 40% of zooplankton variability. The full annual mean GAM explains 70% of variability of zooplankton biomass with significant influences from PP, 4 year lagged NPGO, and 4 year lagged Pacific Decadal Oscillation (PDO). The NPGO affects wind stress, sea surface height, and subtropical gyre circulation and has been linked to mideuphotic zone anomalies in salinity and PP at station ALOHA. Our study broadens the known impact of this climate mode on plankton dynamics in the North Pacific. While lagged transport effects are also evident for subtropical waters, our study highlights a strong coupling between zooplankton fluctuations and PP, which differs from the transport-dominated climate influences that have been found for North Pacific boundary currents.

  19. Compensating for environmental variability in the thermal inertia approach to remote sensing of soil moisture

    NASA Technical Reports Server (NTRS)

    Idso, S. B.; Jackson, R. D.; Reginato, R. J.

    1976-01-01

    A procedure is developed for removing data scatter in the thermal-inertia approach to remote sensing of soil moisture which arises from environmental variability in time and space. It entails the utilization of nearby National Weather Service air temperature measurements to normalize measured diurnal surface temperature variations to what they would have been for a day of standard diurnal air temperature variation, arbitrarily assigned to be 18 C. Tests of the procedure's basic premise on a bare loam soil and a crop of alfalfa indicate it to be conceptually sound. It is possible that the technique could also be useful in other thermal-inertia applications, such as lithographic mapping.

  20. Statistical analysis of environmental variability within the CELSS breadboard project's biomass production chamber

    NASA Technical Reports Server (NTRS)

    Stutte, G. W.; Chetirkin, P. V.; Mackowiak, C. L.; Fortson, R. E.

    1993-01-01

    Variability in the aerial and root environments of NASA's Breadboard Project's Biomass Production Chamber (BPC) was determined. Data from two lettuce and two potato growouts were utilized. One growout of each crop was conducted prior to separating the upper and lower chambers; the other was subsequent to separation. There were little or no differences in pH, EC, or solution temperature between the upper and lower chamber or within a chamber. Variation in the aerial environment within a chamber was two to three times greater than variation between chambers for air temperature, relative humidity, and PPF. High variability in air velocity, relative to tray position, was observed. Separating the BPC had no effect on PPF, air velocity, solution temperature, pH, or EC. Separation reduced the gradient in air temperature and relative humidity between the upper and lower chambers, but increased the variability within a chamber. Variation between upper and lower chambers was within 5 percent of environmental set-points and of little or no physiological significance. In contrast, the variability within a chamber limits the capability of the BPC to generate statistically reliable data from individual tray treatments at this time.

  1. [Spatial pattern of soil fertility in Bashan tea garden: a prediction based on environmental auxiliary variables].

    PubMed

    Qin, Le-feng; Yang, Chao; Lin, Fen-fang; Yang, Ning; Zheng, Xin-yu; Xu, Hong-wei; Wang, Ke

    2010-12-01

    Taking topographic factors and NDVI as auxiliary variables, and by using regression-kriging method, the spatial variation pattern of soil fertility in Bashan tea garden in the hilly area of Fuyang City was explored. The spatial variability of the soil fertility was mainly attributed to the structural factors such as relative elevation and flat/vertical curvature. The lower the relative elevation, the worse the soil fertility was. The overall soil fertility level was relatively high, and the area with lower soil fertility only accounted for 5% of the total. By using regression-kriging method with relative elevation as auxiliary variable, the prediction accuracy of soil fertility was obviously higher than that by using ordinary kriging method, with the mean error and root mean square error being 0. 028 and 0. 108, respectively. It was suggested that the prediction method used in this paper could fully reflect the effects of environmental variables on soil fertility , improve the prediction accuracy about the spatial pattern of soil fertility, and provide scientific basis for the precise management of tea garden.

  2. Methodology for Definition of Yellow Fever Priority Areas, Based on Environmental Variables and Multiple Correspondence Analyses

    PubMed Central

    Moreno, Eduardo Stramandinoli; Barata, Rita de Cássia Barradas

    2012-01-01

    Yellow fever (YF) is endemic in much of Brazil, where cases of the disease are reported every year. Since 2008, outbreaks of the disease have occurred in regions of the country where no reports had been registered for decades, which has obligated public health authorities to redefine risk areas for the disease. The aim of the present study was to propose a methodology of environmental risk analysis for defining priority municipalities for YF vaccination, using as example, the State of São Paulo, Brazil. The municipalities were divided into two groups (affected and unaffected by YF) and compared based on environmental parameters related to the disease's eco-epidemiology. Bivariate analysis was used to identify statistically significant associations between the variables and virus circulation. Multiple correspondence analysis (MCA) was used to evaluate the relationship among the variables and their contribution to the dynamics of YF in Sao Paulo. The MCA generated a factor that was able to differentiate between affected and unaffected municipalities and was used to determine risk levels. This methodology can be replicated in other regions, standardized, and adapted to each context. PMID:22802971

  3. Seasonal influence of environmental variables and artificial aeration on Escherichia coli in small urban lakes.

    PubMed

    Durham, Bart W; Porter, Lucy; Webb, Allie; Thomas, Joshua

    2016-12-01

    This study investigated patterns of Escherichia coli in urban lakes in Lubbock, Texas. Specific objectives were to (1) document seasonal patterns in abundance of E. coli over a 3-year period, (2) identify environmental factors, including effects of migratory geese and artificial aeration devices that may influence E. coli abundance, and (3) determine if E. coli abundance over time was similar for individual lakes. Water samples were collected monthly for 36 months from six lakes, three of which contained artificial aeration devices (fountains). Regression models were constructed to determine which environmental variables most influence E. coli abundance in summer and winter seasons. Escherichia coli is present in the lakes of Lubbock, Texas year-round and typically exceeds established bacterial thresholds for recreational waters. Models most frequently contained pH and dissolved oxygen as predictor variables and explained from 17.4% to 92.4% of total variation in E. coli. Lakes with fountains had a higher oxygen concentration during summer and contained consistently less E. coli. We conclude that solar irradiation in synergy with pH and dissolved oxygen is the primary control mechanism for E. coli in study lakes, and that fountains help control abundance of fecal bacteria within these systems.

  4. Methodology for definition of yellow fever priority areas, based on environmental variables and multiple correspondence analyses.

    PubMed

    Moreno, Eduardo Stramandinoli; Barata, Rita de Cássia Barradas

    2012-01-01

    Yellow fever (YF) is endemic in much of Brazil, where cases of the disease are reported every year. Since 2008, outbreaks of the disease have occurred in regions of the country where no reports had been registered for decades, which has obligated public health authorities to redefine risk areas for the disease. The aim of the present study was to propose a methodology of environmental risk analysis for defining priority municipalities for YF vaccination, using as example, the State of São Paulo, Brazil. The municipalities were divided into two groups (affected and unaffected by YF) and compared based on environmental parameters related to the disease's eco-epidemiology. Bivariate analysis was used to identify statistically significant associations between the variables and virus circulation. Multiple correspondence analysis (MCA) was used to evaluate the relationship among the variables and their contribution to the dynamics of YF in Sao Paulo. The MCA generated a factor that was able to differentiate between affected and unaffected municipalities and was used to determine risk levels. This methodology can be replicated in other regions, standardized, and adapted to each context.

  5. Implementing the distributed consensus-based estimation of environmental variables in unattended wireless sensor networks

    NASA Astrophysics Data System (ADS)

    Contreras, Rodrigo; Restrepo, Silvia E.; Pezoa, Jorge E.

    2014-10-01

    In this paper, the prototype implementation of a scalable, distributed protocol for calculating the global average of sensed environmental variables in unattended wireless sensor networks (WSNs) is presented. The design and implementation of the protocol introduces a communication scheme for discovering the WSN topology. Such scheme uses a synchronous flooding algorithm, which was implemented over an unreliable radiogram-based wireless channel. The topology discovery protocol has been synchronized with sampling time of the WSN and must be executed before the consensus-based estimation of the global averages. An average consensus algorithm, suited for clustered WSNs with static topologies, was selected from the literature. The algorithm was properly modified so that its implementation guarantees that the convergence time is bounded and less than the sampling time of the WSN. Moreover, to implement the consensus algorithm, a reliable packet-passing protocol was designed to exchange the weighting factors among the sensor nodes. Since the amount of data exchanged in each packet is bounded by the degree of the WSN, the scalability of the protocol is guaranteed to be linear. The proposed protocol was implemented in the Sun SPOT hardware/software platform using the Java programming language. All the radio communications were implemented over the IEEE 802.15.4 standard and the sensed environmental variables corresponded to the temperature and luminosity.

  6. Studying the time scale dependence of environmental variables predictability using fractal analysis.

    PubMed

    Yuval; Broday, David M

    2010-06-15

    Prediction of meteorological and air quality variables motivates a lot of research in the atmospheric sciences and exposure assessment communities. An interesting related issue regards the relative predictive power that can be expected at different time scales, and whether it vanishes altogether at certain ranges. An improved understanding of our predictive powers enables better environmental management and more efficient decision making processes. Fractal analysis is commonly used to characterize the self-affinity of time series. This work introduces the Continuous Wavelet Transform (CWT) fractal analysis method as a tool for assessing environmental time series predictability. The high temporal scale resolution of the CWT enables detailed information about the Hurst parameter, a common temporal fractality measure, and thus about time scale variations in predictability. We analyzed a few years records of half-hourly air pollution and meteorological time series from which the trivial seasonal and daily cycles were removed. We encountered a general trend of decreasing Hurst values from about 1.4 (good autocorrelation and predictability), in the sub-daily time scale to 0.5 (which implies complete randomness) in the monthly to seasonal scales. The air pollutants predictability follows that of the meteorological variables in the short time scales but is better at longer scales.

  7. The role of environmental variables in structuring landscape-scale species distributions in seafloor habitats.

    PubMed

    Kraan, Casper; Aarts, Geert; Van der Meer, Jaap; Piersma, Theunis

    2010-06-01

    Ongoing statistical sophistication allows a shift from describing species' spatial distributions toward statistically disentangling the possible roles of environmental variables in shaping species distributions. Based on a landscape-scale benthic survey in the Dutch Wadden Sea, we show the merits of spatially explicit generalized estimating equations (GEE). The intertidal macrozoobenthic species, Macoma balthica, Cerastoderma edule, Marenzelleria viridis, Scoloplos armiger, Corophium volutator, and Urothoe poseidonis served as test cases, with median grain-size and inundation time as typical environmental explanatory variables. GEEs outperformed spatially naive generalized linear models (GLMs), and removed much residual spatial structure, indicating the importance of median grain-size and inundation time in shaping landscape-scale species distributions in the intertidal. GEE regression coefficients were smaller than those attained with GLM, and GEE standard errors were larger. The best fitting GEE for each species was used to predict species' density in relation to median grain-size and inundation time. Although no drastic changes were noted compared to previous work that described habitat suitability for benthic fauna in the Wadden Sea, our predictions provided more detailed and unbiased estimates of the determinants of species-environment relationships. We conclude that spatial GEEs offer the necessary methodological advances to further steps toward linking pattern to process.

  8. Salt marsh sediment diversity: a test of the variability of the rare biosphere among environmental replicates

    PubMed Central

    Bowen, Jennifer L; Morrison, Hilary G; Hobbie, John E; Sogin, Mitchell L

    2012-01-01

    Much of the phylogenetic diversity in microbial systems arises from rare taxa that comprise the long tail of taxon rank distribution curves. This vast diversity presents a challenge to testing hypotheses about the effects of perturbations on microbial community composition because variability of rare taxa among environmental replicates may be sufficiently large that it would require a prohibitive degree of sequencing to discern differences between samples. In this study we used pyrosequencing of 16S rRNA tags to examine the diversity and within-site variability of salt marsh sediment bacteria. Our goal was to determine whether pyrosequencing could produce similar patterns in community composition among replicate environmental samples from the same location. We hypothesized that repeated sampling from the same location would produce different snapshots of the rare community due to incomplete sequencing of the taxonomically rich rare biosphere. We demonstrate that the salt marsh sediments we sampled contain a remarkably diverse array of bacterial taxa and, in contrast to our hypothesis, repeated sampling from within the same site produces reliably similar patterns in bacterial community composition, even among rare organisms. These results demonstrate that deep sequencing of 16s tags is well suited to distinguish site-specific similarities and differences among rare taxa and is a valuable tool for hypothesis testing in microbial ecology. PMID:22739491

  9. Assessment of surf zone environmental variables in a southwestern Atlantic sandy beach (Monte Hermoso, Argentina).

    PubMed

    Menéndez, M Clara; Fernández Severini, Melisa D; Buzzi, Natalia S; Piccolo, M Cintia; Perillo, Gerardo M E

    2016-08-01

    The aim of this study was to investigate the temporal dynamics (monthly/tidal) of water temperature, salinity, chlorophyll-a (chlo-a), suspended particulate matter (SPM), particulate organic carbon (POC), and dissolved nutrients in the surf zone of Monte Hermoso sandy beach, Argentina. We also aimed to understand the underlying mechanisms responsible for the observed variability. Sampling was carried out approximately monthly (September 2009-November 2010), and all samples were collected in a fixed station during high and low tide. Water temperature showed a clear seasonal variability (July: 9 °C-December: 26.5 °C) and a thermal amplitude of 17.5 °C. Salinity ranged from 33 to 37, without a pronounced seasonality. SPM (10-223 mg L(-1)) and POC concentrations (399-6445 mg C m(-3)) were high in surf zone waters. Chlo-a (0.05-9.16 μg L(-1)) was low and did not evidence the occurrence of surf diatom accumulations. Dissolved nutrient concentration was quite fluctuating. None of the variables seemed to be affected by tidal stage. The results showed how fluctuating the physico-chemical and biological variables can be in this particular system. The observed variability can be related with local beach conditions but also with regional processes. The study area is highly influenced by a neighbor estuary and as a consequence, could be vulnerable to their seasonal and inter-annual dynamics. All of these characteristics must be considered for further studies and planning of the uses of natural resources and should be taken into account in any environmental monitoring program conducted in a similar beach system.

  10. Abiotic Methane Synthesis: Caveats and New Results

    NASA Astrophysics Data System (ADS)

    Zou, R.; Sharma, A.

    2005-12-01

    The role of mineral interaction with geochemical fluids under hydrothermal conditions has invoked models of geochemical synthesis of organic molecules at deep crustal conditions. Since Thomas Gold's (1992) hypothesis of the possibility of an abiotic organic synthesis, there have been several reports of hydrocarbon formation under high pressure and temperature conditions. Several previous experimental studies have recognized that small amounts of methane (and other light HC compounds) can be synthesized via catalysis by transition metals: Fe, Ni (Horita and Berndt, 1999 Science) and Cr (Foustavous and Seyfried, 2004 Science). In light of these pioneering experiments, an investigation of the feasibility of abiotic methane synthesis at higher pressure conditions in deep geological setting and the possible role of catalysis warrants a closer look. We conducted three sets of experiments in hydrothermal diamond anvil cell using FeO nanopowder, CaCO 3 and water at 300° - 600° C and 0.5 - 5 GPa : (a) with stainless steel gasket, (b) gold-lined gasket, and (c) gold-lined gasket with added Fe and Ni nanopowder. The reactions were monitored in-situ using micro-Raman spectroscopy with 532nm and 632nm lasers. The solids phases were characterized in-situ using synchrotron X-ray diffraction at CHESS-Cornell and quenched products with an electron microprobe. Interestingly, a variable amount of hydrocarbon was observed only in runs with stainless steel gasket and with Fe, Ni nanoparticles. Experiments with gold-lined reactors did not show any hydrocarbon formation. Added high resolution microscopy of the products and their textural relationship within the diamond cell with Raman spectroscopy data show that the hydrocarbon (methane and other light fractions) synthesis is a direct result of transition metal catalysis, rather than wustite - calcium carbonate reaction as recently reported by Scott et al (2004, PNAS). The author will further present new results highlighting abiotic

  11. Quality of Streams in Johnson County, Kansas, and Relations to Environmental Variables, 2003-07

    USGS Publications Warehouse

    Rasmussen, Teresa J.; Poulton, Barry C.; Graham, Jennifer L.

    2009-01-01

    The quality of streams and relations to environmental variables in Johnson County, northeastern Kansas, were evaluated using water, streambed sediment, land use, streamflow, habitat, algal periphyton (benthic algae), and benthic macroinvertebrate data. Water, streambed sediment, and macroinvertebrate samples were collected in March 2007 during base flow at 20 stream sites that represent 11 different watersheds in the county. In addition, algal periphyton samples were collected twice (spring and summer 2007) at one-half of the sites. Environmental data including water and streambed-sediment chemistry data (primarily nutrients, fecal-indicator bacteria, and organic wastewater compounds), land use, streamflow, and habitat data were used in statistical analyses to evaluate relations between biological conditions and variables that may affect them. This report includes an evaluation of water and streambed-sediment chemistry, assessment of habitat conditions, comparison of biological community attributes (such as composition, diversity, and abundance) among sampling sites, placement of sampling sites into impairment categories, evaluation of biological data relative to environmental variables, and evaluation of changes in biological communities and effects of urbanization. This evaluation is useful for understanding factors that affect stream quality, for improving water-quality management programs, and for documenting changing conditions over time. The information will become increasingly important for protecting streams in the future as urbanization continues. Results of this study indicate that the biological quality at nearly all biological sampling sites in Johnson County has some level of impairment. Periphyton taxa generally were indicative of somewhat degraded conditions with small to moderate amounts of organic enrichment. Camp Branch in the Blue River watershed was the only site that met State criteria for full support of aquatic life in 2007. Since 2003

  12. Environmental and management influences on temporal variability of near saturated soil hydraulic properties☆

    PubMed Central

    Bodner, G.; Scholl, P.; Loiskandl, W.; Kaul, H.-P.

    2013-01-01

    Structural porosity is a decisive property for soil productivity and soil environmental functions. Hydraulic properties in the structural range vary over time in response to management and environmental influences. Although this is widely recognized, there are few field studies that determine dominant driving forces underlying hydraulic property dynamics. During a three year field experiment we measured temporal variability of soil hydraulic properties by tension infiltrometry. Soil properties were characterized by hydraulic conductivity, effective macroporosity and Kosugi's lognormal pore size distribution model. Management related influences comprised three soil cover treatment (mustard and rye vs. fallow) and an initial mechanical soil disturbance with a rotary harrow. Environmental driving forces were derived from meteorological and soil moisture data. Soil hydraulic parameters varied over time by around one order of magnitude. The coefficient of variation of soil hydraulic conductivity K(h) decreased from 69.5% at saturation to 42.1% in the more unsaturated range (− 10 cm pressure head). A slight increase in the Kosugi parameter showing pore heterogeneity was observed under the rye cover crop, reflecting an enhanced structural porosity. The other hydraulic parameters were not significantly influenced by the soil cover treatments. Seedbed preparation with a rotary harrow resulted in a fourfold increase in macroporosity and hydraulic conductivity next to saturation, and homogenized the pore radius distribution. Re-consolidation after mechanical loosening lasted over 18 months until the soil returned to its initial state. The post-tillage trend of soil settlement could be approximated by an exponential decay function. Among environmental factors, wetting-drying cycles were identified as dominant driving force explaining short term hydraulic property changes within the season (r2 = 0.43 to 0.59). Our results suggested that beside considering average

  13. Combination of multispectral remote sensing, variable rate technology and environmental modeling for citrus pest management.

    PubMed

    Du, Qian; Chang, Ni-Bin; Yang, Chenghai; Srilakshmi, Kanth R

    2008-01-01

    The Lower Rio Grande Valley (LRGV) of south Texas is an agriculturally rich area supporting intensive production of vegetables, fruits, grain sorghum, and cotton. Modern agricultural practices involve the combined use of irrigation with the application of large amounts of agrochemicals to maximize crop yields. Intensive agricultural activities in past decades might have caused potential contamination of soil, surface water, and groundwater due to leaching of pesticides in the vadose zone. In an effort to promote precision farming in citrus production, this paper aims at developing an airborne multispectral technique for identifying tree health problems in a citrus grove that can be combined with variable rate technology (VRT) for required pesticide application and environmental modeling for assessment of pollution prevention. An unsupervised linear unmixing method was applied to classify the image for the grove and quantify the symptom severity for appropriate infection control. The PRZM-3 model was used to estimate environmental impacts that contribute to nonpoint source pollution with and without the use of multispectral remote sensing and VRT. Research findings using site-specific environmental assessment clearly indicate that combination of remote sensing and VRT may result in benefit to the environment by reducing the nonpoint source pollution by 92.15%. Overall, this study demonstrates the potential of precision farming for citrus production in the nexus of industrial ecology and agricultural sustainability.

  14. Plant-pollinator interactions in Crambe abyssinica Hochst. (Brassicaceae) associated with environmental variables.

    PubMed

    Simioni, Lívia C; Mussury, Rosilda M; Mauad, Munir; Dresh, Daiane M; Pereira, Fabricio F; Scalon, Silvana P Q

    2015-03-01

    Despite the economic importance of Crambe abyssinica, the present study is the first report on bees that occur with this species, and could aid in developing alternative methods for controlling insect pests without seriously impacting pollinators. The present study examined the following questions: (1) Which species are potential pollinators of C. abyssinica? (2) How do environmental conditions influence pollinator visitation fluctuations? Insects were sampled on a weekly basis between 08:00 and 16:00 during five weeks of flowering. When the results of analyses of variance were significant, the data was adjusted using regression equations at a 5% level of probability; the environmental variables were examined using Pearson's correlation coefficient. Apis mellifera, Geotrigona mombuca, Exomalopsis (Exomalopsis) fulvofasciata, Plebeia sp. and Dialictus sp. were observed visiting C. abyssinica flowers. A. mellifera and G. mombuca were observed to be potential pollinators, with the former demonstrating visitation peaks during flowering weeks II and IV at 12:00 and 08:00, respectively and the latter visiting during weeks III and IV at 12:00 and 10:00, respectively. Environmental factors such as temperature, relative humidity, and wind speed have different effect on the activity of bees.

  15. Expanding knowledge of the Rubisco kinetics variability in plant species: environmental and evolutionary trends.

    PubMed

    Galmés, Jeroni; Kapralov, Maxim V; Andralojc, P John; Conesa, Miquel À; Keys, Alfred J; Parry, Martin A J; Flexas, Jaume

    2014-09-01

    The present study characterizes the kinetic properties of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) from 28 terrestrial plant species, representing different phylogenetic lineages, environmental adaptations and photosynthetic mechanisms. Our findings confirm that past atmospheric CO(2)/O(2) ratio changes and present environmental pressures have influenced Rubisco kinetics. One evolutionary adaptation to a decreasing atmospheric CO(2)/O(2) ratio has been an increase in the affinity of Rubisco for CO(2) (Kc falling), and a consequent decrease in the velocity of carboxylation (kcat (c)), which in turn has been ameliorated by an increase in the proportion of leaf protein accounted by Rubisco. The trade-off between K(c) and k(cat)(c) was not universal among the species studied and deviations from this relationship occur in extant forms of Rubisco. In species adapted to particular environments, including carnivorous plants, crassulacean acid metabolism species and C(3) plants from aquatic and arid habitats, Rubisco has evolved towards increased efficiency, as demonstrated by a higher k(cat)(c)/K(c) ratio. This variability in kinetics was related to the amino acid sequence of the Rubisco large subunit. Phylogenetic analysis identified 13 residues under positive selection during evolution towards specific Rubisco kinetic parameters. This crucial information provides candidate amino acid replacements, which could be implemented to optimize crop photosynthesis under a range of environmental conditions.

  16. The variability and seasonality of the environmental reservoir of Mycobacterium bovis shed by wild European badgers.

    PubMed

    King, Hayley C; Murphy, Andrew; James, Phillip; Travis, Emma; Porter, David; Hung, Yu-Jiun; Sawyer, Jason; Cork, Jennifer; Delahay, Richard J; Gaze, William; Courtenay, Orin; Wellington, Elizabeth M

    2015-08-06

    The incidence of Mycobacterium bovis, the causative agent of bovine tuberculosis, has been increasing in UK cattle herds resulting in substantial economic losses. The European badger (Meles meles) is implicated as a wildlife reservoir of infection. One likely route of transmission to cattle is through exposure to infected badger urine and faeces. The relative importance of the environment in transmission remains unknown, in part due to the lack of information on the distribution and magnitude of environmental reservoirs. Here we identify potential infection hotspots in the badger population and quantify the heterogeneity in bacterial load; with infected badgers shedding between 1 × 10(3)- 4 × 10(5) M. bovis cells g(-1) of faeces, creating a substantial and seasonally variable environmental reservoir. Our findings highlight the potential importance of monitoring environmental reservoirs of M. bovis which may constitute a component of disease spread that is currently overlooked and yet may be responsible for a proportion of transmission amongst badgers and onwards to cattle.

  17. The potential influence of short-term environmental variability on the composition of testate amoeba communities in Sphagnum peatlands.

    PubMed

    Sullivan, Maura E; Booth, Robert K

    2011-07-01

    Testate amoebae are a group of moisture-sensitive, shell-producing protozoa that have been widely used as indicators of changes in mean water-table depth within oligotrophic peatlands. However, short-term environmental variability (i.e., sub-annual) also probably influences community composition. The objective of this study was to assess the potential influence of short-term environmental variability on the composition of testate amoeba communities in Sphagnum-dominated peatlands. Testate amoebae and environmental conditions, including hourly measurements of relative humidity within the upper centimeter of the peatland surface, were examined throughout the 2008 growing season at 72 microsites within 11 peatlands of Pennsylvania and Wisconsin, USA. Relationships among testate amoeba communities, vegetation, depth to water table, pH, and an index of short-term environmental variability (EVI), were examined using nonmetric multidimensional scaling and correlation analysis. Results suggest that EVI influences testate amoeba communities, with some taxa more abundant under highly variable conditions (e.g., Arcella discoides, Difflugia pulex, and Hyalosphenia subflava) and others more abundant when environmental conditions at the peatland surface were relatively stable (e.g., Archerella flavum and Bullinularia indica). The magnitude of environmental variability experienced at the peatland surface appears to be primarily controlled by vegetation composition and density. In particular, sites with dense Sphagnum cover had lower EVI values than sites with loose-growing Sphagnum or vegetation dominated by vascular plants and/or non-Sphagnum bryophytes. Our results suggest that more environmental information may be inferred from testate amoebae than previously recognized. Knowledge of relationships between testate amoebae and short-term environmental variability should lead to more detailed and refined environmental inferences.

  18. Protein Tyrosine Nitration during Development and Abiotic Stress Response in Plants

    PubMed Central

    Mata-Pérez, Capilla; Begara-Morales, Juan C.; Chaki, Mounira; Sánchez-Calvo, Beatriz; Valderrama, Raquel; Padilla, María N.; Corpas, Francisco J.; Barroso, Juan B.

    2016-01-01

    In recent years, the study of nitric oxide (NO) in plant systems has attracted the attention of many researchers. A growing number of investigations have shown the significance of NO as a signal molecule or as a molecule involved in the response against (a)biotic processes. NO can be responsible of the post-translational modifications (NO-PTM) of target proteins by mechanisms such as the nitration of tyrosine residues. The study of protein tyrosine nitration during development and under biotic and adverse environmental conditions has increased in the last decade; nevertheless, there is also an endogenous nitration which seems to have regulatory functions. Moreover, the advance in proteome techniques has enabled the identification of new nitrated proteins, showing the high variability among plant organs, development stage and species. Finally, it may be important to discern between a widespread protein nitration because of greater RNS content, and the specific nitration of key targets which could affect cell-signaling processes. In view of the above point, we present a mini-review that offers an update about the endogenous protein tyrosine nitration, during plant development and under several abiotic stress conditions. PMID:27895655

  19. Effect of environmental variables and stand structure on ecosystem respiration components in a Mediterranean beech forest.

    PubMed

    Guidolotti, Gabriele; Rey, Ana; D'Andrea, Ettore; Matteucci, Giorgio; De Angelis, Paolo

    2013-09-01

    The temporal variability of ecosystem respiration (RECO) has been reported to have important effects on the temporal variability of net ecosystem exchange, the net amount of carbon exchanged between an ecosystem and the atmosphere. However, our understanding of ecosystem respiration is rather limited compared with photosynthesis or gross primary productivity, particularly in Mediterranean montane ecosystems. In order to investigate how environmental variables and forest structure (tree classes) affect different respiration components and RECO in a Mediterranean beech forest, we measured soil, stem and leaf CO2 efflux rates with dynamic chambers and RECO by the eddy-covariance technique over 1 year (2007-2008). Ecosystem respiration showed marked seasonal variation, with the highest rates in spring and autumn and the lowest in summer. We found that the soil respiration (SR) was mainly controlled by soil water content below a threshold value of 0.2 m(3) m(-3), above which the soil temperature explained temporal variation in SR. Stem CO2 effluxes were influenced by air temperature and difference between tree classes with higher rates measured in dominant trees than in co-dominant ones. Leaf respiration (LR) varied significantly between the two canopy layers considered. Non-structural carbohydrates were a very good predictor of LR variability. We used these measurements to scale up respiration components to ecosystem respiration for the whole canopy and obtained cumulative amounts of carbon losses over the year. Based on the up-scaled chamber measurements, the relative contributions of soil, stem and leaves to the total annual CO2 efflux were: 56, 8 and 36%, respectively. These results confirm that SR is the main contributor of ecosystem respiration and provided an insight on the driving factors of respiration in Mediterranean montane beech forests.

  20. Patterns in Temporal Variability of Temperature, Oxygen and pH along an Environmental Gradient in a Coral Reef

    PubMed Central

    Guadayol, Òscar; Silbiger, Nyssa J.; Donahue, Megan J.; Thomas, Florence I. M.

    2014-01-01

    Spatial and temporal environmental variability are important drivers of ecological processes at all scales. As new tools allow the in situ exploration of individual responses to fluctuations, ecologically meaningful ways of characterizing environmental variability at organism scales are needed. We investigated the fine-scale spatial heterogeneity of high-frequency temporal variability in temperature, dissolved oxygen concentration, and pH experienced by benthic organisms in a shallow coastal coral reef. We used a spatio-temporal sampling design, consisting of 21 short-term time-series located along a reef flat-to-reef slope transect, coupled to a long-term station monitoring water column changes. Spectral analyses revealed sharp gradients in variance decomposed by frequency, as well as differences between physically-driven and biologically-reactive parameters. These results highlight the importance of environmental variance at organismal scales and present a new sampling scheme for exploring this variability in situ. PMID:24416364

  1. Local nutrient regimes determine site-specific environmental triggers of cyanobacterial and microcystin variability in urban lakes

    NASA Astrophysics Data System (ADS)

    Sinang, S. C.; Reichwaldt, E. S.; Ghadouani, A.

    2014-10-01

    Toxic cyanobacterial blooms in urban lakes present serious health hazards to humans and animals and require effective management strategies. In the management of toxic cyanobacteria blooms, understanding the roles of environmental factors is crucial. To date, a range of environmental factors have been proposed as potential triggers for the spatiotemporal variability of cyanobacterial biomass and microcystins in freshwater systems. However, the environmental triggers of cyanobacteria and microcystin variability remain a subject of debate due to contrasting findings. This issue has raised the question if the environmental triggers are site-specific and unique between water bodies. In this study, we investigated the site-specificity of environmental triggers for cyanobacterial bloom and cyanotoxins dynamics. Our study suggests that cyanobacterial dominance and cyanobacterial microcystin content variability were significantly correlated to phosphorus and iron concentrations. However, the correlations between phosphorus and iron with cyanobacterial biomass and microcystin variability were not consistent between lakes, thus suggesting a site specificity of these environmental factors. The discrepancies in the correlations could be explained by differences in local nutrient concentration and the cyanobacterial community in the systems. The findings of this study suggest that identification of site-specific environmental factors under unique local conditions is an important strategy to enhance positive outcomes in cyanobacterial bloom control measures.

  2. Biofilm function and variability in a hydrothermal ecosystem: insights from environmental genomes

    NASA Astrophysics Data System (ADS)

    Meyer-Dombard, D. R.; Raymond, J.; Shock, E. L.

    2007-12-01

    The ability to adapt to variable environmental conditions is key to survival for all organisms, but may be especially crucial to microorganisms in extreme environments such as hydrothermal systems. Streamer biofilm communities (SBCs) made up of thermophilic chemotrophic microorganisms are common in alkaline-chloride geothermal environments worldwide, but the in situ physiochemical growth parameters and requirements of SBCs are largely unknown [1]. Hot springs in Yellowstone National Park's alkaline geyser basins support SBC growth. However, despite the relative geochemical homogeneity of source pools and widespread ecosystem suitability in these regions (as indicated by energetic profiling [2]), SBCs are not ubiquitous in these ecosystems. The ability of hydrothermal systems to support the growth of SBCs, the relationship between these geochemically driven environments and the microbes that live there, and the function of individuals in these communities are aspects that are adressed here by applying environmental genomics. Analysis of 16S rRNA and total membrane lipid extracts have revealed that community composition of SBCs in "Bison Pool" varies as a function of changing environmental conditions along the outflow channel. In addition, a significant crenarchaeal component was discovered in the "Bison Pool" SBCs. In general, the SBC bacterial diversity triples while the archaeal component varies little (from 3 to 2 genera) in a 5-10°C gradient with distance from the source. While these SBCs are low in overall diversity, the majority of the taxa identified represent uncultured groups of Bacteria and Archaea. As a result, the community function of these taxa and their role in the formation of the biofilms is unknown. However, recent genomic analysis from environmental DNA affords insight into the roles of specific organisms within SBCs at "Bison Pool," and integration of these data with an extensive corresponding geochemical dataset may indicate shifting community

  3. Integrating omic approaches for abiotic stress tolerance in soybean

    PubMed Central

    Deshmukh, Rupesh; Sonah, Humira; Patil, Gunvant; Chen, Wei; Prince, Silvas; Mutava, Raymond; Vuong, Tri; Valliyodan, Babu; Nguyen, Henry T.

    2014-01-01

    Soybean production is greatly influenced by abiotic stresses imposed by environmental factors such as drought, water submergence, salt, and heavy metals. A thorough understanding of plant response to abiotic stress at the molecular level is a prerequisite for its effective management. The molecular mechanism of stress tolerance is complex and requires information at the omic level to understand it effectively. In this regard, enormous progress has been made in the omics field in the areas of genomics, transcriptomics, and proteomics. The emerging field of ionomics is also being employed for investigating abiotic stress tolerance in soybean. Omic approaches generate a huge amount of data, and adequate advancements in computational tools have been achieved for effective analysis. However, the integration of omic-scale information to address complex genetics and physiological questions is still a challenge. In this review, we have described advances in omic tools in the view of conventional and modern approaches being used to dissect abiotic stress tolerance in soybean. Emphasis was given to approaches such as quantitative trait loci (QTL) mapping, genome-wide association studies (GWAS), and genomic selection (GS). Comparative genomics and candidate gene approaches are also discussed considering identification of potential genomic loci, genes, and biochemical pathways involved in stress tolerance mechanism in soybean. This review also provides a comprehensive catalog of available online omic resources for soybean and its effective utilization. We have also addressed the significance of phenomics in the integrated approaches and recognized high-throughput multi-dimensional phenotyping as a major limiting factor for the improvement of abiotic stress tolerance in soybean. PMID:24917870

  4. Ibero Atlantic Forested Wetlands: Plant-Abiotic Interactions at a Regional Scale

    NASA Astrophysics Data System (ADS)

    Gonzalez, P. R.; Ferreira, T.; Albuquerque, A.; Espirito-Santo, D.; Ramil-Rego, P.

    2005-05-01

    In biogeographical terms, forested wetlands are considered azonal ecosystems due to their special edaphic conditions. Duration of waterlogging decreases the effect of regional climate in vegetation communities. In this work we test this hypothesis by studying the relative contribution of spatial and environmental variation. Plant community composition and vertical structure were inventoried in inland forested wetlands along the Atlantic coast of the Iberian Peninsula. The study area ranges from latitude N 44° to 38° and includes Temperate and Mediterranean climate. Forested wetlands area was delimitated and sampled using plots where all the vascular plants and bryophytes were registered and their percentage cover estimated. Collected environmental regional variables included geographic, climatic, geologic and hydro geomorphologic data. Multivariate analysis was used to interpret species abundance data to assess the relative weight of environmental conditions and the spatial structure in the species data variation. Results of species-environment treatment revealed that tree overstorey species were determinant for vegetation types and that hydroperiod was the key abiotic variable classifying forested wetlands.

  5. Effects of competing environmental variables and signage on route-choices in simulated everyday and emergency wayfinding situations.

    PubMed

    Vilar, Elisângela; Rebelo, Francisco; Noriega, Paulo; Duarte, Emília; Mayhorn, Christopher B

    2014-01-01

    This study examined the relative influence of environmental variables (corridor width and brightness) and signage (directional and exit signs), when presented in competition, on participants' route-choices in two situational variables (everyday vs. emergency), during indoor wayfinding in virtual environments. A virtual reality-based methodology was used. Thus, participants attempted to find a room (everyday situation) in a virtual hotel, followed by a fire-related emergency egress (emergency situation). Different behaviours were observed. In the everyday situation, for no-signs condition, participants choose mostly the wider and brighter corridors, suggesting a heavy reliance on the environmental affordances. Conversely, for signs condition, participants mostly complied with signage, suggesting a greater reliance on the signs rather than on the environmental cues. During emergency, without signage, reliance on environmental affordances seems to be affected by the intersection type. In the sign condition, the reliance on environmental affordances that started strong decreases along the egress route.

  6. Environmental forcing and Southern Ocean marine predator populations: effects of climate change and variability.

    PubMed

    Trathan, P N; Forcada, J; Murphy, E J

    2007-12-29

    The Southern Ocean is a major component within the global ocean and climate system and potentially the location where the most rapid climate change is most likely to happen, particularly in the high-latitude polar regions. In these regions, even small temperature changes can potentially lead to major environmental perturbations. Climate change is likely to be regional and may be expressed in various ways, including alterations to climate and weather patterns across a variety of time-scales that include changes to the long interdecadal background signals such as the development of the El Niño-Southern Oscillation (ENSO). Oscillating climate signals such as ENSO potentially provide a unique opportunity to explore how biological communities respond to change. This approach is based on the premise that biological responses to shorter-term sub-decadal climate variability signals are potentially the best predictor of biological responses over longer time-scales. Around the Southern Ocean, marine predator populations show periodicity in breeding performance and productivity, with relationships with the environment driven by physical forcing from the ENSO region in the Pacific. Wherever examined, these relationships are congruent with mid-trophic-level processes that are also correlated with environmental variability. The short-term changes to ecosystem structure and function observed during ENSO events herald potential long-term changes that may ensue following regional climate change. For example, in the South Atlantic, failure of Antarctic krill recruitment will inevitably foreshadow recruitment failures in a range of higher trophic-level marine predators. Where predator species are not able to accommodate by switching to other prey species, population-level changes will follow. The Southern Ocean, though oceanographically interconnected, is not a single ecosystem and different areas are dominated by different food webs. Where species occupy different positions in

  7. Linking Microbial Community, Environmental Variables, and Methanogenesis in Anaerobic Biogas Digesters of Chemically Enhanced Primary Treatment Sludge.

    PubMed

    Ju, Feng; Lau, Frankie; Zhang, Tong

    2017-04-04

    Understanding the influences of biotic and abiotic factors on microbial community structure and methanogenesis are important for its engineering and ecological significance. In this study, four biogas digesters were supplied with the same inoculum and feeding sludge but operated at different sludge retention time (7 to 16 days) and organic loading rates for 90 days to determine the relative influence of biotic and environmental factors on the microbial community assembly and methanogenic performance. Despite different operational parameters, all digester communities were dominated by Bacteroidales, Clostridiales, and Thermotogales and followed the same trend of population dynamics over time. Network and multivariate analyses suggest that deterministic factors, including microbial competition (involving Bacteroidales spp.), niche differentiation (e.g., within Clostridiales spp.), and periodic microbial immigration (from feed sludge), are the key drivers of microbial community assembly and dynamics. A yet-to-be-cultured phylotype of Bacteroidales (GenBank ID: GU389558.1 ) is implicated as a strong competitor for carbohydrates. Moreover, biogas-producing rate and methane content were significantly related with the abundances of functional populations rather than any operational or physicochemical parameter, revealing microbiological mediation of methanogenesis. Combined, this study enriches our understandings of biological and environmental drivers of microbial community assembly and performance in anaerobic digesters.

  8. Responsiveness of Food Security Reporting to Environmental Variability and Agricultural Production Deficits

    NASA Astrophysics Data System (ADS)

    Brickley, E. B.; Brown, M. E.

    2010-12-01

    This paper uses 1342 food security update reports from the US Agency for International Development (USAID)’s Famine Early Warning System Network (FEWS NET) in an analysis that focuses on the environmental, market, and livelihood influences on the food security in 17 countries in Africa from 2000-2009. A textual analysis was conducted using the reports as a primary data source to evaluate the responsiveness of food security analysis to environmental variability and food production deficits. The research shows that FEWS NET analysts demonstrate a consistent approach across all 17 countries as to the discussion and use of rainfall information, agricultural production, food prices and food access parameters. There are significant differences in the use of remote sensing and other technical information between East, West and Southern African country analysts, with satellite remote sensing of vegetation being used 28% of the time, rainfall imagery 84% and gridded crop models only 10% of the time. Significantly more discussion of biophysical information was seen during the rainy season than during the dry season, and different satellite products were used during periods of drought than periods of adequate moisture. As the demand for early warning information grows to more countries in different ecosystems, there is likely to be an increased need for the effective utilization of remote sensing, market, and livelihood data, and it is also probable that this information will be critical for improved policy-making regarding climate extremes in the future.

  9. Land Use and Environmental Variability Impacts on the Phenology of Arid Agro-Ecosystems

    NASA Astrophysics Data System (ADS)

    Romo-Leon, Jose Raul; van Leeuwen, Willem J. D.; Castellanos-Villegas, Alejandro

    2016-02-01

    The overexploitation of water resources in arid environments often results in abandonment of large extensions of agricultural lands, which may (1) modify phenological trends, and (2) alter the sensitivity of specific phenophases to environmental triggers. In Mexico, current governmental policies subsidize restoration efforts, to address ecological degradation caused by abandonments; however, there is a need for new approaches to assess their effectiveness. Addressing this, we explore a method to monitor and assess (1) land surface phenology trends in arid agro-ecosystems, and (2) the effect of climatic factors and restoration treatments on the phenology of abandoned agricultural fields. We used 16-day normalized difference vegetation index composites from the moderate resolution imaging spectroradiometer from 2000 to 2009 to derive seasonal phenometrics. We then derived phenoclimatic variables and land cover thematic maps, to serve as a set of independent factors that influence vegetation phenology. We conducted a multivariate analysis of variance to analyze phenological trends among land cover types, and developed multiple linear regression models to assess influential climatic factors driving phenology per land cover analyzed. Our results suggest that the start and length of the growing season had different responses to environmental factors depending on land cover type. Our analysis also suggests possible establishment of arid adapted species (from surrounding ecosystems) in abandoned fields with longer times since abandonment. Using this approach, we were able increase our understanding on how climatic factors influence phenology on degraded arid agro-ecosystems, and how this systems evolve after disturbance.

  10. Heterogeneous Multi-Robot System for Mapping Environmental Variables of Greenhouses

    PubMed Central

    Roldán, Juan Jesús; Garcia-Aunon, Pablo; Garzón, Mario; de León, Jorge; del Cerro, Jaime; Barrientos, Antonio

    2016-01-01

    The productivity of greenhouses highly depends on the environmental conditions of crops, such as temperature and humidity. The control and monitoring might need large sensor networks, and as a consequence, mobile sensory systems might be a more suitable solution. This paper describes the application of a heterogeneous robot team to monitor environmental variables of greenhouses. The multi-robot system includes both ground and aerial vehicles, looking to provide flexibility and improve performance. The multi-robot sensory system measures the temperature, humidity, luminosity and carbon dioxide concentration in the ground and at different heights. Nevertheless, these measurements can be complemented with other ones (e.g., the concentration of various gases or images of crops) without a considerable effort. Additionally, this work addresses some relevant challenges of multi-robot sensory systems, such as the mission planning and task allocation, the guidance, navigation and control of robots in greenhouses and the coordination among ground and aerial vehicles. This work has an eminently practical approach, and therefore, the system has been extensively tested both in simulations and field experiments. PMID:27376297

  11. Heterogeneous Multi-Robot System for Mapping Environmental Variables of Greenhouses.

    PubMed

    Roldán, Juan Jesús; Garcia-Aunon, Pablo; Garzón, Mario; de León, Jorge; Del Cerro, Jaime; Barrientos, Antonio

    2016-07-01

    The productivity of greenhouses highly depends on the environmental conditions of crops, such as temperature and humidity. The control and monitoring might need large sensor networks, and as a consequence, mobile sensory systems might be a more suitable solution. This paper describes the application of a heterogeneous robot team to monitor environmental variables of greenhouses. The multi-robot system includes both ground and aerial vehicles, looking to provide flexibility and improve performance. The multi-robot sensory system measures the temperature, humidity, luminosity and carbon dioxide concentration in the ground and at different heights. Nevertheless, these measurements can be complemented with other ones (e.g., the concentration of various gases or images of crops) without a considerable effort. Additionally, this work addresses some relevant challenges of multi-robot sensory systems, such as the mission planning and task allocation, the guidance, navigation and control of robots in greenhouses and the coordination among ground and aerial vehicles. This work has an eminently practical approach, and therefore, the system has been extensively tested both in simulations and field experiments.

  12. Land Use and Environmental Variability Impacts on the Phenology of Arid Agro-Ecosystems.

    PubMed

    Romo-Leon, Jose Raul; van Leeuwen, Willem J D; Castellanos-Villegas, Alejandro

    2016-02-01

    The overexploitation of water resources in arid environments often results in abandonment of large extensions of agricultural lands, which may (1) modify phenological trends, and (2) alter the sensitivity of specific phenophases to environmental triggers. In Mexico, current governmental policies subsidize restoration efforts, to address ecological degradation caused by abandonments; however, there is a need for new approaches to assess their effectiveness. Addressing this, we explore a method to monitor and assess (1) land surface phenology trends in arid agro-ecosystems, and (2) the effect of climatic factors and restoration treatments on the phenology of abandoned agricultural fields. We used 16-day normalized difference vegetation index composites from the moderate resolution imaging spectroradiometer from 2000 to 2009 to derive seasonal phenometrics. We then derived phenoclimatic variables and land cover thematic maps, to serve as a set of independent factors that influence vegetation phenology. We conducted a multivariate analysis of variance to analyze phenological trends among land cover types, and developed multiple linear regression models to assess influential climatic factors driving phenology per land cover analyzed. Our results suggest that the start and length of the growing season had different responses to environmental factors depending on land cover type. Our analysis also suggests possible establishment of arid adapted species (from surrounding ecosystems) in abandoned fields with longer times since abandonment. Using this approach, we were able increase our understanding on how climatic factors influence phenology on degraded arid agro-ecosystems, and how this systems evolve after disturbance.

  13. Distribution and fate of synthetic musks in the Songhua River, Northeastern China: influence of environmental variables.

    PubMed

    Lu, Binyu; Feng, Yujie; Gao, Peng; Zhang, Zhaohan; Lin, Nan

    2015-06-01

    Contamination levels and spatial and temporal distributions of six typical synthetic musks (SMs) in water and sediment of the Songhua River in Northeastern China were investigated. Experimental data for 72 water and 52 sediment samples collected at 29 sampling sites over 12 months spanning 2011-2012 showed that the Songhua River had been contaminated to different degrees at various sites separately from the river's source. The polycyclic musks 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-(g)-2-benzopyran (HHCB) (Galaxolide) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN) (Tonalide) were found most frequently and at the highest levels. Concentrations of HHCB were <2-37 ng/L in water and <0.5-17.5 ng/g dry weight (dw) in sediment. AHTN was <1-8 ng/L in water and <0.5-5.7 ng/g dw in sediment. Statistical relationships between SM concentrations and four environmental variables (temperature, illumination, runoff, and population density) in the Songhua River Basin were formulated. Concentration levels varied proportionately with the size of the city along the river, while the distribution patterns showed clear seasonal variations. HHCB/AHTN ratios mirrored the transfer and transmitting process of SMs. Concentrations of target compounds were correlated with each other, suggesting similar exposure sources. Environmental risk assessment of SMs presented seasonal variations and provided baseline information on SM exposure in the Songhua River Basin.

  14. Complex response of white pines to past environmental variability increases understanding of future vulnerability.

    PubMed

    Iglesias, Virginia; Krause, Teresa R; Whitlock, Cathy

    2015-01-01

    Ecological niche models predict plant responses to climate change by circumscribing species distributions within a multivariate environmental framework. Most projections based on modern bioclimatic correlations imply that high-elevation species are likely to be extirpated from their current ranges as a result of rising growing-season temperatures in the coming decades. Paleoecological data spanning the last 15,000 years from the Greater Yellowstone region describe the response of vegetation to past climate variability and suggest that white pines, a taxon of special concern in the region, have been surprisingly resilient to high summer temperature and fire activity in the past. Moreover, the fossil record suggests that winter conditions and biotic interactions have been critical limiting variables for high-elevation conifers in the past and will likely be so in the future. This long-term perspective offers insights on species responses to a broader range of climate and associated ecosystem changes than can be observed at present and should be part of resource management and conservation planning for the future.

  15. Environmental variability and biodiversity of megabenthos on the Hebrides Terrace Seamount (Northeast Atlantic)

    PubMed Central

    Henry, Lea-Anne; Vad, Johanne; Findlay, Helen S.; Murillo, Javier; Milligan, Rosanna; Roberts, J. Murray

    2014-01-01

    We present the first remotely operated vehicle investigation of megabenthic communities (1004–1695 m water depth) on the Hebrides Terrace Seamount (Northeast Atlantic). Conductivity-temperature-depth casts showed rapid light attenuation below the summit and an oceanographic regime on the flanks consistent with an internal tide, and high short-term variability in water temperature, salinity, light attenuation, aragonite and oxygen down to 1500 m deep. Minor changes in species composition (3–14%) were explained by changes in depth, substratum and oceanographic stability, whereas environmental variability explained substantially more variation in species richness (40–56%). Two peaks in species richness occurred, the first at 1300–1400 m where cooler Wyville Thomson Overflow Water (WTOW) mixes with subtropical gyre waters and the second at 1500–1600 m where WTOW mixes with subpolar mode waters. Our results suggest that internal tides, substrate heterogeneity and oceanographic interfaces may enhance biological diversity on this and adjacent seamounts in the Rockall Trough. PMID:24998523

  16. Mini-UAV based sensory system for measuring environmental variables in greenhouses.

    PubMed

    Roldán, Juan Jesús; Joossen, Guillaume; Sanz, David; del Cerro, Jaime; Barrientos, Antonio

    2015-02-02

    This paper describes the design, construction and validation of a mobile sensory platform for greenhouse monitoring. The complete system consists of a sensory system on board a small quadrotor (i.e., a four rotor mini-UAV). The goals of this system include taking measures of temperature, humidity, luminosity and CO2 concentration and plotting maps of these variables. These features could potentially allow for climate control, crop monitoring or failure detection (e.g., a break in a plastic cover). The sensors have been selected by considering the climate and plant growth models and the requirements for their integration onboard the quadrotor. The sensors layout and placement have been determined through a study of quadrotor aerodynamics and the influence of the airflows from its rotors. All components of the system have been developed, integrated and tested through a set of field experiments in a real greenhouse. The primary contributions of this paper are the validation of the quadrotor as a platform for measuring environmental variables and the determination of the optimal location of sensors on a quadrotor.

  17. Complex Response of White Pines to Past Environmental Variability Increases Understanding of Future Vulnerability

    PubMed Central

    Iglesias, Virginia; Krause, Teresa R.; Whitlock, Cathy

    2015-01-01

    Ecological niche models predict plant responses to climate change by circumscribing species distributions within a multivariate environmental framework. Most projections based on modern bioclimatic correlations imply that high-elevation species are likely to be extirpated from their current ranges as a result of rising growing-season temperatures in the coming decades. Paleoecological data spanning the last 15,000 years from the Greater Yellowstone region describe the response of vegetation to past climate variability and suggest that white pines, a taxon of special concern in the region, have been surprisingly resilient to high summer temperature and fire activity in the past. Moreover, the fossil record suggests that winter conditions and biotic interactions have been critical limiting variables for high-elevation conifers in the past and will likely be so in the future. This long-term perspective offers insights on species responses to a broader range of climate and associated ecosystem changes than can be observed at present and should be part of resource management and conservation planning for the future. PMID:25885810

  18. Mini-UAV Based Sensory System for Measuring Environmental Variables in Greenhouses

    PubMed Central

    Roldán, Juan Jesús; Joossen, Guillaume; Sanz, David; del Cerro, Jaime; Barrientos, Antonio

    2015-01-01

    This paper describes the design, construction and validation of a mobile sensory platform for greenhouse monitoring. The complete system consists of a sensory system on board a small quadrotor (i.e., a four rotor mini-UAV). The goals of this system include taking measures of temperature, humidity, luminosity and CO2 concentration and plotting maps of these variables. These features could potentially allow for climate control, crop monitoring or failure detection (e.g., a break in a plastic cover). The sensors have been selected by considering the climate and plant growth models and the requirements for their integration onboard the quadrotor. The sensors layout and placement have been determined through a study of quadrotor aerodynamics and the influence of the airflows from its rotors. All components of the system have been developed, integrated and tested through a set of field experiments in a real greenhouse. The primary contributions of this paper are the validation of the quadrotor as a platform for measuring environmental variables and the determination of the optimal location of sensors on a quadrotor. PMID:25648713

  19. Environmental variability and biodiversity of megabenthos on the Hebrides Terrace Seamount (Northeast Atlantic).

    PubMed

    Henry, Lea-Anne; Vad, Johanne; Findlay, Helen S; Murillo, Javier; Milligan, Rosanna; Roberts, J Murray

    2014-07-07

    We present the first remotely operated vehicle investigation of megabenthic communities (1004-1695 m water depth) on the Hebrides Terrace Seamount (Northeast Atlantic). Conductivity-temperature-depth casts showed rapid light attenuation below the summit and an oceanographic regime on the flanks consistent with an internal tide, and high short-term variability in water temperature, salinity, light attenuation, aragonite and oxygen down to 1500 m deep. Minor changes in species composition (3-14%) were explained by changes in depth, substratum and oceanographic stability, whereas environmental variability explained substantially more variation in species richness (40-56%). Two peaks in species richness occurred, the first at 1300-1400 m where cooler Wyville Thomson Overflow Water (WTOW) mixes with subtropical gyre waters and the second at 1500-1600 m where WTOW mixes with subpolar mode waters. Our results suggest that internal tides, substrate heterogeneity and oceanographic interfaces may enhance biological diversity on this and adjacent seamounts in the Rockall Trough.

  20. Metamorphosis of the invasive ascidian Ciona savignyi: environmental variables and chemical exposure.

    PubMed

    Cahill, Patrick L; Atalah, Javier; Selwood, Andrew I; Kuhajek, Jeanne M

    2016-01-01

    In this study, the effects of environmental variables on larval metamorphosis of the solitary ascidian Ciona savignyi were investigated in a laboratory setting. The progression of metamorphic changes were tracked under various temperature, photoperiod, substrate, larval density, and vessel size regimes. Metamorphosis was maximised at 18 °C, 12:12 h subdued light:dark, smooth polystyrene substrate, and 10 larvae mL(-1) in a twelve-well tissue culture plate. Eliminating the air-water interface by filling culture vessels to capacity further increased the proportion of metamorphosed larvae; 87 ± 5% of larvae completed metamorphosis within 5 days compared to 45 ± 5% in control wells. The effects of the reference antifouling compounds polygodial, portimine, oroidin, chlorothalonil, and tolylfluanid on C. savignyi were subsequently determined, highlighting (1) the sensitivity of C. savignyi metamorphosis to chemical exposure and (2) the potential to use C. savignyi larvae to screen for bioactivity in an optimised laboratory setting. The compounds were bioactive in the low ng mL(-1) to high µg mL(-1) range. Polygodial was chosen for additional investigations, where it was shown that mean reductions in the proportions of larvae reaching stage E were highly repeatable both within (repeatability = 14 ± 9%) and between (intermediate precision = 17 ± 3%) independent experiments. An environmental extract had no effect on the larvae but exposing larvae to both the extract and polygodial reduced potency relative to polygodial alone. This change in potency stresses the need for caution when working with complex samples, as is routinely implemented when isolating natural compounds from their biological source. Overall, the outcomes of this study highlight the sensitivity of C. savignyi metamorphosis to environmental variations and chemical exposure.

  1. Environmental variables, habitat discontinuity and life history shaping the genetic structure of Pomatoschistus marmoratus

    NASA Astrophysics Data System (ADS)

    González-Wangüemert, Mercedes; Vergara-Chen, Carlos

    2014-06-01

    Coastal lagoons are semi-isolated ecosystems exposed to wide fluctuations of environmental conditions and showing habitat fragmentation. These features may play an important role in separating species into different populations, even at small spatial scales. In this study, we evaluate the concordance between mitochondrial (previous published data) and nuclear data analyzing the genetic variability of Pomatoschistus marmoratus in five localities, inside and outside the Mar Menor coastal lagoon (SE Spain) using eight microsatellites. High genetic diversity and similar levels of allele richness were observed across all loci and localities, although significant genic and genotypic differentiation was found between populations inside and outside the lagoon. In contrast to the F ST values obtained from previous mitochondrial DNA analyses (control region), the microsatellite data exhibited significant differentiation among samples inside the Mar Menor and between lagoonal and marine samples. This pattern was corroborated using Cavalli-Sforza genetic distances. The habitat fragmentation inside the coastal lagoon and among lagoon and marine localities could be acting as a barrier to gene flow and contributing to the observed genetic structure. Our results from generalized additive models point a significant link between extreme lagoonal environmental conditions (mainly maximum salinity) and P. marmoratus genetic composition. Thereby, these environmental features could be also acting on genetic structure of coastal lagoon populations of P. marmoratus favoring their genetic divergence. The mating strategy of P. marmoratus could be also influencing our results obtained from mitochondrial and nuclear DNA. Therefore, a special consideration must be done in the selection of the DNA markers depending on the reproductive strategy of the species.

  2. Evaluating environmental drivers of spatial variability in free-living nematode assemblages along the Portuguese margin

    NASA Astrophysics Data System (ADS)

    Lins, Lidia; Leliaert, Frederik; Riehl, Torben; Pinto Ramalho, Sofia; Alfaro Cordova, Eliana; Morgado Esteves, André; Vanreusel, Ann

    2017-02-01

    Understanding processes responsible for shaping biodiversity patterns on continental margins is an important requirement for comprehending anthropogenic impacts in these environments and further management of biodiversity. Continental margins perform crucial functions linked to key ecological processes which are mainly structured by surface primary productivity and particulate organic matter flux to the seafloor, but also by heterogeneity in seafloor characteristics. However, to what extent these processes control local and regional biodiversity remains unclear. In this study, two isobathic parallel transects located at the shelf break (300-400 m) and upper slope (1000 m) of the western Iberian margin were used to test how food input and sediment heterogeneity affect nematode diversity independently from the spatial factors geographical distance and water depth. We also examined the potential role of connectedness between both depth transects through molecular phylogenetic analyses. Regional generic diversity and turnover were investigated at three levels: within a station, between stations from the same depth transect, and between transects. High variability in food availability and high sediment heterogeneity at the shelf-break transect were directly linked to high diversity within stations and higher variation in community structure across stations compared to the upper slope transect. Contrastingly, environmental factors (food availability and sediment) did not vary significantly between stations located at the upper slope, and this lack of differences were also reflected in a low community turnover between these deeper stations. Finally, differences in nematode communities between both transects were more pronounced than differences within each of the isobathic transects, but these changes were paralleled by the previously mentioned environmental changes. These results suggest that changes in community structure are mainly dictated by environmental factors

  3. Metamorphosis of the invasive ascidian Ciona savignyi: environmental variables and chemical exposure

    PubMed Central

    Atalah, Javier; Selwood, Andrew I.; Kuhajek, Jeanne M.

    2016-01-01

    In this study, the effects of environmental variables on larval metamorphosis of the solitary ascidian Ciona savignyi were investigated in a laboratory setting. The progression of metamorphic changes were tracked under various temperature, photoperiod, substrate, larval density, and vessel size regimes. Metamorphosis was maximised at 18 °C, 12:12 h subdued light:dark, smooth polystyrene substrate, and 10 larvae mL−1 in a twelve-well tissue culture plate. Eliminating the air-water interface by filling culture vessels to capacity further increased the proportion of metamorphosed larvae; 87 ± 5% of larvae completed metamorphosis within 5 days compared to 45 ± 5% in control wells. The effects of the reference antifouling compounds polygodial, portimine, oroidin, chlorothalonil, and tolylfluanid on C. savignyi were subsequently determined, highlighting (1) the sensitivity of C. savignyi metamorphosis to chemical exposure and (2) the potential to use C. savignyi larvae to screen for bioactivity in an optimised laboratory setting. The compounds were bioactive in the low ng mL−1 to high µg mL−1 range. Polygodial was chosen for additional investigations, where it was shown that mean reductions in the proportions of larvae reaching stage E were highly repeatable both within (repeatability = 14 ± 9%) and between (intermediate precision = 17 ± 3%) independent experiments. An environmental extract had no effect on the larvae but exposing larvae to both the extract and polygodial reduced potency relative to polygodial alone. This change in potency stresses the need for caution when working with complex samples, as is routinely implemented when isolating natural compounds from their biological source. Overall, the outcomes of this study highlight the sensitivity of C. savignyi metamorphosis to environmental variations and chemical exposure. PMID:26966668

  4. Ecosystem properties of semiarid savanna grassland in West Africa and its relationship with environmental variability.

    PubMed

    Tagesson, Torbern; Fensholt, Rasmus; Guiro, Idrissa; Rasmussen, Mads Olander; Huber, Silvia; Mbow, Cheikh; Garcia, Monica; Horion, Stéphanie; Sandholt, Inge; Holm-Rasmussen, Bo; Göttsche, Frank M; Ridler, Marc-Etienne; Olén, Niklas; Lundegard Olsen, Jørgen; Ehammer, Andrea; Madsen, Mathias; Olesen, Folke S; Ardö, Jonas

    2015-01-01

    The Dahra field site in Senegal, West Africa, was established in 2002 to monitor ecosystem properties of semiarid savanna grassland and their responses to climatic and environmental change. This article describes the environment and the ecosystem properties of the site using a unique set of in situ data. The studied variables include hydroclimatic variables, species composition, albedo, normalized difference vegetation index (NDVI), hyperspectral characteristics (350-1800 nm), surface reflectance anisotropy, brightness temperature, fraction of absorbed photosynthetic active radiation (FAPAR), biomass, vegetation water content, and land-atmosphere exchanges of carbon (NEE) and energy. The Dahra field site experiences a typical Sahelian climate and is covered by coexisting trees (~3% canopy cover) and grass species, characterizing large parts of the Sahel. This makes the site suitable for investigating relationships between ecosystem properties and hydroclimatic variables for semiarid savanna ecosystems of the region. There were strong interannual, seasonal and diurnal dynamics in NEE, with high values of ~-7.5 g C m(-2)  day(-1) during the peak of the growing season. We found neither browning nor greening NDVI trends from 2002 to 2012. Interannual variation in species composition was strongly related to rainfall distribution. NDVI and FAPAR were strongly related to species composition, especially for years dominated by the species Zornia glochidiata. This influence was not observed in interannual variation in biomass and vegetation productivity, thus challenging dryland productivity models based on remote sensing. Surface reflectance anisotropy (350-1800 nm) at the peak of the growing season varied strongly depending on wavelength and viewing angle thereby having implications for the design of remotely sensed spectral vegetation indices covering different wavelength regions. The presented time series of in situ data have great potential for dryland dynamics

  5. Interannual variability in the timing of New England shellfish toxicity and relationships to environmental forcing

    PubMed Central

    Nair, Apurva; Thomas, Andrew C.; Borsuk, Mark E.

    2013-01-01

    Routine monitoring along the coast of the Gulf of Maine (GoM) reveals shellfish toxicity nearly every summer, but at varying times, locations, and magnitudes. The responsible toxin is known to be produced by the dinoflagellate Alexandrium fundyense, yet there is little apparent association between Alexandrium abundance and shellfish toxicity. One possibility is that toxic cells are persistent in offshore areas and variability in shellfish toxicity is caused not by changes in overall abundance, but rather by variability in transport processes. Measurements of offshore Alexandrium biomass are scarce, so we bypass cell abundance as an explanatory variable and focus instead on the relations between shellfish toxicity and concurrent metrics of GoM meteorology, hydrology, and oceanography. While this yields over two decades (1985–2005) of data representing a variety of interannual conditions, the toxicity data are gappy in spatial and temporal coverage. We address this through a combination of parametric curve fitting and hierarchical cluster analysis to reveal eight archetypical modes of seasonal toxicity timing. Groups of locations are then formed that have similar interannual patterns in these archetypes. Finally, the interannual patterns within each group are related to available environmental metrics using classification trees. Results indicate that a weak cross-shore sea surface temperature (SST) gradient in the summer is the strongest correlate of shellfish toxicity, likely by signifying a hydrological connection between offshore Alexandrium populations and near-shore shellfish beds. High cumulative downwelling wind strength early in the season is revealed as a precursor consistent with this mechanism. Although previous studies suggest that alongshore transport is important in moving Alexandrium from the eastern to western GoM, alongshore SST gradient is not an important correlate of toxicity in our study. We conclude by discussing the implications of our

  6. Influence of environmental variables on diffusive greenhouse gas fluxes at hydroelectric reservoirs in Brazil.

    PubMed

    Rogério, J P; Santos, M A; Santos, E O

    2013-11-01

    For almost two decades, studies have been under way in Brazil, showing how hydroelectric reservoirs produce biogenic gases, mainly methane (CH4) and carbon dioxide (CO2), through the organic decomposition of flooded biomass. This somewhat complex phenomenon is due to a set of variables with differing levels of interdependence that directly or indirectly affect greenhouse gas (GHG) emissions. The purpose of this paper is to determine, through a statistical data analysis, the relation between CO2, CH4 diffusive fluxes and environmental variables at the Furnas, Itumbiara and Serra da Mesa hydroelectric reservoirs, located in the Cerrado biome on Brazil's high central plateau. The choice of this region was prompted by its importance in the national context, covering an area of some two million square kilometers, encompassing two major river basins (Paraná and Tocantins-Araguaia), with the largest installed power generation capacity in Brazil, together accounting for around 23% of Brazilian territory. This study shows that CH4 presented a moderate negative correlation between CO2 and depth. Additionally, a moderate positive correlation was noted for pH, water temperature and wind. The CO2 presented a moderate negative correlation for pH, wind speed, water temperature and air temperature. Additionally, a moderate positive correlation was noted for CO2 and water temperature. The complexity of the emission phenomenon is unlikely to occur through a simultaneous understanding of all the factors, due to difficulties in accessing and analyzing all the variables that have real, direct effects on GHG production and emission.

  7. Influence of Environmental Variables on Gambierdiscus spp. (Dinophyceae) Growth and Distribution

    PubMed Central

    Xu, Yixiao; Richlen, Mindy L.; Liefer, Justin D.; Robertson, Alison; Kulis, David; Smith, Tyler B.; Parsons, Michael L.; Anderson, Donald M.

    2016-01-01

    Benthic dinoflagellates in the genus Gambierdiscus produce the ciguatoxin precursors responsible for the occurrence of ciguatera toxicity. The prevalence of ciguatera toxins in fish has been linked to the presence and distribution of toxin-producing species in coral reef ecosystems, which is largely determined by the presence of suitable benthic habitat and environmental conditions favorable for growth. Here using single factor experiments, we examined the effects of salinity, irradiance, and temperature on growth of 17 strains of Gambierdiscus representing eight species/phylotypes (G. belizeanus, G. caribaeus, G. carolinianus, G. carpenteri, G. pacificus, G. silvae, Gambierdiscus sp. type 4–5), most of which were established from either Marakei Island, Republic of Kiribati, or St. Thomas, United States Virgin Island (USVI). Comparable to prior studies, growth rates fell within the range of 0–0.48 divisions day-1. In the salinity and temperature studies, Gambierdiscus responded in a near Gaussian, non-linear manner typical for such studies, with optimal and suboptimal growth occurring in the range of salinities of 25 and 45 and 21.0 and 32.5°C. In the irradiance experiment, no mortality was observed; however, growth rates at 55μmol photons · m-2 · s-1 were lower than those at 110–400μmol photons · m-2 · s-1. At the extremes of the environmental conditions tested, growth rates were highly variable, evidenced by large coefficients of variability. However, significant differences in intraspecific growth rates were typically found only at optimal or near-optimal growth conditions. Polynomial regression analyses showed that maximum growth occurred at salinity and temperature levels of 30.1–38.5 and 23.8–29.2°C, respectively. Gambierdiscus growth patterns varied among species, and within individual species: G. belizeanus, G. caribaeus, G. carpenteri, and G. pacificus generally exhibited a wider range of tolerance to environmental conditions, which may

  8. Linking environmental variability to village-scale malaria transmission using a simple immunity model

    PubMed Central

    2013-01-01

    Background Individuals continuously exposed to malaria gradually acquire immunity that protects from severe disease and high levels of parasitization. Acquired immunity has been incorporated into numerous models of malaria transmission of varying levels of complexity (e.g. Bull World Health Organ 50:347, 1974; Am J Trop Med Hyg 75:19, 2006; Math Biosci 90:385–396, 1988). Most such models require prescribing inputs of mosquito biting rates or other entomological or epidemiological information. Here, we present a model with a novel structure that uses environmental controls of mosquito population dynamics to simulate the mosquito biting rates, malaria prevalence as well as variability in protective immunity of the population. Methods A simple model of acquired immunity to malaria is presented and tested within the framework of the Hydrology, Entomology and Malaria Transmission Simulator (HYDREMATS), a coupled hydrology and agent-based entomology model. The combined model uses environmental data including rainfall, temperature, and topography to simulate malaria prevalence and level of acquired immunity in the human population. The model is used to demonstrate the effect of acquired immunity on malaria prevalence in two Niger villages that are hydrologically and entomologically very different. Simulations are conducted for the year 2006 and compared to malaria prevalence observations collected from the two villages. Results Blood smear samples from children show no clear difference in malaria prevalence between the two villages despite pronounced differences in observed mosquito abundance. The similarity in prevalence is attributed to the moderating effect of acquired immunity, which depends on prior exposure to the parasite through infectious bites - and thus the hydrologically determined mosquito abundance. Modelling the level of acquired immunity can affect village vulnerability to climatic anomalies. Conclusions The model presented has a novel structure

  9. Influence of Environmental Variables on Gambierdiscus spp. (Dinophyceae) Growth and Distribution.

    PubMed

    Xu, Yixiao; Richlen, Mindy L; Liefer, Justin D; Robertson, Alison; Kulis, David; Smith, Tyler B; Parsons, Michael L; Anderson, Donald M

    2016-01-01

    Benthic dinoflagellates in the genus Gambierdiscus produce the ciguatoxin precursors responsible for the occurrence of ciguatera toxicity. The prevalence of ciguatera toxins in fish has been linked to the presence and distribution of toxin-producing species in coral reef ecosystems, which is largely determined by the presence of suitable benthic habitat and environmental conditions favorable for growth. Here using single factor experiments, we examined the effects of salinity, irradiance, and temperature on growth of 17 strains of Gambierdiscus representing eight species/phylotypes (G. belizeanus, G. caribaeus, G. carolinianus, G. carpenteri, G. pacificus, G. silvae, Gambierdiscus sp. type 4-5), most of which were established from either Marakei Island, Republic of Kiribati, or St. Thomas, United States Virgin Island (USVI). Comparable to prior studies, growth rates fell within the range of 0-0.48 divisions day(-1). In the salinity and temperature studies, Gambierdiscus responded in a near Gaussian, non-linear manner typical for such studies, with optimal and suboptimal growth occurring in the range of salinities of 25 and 45 and 21.0 and 32.5°C. In the irradiance experiment, no mortality was observed; however, growth rates at 55 μmol photons · m(-2) · s(-1) were lower than those at 110-400 μmol photons · m(-2) · s(-1). At the extremes of the environmental conditions tested, growth rates were highly variable, evidenced by large coefficients of variability. However, significant differences in intraspecific growth rates were typically found only at optimal or near-optimal growth conditions. Polynomial regression analyses showed that maximum growth occurred at salinity and temperature levels of 30.1-38.5 and 23.8-29.2°C, respectively. Gambierdiscus growth patterns varied among species, and within individual species: G. belizeanus, G. caribaeus, G. carpenteri, and G. pacificus generally exhibited a wider range of tolerance to environmental conditions, which may

  10. Spatially dependent biotic and abiotic factors drive survivorship and physical structure of green roof vegetation.

    PubMed

    Aloisio, Jason M; Palmer, Matthew I; Giampieri, Mario A; Tuininga, Amy R; Lewis, James D

    2017-01-01

    Plant survivorship depends on biotic and abiotic factors that vary at local and regional scales. This survivorship, in turn, has cascading effects on community composition and the physical structure of vegetation. Survivorship of native plant species is variable among populations planted in environmentally stressful habitats like urban roofs, but the degree to which factors at different spatial scales affect survivorship in urban systems is not well understood. We evaluated the effects of biotic and abiotic factors on survivorship, composition, and physical structure of two native perennial species assemblages, one characterized by a mixture of C4 grasses and forbs (Hempstead Plains, HP) and one characterized by a mixture of C3 grasses and forbs (Rocky Summit, RS), that were initially sown at equal ratios of growth forms (5:1:4; grass, N-fixing forb and non-N-fixing forb) in replicate 2-m(2) plots planted on 10 roofs in New York City (New York, USA). Of 24 000 installed plants, 40% survived 23 months after planting. Within-roof factors explained 71% of variation in survivorship, with biotic (species identity and assemblage) factors accounting for 54% of the overall variation, and abiotic (growing medium depth and plot location) factors explaining 17% of the variation. Among-roof factors explained 29% of variation in survivorship and increased solar radiation correlated with decreased survivorship. While growing medium properties (pH, nutrients, metals) differed among roofs there was no correlation with survivorship. Percent cover and sward height increased with increasing survivorship. At low survivorship, cover of the HP assemblage was greater compared to the RS assemblage. Sward height of the HP assemblage was about two times greater compared to the RS assemblage. These results highlight the effects of local biotic and regional abiotic drivers on community composition and physical structure of green roof vegetation. As a result, initial green roof plant

  11. Exploration of Genetic and Genomic Resources for Abiotic and Biotic Stress Tolerance in Pearl Millet

    PubMed Central

    Shivhare, Radha; Lata, Charu

    2017-01-01

    Pearl millet is one of the most important small-grained C4 Panicoid crops with a large genome size (∼2352 Mb), short life cycle and outbreeding nature. It is highly resilient to areas with scanty rain and high temperature. Pearl millet is a nutritionally superior staple crop for people inhabiting hot, drought-prone arid and semi-arid regions of South Asia and Africa where it is widely grown and used for food, hay, silage, bird feed, building material, and fuel. Having excellent nutrient composition and exceptional buffering capacity against variable climatic conditions and pathogen attack makes pearl millet a wonderful model crop for stress tolerance studies. Pearl millet germplasm show a large range of genotypic and phenotypic variations including tolerance to abiotic and biotic stresses. Conventional breeding for enhancing abiotic and biotic stress resistance in pearl millet have met with considerable success, however, in last few years various novel approaches including functional genomics and molecular breeding have been attempted in this crop for augmenting yield under adverse environmental conditions, and there is still a lot of scope for further improvement using genomic tools. Discovery and use of various DNA-based markers such as EST-SSRs, DArT, CISP, and SSCP-SNP in pearl millet not only help in determining population structure and genetic diversity but also prove to be important for developing strategies for crop improvement at a faster rate and greater precision. Molecular marker-based genetic linkage maps and identification of genomic regions determining yield under abiotic stresses particularly terminal drought have paved way for marker-assisted selection and breeding of pearl millet cultivars. Reference collections and marker-assisted backcrossing have also been used to improve biotic stress resistance in pearl millet specifically to downy mildew. Whole genome sequencing of pearl millet genome will give new insights for processing of functional

  12. Hormone balance and abiotic stress tolerance in crop plants.

    PubMed

    Peleg, Zvi; Blumwald, Eduardo

    2011-06-01

    Plant hormones play central roles in the ability of plants to adapt to changing environments, by mediating growth, development, nutrient allocation, and source/sink transitions. Although ABA is the most studied stress-responsive hormone, the role of cytokinins, brassinosteroids, and auxins during environmental stress is emerging. Recent evidence indicated that plant hormones are involved in multiple processes. Cross-talk between the different plant hormones results in synergetic or antagonic interactions that play crucial roles in response of plants to abiotic stress. The characterization of the molecular mechanisms regulating hormone synthesis, signaling, and action are facilitating the modification of hormone biosynthetic pathways for the generation of transgenic crop plants with enhanced abiotic stress tolerance.

  13. SUMO, a heavyweight player in plant abiotic stress responses.

    PubMed

    Castro, Pedro Humberto; Tavares, Rui Manuel; Bejarano, Eduardo R; Azevedo, Herlânder

    2012-10-01

    Protein post-translational modifications diversify the proteome and install new regulatory levels that are crucial for the maintenance of cellular homeostasis. Over the last decade, the ubiquitin-like modifying peptide small ubiquitin-like modifier (SUMO) has been shown to regulate various nuclear processes, including transcriptional control. In plants, the sumoylation pathway has been significantly implicated in the response to environmental stimuli, including heat, cold, drought, and salt stresses, modulation of abscisic acid and other hormones, and nutrient homeostasis. This review focuses on the emerging importance of SUMO in the abiotic stress response, summarizing the molecular implications of sumoylation and emphasizing how high-throughput approaches aimed at identifying the full set of SUMO targets will greatly enhance our understanding of the SUMO-abiotic stress association.

  14. Arbuscular mycorrhizal fungal responses to abiotic stresses: A review.

    PubMed

    Lenoir, Ingrid; Fontaine, Joël; Lounès-Hadj Sahraoui, Anissa

    2016-03-01

    The majority of plants live in close collaboration with a diversity of soil organisms among which arbuscular mycorrhizal fungi (AMF) play an essential role. Mycorrhizal symbioses contribute to plant growth and plant protection against various environmental stresses. Whereas the resistance mechanisms induced in mycorrhizal plants after exposure to abiotic stresses, such as drought, salinity and pollution, are well documented, the knowledge about the stress tolerance mechanisms implemented by the AMF themselves is limited. This review provides an overview of the impacts of various abiotic stresses (pollution, salinity, drought, extreme temperatures, CO2, calcareous, acidity) on biodiversity, abundance and development of AMF and examines the morphological, biochemical and molecular mechanisms implemented by AMF to survive in the presence of these stresses.

  15. Abiotic stress and the plant circadian clock

    PubMed Central

    Sanchez, Alfredo; Shin, Jieun

    2011-01-01

    In this review, we focus on the interaction between the circadian clock of higher plants to that of metabolic and physiological processes that coordinate growth and performance under a predictable, albeit changing environment. In this, the phytochrome and cryptochrome photoreceptors have shown to be important, but not essential for oscillator control under diurnal cycles of light and dark. From this foundation, we will examine how emerging findings have firmly linked the circadian clock, as a central mediator in the coordination of metabolism, to maintain homeostasis. This occurs by oscillator synchronization of global transcription, which leads to a dynamic control of a host of physiological processes. These include the determination of the levels of primary and secondary metabolites, and the anticipation of future environmental stresses, such as mid-day drought and midnight coldness. Interestingly, metabolic and stress cues themselves appear to feedback on oscillator function. In such a way, the circadian clock of plants and abiotic-stress tolerance appear to be firmly interconnected processes. PMID:21325898

  16. Back to the Future -Precipitation Extremes, Climate Variability, Environmental Planning and Adaptation

    NASA Astrophysics Data System (ADS)

    Barros, A. P.

    2008-12-01

    uncertainty and separating climatic variability and change from model error. Nonstationarity and persistence at multiple scales confound the problem. From an economics perspective, the unprecedented success of environmental control and "conservation" in the 20th century, present another yet challenge in terms of social expectations and human development, including the right to sustainable (high) quality of life. In this presentation, we illustrate these challenges by considering first the estimation of Probable Maximum Precipitation, an engineering design criterion typically used in dam design, and examine how it varies spatially across the continental US according to physiographic region and as a function of climate regime. Second, we explore the spatial and temporal scales that link climate variability to macroscale environmental planning, and the notion of place-based adaptive riskgrade analysis.

  17. Coccolithophore responses to environmental variability in the South China Sea: species composition and calcite content

    NASA Astrophysics Data System (ADS)

    Jin, Xiaobo; Liu, Chuanlian; Poulton, Alex J.; Dai, Minhan; Guo, Xianghui

    2016-08-01

    Coccolithophore contributions to the global marine carbon cycle are regulated by the calcite content of their scales (coccoliths) and the relative cellular levels of photosynthesis and calcification rates. All three of these factors vary between coccolithophore species and with response to the growth environment. Here, water samples were collected in the northern basin of the South China Sea (SCS) during summer 2014 in order to examine how environmental variability influenced species composition and cellular levels of calcite content. Average coccolithophore abundance and their calcite concentration in the water column were 11.82 cells mL-1 and 1508.3 pg C mL-1, respectively, during the cruise. Water samples can be divided into three floral groups according to their distinct coccolithophore communities. The vertical structure of the coccolithophore community in the water column was controlled by the trophic conditions, which were regulated by mesoscale eddies across the SCS basin. The evaluation of coccolithophore-based calcite in the surface ocean also showed that three key species in the SCS (Emiliania huxleyi, Gephyrocapsa oceanica, Florisphaera profunda) and other larger, numerically rare species made almost equal contributions to total coccolith-based calcite in the water column. For Emiliania huxleyi biometry measurements, coccolith size positively correlated with nutrients (nitrate, phosphate), and it is suggested that coccolith length is influenced by light and nutrients through the regulation of growth rates. Larger-sized coccoliths were also linked statistically to low pH and calcite saturation states; however, it is not a simple cause and effect relationship, as carbonate chemistry was strongly co-correlated with the other key environmental factors (nutrients, light).

  18. Improvement of plant abiotic stress tolerance through modulation of the polyamine pathway.

    PubMed

    Shi, Haitao; Chan, Zhulong

    2014-02-01

    Polyamines (mainly putrescine (Put), spermidine (Spd), and spermine (Spm)) have been widely found in a range of physiological processes and in almost all diverse environmental stresses. In various plant species, abiotic stresses modulated the accumulation of polyamines and related gene expression. Studies using loss-of-function mutants and transgenic overexpression plants modulating polyamine metabolic pathways confirmed protective roles of polyamines during plant abiotic stress responses, and indicated the possibility to improve plant tolerance through genetic manipulation of the polyamine pathway. Additionally, putative mechanisms of polyamines involved in plant abiotic stress tolerance were thoroughly discussed and crosstalks among polyamine, abscisic acid, and nitric oxide in plant responses to abiotic stress were emphasized. Special attention was paid to the interaction between polyamine and reactive oxygen species, ion channels, amino acid and carbon metabolism, and other adaptive responses. Further studies are needed to elucidate the polyamine signaling pathway, especially polyamine-regulated downstream targets and the connections between polyamines and other stress responsive molecules.

  19. Relative importance of dynamic and static environmental variables as predictors of amphibian diversity patterns

    NASA Astrophysics Data System (ADS)

    Gómez-Rodríguez, Carola; Díaz-Paniagua, Carmen; Bustamante, Javier; Serrano, Laura; Portheault, Alexandre

    2010-11-01

    In this study, we evaluated whether static approaches, such as including only habitat characteristics that do not change over time, are adequate for the assessment of diversity-habitat relationships. We assessed the contribution of habitat characteristics that change over time to the spatial pattern of diversity (variation in species richness and in assemblage composition) in comparison to those characteristics that do not change. We have also provided an integral analysis to evaluate the role of the hydroperiod in structuring amphibian assemblages at any diversity level, including variation in species richness, variation in assemblage composition (i.e., nested pattern or species turnover) and variation in beta diversity. We monitored 19 amphibian assemblages from 2003 to 2006 in a highly fluctuating ecosystem, the temporary ponds in Doñana National Park. Both sets of habitat variables (temporally fixed and temporally variable) were necessary to develop a realistic understanding of amphibian diversity patterns, both when considering data collected in particular years or over several years. We found that environmental attributes that are irrelevant for pond species richness (alpha diversity) might be responsible for the variation in assemblage composition among ponds (beta diversity) and, hence, contribute to species diversity in the entire study area (gamma diversity). Therefore, we illustrate the need for an integral analysis of diversity in order not to disregard any relevant habitat factor. Alternatively, the relevance of the hydroperiod was not constant across time and was negligible in the wet year, while, in the dry year, we observed a strong nested pattern along the hydroperiod gradient and small differences in species predominance among assemblages. Therefore, our results show two conservation priorities in the study area: the preservation of ponds along the wide hydroperiod gradient; and a particular concern for the preservation of ponds with a long

  20. The importance of environmental variability and management control error to optimal harvest policies

    USGS Publications Warehouse

    Hunter, C.M.; Runge, M.C.

    2004-01-01

    State-dependent strategies (SDSs) are the most general form of harvest policy because they allow the harvest rate to depend, without constraint, on the state of the system. State-dependent strategies that provide an optimal harvest rate for any system state can be calculated, and stochasticity can be appropriately accommodated in this optimization. Stochasticity poses 2 challenges to harvest policies: (1) the population will never be at the equilibrium state; and (2) stochasticity induces uncertainty about future states. We investigated the effects of 2 types of stochasticity, environmental variability and management control error, on SDS harvest policies for a white-tailed deer (Odocoileus virginianus) model, and contrasted these with a harvest policy based on maximum sustainable yield (MSY). Increasing stochasticity resulted in more conservative SDSs; that is, higher population densities were required to support the same harvest rate, but these effects were generally small. As stochastic effects increased, SDSs performed much better than MSY. Both deterministic and stochastic SDSs maintained maximum mean annual harvest yield (AHY) and optimal equilibrium population size (Neq) in a stochastic environment, whereas an MSY policy could not. We suggest 3 rules of thumb for harvest management of long-lived vertebrates in stochastic systems: (1) an SDS is advantageous over an MSY policy, (2) using an SDS rather than an MSY is more important than whether a deterministic or stochastic SDS is used, and (3) for SDSs, rankings of the variability in management outcomes (e.g., harvest yield) resulting from parameter stochasticity can be predicted by rankings of the deterministic elasticities.

  1. Variable g- Mars environmental chamber: a small window of the martian environment for life science investigations

    NASA Astrophysics Data System (ADS)

    Sgambati, Antonella; Slenzka, Klaus; Schmeyers, Bernd; Di Capua, Massimiliano; Harting, Benjamin

    Human exploration and permanent settlement on the Martian surface is the one of the most attractive and ambitious endeavors mankind has ever faced. As technology and research progress, solutions and information that were before unavailable are slowly making the dream become everyday more feasible. In the past years a huge amount of knowledge was gathered by the Mars Exploration Rovers Spirit and Opportunity and now, even more insight is being gathered through the latest rover of the family, Curiosity. In this work, data from the various missions will be used to define and reproduce on Earth the characteristic Martian atmospheric conditions. A small Mars environmental chamber has been designed and built with the objective of studying the effects of the Martian environment on biological systems. The Variable gravity Mars Environmental Chamber (VgMEC) will allow researchers to replicate atmospheric pressure, gas composition, temperature and UVA/B exposure typical of the equatorial regions of Mars. By exposing biological systems to a controllable set of stressor it will be possible to identify both multi and single stressor effects on the system of interest. While several Mars environment simulation facilities exist, due to their size and mass, all are confined to floor-fixed laboratory settings. The VgMEC is an OHB funded project that wishes to bring together the scientific community and the industry. Collaborations will be enabled by granting low cost access to cutting-edge instrumentation and services. Developed at OHB System AG, VgMEC has been designed from the ground up to be a 28L, compact and lightweight test volume capable of being integrated in existing centrifuges (such as the ESA-ESTEC LCD), gimbal systems and parabolic flight aircraft. The VgMEC support systems were designed to accommodate continuous operations of virtually unlimited duration through the adoption of solutions such as: hot swappable gas/liquid consumables bottles, low power requirements, an

  2. Ecohydrological responses of dense canopies to environmental variability: 1. Interplay between vertical structure and photosynthetic pathway

    NASA Astrophysics Data System (ADS)

    Drewry, D. T.; Kumar, P.; Long, S.; Bernacchi, C.; Liang, X.-Z.; Sivapalan, M.

    2010-12-01

    Vegetation acclimation to changing climate, in particular elevated atmospheric concentrations of carbon dioxide (CO2), has been observed to include modifications to the biochemical and ecophysiological functioning of leaves and the structural components of the canopy. These responses have the potential to significantly modify plant carbon uptake and surface energy partitioning, and have been attributed with large-scale changes in surface hydrology over recent decades. While the aggregated effects of vegetation acclimation can be pronounced, they often result from subtle changes in canopy properties that require the resolution of physical, biochemical and ecophysiological processes through the canopy for accurate estimation. In this paper, the first of two, a multilayer canopy-soil-root system model developed to capture the emergent vegetation responses to environmental change is presented. The model incorporates both C3 and C4 photosynthetic pathways, and resolves the vertical radiation, thermal, and environmental regimes within the canopy. The tight coupling between leaf ecophysiological functioning and energy balance determines vegetation responses to climate states and perturbations, which are modulated by soil moisture states through the depth of the root system. The model is validated for three growing seasons each for soybean (C3) and maize (C4) using eddy-covariance fluxes of CO2, latent, and sensible heat collected at the Bondville (Illinois) Ameriflux tower site. The data set provides an opportunity to examine the role of important environmental drivers and model skill in capturing variability in canopy-atmosphere exchange. Vertical variation in radiative states and scalar fluxes over a mean diurnal cycle are examined to understand the role of canopy structure on the patterns of absorbed radiation and scalar flux magnitudes and the consequent differences in sunlit and shaded source/sink locations through the canopies. An analysis is made of the impact of

  3. Abiotic and biotic controls on local spatial distribution and performance of Boechera stricta.

    PubMed

    Naithani, Kusum J; Ewers, Brent E; Adelman, Jonathan D; Siemens, David H

    2014-01-01

    This study investigates the relative influence of biotic and abiotic factors on community dynamics using an integrated approach and highlights the influence of space on genotypic and phenotypic traits in plant community structure. We examined the relative influence of topography, environment, spatial distance, and intra- and interspecific interactions on spatial distribution and performance of Boechera stricta (rockcress), a close perennial relative of model plant Arabidopsis. First, using Bayesian kriging, we mapped the topography and environmental gradients and explored the spatial distribution of naturally occurring rockcress plants and two neighbors, Taraxacum officinale (dandelion) and Solidago missouriensis (goldenrod) found in close proximity within a typical diverse meadow community across topographic and environmental gradients. We then evaluated direct and indirect relationships among variables using Mantel path analysis and developed a network displaying abiotic and biotic interactions in this community. We found significant spatial autocorrelation among rockcress individuals, either because of common microhabitats as displayed by high density of individuals at lower elevation and high soil moisture area, or limited dispersal as shown by significant spatial autocorrelation of naturally occurring inbred lines, or a combination of both. Goldenrod and dandelion density around rockcress does not show any direct relationship with rockcress fecundity, possibly due to spatial segregation of resources. However, dandelion density around rockcress shows an indirect negative influence on rockcress fecundity via herbivory, indicating interspecific competition. Overall, we suggest that common microhabitat preference and limited dispersal are the main drivers for spatial distribution. However, intra-specific interactions and insect herbivory are the main drivers of rockcress performance in the meadow community.

  4. Biotic and abiotic controls of argentine ant invasion success at local and landscape scales

    USGS Publications Warehouse

    Menke, S.B.; Fisher, R.N.; Jetz, W.; Holway, D.A.

    2007-01-01

    Although the ecological success of introduced species hinges on biotic interactions and physical conditions, few experimental studies - especially on animals - have simultaneously investigated the relative importance of both types of factors. The lack of such research may stem from the common assumption that native and introduced species exhibit similar environmental tolerances. Here we combine experimental and spatial modeling approaches (1) to determine the relative importance of biotic and abiotic controls of Argentine ant (Linepithema humile) invasion success, (2) to examine how the importance of these factors changes with spatial scale in southern California (USA), and (3) to assess how Argentine ants differ from native ants in their environmental tolerances. A factorial field experiment that combined native ant removal with irrigation revealed that Argentine ants failed to invade any dry plots (even those lacking native ants) but readily invaded all moist plots. Native ants slowed the spread of Argentine ants into irrigated plots but did not prevent invasion. In areas without Argentine ants, native ant species showed variable responses to irrigation. At the landscape scale, Argentine ant occurrence was positively correlated with minimum winter temperature (but not precipitation), whereas native ant diversity increased with precipitation and was negatively correlated with minimum winter temperature. These results are of interest for several reasons. First, they demonstrate that fine-scale differences in the physical environment can eclipse biotic resistance from native competitors in determining community susceptibility to invasion. Second, our results illustrate surprising complexities with respect to how the abiotic factors limiting invasion can change with spatial scale, and third, how native and invasive species can differ in their responses to the physical environment. Idiosyncratic and scale-dependent processes complicate attempts to forecast where

  5. Hydraulic fracturing water use variability in the United States and potential environmental implications

    NASA Astrophysics Data System (ADS)

    Gallegos, Tanya J.; Varela, Brian A.; Haines, Seth S.; Engle, Mark A.

    2015-07-01

    Until now, up-to-date, comprehensive, spatial, national-scale data on hydraulic fracturing water volumes have been lacking. Water volumes used (injected) to hydraulically fracture over 263,859 oil and gas wells drilled between 2000 and 2014 were compiled and used to create the first U.S. map of hydraulic fracturing water use. Although median annual volumes of 15,275 m3 and 19,425 m3 of water per well was used to hydraulically fracture individual horizontal oil and gas wells, respectively, in 2014, about 42% of wells were actually either vertical or directional, which required less than 2600 m3 water per well. The highest average hydraulic fracturing water usage (10,000-36,620 m3 per well) in watersheds across the United States generally correlated with shale-gas areas (versus coalbed methane, tight oil, or tight gas) where the greatest proportion of hydraulically fractured wells were horizontally drilled, reflecting that the natural reservoir properties influence water use. This analysis also demonstrates that many oil and gas resources within a given basin are developed using a mix of horizontal, vertical, and some directional wells, explaining why large volume hydraulic fracturing water usage is not widespread. This spatial variability in hydraulic fracturing water use relates to the potential for environmental impacts such as water availability, water quality, wastewater disposal, and possible wastewater injection-induced earthquakes.

  6. Biological versus technical variability in 2-D DIGE experiments with environmental bacteria.

    PubMed

    Zech, Hajo; Echtermeyer, Christoph; Wöhlbrand, Lars; Blasius, Bernd; Rabus, Ralf

    2011-08-01

    Two-dimensional difference gel electrophoresis (2-D DIGE) allows for reliable quantification of global protein abundance changes. The threshold of significance for protein abundance changes depends on the experimental variation (biological and technical). This study estimates biological, technical and total variation inherent to 2-D DIGE analysis of environmental bacteria, using the model organisms "Aromatoleum aromaticum" EbN1 and Phaeobacter gallaeciensis DSM 17395. Of both bacteria the soluble proteomes were analyzed from replicate cultures. For strains EbN1 and DSM 17395, respectively, CV revealed a total variation of below 19 and 15%, an average technical variation of 12 and 7%, and an average biological variation of 18 and 17%. Multivariate analysis of variance confirmed domination of biological over technical variance to be significant in most cases. To visualize variances, the complex protein data have been plotted with a multidimensional scaling technique. Furthermore, comparison of different treatment groups (different substrate conditions) demonstrated that variability within groups is significantly smaller than differences caused by treatment.

  7. Hydraulic fracturing water use variability in the United States and potential environmental implications

    USGS Publications Warehouse

    Gallegos, Tanya J.; Varela, Brian A.; Haines, Seth S.; Engle, Mark A.

    2015-01-01

    Until now, up-to-date, comprehensive, spatial, national-scale data on hydraulic fracturing water volumes have been lacking. Water volumes used (injected) to hydraulically fracture over 263,859 oil and gas wells drilled between 2000 and 2014 were compiled and used to create the first U.S. map of hydraulic fracturing water use. Although median annual volumes of 15,275 m3 and 19,425 m3 of water per well was used to hydraulically fracture individual horizontal oil and gas wells, respectively, in 2014, about 42% of wells were actually either vertical or directional, which required less than 2600 m3 water per well. The highest average hydraulic fracturing water usage (10,000−36,620 m3 per well) in watersheds across the United States generally correlated with shale-gas areas (versus coalbed methane, tight oil, or tight gas) where the greatest proportion of hydraulically fractured wells were horizontally drilled, reflecting that the natural reservoir properties influence water use. This analysis also demonstrates that many oil and gas resources within a given basin are developed using a mix of horizontal, vertical, and some directional wells, explaining why large volume hydraulic fracturing water usage is not widespread. This spatial variability in hydraulic fracturing water use relates to the potential for environmental impacts such as water availability, water quality, wastewater disposal, and possible wastewater injection-induced earthquakes.

  8. Variable-Speed Induction Motor Drives for Aircraft Environmental Control Compressors

    NASA Technical Reports Server (NTRS)

    Mildice, J. W.; Hansen, I. G.; Schreiner, K. E.; Roth, M. E.

    1996-01-01

    New, more-efficient designs for aircraft jet engines are not capable of supplying the large quantities of bleed air necessary to provide pressurization and air conditioning for the environmental control systems (ECS) of the next generation of large passenger aircraft. System analysis and engineering have determined that electrically-driven ECS can help to maintain the improved fuel efficiencies; and electronic controllers and induction motors are now being developed in a NASA/NPD SBIR Program to drive both types of ECS compressors. Previous variable-speed induction motor/controller system developments and publications have primarily focused on field-oriented control, with large transient reserve power, for maximum acceleration and optimum response in actuator and robotics systems. The application area addressed herein is characterized by slowly-changing inputs and outputs, small reserve power capability for acceleration, and optimization for maximum efficiency. This paper therefore focuses on the differences between this case and the optimum response case, and shows the development of this new motor/controller approach. It starts with the creation of a new set of controller requirements. In response to those requirements, new control algorithms are being developed and implemented in an embedded computer, which is integrated into the motor controller closed loop. Buffered logic outputs are used to drive the power switches in a resonant-technology, power processor/motor-controller, at switching/resonant frequencies high enough to support efficient high-frequency induction motor operation at speeds up to 50,000-RPA

  9. Relationships among environmental variables and distribution of tree species at high elevation in the Olympic Mountains

    USGS Publications Warehouse

    Woodward, Andrea

    1998-01-01

    Relationships among environmental variables and occurrence of tree species were investigated at Hurricane Ridge in Olympic National Park, Washington, USA. A transect consisting of three plots was established down one north-and one south-facing slope in stands representing the typical elevational sequence of tree species. Tree species included subalpine fir (Abies lasiocarpa), Douglas-fir (Pseudotsuga menziesii), mountain hemlock (Tsuga mertensiana), and Pacific silver fir (Abies amabilis). Air and soil temperature, precipitation, and soil moisture were measured during three growing seasons. Snowmelt patterns, soil carbon and moisture release curves were also determined. The plots represented a wide range in soil water potential, a major determinant of tree species distribution (range of minimum values = -1.1 to -8.0 MPa for Pacific silver fir and Douglas-fir plots, respectively). Precipitation intercepted at plots depended on topographic location, storm direction and storm type. Differences in soil moisture among plots was related to soil properties, while annual differences at each plot were most often related to early season precipitation. Changes in climate due to a doubling of atmospheric CO2 will likely shift tree species distributions within, but not among aspects. Change will be buffered by innate tolerance of adult trees and the inertia of soil properties.

  10. Accounting for environmental variability, modeling errors, and parameter estimation uncertainties in structural identification

    NASA Astrophysics Data System (ADS)

    Behmanesh, Iman; Moaveni, Babak

    2016-07-01

    This paper presents a Hierarchical Bayesian model updating framework to account for the effects of ambient temperature and excitation amplitude. The proposed approach is applied for model calibration, response prediction and damage identification of a footbridge under changing environmental/ambient conditions. The concrete Young's modulus of the footbridge deck is the considered updating structural parameter with its mean and variance modeled as functions of temperature and excitation amplitude. The identified modal parameters over 27 months of continuous monitoring of the footbridge are used to calibrate the updating parameters. One of the objectives of this study is to show that by increasing the levels of information in the updating process, the posterior variation of the updating structural parameter (concrete Young's modulus) is reduced. To this end, the calibration is performed at three information levels using (1) the identified modal parameters, (2) modal parameters and ambient temperatures, and (3) modal parameters, ambient temperatures, and excitation amplitudes. The calibrated model is then validated by comparing the model-predicted natural frequencies and those identified from measured data after deliberate change to the structural mass. It is shown that accounting for modeling error uncertainties is crucial for reliable response prediction, and accounting only the estimated variability of the updating structural parameter is not sufficient for accurate response predictions. Finally, the calibrated model is used for damage identification of the footbridge.

  11. Environmental variables and releasing-valence transfer in stimulus-directed pecking of chicks.

    PubMed

    Suboski, M D

    1987-05-01

    Releasing valence transfer occurs when the power or valence to release responses is transferred from a primary releasing stimulus to a second, initially neutral, stimulus. In the exemplar, pecking responses by neonatal chicks are released and directed by a pointed object operated to make pecking movements. Stimuli attached to or pecked by the arrow thereby acquire enhanced releasing valence. Chicks peck at matching stimuli in preference to comparable but unenhanced stimuli. Research reported here shows that primary and transferred releasing valences are differentially affected by environmental variables. Specific findings were Pecking by chicks occurs only within a narrow range of ambient temperature. Outside of this range, pecking is low in frequency and insensitive to valence-enhanced release. Pecking by chicks appears to be finely tuned to arrow peck rates between 120 and 180 pecks per minute. Within this range, frequency of pecks by chicks is low whereas the percentage of pecks to the valence-enhanced stimulus is maximal. The maternal food call was a weak releaser of pecking by chicks with no valence-enhancing properties.

  12. Hydraulic fracturing water use variability in the United States and potential environmental implications

    PubMed Central

    Varela, Brian A.; Haines, Seth S.; Engle, Mark A.

    2015-01-01

    Abstract Until now, up‐to‐date, comprehensive, spatial, national‐scale data on hydraulic fracturing water volumes have been lacking. Water volumes used (injected) to hydraulically fracture over 263,859 oil and gas wells drilled between 2000 and 2014 were compiled and used to create the first U.S. map of hydraulic fracturing water use. Although median annual volumes of 15,275 m3 and 19,425 m3 of water per well was used to hydraulically fracture individual horizontal oil and gas wells, respectively, in 2014, about 42% of wells were actually either vertical or directional, which required less than 2600 m3 water per well. The highest average hydraulic fracturing water usage (10,000−36,620 m3 per well) in watersheds across the United States generally correlated with shale‐gas areas (versus coalbed methane, tight oil, or tight gas) where the greatest proportion of hydraulically fractured wells were horizontally drilled, reflecting that the natural reservoir properties influence water use. This analysis also demonstrates that many oil and gas resources within a given basin are developed using a mix of horizontal, vertical, and some directional wells, explaining why large volume hydraulic fracturing water usage is not widespread. This spatial variability in hydraulic fracturing water use relates to the potential for environmental impacts such as water availability, water quality, wastewater disposal, and possible wastewater injection‐induced earthquakes. PMID:26937056

  13. Remote Sensing-Driven Climatic/Environmental Variables for Modelling Malaria Transmission in Sub-Saharan Africa

    PubMed Central

    Ebhuoma, Osadolor; Gebreslasie, Michael

    2016-01-01

    Malaria is a serious public health threat in Sub-Saharan Africa (SSA), and its transmission risk varies geographically. Modelling its geographic characteristics is essential for identifying the spatial and temporal risk of malaria transmission. Remote sensing (RS) has been serving as an important tool in providing and assessing a variety of potential climatic/environmental malaria transmission variables in diverse areas. This review focuses on the utilization of RS-driven climatic/environmental variables in determining malaria transmission in SSA. A systematic search on Google Scholar and the Institute for Scientific Information (ISI) Web of KnowledgeSM databases (PubMed, Web of Science and ScienceDirect) was carried out. We identified thirty-five peer-reviewed articles that studied the relationship between remotely-sensed climatic variable(s) and malaria epidemiological data in the SSA sub-regions. The relationship between malaria disease and different climatic/environmental proxies was examined using different statistical methods. Across the SSA sub-region, the normalized difference vegetation index (NDVI) derived from either the National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) or Moderate-resolution Imaging Spectrometer (MODIS) satellite sensors was most frequently returned as a statistically-significant variable to model both spatial and temporal malaria transmission. Furthermore, generalized linear models (linear regression, logistic regression and Poisson regression) were the most frequently-employed methods of statistical analysis in determining malaria transmission predictors in East, Southern and West Africa. By contrast, multivariate analysis was used in Central Africa. We stress that the utilization of RS in determining reliable malaria transmission predictors and climatic/environmental monitoring variables would require a tailored approach that will have cognizance of the geographical

  14. Remote Sensing-Driven Climatic/Environmental Variables for Modelling Malaria Transmission in Sub-Saharan Africa.

    PubMed

    Ebhuoma, Osadolor; Gebreslasie, Michael

    2016-06-14

    Malaria is a serious public health threat in Sub-Saharan Africa (SSA), and its transmission risk varies geographically. Modelling its geographic characteristics is essential for identifying the spatial and temporal risk of malaria transmission. Remote sensing (RS) has been serving as an important tool in providing and assessing a variety of potential climatic/environmental malaria transmission variables in diverse areas. This review focuses on the utilization of RS-driven climatic/environmental variables in determining malaria transmission in SSA. A systematic search on Google Scholar and the Institute for Scientific Information (ISI) Web of Knowledge(SM) databases (PubMed, Web of Science and ScienceDirect) was carried out. We identified thirty-five peer-reviewed articles that studied the relationship between remotely-sensed climatic variable(s) and malaria epidemiological data in the SSA sub-regions. The relationship between malaria disease and different climatic/environmental proxies was examined using different statistical methods. Across the SSA sub-region, the normalized difference vegetation index (NDVI) derived from either the National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) or Moderate-resolution Imaging Spectrometer (MODIS) satellite sensors was most frequently returned as a statistically-significant variable to model both spatial and temporal malaria transmission. Furthermore, generalized linear models (linear regression, logistic regression and Poisson regression) were the most frequently-employed methods of statistical analysis in determining malaria transmission predictors in East, Southern and West Africa. By contrast, multivariate analysis was used in Central Africa. We stress that the utilization of RS in determining reliable malaria transmission predictors and climatic/environmental monitoring variables would require a tailored approach that will have cognizance of the geographical

  15. Abscisic Acid and Abiotic Stress Tolerance in Crop Plants

    PubMed Central

    Sah, Saroj K.; Reddy, Kambham R.; Li, Jiaxu

    2016-01-01

    Abiotic stress is a primary threat to fulfill the demand of agricultural production to feed the world in coming decades. Plants reduce growth and development process during stress conditions, which ultimately affect the yield. In stress conditions, plants develop various stress mechanism to face the magnitude of stress challenges, although that is not enough to protect them. Therefore, many strategies have been used to produce abiotic stress tolerance crop plants, among them, abscisic acid (ABA) phytohormone engineering could be one of the methods of choice. ABA is an isoprenoid phytohormone, which regulates various physiological processes ranging from stomatal opening to protein storage and provides adaptation to many stresses like drought, salt, and cold stresses. ABA is also called an important messenger that acts as the signaling mediator for regulating the adaptive response of plants to different environmental stress conditions. In this review, we will discuss the role of ABA in response to abiotic stress at the molecular level and ABA signaling. The review also deals with the effect of ABA in respect to gene expression. PMID:27200044

  16. Determination of Pre-Service Science Teachers' Level of Awareness of Environmental Ethics in Relation to Different Variables

    ERIC Educational Resources Information Center

    Keles, Özgül; Özer, Nilgün

    2016-01-01

    The purpose of the current study is to determine the pre-service science teachers' awareness levels of environmental ethics in relation to different variables. The sampling of the present study is comprised of 1,023 third and fourth year pre-service science teachers selected from 12 different universities in the spring term of 2013-2014 academic…

  17. Associations among fish assemblage structure and environmental variables in Willamette Basin streams, Oregon

    USGS Publications Warehouse

    Waite, I.R.; Carpenter, K.D.

    2000-01-01

    As part of the U.S. Geological Survey's National Water-Quality Assessment Program, fish were collected from 24 selected stream sites in the Willamette Basin during 1993-1995 to determine the composition of the fish assemblages and their relation to the chemical and physical environment. Variance in fish relative abundance was greater among all sites than among spatially distinct reaches within a site (spatial variation) or among multiple sampled years at a site (temporal variation). Therefore, data from a single reach in an individual year was considered to be a reliable estimator of the fish assemblage structure at a site when the data were normalized by percent relative abundance. Multivariate classification and ordination were used to examine patterns in environmental variables and fish relative abundance over differing spatial scales (among versus within ecoregions). Across all ecoregions (all sites), fish assemblages were primarily structured along environmental gradients of water temperature and stream gradient (coldwater, high-gradient forested sites versus warmwater, low-gradient Willamette Valley sites); this pattern superseded patterns that were ecoregion specific. Water temperature, dissolved oxygen, and physical habitat (e.g., riparian canopy and percent riffles) were associated with patterns of fish assemblages across all ecoregions; however, pesticide and total phosphorus concentrations were more important than physical habitat within the Willamette Valley ecoregion. Consideration of stream site stratification (e.g., stream size, ecoregion, and stream gradient), identification of fish to species level (particularly the sculpin family), and detailed measurement of habitat, diurnal dissolved oxygen, and water temperature were critical in evaluating the composition of fish assemblages in relation to land use. In general, these low-gradient valley streams typical of other agricultural regions had poor riparian systems and showed increases in water

  18. Near-global freshwater-specific environmental variables for biodiversity analyses in 1 km resolution

    NASA Astrophysics Data System (ADS)

    Domisch, Sami; Amatulli, Giuseppe; Jetz, Walter

    2015-12-01

    The lack of freshwater-specific environmental information at sufficiently fine spatial grain hampers broad-scale analyses in aquatic biology, biogeography, conservation, and ecology. Here we present a near-global, spatially continuous, and freshwater-specific set of environmental variables in a standardized 1 km grid. We delineate the sub-catchment for each grid cell along the HydroSHEDS river network and summarize the upstream climate, topography, land cover, surface geology and soil to each grid cell using various metrics (average, minimum, maximum, range, sum, inverse distance-weighted average and sum). All variables were subsequently averaged across single lakes and reservoirs of the Global lakes and Wetlands Database that are connected to the river network. Monthly climate variables were summarized into 19 long-term climatic variables following the ‘bioclim’ framework. This new set of variables provides a basis for spatial ecological and biodiversity analyses in freshwater ecosystems at near global extent, yet fine spatial grain. To facilitate the generation of freshwater variables for custom study areas and spatial grains, we provide the ‘r.stream.watersheds’ and ‘r.stream.variables’ add-ons for the GRASS GIS software.

  19. Near-global freshwater-specific environmental variables for biodiversity analyses in 1 km resolution

    PubMed Central

    Domisch, Sami; Amatulli, Giuseppe; Jetz, Walter

    2015-01-01

    The lack of freshwater-specific environmental information at sufficiently fine spatial grain hampers broad-scale analyses in aquatic biology, biogeography, conservation, and ecology. Here we present a near-global, spatially continuous, and freshwater-specific set of environmental variables in a standardized 1 km grid. We delineate the sub-catchment for each grid cell along the HydroSHEDS river network and summarize the upstream climate, topography, land cover, surface geology and soil to each grid cell using various metrics (average, minimum, maximum, range, sum, inverse distance-weighted average and sum). All variables were subsequently averaged across single lakes and reservoirs of the Global lakes and Wetlands Database that are connected to the river network. Monthly climate variables were summarized into 19 long-term climatic variables following the ‘bioclim’ framework. This new set of variables provides a basis for spatial ecological and biodiversity analyses in freshwater ecosystems at near global extent, yet fine spatial grain. To facilitate the generation of freshwater variables for custom study areas and spatial grains, we provide the ‘r.stream.watersheds’ and ‘r.stream.variables’ add-ons for the GRASS GIS software. PMID:26647296

  20. The Impact of Affective Constraints on Shaping Environmental Literacy: Model Testing Using Mediator and Moderator Variables

    ERIC Educational Resources Information Center

    Öztürk, Nilay; Teksöz, Gaye

    2016-01-01

    The aims of this study were; first to investigate the mediating effects of pre-service teachers' (PTs) attitude toward environment on the relationship between their environmental concern and environmental responsibility, and second, to explore the moderating effect of gender on the relationships between; PTs' environmental concern and…

  1. Environmental Variables Shaping the Ecological Niche of Thaumarchaeota in Soil: Direct and Indirect Causal Effects.

    PubMed

    Hong, Jin-Kyung; Cho, Jae-Chang

    2015-01-01

    To find environmental variables (EVs) shaping the ecological niche of the archaeal phylum Thaumarchaeota in terrestrial environments, we determined the abundance of Thaumarchaeota in various soil samples using real-time PCR targeting thaumarchaeotal 16S rRNA gene sequences. We employed our previously developed primer, THAUM-494, which had greater coverage for Thaumarchaeota and lower tolerance to nonthaumarchaeotal taxa than previous Thaumarchaeota-directed primers. The relative abundance estimates (RVs) of Thaumarchaeota (RTHAUM), Archaea (RARCH), and Bacteria (RBACT) were subjected to a series of statistical analyses. Redundancy analysis (RDA) showed a significant (p < 0.05) canonical relationship between RVs and EVs. Negative causal relationships between RTHAUM and nutrient level-related EVs were observed in an RDA biplot. These negative relationships were further confirmed by correlation and regression analyses. Total nitrogen content (TN) appeared to be the EV that affected RTHAUM most strongly, and total carbon content (TC), which reflected the content of organic matter (OM), appeared to be the EV that affected it least. However, in the path analysis, a path model indicated that TN might be a mediator EV that could be controlled directly by the OM. Additionally, another path model implied that water content (WC) might also indirectly affect RTHAUM by controlling ammonium nitrogen (NH4+-N) level through ammonification. Thus, although most directly affected by NH4+-N, RTHAUM could be ultimately determined by OM content, suggesting that Thaumarchaeota could prefer low-OM or low-WC conditions, because either of these EVs could subsequently result in low levels of NH4+-N in soil.

  2. Effect of environmental variables on eukaryotic microbial community structure of land-fast Arctic sea ice.

    PubMed

    Eddie, Brian; Juhl, Andrew; Krembs, Christopher; Baysinger, Charles; Neuer, Susanne

    2010-03-01

    Sea ice microbial community structure affects carbon and nutrient cycling in polar seas, but its susceptibility to changing environmental conditions is not well understood. We studied the eukaryotic microbial community in sea ice cores recovered near Point Barrow, AK in May 2006 by documenting the composition of the community in relation to vertical depth within the cores, as well as light availability (mainly as variable snow cover) and nutrient concentrations. We applied a combination of epifluorescence microscopy, denaturing gradient gel electrophoresis and clone libraries of a section of the 18S rRNA gene in order to compare the community structure of the major eukaryotic microbial phylotypes in the ice. We find that the community composition of the sea ice is more affected by the depth horizon in the ice than by light availability, although there are significant differences in the abundance of some groups between light regimes. Epifluorescence microscopy shows a shift from predominantly heterotrophic life styles in the upper ice to autotrophy prevailing in the bottom ice. This is supported by the statistical analysis of the similarity between the samples based on the denaturing gradient gel electrophoresis banding patterns, which shows a clear difference between upper and lower ice sections with respect to phylotypes and their proportional abundance. Clone libraries constructed using diatom-specific primers confirm the high diversity of diatoms in the sea ice, and support the microscopic counts. Evidence of protistan grazing upon diatoms was also found in lower sections of the core, with implications for carbon and nutrient recycling in the ice.

  3. Associations of benthic macroinvertebrate assemblages with environmental variables in the upper Clear Creek watershed, California

    USGS Publications Warehouse

    Brown, Larry R.; May, Jason T.; Wulff, Marissa

    2012-01-01

    Benthic macroinvertebrates are integral components of stream ecosystems and are often used to assess the ecological integrity of streams. We sampled streams in the upper Clear Creek drainage in the Klamath—Siskiyou Ecoregion of northwestern California in fall 2004 (17 sites) and 2005 (original 17 plus 4 new sites) with the objectives of documenting the benthic macroinvertebrate assemblages supported by the streams in the area, determining how those assemblages respond to environmental variables, assessing the biological condition of the streams using a benthic index of biotic integrity (IBI), and understanding the assemblages in the context of biodiversity of the ecoregion. We collected both reach-wide (RW) and targeted-riffle (TR) macroinvertebrate samples at each site. The macroinvertebrate assemblages were diverse, with over 150 genera collected for each sampling protocol. The macroinvertebrate assemblages appeared to be most responsive to a general habitat gradient based on stream size, gradient, flow, and dominance of riffles. A second important habitat gradient was based on elevation and dominance of riffles. A gradient in water quality based on concentrations of dissolved ions and metals was also important. Models based on these 3 gradients had Spearman's rank correlations with macroinvertebrate taxonomic composition of 0.60 and 0.50 for the TR and RW samples, respectively. The majority (>50%) of the sites were in good or very good biological condition based on IBI scores. The diversity of macroinvertebrate assemblages is associated with the diversity of habitats available in the Klamath—Siskiyou Ecoregion. Maintaining the aquatic habitats in good condition is important in itself but is also vital to maintaining biodiversity in this diverse and unique ecoregion.

  4. Linking the lytic and lysogenic bacteriophage cycles to environmental conditions, host physiology and their variability in coastal lagoons.

    PubMed

    Maurice, C F; Bouvier, C; de Wit, R; Bouvier, T

    2013-09-01

    Changes in environmental conditions and prokaryote physiology can strongly affect the dynamics of both the lysogenic and lytic bacteriophage replication cycles in aquatic systems. However, it remains unclear whether it is the nature, amplitude or frequency of these changes that alter the phage replication cycles. We performed an annual survey of three Mediterranean lagoons with contrasting levels of chlorophyll a concentration and salinity to explore how these cues and their variability influence either replication cycle. The lytic cycle was always detected and showed seasonal patterns, whereas the lysogenic cycle was often undetected and highly variable. The lytic cycle was influenced by environmental and prokaryotic physiological cues, increasing with concentrations of dissolved organic carbon, chlorophyll a, and the proportion of respiring cells, and decreasing with the proportion of damaged cells. In contrast, lysogeny was not explained by the magnitude of any environmental or physiological parameter, but increased with the amplitude of change in prokaryote physiology. Our study suggests that both cycles are regulated by distinct factors: the lytic cycle is dependent on environmental parameters and host physiology, while lysogeny is dependent on the variability of prokaryote physiology. This could lead to the contrasting patterns observed between both cycles in aquatic systems.

  5. Large-scale Environmental Variables and Transition to Deep Convection in Cloud Resolving Model Simulations: A Vector Representation

    SciTech Connect

    Hagos, Samson M.; Leung, Lai-Yung R.

    2012-11-01

    Cloud resolving model simulations and vector analysis are used to develop a quantitative method of assessing regional variations in the relationships between various large-scale environmental variables and the transition to deep convection. Results of the CRM simulations from three tropical regions are used to cluster environmental conditions under which transition to deep convection does and does not take place. Projections of the large-scale environmental variables on the difference between these two clusters are used to quantify the roles of these variables in the transition to deep convection. While the transition to deep convection is most sensitive to moisture and vertical velocity perturbations, the details of the profiles of the anomalies vary from region to region. In comparison, the transition to deep convection is found to be much less sensitive to temperature anomalies over all three regions. The vector formulation presented in this study represents a simple general framework for quantifying various aspects of how the transition to deep convection is sensitive to environmental conditions.

  6. Spatio-temporal natural and anthropogenic environmental variability during the last 1500yrs in an ombrotrophic bog (East Belgium).

    NASA Astrophysics Data System (ADS)

    de Vleeschouwer, François; Fagel, Nathalie; Allan, Mohammed; Javaux, Emmanuelle; Gerrienne, Philippe; Streel, Maurice; Luthers, Cédric; Hindrycks, Marie-Noëlle; Wastiaux, Cécile; Leclercq, Louis

    2010-05-01

    Peatlands cover ca. 3 % of the Earth's surface and provide crucial continental archives for deciphering past climatic changes and anthropogenic impacts on decadal to millennial timescales. Numerous studies have demonstrated that peat bogs are excellent archives to investigate past environmental and ecological changes during the Holocene. Studies which focus on intra-site variability at high resolution are rare however, despite their potential to provide constraints on the reliability of the palaeoenvironmental reconstruction and the influence of micro-scale variability. Such variability must be taken into account in any peatland restoration process linked with recent environmental changes, particularly human-derived impact such as peat cutting, drainage and tree cultivation. Four 1m-long Wardenaar monoliths were retrieved from the Misten bog (Hautes-Fagnes, East Belgium). The cores were investigated using chronological (radiocarbon AMS dating of plant macrofossils, 210Pb age modelling), biological (macrofossils, pollen content, testate amoebae), organic (humification level) and geochemical proxies (major and trace geochemistry, Nd and Pb isotopes). The aims of this research were to: (1) to assess whether the bog vegetation and other environmental indicators have changed simultaneously in time and space, (2) identify the most sensitive palaeoenvironmental indicator(s) and (3) assess to what extent variation in peat accumulation rates affects the record of each proxy. Preliminary interpretations show great variability (up to 50%) in peat development on a decimetre depth-scale as assessed by the variation in peat palynological and macrofossils zones from one core to another. In addition, our recent high-resolution records of environmental change have high applied palaeoecological value since they can be used to inform conservation management (‘natural' changes in the composition of the peat forming vegetation and the range of water table depth variability over a

  7. In vivo role of nitric oxide in plant response to abiotic and biotic stress.

    PubMed

    Shi, Hai-Tao; Li, Rong-Jun; Cai, Wei; Liu, Wen; Fu, Zheng-Wei; Lu, Ying-Tang

    2012-03-01

    Over the past few years, nitric oxide (NO) has emerged as an important regulator in many physiological events, especially in response to abiotic and biotic stress. However, the roles of NO were mostly derived from pharmacological studies or the mutants impaired NO synthesis unspecifically. In our recent study, we highlighted a novel strategy by expressing the rat neuronal NO synthase (nNOS) in Arabidopsis to explore the in vivo role of NO. Our results suggested that plants were able to perform well in the constitutive presence of nNOS, and provided a new class of plant experimental system with specific in vivo NO release. Furthermore, our findings also confirmed that the in vivo NO is essential for most of environmental abiotic stresses and disease resistance against pathogen infection. Proper level of NO may be necessary and beneficial, not only in plant response to the environmental abiotic stress, but also to biotic stress.

  8. An innovative statistical approach for analysing non-continuous variables in environmental monitoring: assessing temporal trends of TBT pollution.

    PubMed

    Santos, José António; Galante-Oliveira, Susana; Barroso, Carlos

    2011-03-01

    The current work presents an innovative statistical approach to model ordinal variables in environmental monitoring studies. An ordinal variable has values that can only be compared as "less", "equal" or "greater" and it is not possible to have information about the size of the difference between two particular values. The example of ordinal variable under this study is the vas deferens sequence (VDS) used in imposex (superimposition of male sexual characters onto prosobranch females) field assessment programmes for monitoring tributyltin (TBT) pollution. The statistical methodology presented here is the ordered logit regression model. It assumes that the VDS is an ordinal variable whose values match up a process of imposex development that can be considered continuous in both biological and statistical senses and can be described by a latent non-observable continuous variable. This model was applied to the case study of Nucella lapillus imposex monitoring surveys conducted in the Portuguese coast between 2003 and 2008 to evaluate the temporal evolution of TBT pollution in this country. In order to produce more reliable conclusions, the proposed model includes covariates that may influence the imposex response besides TBT (e.g. the shell size). The model also provides an analysis of the environmental risk associated to TBT pollution by estimating the probability of the occurrence of females with VDS ≥ 2 in each year, according to OSPAR criteria. We consider that the proposed application of this statistical methodology has a great potential in environmental monitoring whenever there is the need to model variables that can only be assessed through an ordinal scale of values.

  9. Asymmetric coexistence: bidirectional abiotic and biotic effects between goose barnacles and mussels.

    PubMed

    Kawai, Takashi; Tokeshi, Mutsunori

    2006-07-01

    1. Species coexistence depends on the net effect of interacting species, representing the sum of multiple interaction components that may act simultaneously and vary independently depending on ambient environmental conditions. Consequently, for a comprehensive understanding of the compound nature of species interactions and coexistence, a mechanistic approach that allows a separate evaluation of each interaction component is required. 2. Two sessile filter-feeders, the goose barnacle Capitulum mitella and the mussel Septifer virgatus, coexist on moderately wave-exposed rocky shores in south-western Japan. In the upper intertidal, Capitulum positively influenced Septifer survivorship and growth through amelioration of thermal stress and of physical disturbance. On the other hand, these species are potential competitors as they have similar body sizes and modes of resource utilization. These opposite processes, facilitation and competition, are based on abiotic characteristics and biotic functions of the two species, respectively. 3. In order to quantify the bidirectional abiotic, biotic and net effects, a series of experimental manipulations was conducted involving the use of living neighbours with both abiotic and biotic effects, and artificial mimics to simulate abiotic effects without biotic effects. 4. Capitulum had strong positive abiotic effects on the mussel survivorship in most experimental periods, while the biotic effect was negligible or weakly negative, suggesting that the net effect of Capitulum on mussel survival was largely attributable to the abiotic effect. In contrast, a significantly negative biotic effect on the mussel growth rate was always present, though this was cancelled out by the larger, positive abiotic effect. In the case of Septifer, its abiotic and biotic effects on the survivorship of goose barnacles were negligible, while those on the growth rate showed temporal variation. 5. With respect to the relationship between species

  10. Spatio-temporal environmental correlation and population variability in simple metacommunities.

    PubMed

    Ruokolainen, Lasse

    2013-01-01

    Natural populations experience environmental conditions that vary across space and over time. This variation is often correlated between localities depending on the geographical separation between them, and different species can respond to local environmental fluctuations similarly or differently, depending on their adaptation. How this emerging structure in environmental correlation (between-patches and between-species) affects spatial community dynamics is an open question. This paper aims at a general understanding of the interactions between the environmental correlation structure and population dynamics in spatial networks of local communities (metacommunities), by studying simple two-patch, two-species systems. Three different pairs of interspecific interactions are considered: competition, consumer-resource interaction, and host-parasitoid interaction. While the results paint a relatively complex picture of the effect of environmental correlation, the interaction between environmental forcing, dispersal, and local interactions can be understood via two mechanisms. While increasing between-patch environmental correlation couples immigration and local densities (destabilising effect), the coupling between local populations under increased between-species environmental correlation can either amplify or dampen population fluctuations, depending on the patterns in density dependence. This work provides a unifying framework for modelling stochastic metacommunities, and forms a foundation for a better understanding of population responses to environmental fluctuations in natural systems.

  11. Focusing on Environmental Biofilms With Variable-Pressure Scanning Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Joubert, L.; Wolfaardt, G. M.; Du Plessis, K.

    2006-12-01

    Since the term biofilm has been coined almost 30 years ago, visualization has formed an integral part of investigations on microbial attachment. Electron microscopic (EM) biofilm studies, however, have been limited by the hydrated extracellular matrix which loses structural integrity with conventional preparative techniques, and under required high-vacuum conditions, resulting in a loss of information on spatial relationships and distribution of biofilm microbes. Recent advances in EM technology enable the application of Variable Pressure Scanning Electron Microscopy (VP SEM) to biofilms, allowing low vacuum and hydrated chamber atmosphere during visualization. Environmental biofilm samples can be viewed in situ, unfixed and fully hydrated, with application of gold-sputter-coating only, to increase image resolution. As the impact of microbial biofilms can be both hazardous and beneficial to man and his environment, recognition of biofilms as a natural form of microbial existence is needed to fully assess the potential role of microbial communities on technology. The integration of multiple techniques to elucidate biofilm processes has become imperative for unraveling complex phenotypic adaptations of this microbial lifestyle. We applied VP SEM as integrative technique with traditional and novel analytical techniques to (1)localize lignocellulosic microbial consortia applied for producing alternative bio-energy sources in the mining wastewater industry, (2) characterize and visualize wetland microbial communities in the treatment of winery wastewater, and (3)determine the impact of recombinant technology on yeast biofilm behavior. Visualization of microbial attachment to a lignocellulose substrate, and degradation of exposed plant tissue, gave insight into fiber degradation and volatile fatty acid production for biological sulphate removal from mining wastewater. Also, the 3D-architecture of complex biofilms developing in constructed wetlands was correlated with

  12. The relationship between environmental variables and response of cotton to nematicides.

    PubMed

    Wheeler, T A; Lawrence, K S; Porter, D O; Keeling, W; Mullinix, B G

    2013-03-01

    Nematicide/irrigation rate trials were conducted in Texas (TX) in 2009 and 2010 in cotton grown at three irrigation rates, where irrigation rate (base (B), B - 33%, B + 33%) was the main plot and treatment (untreated check, aldicarb, and nematicide seed treatment (NST) and NST + aldicarb) were the subplots. Aldicarb improved cotton lint yield with the base (medium) irrigation rate over the untreated check, but not at the B - 33% and B + 33% irrigation rates. In a second evaluation, 20 tests conducted over 7 yr at the same field in TX and 12 tests conducted over 6 yr at the same field in Alabama (AL) were examined for impact of environmental variables (EV) on the response to NST (containing thiodicarb or abamectin), aldicarb, a nontreated check (CK), insecticide seed treatment (TX only), and a combination of NST + aldicarb + oxamyl (NST/A/O, AL only) on root galls (TX only), early season nematode eggs (AL only), and yield (both sites). Galls/root system were lower with aldicarb-treated plots, than for the CK- or NST-treated plots. As water (irrigation plus rain) in May increased, galls/root system increased for CK or insecticide-only-treated plots, and decreased for NST- and aldicarb-treated plots, suggesting efficacy of nematicides was strongly improved by adequate soil moisture. Nematode reproduction was not affected by EV in either location, though yield was negatively affected by root-knot nematode eggs in AL at 60 d. Yield in both AL and TX was negatively related to temperature parameters and positively related to water parameters. With the addition of EV in TX, chemical treatments went from not significantly different in the absence of EV to aldicarb-treated plots having higher yields than nonnematicide-treated plots in the presence of EV. In AL, NST/A/O-treated plots yielded similar to aldicarb and better than CK or NST in the absence of EV and had significantly higher yields than all other treatments in the presence of most EV.

  13. Ecological Sexual Dimorphism and Environmental Variability within a Community of Antarctic Penguins (Genus Pygoscelis)

    PubMed Central

    Gorman, Kristen B.; Williams, Tony D.; Fraser, William R.

    2014-01-01

    Background Sexual segregation in vertebrate foraging niche is often associated with sexual size dimorphism (SSD), i.e., ecological sexual dimorphism. Although foraging behavior of male and female seabirds can vary markedly, differences in isotopic (carbon, δ13C and nitrogen, δ15N) foraging niche are generally more pronounced within sexually dimorphic species and during phases when competition for food is greater. We examined ecological sexual dimorphism among sympatric nesting Pygoscelis penguins asking whether environmental variability is associated with differences in male and female pre-breeding foraging niche. We predicted that all Pygoscelis species would forage sex-specifically, and that higher quality winter habitat, i.e., higher or lower sea ice coverage for a given species, would be associated with a more similar foraging niche among the sexes. Results P2/P8 primers reliably amplified DNA of all species. On average, male Pygoscelis penguins are structurally larger than female conspecifics. However, chinstrap penguins were more sexually dimorphic in culmen and flipper features than Adélie and gentoo penguins. Adélies and gentoos were more sexually dimorphic in body mass than chinstraps. Only male and female chinstraps and gentoos occupied separate δ15N foraging niches. Strong year effects in δ15N signatures were documented for all three species, however, only for Adélies, did yearly variation in δ15N signatures tightly correlate with winter sea ice conditions. There was no evidence that variation in sex-specific foraging niche interacted with yearly winter habitat quality. Conclusion Chinstraps were most sexually size dimorphic followed by gentoos and Adélies. Pre-breeding sex-specific foraging niche was associated with overall SSD indices across species; male chinstrap and gentoo penguins were enriched in δ15N relative to females. Our results highlight previously unknown trophic pathways that link Pygoscelis penguins with variation in Southern

  14. Long-Range Underwater Sound Propagation: Environmental Variability, Signal Stability and Signal Coherence

    DTIC Science & Technology

    2014-09-30

    Variability, Signal Stability and Signal Coherence Michael G. Brown Division of Applied Marine Physics Rosenstiel School of Marine and...variability on signal stability and coherence . We seek to understand the fundamental limits to signal processing imposed by ocean variability to enable...logistics of which is very simple. That field work has been partially supported by NSF. Field work has been complemented by data-driven theoretical

  15. Long-Range Underwater Sound Propagation: Environmental Variability, Signal Stability and Signal Coherence

    DTIC Science & Technology

    2013-09-30

    Variability, Signal Stability and Signal Coherence Michael G. Brown Division of Applied Marine Physics Rosenstiel School of Marine and...variability on signal stability and coherence . We seek to understand the fundamental limits to signal processing imposed by ocean variability to enable...stability parameter α or the asymptotically equivalent mode-based waveguide invariant β) of the background sound speed profile, rather than details

  16. Local nutrient regimes determine site-specific environmental triggers of cyanobacterial and microcystin variability in urban lakes

    NASA Astrophysics Data System (ADS)

    Sinang, S. C.; Reichwaldt, E. S.; Ghadouani, A.

    2015-05-01

    Toxic cyanobacterial blooms in urban lakes present serious health hazards to humans and animals and require effective management strategies. Managing such blooms requires a sufficient understanding of the controlling environmental factors. A range of them has been proposed in the literature as potential triggers for cyanobacterial biomass development and cyanotoxin (e.g. microcystin) production in freshwater systems. However, the environmental triggers of cyanobacteria and microcystin variability remain a subject of debate due to contrasting findings. This issue has raised the question of whether the relevance of environmental triggers may depend on site-specific combinations of environmental factors. In this study, we investigated the site-specificity of environmental triggers for cyanobacterial bloom and microcystin dynamics in three urban lakes in Western Australia. Our study suggests that cyanobacterial biomass, cyanobacterial dominance and cyanobacterial microcystin content variability were significantly correlated to phosphorus and iron concentrations. However, the correlations were different between lakes, thus suggesting a site-specific effect of these environmental factors. The discrepancies in the correlations could be explained by differences in local nutrient concentration. For instance, we found no correlation between cyanobacterial fraction and total phosphorous (TP) in the lake with the highest TP concentration, while correlations were significant and negative in the other two lakes. In addition, our study indicates that the difference of the correlation between total iron (TFe) and the cyanobacterial fraction between lakes might have been a consequence of differences in the cyanobacterial community structure, specifically the presence or absence of nitrogen-fixing species. In conclusion, our study suggests that identification of significant environmental factors under site-specific conditions is an important strategy to enhance successful outcomes

  17. The Roles of Attitudinal and Personality Variables in the Prediction of Environmental Behavior and Knowledge

    ERIC Educational Resources Information Center

    Arbuthnot, Jack

    1977-01-01

    This study explored the relationships among selected attitudinal and personality characteristics, attitudes toward environmental problems, and environmental knowledge and behavioral commitment of two diverse samples: 85 users of a recycling center and 60 conservative church members. Multiple regression analysis was utilized to determine the best…

  18. Abiotic factors influence plant storage lipid accumulation and composition.

    PubMed

    Singer, Stacy D; Zou, Jitao; Weselake, Randall J

    2016-02-01

    The demand for plant-derived oils has increased substantially over the last decade, and is sure to keep growing. While there has been a surge in research efforts to produce plants with improved oil content and quality, in most cases the enhancements have been small. To add further complexity to this situation, substantial differences in seed oil traits among years and field locations have indicated that plant lipid biosynthesis is also influenced to a large extent by multiple environmental factors such as temperature, drought, light availability and soil nutrients. On the molecular and biochemical levels, the expression and/or activities of fatty acid desaturases, as well as diacylglycerol acyltransferase 1, have been found to be affected by abiotic factors, suggesting that they play a role in the lipid content and compositional changes seen under abiotic stress conditions. Unfortunately, while only a very small number of strategies have been developed as of yet to minimize these environmental effects on the production of storage lipids, it is clear that this feat will be of the utmost importance for developing superior oil crops with the capability to perform in a consistent manner in field conditions in the future.

  19. Influence of abiotic stress signals on secondary metabolites in plants

    PubMed Central

    Ramakrishna, Akula; Ravishankar, Gokare Aswathanarayana

    2011-01-01

    Plant secondary metabolites are unique sources for pharmaceuticals, food additives, flavors, and industrially important biochemicals. Accumulation of such metabolites often occurs in plants subjected to stresses including various elicitors or signal molecules. Secondary metabolites play a major role in the adaptation of plants to the environment and in overcoming stress conditions. Environmental factors viz. temperature, humidity, light intensity, the supply of water, minerals, and CO2 influence the growth of a plant and secondary metabolite production. Drought, high salinity, and freezing temperatures are environmental conditions that cause adverse effects on the growth of plants and the productivity of crops. Plant cell culture technologies have been effective tools for both studying and producing plant secondary metabolites under in vitro conditions and for plant improvement. This brief review summarizes the influence of different abiotic factors include salt, drought, light, heavy metals, frost etc. on secondary metabolites in plants. The focus of the present review is the influence of abiotic factors on secondary metabolite production and some of important plant pharmaceuticals. Also, we describe the results of in vitro cultures and production of some important secondary metabolites obtained in our laboratory. PMID:22041989

  20. Phenology Analysis of Forest Vegetation to Environmental Variables during - and Post-Monsoon Seasons in Western Himalayan Region of India

    NASA Astrophysics Data System (ADS)

    Khare, S.; Latifi, H.; Ghosh, K.

    2016-06-01

    To assess the phenological changes in Moist Deciduous Forest (MDF) of western Himalayan region of India, we carried out NDVI time series analysis from 2013 to 2015 using Landsat 8 OLI data. We used the vegetation index differencing method to calculate the change in NDVI (NDVIchange) during pre and post monsoon seasons and these changes were used to assess the phenological behaviour of MDF by taking the effect of a set of environmental variables into account. To understand the effect of environmental variables on change in phenology, we designed a linear regression analysis with sample-based NDVIchange values as the response variable and elevation aspect, and Land Surface Temperature (LST) as explanatory variables. The Landsat-8 derived phenology transition stages were validated by calculating the phenology variation from Nov 2008 to April 2009 using Landsat-7 which has the same spatial resolution as Landsat-8. The Landsat-7 derived NDVI trajectories were plotted in accordance with MODIS derived phenology stages (from Nov 2008 to April 2009) of MDF. Results indicate that the Landsat -8 derived NDVI trajectories describing the phenology variation of MDF during spring, monsoon autumn and winter seasons agreed closely with Landsat-7 and MODIS derived phenology transition from Nov 2008 to April 2009. Furthermore, statistical analysis showed statistically significant correlations (p < 0.05) amongst the environmental variables and the NDVIchange between full greenness and maximum frequency stage of Onset of Greenness (OG) activity.. The major change in NDVI was observed in medium (600 to 650 m) and maximum (650 to 750 m) elevation areas. The change in LST showed also to be highly influential. The results of this study can be used for large scale monitoring of difficult-to-reach mountainous forests, with additional implications in biodiversity assessment. By means of a sufficient amount of available cloud-free imagery, detailed phenological trends across mountainous

  1. Forecasting Large-Scale Habitat Suitability of European Bustards under Climate Change: The Role of Environmental and Geographic Variables.

    PubMed

    Estrada, Alba; Delgado, M Paula; Arroyo, Beatriz; Traba, Juan; Morales, Manuel B

    2016-01-01

    We modelled the distribution of two vulnerable steppe birds, Otis tarda and Tetrax tetrax, in the Western Palearctic and projected their suitability up to the year 2080. We performed two types of models for each species: one that included environmental and geographic variables (space-included model) and a second one that only included environmental variables (space-excluded model). Our assumption was that ignoring geographic variables in the modelling procedure may result in inaccurate forecasting of species distributions. On the other hand, the inclusion of geographic variables may generate an artificial constraint on future projections. Our results show that space-included models performed better than space-excluded models. While distribution of suitable areas for T. tetrax in the future was approximately the same as at present in the space-included model, the space-excluded model predicted a pronounced geographic change of suitable areas for this species. In the case of O. tarda, the space-included model showed that many areas of current presence shifted to low or medium suitability in the future, whereas a northward expansion of intermediate suitable areas was predicted by the space-excluded one. According to the best models, current distribution of these species can restrict future distribution, probably due to dispersal constraints and site fidelity. Species ranges would be expected to shift gradually over the studied time period and, therefore, we consider it unlikely that most of the current distribution of these species in southern Europe will disappear in less than one hundred years. Therefore, populations currently occupying suitable areas should be a priority for conservation policies. Our results also show that climate-only models may have low explanatory power, and could benefit from adjustments using information on other environmental variables and biological traits; if the latter are not available, including the geographic predictor may improve the

  2. Forecasting Large-Scale Habitat Suitability of European Bustards under Climate Change: The Role of Environmental and Geographic Variables

    PubMed Central

    Estrada, Alba; Delgado, M. Paula; Arroyo, Beatriz; Traba, Juan; Morales, Manuel B.

    2016-01-01

    We modelled the distribution of two vulnerable steppe birds, Otis tarda and Tetrax tetrax, in the Western Palearctic and projected their suitability up to the year 2080. We performed two types of models for each species: one that included environmental and geographic variables (space-included model) and a second one that only included environmental variables (space-excluded model). Our assumption was that ignoring geographic variables in the modelling procedure may result in inaccurate forecasting of species distributions. On the other hand, the inclusion of geographic variables may generate an artificial constraint on future projections. Our results show that space-included models performed better than space-excluded models. While distribution of suitable areas for T. tetrax in the future was approximately the same as at present in the space-included model, the space-excluded model predicted a pronounced geographic change of suitable areas for this species. In the case of O. tarda, the space-included model showed that many areas of current presence shifted to low or medium suitability in the future, whereas a northward expansion of intermediate suitable areas was predicted by the space-excluded one. According to the best models, current distribution of these species can restrict future distribution, probably due to dispersal constraints and site fidelity. Species ranges would be expected to shift gradually over the studied time period and, therefore, we consider it unlikely that most of the current distribution of these species in southern Europe will disappear in less than one hundred years. Therefore, populations currently occupying suitable areas should be a priority for conservation policies. Our results also show that climate-only models may have low explanatory power, and could benefit from adjustments using information on other environmental variables and biological traits; if the latter are not available, including the geographic predictor may improve the

  3. A robust damage-detection technique with environmental variability combining time-series models with principal components

    NASA Astrophysics Data System (ADS)

    Lakshmi, K.; Rama Mohan Rao, A.

    2014-10-01

    In this paper, a novel output-only damage-detection technique based on time-series models for structural health monitoring in the presence of environmental variability and measurement noise is presented. The large amount of data obtained in the form of time-history response is transformed using principal component analysis, in order to reduce the data size and thereby improve the computational efficiency of the proposed algorithm. The time instant of damage is obtained by fitting the acceleration time-history data from the structure using autoregressive (AR) and AR with exogenous inputs time-series prediction models. The probability density functions (PDFs) of damage features obtained from the variances of prediction errors corresponding to references and healthy current data are found to be shifting from each other due to the presence of various uncertainties such as environmental variability and measurement noise. Control limits using novelty index are obtained using the distances of the peaks of the PDF curves in healthy condition and used later for determining the current condition of the structure. Numerical simulation studies have been carried out using a simply supported beam and also validated using an experimental benchmark data corresponding to a three-storey-framed bookshelf structure proposed by Los Alamos National Laboratory. Studies carried out in this paper clearly indicate the efficiency of the proposed algorithm for damage detection in the presence of measurement noise and environmental variability.

  4. Benthic infauna variability in relation to environmental factors and organic pollutants in tropical coastal lagoons from the northern Yucatan Peninsula.

    PubMed

    Kuk-Dzul, J Gabriel; Gold-Bouchot, G; Ardisson, P-L

    2012-12-01

    We examine the abundance and species composition variability of benthic infauna from tropical coastal lagoons in relation to environmental factors and organic pollutants. Sediment samples were collected at 40 sites in four lagoons in the northern Yucatan Peninsula. A total of 7985 individuals belonging to 173 species were sampled. While the eastern lagoons were dominated by polychaetes, the western ones were dominated by crustaceans. Overall, polychaetes had the highest abundance (48%), followed by crustaceans (42%). According to canonical correspondence analysis, species attributes were correlated with water salinity, pH and temperature, but also with sediment pentachlorobenzene, trichlorobenzene, and low molecular weight polycyclic aromatic hydrocarbons. Some pollutants exceeded sediment quality guidelines, representing a potential environmental risk to benthic infauna. Together, environmental factors and pollutants explained 52% of the variance in abundance and species composition among sites.

  5. Relative importance of multiple environmental variables in structuring benthic macroinfaunal assemblages in chronically metal-polluted salt marshes.

    PubMed

    Goto, Daisuke; Wallace, William G

    2010-03-01

    In this study, we assessed importance of sediment-associated trace metals in structuring benthic macroinfaunal assemblages along multiple environmental gradients in chronically polluted salt marshes of the Arthur Kill - AK (New York, USA). More than 90% of benthic macroinfaunal communities at the northern AK sites consisted of a considerably large number of only a few polychaete and oligochaete species. Approximately 70% of among-site variances in abundance and biomass of benthic macroinfaunal communities was strongly associated with a few environmental variables; only sediment-associated mercury consistently contributed to a significant proportion of the explained variances in species composition along natural environmental gradients (e.g., salinity). Although sediment-associated copper, lead, and zinc were substantially elevated at some of the AK sites, their ecological impacts on benthic macroinfaunal communities appeared to be negligible. These findings suggest that cumulative metal-specific impacts may have played an important role in structuring benthic macroinfaunal communities in chronically polluted AK ecosystems.

  6. Bacterioplankton community responses to key environmental variables in plateau freshwater lake ecosystems: A structural equation modeling and change point analysis.

    PubMed

    Cao, Xiaofeng; Wang, Jie; Liao, Jingqiu; Gao, Zhe; Jiang, Dalin; Sun, Jinhua; Zhao, Lei; Huang, Yi; Luan, Shengji

    2017-02-15

    Elevated environmental pressures negatively affect the bacterial community structure. However, little knowledge about the nonlinear responses of spatially related environmental variable across multiple plateau lake ecosystems on bacterioplankton communities has been gathered. Here, we used 454 pyrosequencing of 16S rRNA genes to study the associations of bacterial communities in terms of environmental characteristics as well as the potentially ecological threshold-inducing shifts of the bacterial community structure along the key environmental variables based on hypothesized structural equation models and the SEGMENTED method in 21 plateau lakes. Our results showed that water transparency was the major driving force and that total nitrogen was more significant than total phosphorus in determining the taxon composition of the bacterioplankton community. Significant community threshold estimates for bacterioplankton were observed at 7.36 for pH and 25.6% for the percentage of the agricultural area, while the remarkable change point of the cyanobacteria community structure responding to pH was at 7.74. Furthermore, the findings indicated that increasing nutrient loads can induce a distinct shift in dominance from Proteobacteria to Cyanobacteria, as well as a sharp decrease and adjacent increase when crossing the change point for Actinobacteria and Bacteroidetes along the gradient of the agricultural area.

  7. Impact of Environmental and Disturbance Variables on Avian Community Structure along a Gradient of Urbanization in Jamshedpur, India.

    PubMed

    Verma, Sushant Kumar; Murmu, Thakur Das

    2015-01-01

    Gradient pattern analysis was used to investigate the impact of environmental and disturbance variables on species richness, species diversity, abundance and seasonal variation of birds in and around Jamshedpur, which is one of the fastest growing cities of India. It was observed that avian community structure is highly influenced by the vegetation habitat variables, food availability and human-related disturbance variables. A total of 61 species belonging to 33 families were recorded from the suburban area. 55 species belonging to 32 families were observed in nearby wildland habitat consisting of natural vegetation whereas only 26 species belonging to 18 families were observed in urban area. Results indicated that the suburban habitat had more complex bird community structure in terms of higher species richness, higher species diversity and higher evenness in comparison to urban and wildland habitat. Bird species richness and diversity varied across seasons. Maximum species richness and diversity was observed during spring season in all type of habitat. Most of the birds observed in urban areas were found to belong to either rare or irregular category on the basis of their abundance. The observed pattern of avian community structure is due to combined effect of both environmental and human related disturbance variables.

  8. Impact of Environmental and Disturbance Variables on Avian Community Structure along a Gradient of Urbanization in Jamshedpur, India

    PubMed Central

    Verma, Sushant Kumar; Murmu, Thakur Das

    2015-01-01

    Gradient pattern analysis was used to investigate the impact of environmental and disturbance variables on species richness, species diversity, abundance and seasonal variation of birds in and around Jamshedpur, which is one of the fastest growing cities of India. It was observed that avian community structure is highly influenced by the vegetation habitat variables, food availability and human-related disturbance variables. A total of 61 species belonging to 33 families were recorded from the suburban area. 55 species belonging to 32 families were observed in nearby wildland habitat consisting of natural vegetation whereas only 26 species belonging to 18 families were observed in urban area. Results indicated that the suburban habitat had more complex bird community structure in terms of higher species richness, higher species diversity and higher evenness in comparison to urban and wildland habitat. Bird species richness and diversity varied across seasons. Maximum species richness and diversity was observed during spring season in all type of habitat. Most of the birds observed in urban areas were found to belong to either rare or irregular category on the basis of their abundance. The observed pattern of avian community structure is due to combined effect of both environmental and human related disturbance variables. PMID:26218583

  9. Jensen's Inequality and the Impact of Short-Term Environmental Variability on Long-Term Population Growth Rates.

    PubMed

    Pickett, Evan J; Thomson, David L; Li, Teng A; Xing, Shuang

    2015-01-01

    It is well established in theory that short-term environmental fluctuations could affect the long-term growth rates of wildlife populations, but this theory has rarely been tested and there remains little empirical evidence that the effect is actually important in practice. Here we develop models to quantify the effects of daily, seasonal, and yearly temperature fluctuations on the average population growth rates, and we apply them to long-term data on the endangered Black-faced Spoonbill (Platalea minor); an endothermic species whose population growth rates follow a concave relationship with temperature. We demonstrate for the first time that the current levels of temperature variability, particularly seasonal variability, are already large enough to substantially reduce long-term population growth rates. As the climate changes, our results highlight the importance of considering the ecological effects of climate variability and not just average conditions.

  10. Jensen’s Inequality and the Impact of Short-Term Environmental Variability on Long-Term Population Growth Rates

    PubMed Central

    Pickett, Evan J.; Thomson, David L.; Li, Teng A.; Xing, Shuang

    2015-01-01

    It is well established in theory that short-term environmental fluctuations could affect the long-term growth rates of wildlife populations, but this theory has rarely been tested and there remains little empirical evidence that the effect is actually important in practice. Here we develop models to quantify the effects of daily, seasonal, and yearly temperature fluctuations on the average population growth rates, and we apply them to long-term data on the endangered Black-faced Spoonbill (Platalea minor); an endothermic species whose population growth rates follow a concave relationship with temperature. We demonstrate for the first time that the current levels of temperature variability, particularly seasonal variability, are already large enough to substantially reduce long-term population growth rates. As the climate changes, our results highlight the importance of considering the ecological effects of climate variability and not just average conditions. PMID:26352857

  11. Abiotic Versus Biotic Weathering Of Olivine As Possible Biosignatures

    NASA Technical Reports Server (NTRS)

    Longazo, Teresa G.; Wentworth, Susan J.; Clemett, Simon J.; Southam, Gordon; McKay, David S.

    2001-01-01

    ranged from tens to a few microns with textures that remained relatively sharp and were crystallographically controlled. These results were comparable to that observed in the "naturally" weathered comparison/reference grains. Chemical analysis by EDS indicates these textures correlated with the relative loss of Mg and Fe cations by diffusional processes. In contrast the biotic results indicated changes in the etching patterns on the scale of hundreds of nm, which are neither sharp nor crystallographically controlled (nanoetching). Organisms, organic debris and/or extracellular polymeric substances (biofilm) were often in close proximity or direct contact with the nanoetching. While there are many poorly constrained variables in natural weathering experiments to contend with, such as the time scale, the chemistry of the fluids and degree of biologic participation, some preliminary observations can be made: (1) certain distinct surface textures appear correlated with the specific processes giving rise to these textures; (2) the process of diffusing cations can produce many similar styles of surface textural changes; and (3) the main difference between abiotic and biotically produced weathering is the scale (microns versus nanometers) and the style (crystallographically versus noncrystallographically controlled) of the textural features. Further investigation into nanosize scale surface textures should attempt to quantify both textures and chemical changes of the role of microorganisms in the weathering of silicates. Additional experiments addressing nanoscale textures of shock features for comparison with the current data set.

  12. Debates in the late Quaternary of central southern Africa: climate change, environmental variability or just plain poor data?

    NASA Astrophysics Data System (ADS)

    Thomas, D. S.; Burrough, S. L.

    2012-12-01

    Quaternary palaeoclimatic/environmental analyses in dryland regions are well-known for the limited range of proxy data sets available, resulting in debates about achieving robust reconstructions (e.g. Butzer 1984, Thomas 1986, Maslin and Christiansen 2007). In some regions, e.g. central southern Africa, this has resulted in reliance on geoproxies: the analysis and dating of depositional landforms and associated sediments. Despite significant advances in geoproxy interpretation and chronometric control, their efficacy remains contentious, not least because of apparent temporal contradictions in reconstructions of past drier and past more humid conditions. Consequently their use has been eschewed in favour of spatially extensive extrapolations from higher-resolution, but geographically-distant, data sets (e.g. Chase and Meadows 2008); an approach not without its own limitations (e.g. Gasse et al. 2008, Thomas and Burrough 2012, Thomas et al. 2012), given the variability in modern terrestrial conditions in dryland regions today. It is therefore highly appropriate to revisit the debates of Butzer (1984) and Thomas (1986) regarding data quality and data extrapolation, but to add in the very relevant characteristic of temporal and spatial environmental variability. Environmental and climatic variability at a range of temporal and spatial scales are significant traits of drylands in southern Africa and worldwide, impacting on ecosystem and geomorphic processes, and human behaviour. It can be hypothesised that while environmental variability has been an important trait of Late Quaternary environments and climate in southern Africa. It has rarely been considered as a viable environmental 'state' when proxy records are analysed and integrated, particularly in the case of spatially extensive geoproxies and in contexts where palaeoenvironment and palaeoclimate are used interchangeably. We present examples where debates over the nature of past changes and quality of datasets

  13. Modeling Geographic and Demographic Variability in Residential Concentrations of Environmental Tobacco Smoke Using National Data Sets

    EPA Science Inventory

    Despite substantial attention toward environmental tobacco smoke (ETS) exposure, previous studies have not provided adequate information to apply broadly within community-scale risk assessments. We aim to estimate residential concentrations of particulate matter (PM) from ETS in ...

  14. Hydraulic fracturing water use variability in the United States and potential environmental implications.

    PubMed

    Gallegos, Tanya J; Varela, Brian A; Haines, Seth S; Engle, Mark A

    2015-07-01

    A U.S. map of water volumes used to hydraulically fracture oil and gas wells, 2011-2014Hydraulic fracturing water volumes differ regionally across the U.S.Discussion of variation in water use and potential environmental implications.

  15. RELATIONSHIPS BETWEEN ENVIRONMENTAL VARIABLES AND BENTHIC DIATOM ASSEMBLAGES IN CALIFORNIA CENTRAL VALLEY STREAMS (USA)

    EPA Science Inventory

    Streams and rivers in the California Central Valley Ecoregion have been substantially modified by human activities. This study examines distributional patterns of benthic diatom assemblages in relation to environmental characteristics in streams and rivers of this region. Benthic...

  16. [Bioindication of environmental quality based on plant mutational and modification variability].

    PubMed

    Mamedova, A O

    2009-01-01

    The level of mutations (aberrations of chromosomes, gene mutations) and modifications (bilateral asymmetry of the leaves) induced with NG (N-methyl-N-nitro-N-nitro-zoguanidine) and granozane, as well as with environmental pollutants have been studied on Vicia faba, Triticum aestivum, Arabidopsis thaliana, Ligustrum japonicum, Olea europea. The tested xenobiotic increased the level of mutations and modifications. The bilateral asymmetry is suggested as a test for environmental quality assessment.

  17. Endophytic fungi: resource for gibberellins and crop abiotic stress resistance.

    PubMed

    Khan, Abdul Latif; Hussain, Javid; Al-Harrasi, Ahmed; Al-Rawahi, Ahmed; Lee, In-Jung

    2015-03-01

    The beneficial effects of endophytes on plant growth are important for agricultural ecosystems because they reduce the need for fertilizers and decrease soil and water pollution while compensating for environmental perturbations. Endophytic fungi are a novel source of bioactive secondary metabolites; moreover, recently they have been found to produce physiologically active gibberellins as well. The symbiosis of gibberellins producing endophytic fungi with crops can be a promising strategy to overcome the adverse effects of abiotic stresses. The association of such endophytes has not only increased plant biomass but also ameliorated plant-growth during extreme environmental conditions. Endophytic fungi represent a trove of unexplored biodiversity and a frequently overlooked component of crop ecology. The present review describes the role of gibberellins producing endophytic fungi, suggests putative mechanisms involved in plant endophyte stress interactions and discusses future prospects in this field.

  18. A survey of abiotic stress tolerance variability in cotton germplasm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The High Plains of Texas grows about 20% of the cotton fiber produced in the United States. The Ogallala Aquifer is the major water source of irrigation for agricultural production but is declining and future water availability will be significantly reduced. Water-deficit stress has a significant i...

  19. DETERMINANTS OF TEMPORAL VARIABILITY IN NHEXAS-MARYLAND ENVIRONMENTAL CONCENTRATIONS, EXPOSURES, AND BIOMARKERS

    EPA Science Inventory

    The longitudinal NHEXAS-Maryland study measured metals, PAHs, and pesticides in several media to capture temporal variability. Questionnaires were concurrently administered to identify factors that influenced changes in contaminant levels over time. We constructed mixed-effects...

  20. Early subtropical forest growth is driven by community mean trait values and functional diversity rather than the abiotic environment

    PubMed Central

    Kröber, Wenzel; Li, Ying; Härdtle, Werner; Ma, Keping; Schmid, Bernhard; Schmidt, Karsten; Scholten, Thomas; Seidler, Gunnar; von Oheimb, Goddert; Welk, Erik; Wirth, Christian; Bruelheide, Helge

    2015-01-01

    While functional diversity (FD) has been shown to be positively related to a number of ecosystem functions including biomass production, it may have a much less pronounced effect than that of environmental factors or species-specific properties. Leaf and wood traits can be considered particularly relevant to tree growth, as they reflect a trade-off between resources invested into growth and persistence. Our study focussed on the degree to which early forest growth was driven by FD, the environment (11 variables characterizing abiotic habitat conditions), and community-weighted mean (CWM) values of species traits in the context of a large-scale tree diversity experiment (BEF-China). Growth rates of trees with respect to crown diameter were aggregated across 231 plots (hosting between one and 23 tree species) and related to environmental variables, FD, and CWM, the latter two of which were based on 41 plant functional traits. The effects of each of the three predictor groups were analyzed separately by mixed model optimization and jointly by variance partitioning. Numerous single traits predicted plot-level tree growth, both in the models based on CWMs and FD, but none of the environmental variables was able to predict tree growth. In the best models, environment and FD explained only 4 and 31% of variation in crown growth rates, respectively, while CWM trait values explained 42%. In total, the best models accounted for 51% of crown growth. The marginal role of the selected environmental variables was unexpected, given the high topographic heterogeneity and large size of the experiment, as was the significant impact of FD, demonstrating that positive diversity effects already occur during the early stages in tree plantations. PMID:26380685

  1. Bayesian data fusion for spatial prediction of categorical variables in environmental sciences

    SciTech Connect

    Gengler, Sarah Bogaert, Patrick

    2014-12-05

    First developed to predict continuous variables, Bayesian Maximum Entropy (BME) has become a complete framework in the context of space-time prediction since it has been extended to predict categorical variables and mixed random fields. This method proposes solutions to combine several sources of data whatever the nature of the information. However, the various attempts that were made for adapting the BME methodology to categorical variables and mixed random fields faced some limitations, as a high computational burden. The main objective of this paper is to overcome this limitation by generalizing the Bayesian Data Fusion (BDF) theoretical framework to categorical variables, which is somehow a simplification of the BME method through the convenient conditional independence hypothesis. The BDF methodology for categorical variables is first described and then applied to a practical case study: the estimation of soil drainage classes using a soil map and point observations in the sandy area of Flanders around the city of Mechelen (Belgium). The BDF approach is compared to BME along with more classical approaches, as Indicator CoKringing (ICK) and logistic regression. Estimators are compared using various indicators, namely the Percentage of Correctly Classified locations (PCC) and the Average Highest Probability (AHP). Although BDF methodology for categorical variables is somehow a simplification of BME approach, both methods lead to similar results and have strong advantages compared to ICK and logistic regression.

  2. Variation in stability of elk and red deer populations with abiotic and biotic factors at the species-distribution scale.

    PubMed

    Ahrestani, Farshid S; Smith, William K; Hebblewhite, Mark; Running, Steven; Post, Eric

    2016-11-01

    Stability in population dynamics is an emergent property of the interaction between direct and delayed density dependence, the strengths of which vary with environmental covariates. Analysis of variation across populations in the strength of direct and delayed density dependence can reveal variation in stability properties of populations at the species level. We examined the stability properties of 22 elk/red deer populations in a two-stage analysis. First, we estimated direct and delayed density dependence applying an AR(2) model in a Bayesian hierarchical framework. Second, we plotted the coefficients of direct and delayed density dependence in the Royama parameter plane. We then used a hierarchical approach to test the significance of environmental covariates of direct and delayed density dependence. Three populations exhibited highly stable and convergent dynamics with strong direct, and weak delayed, density dependence. The remaining 19 populations exhibited more complex dynamics characterized by multi-annual fluctuations. Most (15 of 19) of these exhibited a combination of weak to moderate direct and delayed density dependence. Best-fit models included environmental covariates in 17 populations (77% of the total). Of these, interannual variation in growing-season primary productivity and interannual variation in winter temperature were the most common, performing as the best-fit covariate in six and five populations, respectively. Interannual variation in growing-season primary productivity was associated with the weakest combination of direct and delayed density dependence, while interannual variation in winter temperature was associated with the strongest combination of direct and delayed density dependence. These results accord with a classic theoretical prediction that environmental variability should weaken population stability. They furthermore suggest that two forms of environmental variability, one related to forage resources and the other related to

  3. Human impacts in Antartic marine soft-sediment assemblages: correlations between multivariate biological patterns and environmental variables at Casey Station

    NASA Astrophysics Data System (ADS)

    Stark, Jonathan S.; Riddle, Martin J.; Snape, Ian; Scouller, Rebecca C.

    2003-03-01

    Correlations between the spatial distribution of soft-sediment assemblages and environmental variables were evaluated at a number of control and potentially impacted locations (waste dumps, a sewage outfall and a wharf) at Casey Station, East Antarctica. Patterns of assemblage composition were compared with patterns of environmental variables using univariate and multivariate techniques. The utility of these methods, however, is uncertain in areas of significant habitat heterogeneity (at scales <10 m), such as at Casey Station. A number of environmental variables were measured to determine their potential influence on assemblage structure including sediment heavy metal concentrations, total organic carbon (TOC), grain size and depth. Soft-sediment assemblages clustered strongly into two groups and this pattern was found to be most highly correlated with concentrations of heavy metals of anthropogenic origin: cadmium, copper, lead, tin and zinc. The relationship, however, is complex and is likely to be further influenced by variables affecting the bioavailability of metals such as grain size, TOC and sediment anoxia. Impacted locations were characterised by fewer taxa, lower diversity and lower species richness. One of the control locations was found to have naturally high levels of cadmium, nickel and zinc and had assemblages very similar to those at the potentially impacted, polluted locations. One of the potentially impacted locations had coarse sediments and low levels of heavy metals but had assemblages very similar to other impacted locations. Problems of sampling design for human impacts detection in real world situations are discussed in relation to this study. This study provides evidence that these multivariate statistical methods are useful in heterogeneous environments and across pollution gradients where pollutants have the potential to act as a primary cause of spatial variation in assemblage structure.

  4. Long-term variability and environmental preferences of calycophoran siphonophores in the Bay of Villefranche (north-western Mediterranean)

    NASA Astrophysics Data System (ADS)

    Licandro, P.; Souissi, S.; Ibanez, F.; Carré, C.

    2012-05-01

    Long-term variability of the main calycophoran siphonophores was investigated between 1974 and 1999 in a coastal station in the north-western Mediterranean. The data were collected at weekly frequency using a macroplankton net (680 μm mesh size) adapted to quantitatively sample delicate gelatinous plankton. A 3-year collection (1967-1969) of siphonophores from offshore waters using the same methodology showed that the patterns of variability observed inshore were representative of siphonophores’ changes at a regional scale. The aims of the study were: (i) to investigate the patterns of variability that characterised the dominant calycophoran species and assemblages; (ii) to identify the environmental optima that were associated with a significant increase in the dominant siphonophore species and (iii) to verify the influence of hydroclimatic variability on long-term changes of siphonophores. Our results showed that during nearly 3 decades the standing stock of calycophoran siphonophores did not show any significant change, with the annual maximum usually recorded in spring as a result of high densities of the dominant species Lensia subtilis, Muggiaea kochi and Muggiaea atlantica. Nevertheless, major changes in community composition occurred within the calycophoran population. Since the middle 1980s, M. kochi, once the most dominant species, started to decrease allowing other species, the congeneric M. atlantica and Chelophyes appendiculata, to increasingly dominate in spring and summer-autumn, respectively. The comparison of environmental and biotic long-term trends suggests that the decrease of M. kochi was triggered by hydrological changes that occurred in the north-western Mediterranean under the forcing of large-scale climate oscillations. Salinity, water stratification and water temperature were the main hydroclimatic factors associated with a significant increase of siphonophores, different species showing different environmental preferences.

  5. Hydrogen peroxide priming modulates abiotic oxidative stress tolerance: insights from ROS detoxification and scavenging

    PubMed Central

    Hossain, Mohammad A.; Bhattacharjee, Soumen; Armin, Saed-Moucheshi; Qian, Pingping; Xin, Wang; Li, Hong-Yu; Burritt, David J.; Fujita, Masayuki; Tran, Lam-Son P.

    2015-01-01

    Plants are constantly challenged by various abiotic stresses that negatively affect growth and productivity worldwide. During the course of their evolution, plants have developed sophisticated mechanisms to recognize external signals allowing them to respond appropriately to environmental conditions, although the degree of adjustability or tolerance to specific stresses differs from species to species. Overproduction of reactive oxygen species (ROS; hydrogen peroxide, H2O2; superoxide, O2⋅-; hydroxyl radical, OH⋅ and singlet oxygen, 1O2) is enhanced under abiotic and/or biotic stresses, which can cause oxidative damage to plant macromolecules and cell structures, leading to inhibition of plant growth and development, or to death. Among the various ROS, freely diffusible and relatively long-lived H2O2 acts as a central player in stress signal transduction pathways. These pathways can then activate multiple acclamatory responses that reinforce resistance to various abiotic and biotic stressors. To utilize H2O2 as a signaling molecule, non-toxic levels must be maintained in a delicate balancing act between H2O2 production and scavenging. Several recent studies have demonstrated that the H2O2-priming can enhance abiotic stress tolerance by modulating ROS detoxification and by regulating multiple stress-responsive pathways and gene expression. Despite the importance of the H2O2-priming, little is known about how this process improves the tolerance of plants to stress. Understanding the mechanisms of H2O2-priming-induced abiotic stress tolerance will be valuable for identifying biotechnological strategies to improve abiotic stress tolerance in crop plants. This review is an overview of our current knowledge of the possible mechanisms associated with H2O2-induced abiotic oxidative stress tolerance in plants, with special reference to antioxidant metabolism. PMID:26136756

  6. Abiotic Bromination of Soil Organic Matter.

    PubMed

    Leri, Alessandra C; Ravel, Bruce

    2015-11-17

    Biogeochemical transformations of plant-derived soil organic matter (SOM) involve complex abiotic and microbially mediated reactions. One such reaction is halogenation, which occurs naturally in the soil environment and has been associated with enzymatic activity of decomposer organisms. Building on a recent finding that naturally produced organobromine is ubiquitous in SOM, we hypothesized that inorganic bromide could be subject to abiotic oxidations resulting in bromination of SOM. Through lab-based degradation treatments of plant material and soil humus, we have shown that abiotic bromination of particulate organic matter occurs in the presence of a range of inorganic oxidants, including hydrogen peroxide and assorted forms of ferric iron, producing both aliphatic and aromatic forms of organobromine. Bromination of oak and pine litter is limited primarily by bromide concentration. Fresh plant material is more susceptible to bromination than decayed litter and soil humus, due to a labile pool of mainly aliphatic compounds that break down during early stages of SOM formation. As the first evidence of abiotic bromination of particulate SOM, this study identifies a mechanistic source of the natural organobromine in humic substances and the soil organic horizon. Formation of organobromine through oxidative treatments of plant material also provides insights into the relative stability of aromatic and aliphatic components of SOM.

  7. Ubiquitination pathway as a target to develop abiotic stress tolerance in rice

    PubMed Central

    Dametto, Andressa; Buffon, Giseli; Dos Reis Blasi, Édina Aparecida; Sperotto, Raul Antonio

    2015-01-01

    Abiotic stresses may result in significant losses in rice grain productivity. Protein regulation by the ubiquitin/proteasome system has been studied as a target mechanism to optimize adaptation and survival strategies of plants to different environmental stresses. This article aimed at highlighting recent discoveries about the roles ubiquitination may play in the exposure of rice plants to different abiotic stresses, enabling the development of modified plants tolerant to stress. Responses provided by the ubiquitination process include the regulation of the stomatal opening, phytohormones levels, protein stabilization, cell membrane integrity, meristematic cell maintenance, as well as the regulation of reactive oxygen species and heavy metals levels. It is noticeable that ubiquitination is a potential means for developing abiotic stress tolerant plants, being an excellent alternative to rice (and other cultures) improvement programs. PMID:26236935

  8. Measuring the environmental effects of organic farming: A meta-analysis of structural variables in empirical research.

    PubMed

    Lee, Ki Song; Choe, Young Chan; Park, Sung Hee

    2015-10-01

    This study examined the structural variables affecting the environmental effects of organic farming compared to those of conventional farming. A meta-analysis based on 107 studies and 360 observations published from 1977 to 2012 compared energy efficiency (EE) and greenhouse gas emissions (GHGE) for organic and conventional farming. The meta-analysis systematically analyzed the results of earlier comparative studies and used logistic regression to identify the structural variables that contributed to differences in the effects of organic and conventional farming on the environment. The statistical evidence identified characteristics that differentiated the environmental effects of organic and conventional farming, which is controversial. The results indicated that data sources, sample size and product type significantly affected EE, whereas product type, cropping pattern and measurement unit significantly affected the GHGE of organic farming compared to conventional farming. Superior effects of organic farming on the environment were more likely to appear for larger samples, primary data rather than secondary data, monocropping rather than multicropping, and crops other than fruits and vegetables. The environmental effects of organic farming were not affected by the study period, geographic location, farm size, cropping pattern, or measurement method.

  9. The value of crossdating to retain high-frequency variability, climate signals, and extreme events in environmental proxies.

    PubMed

    Black, Bryan A; Griffin, Daniel; van der Sleen, Peter; Wanamaker, Alan D; Speer, James H; Frank, David C; Stahle, David W; Pederson, Neil; Copenheaver, Carolyn A; Trouet, Valerie; Griffin, Shelly; Gillanders, Bronwyn M

    2016-07-01

    High-resolution biogenic and geologic proxies in which one increment or layer is formed per year are crucial to describing natural ranges of environmental variability in Earth's physical and biological systems. However, dating controls are necessary to ensure temporal precision and accuracy; simple counts cannot ensure that all layers are placed correctly in time. Originally developed for tree-ring data, crossdating is the only such procedure that ensures all increments have been assigned the correct calendar year of formation. Here, we use growth-increment data from two tree species, two marine bivalve species, and a marine fish species to illustrate sensitivity of environmental signals to modest dating error rates. When falsely added or missed increments are induced at one and five percent rates, errors propagate back through time and eliminate high-frequency variability, climate signals, and evidence of extreme events while incorrectly dating and distorting major disturbances or other low-frequency processes. Our consecutive Monte Carlo experiments show that inaccuracies begin to accumulate in as little as two decades and can remove all but decadal-scale processes after as little as two centuries. Real-world scenarios may have even greater consequence in the absence of crossdating. Given this sensitivity to signal loss, the fundamental tenets of crossdating must be applied to fully resolve environmental signals, a point we underscore as the frontiers of growth-increment analysis continue to expand into tropical, freshwater, and marine environments.

  10. Relationships between ecosystem metabolism, benthic macroinvertebrate densities, and environmental variables in a sub-arctic Alaskan river

    USGS Publications Warehouse

    Benson, Emily R.; Wipfli, Mark S.; Clapcott, Joanne E.; Hughes, Nicholas F.

    2013-01-01

    Relationships between environmental variables, ecosystem metabolism, and benthos are not well understood in sub-arctic ecosystems. The goal of this study was to investigate environmental drivers of river ecosystem metabolism and macroinvertebrate density in a sub-arctic river. We estimated primary production and respiration rates, sampled benthic macroinvertebrates, and monitored light intensity, discharge rate, and nutrient concentrations in the Chena River, interior Alaska, over two summers. We employed Random Forests models to identify predictor variables for metabolism rates and benthic macroinvertebrate density and biomass, and calculated Spearman correlations between in-stream nutrient levels and metabolism rates. Models indicated that discharge and length of time between high water events were the most important factors measured for predicting metabolism rates. Discharge was the most important variable for predicting benthic macroinvertebrate density and biomass. Primary production rate peaked at intermediate discharge, respiration rate was lowest at the greatest time since last high water event, and benthic macroinvertebrate density was lowest at high discharge rates. The ratio of dissolved inorganic nitrogen to soluble reactive phosphorus ranged from 27:1 to 172:1. We found that discharge plays a key role in regulating stream ecosystem metabolism, but that low phosphorous levels also likely limit primary production in this sub-arctic stream.

  11. Effects of input uncertainty and variability on the modelled environmental fate of organic pollutants under global climate change scenarios.

    PubMed

    Kong, Deguo; MacLeod, Matthew; Li, Zhe; Cousins, Ian T

    2013-11-01

    Global climate change (GCC) is expected to influence the fate, exposure and risks of organic pollutants to wildlife and humans. Multimedia chemical fate models have been previously applied to estimate how GCC affects pollutant concentrations in the environment and biota, but previous studies have not addressed how uncertainty and variability of model inputs affect model predictions. Here, we assess the influence of climate variability and chemical property uncertainty on future projections of environmental fate of six polychlorinated biphenyl congeners under different GCC scenarios using a spreadsheet version of the ChemCAN model and the Crystal Ball® software. Regardless of emission mode, results demonstrate: (i) uncertainty in degradation half-lives dominates the variance of modelled absolute levels of PCB congeners under GCC scenarios; (ii) when the ratios of predictions under GCC to predictions under present day climate are modelled, climate variability dominates the variance of modelled ratios; and (iii) the ratios also indicate a maximum of about a factor of 2 change in the long-term average environmental concentrations due to GCC that is forecasted between present conditions and the period between 2080 and 2099. We conclude that chemical property uncertainty does not preclude assessing relative changes in a GCC scenario compared to a present-day scenario if variance in model outputs due to chemical properties and degradation half-lives can be assumed to cancel out in the two scenarios.

  12. A multi-model approach to evaluate the role of environmental variability and fishing pressure in sardine fisheries

    NASA Astrophysics Data System (ADS)

    Leitão, F.; Alms, V.; Erzini, K.

    2014-11-01

    Understanding the fluctuations in population abundance is a central question in fisheries. Sardine fisheries is of great importance to Portugal and is data-rich and of primary concern to fisheries managers. In Portugal, sub-stocks of Sardina pilchardus (sardine) are found in different regions: the Northwest (IXaCN), Southwest (IXaCS) and the South coast (IXaS-Algarve). Each of these sardine sub-stocks is affected differently by a unique set of climate and ocean conditions, mainly during larval development and recruitment, which will consequently affect sardine fisheries in the short term. Taking this hypothesis into consideration we examined the effects of hydrographic (river discharge), sea surface temperature, wind driven phenomena, upwelling, climatic (North Atlantic Oscillation) and fisheries variables (fishing effort) on S. pilchardus catch rates (landings per unit effort, LPUE, as a proxy for sardine biomass). A 20-year time series (1989-2009) was used, for the different subdivisions of the Portuguese coast (sardine sub-stocks). For the purpose of this analysis a multi-model approach was used, applying different time series models for data fitting (Dynamic Factor Analysis, Generalised Least Squares), forecasting (Autoregressive Integrated Moving Average), as well as Surplus Production stock assessment models. The different models were evaluated, compared and the most important variables explaining changes in LPUE were identified. The type of relationship between catch rates of sardine and environmental variables varied across regional scales due to region-specific recruitment responses. Seasonality plays an important role in sardine variability within the three study regions. In IXaCN autumn (season with minimum spawning activity, larvae and egg concentrations) SST, northerly wind and wind magnitude were negatively related with LPUE. In IXaCS none of the explanatory variables tested was clearly related with LPUE. In IXaS-Algarve (South Portugal) both spring

  13. Molecular and physiological responses to abiotic stress in forest trees and their relevance to tree improvement.

    PubMed

    Harfouche, Antoine; Meilan, Richard; Altman, Arie

    2014-11-01

    Abiotic stresses, such as drought, salinity and cold, are the major environmental stresses that adversely affect tree growth and, thus, forest productivity, and play a major role in determining the geographic distribution of tree species. Tree responses and tolerance to abiotic stress are complex biological processes that are best analyzed at a systems level using genetic, genomic, metabolomic and phenomic approaches. This will expedite the dissection of stress-sensing and signaling networks to further support efficient genetic improvement programs. Enormous genetic diversity for stress tolerance exists within some forest-tree species, and due to advances in sequencing technologies the molecular genetic basis for this diversity has been rapidly unfolding in recent years. In addition, the use of emerging phenotyping technologies extends the suite of traits that can be measured and will provide us with a better understanding of stress tolerance. The elucidation of abiotic stress-tolerance mechanisms will allow for effective pyramiding of multiple tolerances in a single tree through genetic engineering. Here we review recent progress in the dissection of the molecular basis of abiotic stress tolerance in forest trees, with special emphasis on Populus, Pinus, Picea, Eucalyptus and Quercus spp. We also outline practices that will enable the deployment of trees engineered for abiotic stress tolerance to land owners. Finally, recommendations for future work are discussed.

  14. AP2/ERF family transcription factors in plant abiotic stress responses.

    PubMed

    Mizoi, Junya; Shinozaki, Kazuo; Yamaguchi-Shinozaki, Kazuko

    2012-02-01

    In terrestrial environments, temperature and water conditions are highly variable, and extreme temperatures and water conditions affect the survival, growth and reproduction of plants. To protect cells and sustain growth under such conditions of abiotic stress, plants respond to unfavourable changes in their environments in developmental, physiological and biochemical ways. These responses require expression of stress-responsive genes, which are regulated by a network of transcription factors. The AP2/ERF family is a large family of plant-specific transcription factors that share a well-conserved DNA-binding domain. This transcription factor family includes DRE-binding proteins (DREBs), which activate the expression of abiotic stress-responsive genes via specific binding to the dehydration-responsive element/C-repeat (DRE/CRT) cis-acting element in their promoters. In this review, we discuss the functions of the AP2/ERF-type transcription factors in plant abiotic stress responses, with special emphasis on the regulations and functions of two major types of DREBs, DREB1/CBF and DREB2. In addition, we summarise the involvement of other AP2/ERF-type transcription factors in abiotic stress responses, which has recently become clear. This article is part of a Special Issue entitled: Plant gene regulation in response to abiotic stress.

  15. Variables Associated with Environmental Scanning among Clinicians at Substance Abuse Treatment Clinics

    ERIC Educational Resources Information Center

    Koch, Alison L.; Arfken, Cynthia L.; Agius, Elizabeth; Dickson, Marcus W.; Mitchelson, Jacqueline K.

    2005-01-01

    Introduction: Environmental scanning, as a component of absorptive capacity, has been shown to be associated with increased use of innovative treatment techniques at substance abuse treatment programmes. As the transfer of innovative, evidence-based treatment techniques from research to practice is gaining attention, we aimed to identify variables…

  16. Omics for aquatic ecotoxicology: Control of extraneous variability to enhance the analysis of environmental effects

    EPA Science Inventory

    There are multiple sources of biological and technical variation in a typical ecotoxicology study that may not be revealed by traditional endpoints but that become apparent in an omics dataset. As researchers increasingly apply omics technologies to environmental studies, it will...

  17. Estimating juniper cover from NAIP imagery and evaluating relationships between potential cover and environmental variables

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Juniper management is constrained by limited tools to estimate juniper cover and potential cover at stand closure across landscapes. We evaluated if remotely sensed imagery (NAIP) could be used to estimate juniper cover and if environmental characteristic could be used to determine potential junipe...

  18. Environmental variables and definitive host distribution: a habitat suitability modelling for endohelminth parasites in the marine realm

    PubMed Central

    Kuhn, Thomas; Cunze, Sarah; Kochmann, Judith; Klimpel, Sven

    2016-01-01

    Marine nematodes of the genus Anisakis are common parasites of a wide range of aquatic organisms. Public interest is primarily based on their importance as zoonotic agents of the human Anisakiasis, a severe infection of the gastro-intestinal tract as result of consuming live larvae in insufficiently cooked fish dishes. The diverse nature of external impacts unequally influencing larval and adult stages of marine endohelminth parasites requires the consideration of both abiotic and biotic factors. Whereas abiotic factors are generally more relevant for early life stages and might also be linked to intermediate hosts, definitive hosts are indispensable for a parasite’s reproduction. In order to better understand the uneven occurrence of parasites in fish species, we here use the maximum entropy approach (Maxent) to model the habitat suitability for nine Anisakis species accounting for abiotic parameters as well as biotic data (definitive hosts). The modelled habitat suitability reflects the observed distribution quite well for all Anisakis species, however, in some cases, habitat suitability exceeded the known geographical distribution, suggesting a wider distribution than presently recorded. We suggest that integrative modelling combining abiotic and biotic parameters is a valid approach for habitat suitability assessments of Anisakis, and potentially other marine parasite species. PMID:27507328

  19. Environmental variables and definitive host distribution: a habitat suitability modelling for endohelminth parasites in the marine realm

    NASA Astrophysics Data System (ADS)

    Kuhn, Thomas; Cunze, Sarah; Kochmann, Judith; Klimpel, Sven

    2016-08-01

    Marine nematodes of the genus Anisakis are common parasites of a wide range of aquatic organisms. Public interest is primarily based on their importance as zoonotic agents of the human Anisakiasis, a severe infection of the gastro-intestinal tract as result of consuming live larvae in insufficiently cooked fish dishes. The diverse nature of external impacts unequally influencing larval and adult stages of marine endohelminth parasites requires the consideration of both abiotic and biotic factors. Whereas abiotic factors are generally more relevant for early life stages and might also be linked to intermediate hosts, definitive hosts are indispensable for a parasite’s reproduction. In order to better understand the uneven occurrence of parasites in fish species, we here use the maximum entropy approach (Maxent) to model the habitat suitability for nine Anisakis species accounting for abiotic parameters as well as biotic data (definitive hosts). The modelled habitat suitability reflects the observed distribution quite well for all Anisakis species, however, in some cases, habitat suitability exceeded the known geographical distribution, suggesting a wider distribution than presently recorded. We suggest that integrative modelling combining abiotic and biotic parameters is a valid approach for habitat suitability assessments of Anisakis, and potentially other marine parasite species.

  20. Coupled Abiotic-Biotic Degradation of Bisphenol A

    NASA Astrophysics Data System (ADS)

    Im, J.; Prevatte, C.; Campagna, S. R.; Loeffler, F.

    2014-12-01

    Bisphenol A (BPA) is a ubiquitous environmental contaminant with weak estrogenic activity. BPA is readily biodegradable with oxygen available, but is recalcitrant to microbial degradation under anoxic conditions. However, BPA is susceptible to abiotic transformation under anoxic conditions. To better understand the fate of BPA in anoxic environments, the kinetics of BPA transformation by manganese oxide (d-MnO2) were investigated. BPA was rapidly transformed by MnO2 with a pseudo-first-order rate constant of 0.413 min-1. NMR and LC-MS analyses identified 4-hydroxycumyl alcohol (HCA) as a major intermediate. Up to 64% of the initial amount of BPA was recovered as HCA within 5 min, but the conversion efficiency decreased with time, suggesting that HCA was further degraded by MnO2. Further experiments confirmed that HCA was also susceptible to transformation by MnO2, albeit at 5-fold lower rates than BPA transformation. Mass balance approaches suggested that HCA was the major BPA transformation intermediate, but other compounds may also be formed. The abiotic transformation of BPA by MnO2 was affected by pH, and 10-fold higher transformation rates were observed at pH 4.5 than at pH 10. Compared to BPA, HCA has a lower octanol-water partitioning coefficient (Log Kow) of 0.76 vs 2.76 for BPA and a higher aqueous solubility of 2.65 g L-1 vs 0.31 g L-1 for BPA, suggesting higher mobility of HCA in the environment. Microcosms established with freshwater sediment materials collected from four geographically distinct locations and amended with HCA demonstrated rapid HCA biodegradation under oxic, but not under anoxic conditions. These findings suggest that BPA is not inert under anoxic conditions and abiotic reactions with MnO2 generate HCA, which has increased mobility and is susceptible to aerobic degradation. Therefore, coupled abiotic-biotic processes can affect the fate and longevity of BPA in terrestrial environments.

  1. Long-term abundance patterns of macroalgae in relation to environmental variables in the Tagus Estuary (Portugal)

    NASA Astrophysics Data System (ADS)

    Sousa-Dias, Abel; Melo, Ricardo A.

    2008-01-01

    Seasonal and inter-annual patterns of macroalgal abundance in a Tagus Estuary oyster reef are described. Macroalgal abundance was estimated as canopy percent cover by three permanent point intercept transects over a 7-year period. Four categories were defined, corresponding to bare substrate and three different macroalgal functional-form groups: (1) ULVA, foliose group, included Ulva spp.; (2) GRACIL, terete corticated macrophyte group, included only Gracilaria gracilis; and (3) FILAM, small (<10 cm) filamentous group, including eight species. A canonical correspondence analysis (CCA) showed that: (1) ULVA were associated with long and hot days, being usually dominant during spring and especially summer; (2) FILAM were associated with mild temperatures and relatively long days, abundant in spring but showed frequent peaks in summer; and (3) GRACIL were also favoured by spring season, although associated to lower temperature and less daylight hours than FILAM. GRACIL and FILAM were present throughout the year. On the contrary, ULVA were absent or with low cover during colder periods. A negative correlation between GRACIL and FILAM seems to indicate competition between the two categories. The applied models explained 23.3% of the temporal variance in category abundance. Rainfall negatively affected macroalgal cover, as indicated by the positive correlation between rainfall and bare substrate. Our conclusions are in agreement with previous studies that consider algae as excellent environmental integrators, even on a small scale, due to a strong link between the macroalgal communities and relevant environmental variables. It is also relevant that this study used open-access databases of environmental variables, which open up new possibilities for mining existing data resources in new ways. Due to large inter-annual variability, long-term studies are essential to understand population dynamics in estuarine phytobenthic communities.

  2. Relative linkages of canopy-level CO₂ fluxes with the climatic and environmental variables for US deciduous forests.

    PubMed

    Ishtiaq, Khandker S; Abdul-Aziz, Omar I

    2015-04-01

    We used a simple, systematic data-analytics approach to determine the relative linkages of different climate and environmental variables with the canopy-level, half-hourly CO2 fluxes of US deciduous forests. Multivariate pattern recognition techniques of principal component and factor analyses were utilized to classify and group climatic, environmental, and ecological variables based on their similarity as drivers, examining their interrelation patterns at different sites. Explanatory partial least squares regression models were developed to estimate the relative linkages of CO2 fluxes with the climatic and environmental variables. Three biophysical process components adequately described the system-data variances. The 'radiation-energy' component had the strongest linkage with CO2 fluxes, whereas the 'aerodynamic' and 'temperature-hydrology' components were low to moderately linked with the carbon fluxes. On average, the 'radiation-energy' component showed 5 and 8 times stronger carbon flux linkages than that of the 'temperature-hydrology' and 'aerodynamic' components, respectively. The similarity of observed patterns among different study sites (representing gradients in climate, canopy heights and soil-formations) indicates that the findings are potentially transferable to other deciduous forests. The similarities also highlight the scope of developing parsimonious data-driven models to predict the potential sequestration of ecosystem carbon under a changing climate and environment. The presented data-analytics provides an objective, empirical foundation to obtain crucial mechanistic insights; complementing process-based model building with a warranted complexity. Model efficiency and accuracy (R(2) = 0.55-0.81; ratio of root-mean-square error to the observed standard deviations, RSR = 0.44-0.67) reiterate the usefulness of multivariate analytics models for gap-filling of instantaneous flux data.

  3. Relative Linkages of Canopy-Level CO2 Fluxes with the Climatic and Environmental Variables for US Deciduous Forests

    NASA Astrophysics Data System (ADS)

    Ishtiaq, Khandker S.; Abdul-Aziz, Omar I.

    2015-04-01

    We used a simple, systematic data-analytics approach to determine the relative linkages of different climate and environmental variables with the canopy-level, half-hourly CO2 fluxes of US deciduous forests. Multivariate pattern recognition techniques of principal component and factor analyses were utilized to classify and group climatic, environmental, and ecological variables based on their similarity as drivers, examining their interrelation patterns at different sites. Explanatory partial least squares regression models were developed to estimate the relative linkages of CO2 fluxes with the climatic and environmental variables. Three biophysical process components adequately described the system-data variances. The `radiation-energy' component had the strongest linkage with CO2 fluxes, whereas the `aerodynamic' and `temperature-hydrology' components were low to moderately linked with the carbon fluxes. On average, the `radiation-energy' component showed 5 and 8 times stronger carbon flux linkages than that of the `temperature-hydrology' and `aerodynamic' components, respectively. The similarity of observed patterns among different study sites (representing gradients in climate, canopy heights and soil-formations) indicates that the findings are potentially transferable to other deciduous forests. The similarities also highlight the scope of developing parsimonious data-driven models to predict the potential sequestration of ecosystem carbon under a changing climate and environment. The presented data-analytics provides an objective, empirical foundation to obtain crucial mechanistic insights; complementing process-based model building with a warranted complexity. Model efficiency and accuracy ( R 2 = 0.55-0.81; ratio of root-mean-square error to the observed standard deviations, RSR = 0.44-0.67) reiterate the usefulness of multivariate analytics models for gap-filling of instantaneous flux data.

  4. Linking Bovine Tuberculosis on Cattle Farms to White-Tailed Deer and Environmental Variables Using Bayesian Hierarchical Analysis

    PubMed Central

    Walter, W. David; Smith, Rick; Vanderklok, Mike; VerCauteren, Kurt C.

    2014-01-01

    Bovine tuberculosis is a bacterial disease caused by Mycobacterium bovis in livestock and wildlife with hosts that include Eurasian badgers (Meles meles), brushtail possum (Trichosurus vulpecula), and white-tailed deer (Odocoileus virginianus). Risk-assessment efforts in Michigan have been initiated on farms to minimize interactions of cattle with wildlife hosts but research on M. bovis on cattle farms has not investigated the spatial context of disease epidemiology. To incorporate spatially explicit data, initial likelihood of infection probabilities for cattle farms tested for M. bovis, prevalence of M. bovis in white-tailed deer, deer density, and environmental variables for each farm were modeled in a Bayesian hierarchical framework. We used geo-referenced locations of 762 cattle farms that have been tested for M. bovis, white-tailed deer prevalence, and several environmental variables that may lead to long-term survival and viability of M. bovis on farms and surrounding habitats (i.e., soil type, habitat type). Bayesian hierarchical analyses identified deer prevalence and proportion of sandy soil within our sampling grid as the most supported model. Analysis of cattle farms tested for M. bovis identified that for every 1% increase in sandy soil resulted in an increase in odds of infection by 4%. Our analysis revealed that the influence of prevalence of M. bovis in white-tailed deer was still a concern even after considerable efforts to prevent cattle interactions with white-tailed deer through on-farm mitigation and reduction in the deer population. Cattle farms test positive for M. bovis annually in our study area suggesting that the potential for an environmental source either on farms or in the surrounding landscape may contributing to new or re-infections with M. bovis. Our research provides an initial assessment of potential environmental factors that could be incorporated into additional modeling efforts as more knowledge of deer herd factors and cattle

  5. Linking bovine tuberculosis on cattle farms to white-tailed deer and environmental variables using Bayesian hierarchical analysis.

    PubMed

    Walter, W David; Smith, Rick; Vanderklok, Mike; VerCauteren, Kurt C

    2014-01-01

    Bovine tuberculosis is a bacterial disease caused by Mycobacterium bovis in livestock and wildlife with hosts that include Eurasian badgers (Meles meles), brushtail possum (Trichosurus vulpecula), and white-tailed deer (Odocoileus virginianus). Risk-assessment efforts in Michigan have been initiated on farms to minimize interactions of cattle with wildlife hosts but research on M. bovis on cattle farms has not investigated the spatial context of disease epidemiology. To incorporate spatially explicit data, initial likelihood of infection probabilities for cattle farms tested for M. bovis, prevalence of M. bovis in white-tailed deer, deer density, and environmental variables for each farm were modeled in a Bayesian hierarchical framework. We used geo-referenced locations of 762 cattle farms that have been tested for M. bovis, white-tailed deer prevalence, and several environmental variables that may lead to long-term survival and viability of M. bovis on farms and surrounding habitats (i.e., soil type, habitat type). Bayesian hierarchical analyses identified deer prevalence and proportion of sandy soil within our sampling grid as the most supported model. Analysis of cattle farms tested for M. bovis identified that for every 1% increase in sandy soil resulted in an increase in odds of infection by 4%. Our analysis revealed that the influence of prevalence of M. bovis in white-tailed deer was still a concern even after considerable efforts to prevent cattle interactions with white-tailed deer through on-farm mitigation and reduction in the deer population. Cattle farms test positive for M. bovis annually in our study area suggesting that the potential for an environmental source either on farms or in the surrounding landscape may contributing to new or re-infections with M. bovis. Our research provides an initial assessment of potential environmental factors that could be incorporated into additional modeling efforts as more knowledge of deer herd factors and cattle

  6. Prediction of space sickness in astronauts from preflight fluid, electrolyte, and cardiovascular variables and Weightless Environmental Training Facility (WETF) training

    NASA Technical Reports Server (NTRS)

    Simanonok, K.; Mosely, E.; Charles, J.

    1992-01-01

    Nine preflight variables related to fluid, electrolyte, and cardiovascular status from 64 first-time Shuttle crewmembers were differentially weighted by discrimination analysis to predict the incidence and severity of each crewmember's space sickness as rated by NASA flight surgeons. The nine variables are serum uric acid, red cell count, environmental temperature at the launch site, serum phosphate, urine osmolality, serum thyroxine, sitting systolic blood pressure, calculated blood volume, and serum chloride. Using two methods of cross-validation on the original samples (jackknife and a stratefied random subsample), these variables enable the prediction of space sickness incidence (NONE or SICK) with 80 percent sickness and space severity (NONE, MILD, MODERATE, of SEVERE) with 59 percent success by one method of cross-validation and 67 percent by another method. Addition of a tenth variable, hours spent in the Weightlessness Environment Training Facility (WETF) did not improve the prediction of space sickness incidences but did improve the prediction of space sickness severity to 66 percent success by the first method of cross-validation of original samples and to 71 percent by the second method. Results to date suggest the presence of predisposing physiologic factors to space sickness that implicate fluid shift etiology. The data also suggest that prior exposure to fluid shift during WETF training may produce some circulatory pre-adaption to fluid shifts in weightlessness that results in a reduction of space sickness severity.

  7. Distribution and relative abundance of humpback whales in relation to environmental variables in coastal British Columbia and adjacent waters

    NASA Astrophysics Data System (ADS)

    Dalla Rosa, Luciano; Ford, John K. B.; Trites, Andrew W.

    2012-03-01

    Humpback whales are common in feeding areas off British Columbia (BC) from spring to fall, and are widely distributed along the coast. Climate change and the increase in population size of North Pacific humpback whales may lead to increased anthropogenic impact and require a better understanding of species-habitat relationships. We investigated the distribution and relative abundance of humpback whales in relation to environmental variables and processes in BC waters using GIS and generalized additive models (GAMs). Six non-systematic cetacean surveys were conducted between 2004 and 2006. Whale encounter rates and environmental variables (oceanographic and remote sensing data) were recorded along transects divided into 4 km segments. A combined 3-year model and individual year models (two surveys each) were fitted with the mgcv R package. Model selection was based primarily on GCV scores. The explained deviance of our models ranged from 39% for the 3-year model to 76% for the 2004 model. Humpback whales were strongly associated with latitude and bathymetric features, including depth, slope and distance to the 100-m isobath. Distance to sea-surface-temperature fronts and salinity (climatology) were also constantly selected by the models. The shapes of smooth functions estimated for variables based on chlorophyll concentration or net primary productivity with different temporal resolutions and time lags were not consistent, even though higher numbers of whales seemed to be associated with higher primary productivity for some models. These and other selected explanatory variables may reflect areas of higher biological productivity that favor top predators. Our study confirms the presence of at least three important regions for humpback whales along the BC coast: south Dixon Entrance, middle and southwestern Hecate Strait and the area between La Perouse Bank and the southern edge of Juan de Fuca Canyon.

  8. Transgenic expression of TaMYB2A confers enhanced tolerance to multiple abiotic stresses in Arabidopsis.

    PubMed

    Mao, Xinguo; Jia, Dongsheng; Li, Ang; Zhang, Hongying; Tian, Shanjun; Zhang, Xiaoke; Jia, Jizeng; Jing, Ruilian

    2011-09-01

    Osmotic stresses such as drought, salinity, and cold are major environmental factors that limit agricultural productivity. Transcription factors play essential roles in abiotic stress signaling in plants. Three TaMYB2 members were identified and designated TaMYB2A, TaMYB2B, and TaMYB2D based on their genomic origins. The cis-regulatory elements in the promoter regions were compared, and their diverse expression patterns under different abiotic stress conditions were identified. TaMYB2A was further characterized because of its earlier response to stresses. Subcellular localization revealed that TaMYB2A localized in the nucleus. To examine the role of TaMYB2A under various environmental stresses, transgenic Arabidopsis plants carrying TaMYB2A controlled by the CaMV 35S promoter were generated and subjected to severe abiotic stress. TaMYB2A transgenics had enhanced tolerance to drought, salt, and freezing stresses, which were confirmed by the enhanced expressions of abiotic stress-responsive genes and several physiological indices, including decreased rate of water loss, enhanced cell membrane stability, improved photosynthetic potential, and reduced osmotic potential. TaMYB2A is a multifunctional regulatory factor. Its overexpression confers enhanced tolerance to multiple abiotic stresses while having no obvious negative effects on phenotype under well-watered and stressed conditions; thus, TaMYB2A has the potential for utilization in transgenic breeding to improve abiotic stress tolerances in crops.

  9. Adélie penguin survival: age structure, temporal variability and environmental influences.

    PubMed

    Emmerson, Louise; Southwell, Colin

    2011-12-01

    The driving factors of survival, a key demographic process, have been particularly challenging to study, especially for winter migratory species such as the Adélie penguin (Pygoscelis adeliae). While winter environmental conditions clearly influence Antarctic seabird survival, it has been unclear to which environmental features they are most likely to respond. Here, we examine the influence of environmental fluctuations, broad climatic conditions and the success of the breeding season prior to winter on annual survival of an Adélie penguin population using mark-recapture models based on penguin tag and resight data over a 16-year period. This analysis required an extension to the basic Cormack-Jolly-Seber model by incorporating age structure in recapture and survival sub-models. By including model covariates, we show that survival of older penguins is primarily related to the amount and concentration of ice present in their winter foraging grounds. In contrast, fledgling and yearling survival depended on other factors in addition to the physical marine environment and outcomes of the previous breeding season, but we were unable to determine what these were. The relationship between sea-ice and survival differed with penguin age: extensive ice during the return journey to breeding colonies was detrimental to survival for the younger penguins, whereas either too little or too much ice (between 15 and 80% cover) in the winter foraging grounds was detrimental for adults. Our results demonstrate that predictions of Adélie penguin survival can be improved by taking into account penguin age, prior breeding conditions and environmental features.

  10. Variability in human embryonic development and its implications for the susceptibility to environmental teratogenesis.

    PubMed

    Shiota, Kohei

    2009-08-01

    Considerable variability is observed in the size and developmental stage among human embryos at a given gestational age, suggesting that prenatal development does not proceed at the same speed in every embryo. Such variability in embryonic development seems to occur in many (probably all) animal species, and is probably a normal "biologic" phenomenon to some extent. In the case of humans, some other factors (e.g., maternal memory bias, difficulty in assessing the timing of ovulation and fertilization) make it more difficult to assess the developmental stage of embryos in utero. Such facts related to human embryonic development should be taken into account when the teratogenic risk of a human embryo is considered.

  11. Optimized MPPT algorithm for boost converters taking into account the environmental variables

    NASA Astrophysics Data System (ADS)

    Petit, Pierre; Sawicki, Jean-Paul; Saint-Eve, Frédéric; Maufay, Fabrice; Aillerie, Michel

    2016-07-01

    This paper presents a study on the specific behavior of the Boost DC-DC converters generally used for powering conversion of PV panels connected to a HVDC (High Voltage Direct Current) Bus. It follows some works pointing out that converter MPPT (Maximum Power Point Tracker) is severely perturbed by output voltage variations due to physical dependency of parameters as the input voltage, the output voltage and the duty cycle of the PWM switching control of the MPPT. As a direct consequence many converters connected together on a same load perturb each other because of the output voltage variations induced by fluctuations on the HVDC bus essentially due to a not insignificant bus impedance. In this paper we show that it is possible to include an internal computed variable in charge to compensate local and external variations to take into account the environment variables.

  12. Environmentally associated signal-to-interference variability in low-frequency active sonar in Korea Strait

    NASA Astrophysics Data System (ADS)

    Cable, P. G.; Carey, W. M.

    2005-09-01

    An analysis has been conducted of spatial and temporal variability of target echo-to-interference measurements made during Area Characterization Test III (ACT III) in 1995 in the Korea Strait. The measurements were made over a 5-day period for five fixed bistatic geometries (spatial scale of order 200 square km) using explosive sources, bottom-mounted horizontal receiving hydrophone arrays, and passive reflector targets in 100-m-depth water under downward-refracting acoustic conditions. The bottom at the ACT III site was nearly flat, of sand-silt composition. Meteorological conditions were relatively calm over the conduction of the measurements, but the main proximate oceanographic feature, the South Korean Coastal Front, did result in a relatively varied and complex sound-speed environment. The signal-to-interference fluctuation statistics associated with a single ping was determined to give a standard deviation of order 1 dB, while the observed variability of signal-to-interference over the spatial and temporal scales of the measurements gave a standard deviation of about 2 dB. The observed variability of received signal-to-interference will be discussed in terms of physical causes and measurement error. [Work supported by ONR Code OA321.

  13. An Examination of the Demographic and Environmental Variables Correlated with Lyme Disease Emergence in Virginia.

    PubMed

    Seukep, Sara E; Kolivras, Korine N; Hong, Yili; Li, Jie; Prisley, Stephen P; Campbell, James B; Gaines, David N; Dymond, Randel L

    2015-12-01

    Lyme disease is the United States' most significant vector-borne illness. Virginia, on the southern edge of the disease's currently expanding range, has experienced an increase in Lyme disease both spatially and temporally, with steadily increasing rates over the past decade and disease spread from the northern to the southwestern part of the state. This study used a Geographic Information System and a spatial Poisson regression model to examine correlations between demographic and land cover variables, and human Lyme disease from 2006 to 2010 in Virginia. Analysis indicated that herbaceous land cover is positively correlated with Lyme disease incidence rates. Areas with greater interspersion between herbaceous and forested land were also positively correlated with incidence rates. In addition, income and age were positively correlated with incidence rates. Levels of development, interspersion of herbaceous and developed land, and population density were negatively correlated with incidence rates. Abundance of forest fragments less than 2 hectares in area was not significantly correlated. Our results support some findings of previous studies on ecological variables and Lyme disease in endemic areas, but other results have not been found in previous studies, highlighting the potential contribution of new variables as Lyme disease continues to emerge southward.

  14. Variability in environmental impacts of Brazilian soybean according to crop production and transport scenarios.

    PubMed

    da Silva, Vamilson Prudêncio; van der Werf, Hayo M G; Spies, Airton; Soares, Sebastião Roberto

    2010-09-01

    Soybean production and its supply chain are highly dependent on inputs such as land, fertilizer, fuel, machines, pesticides and electricity. The expansion of this crop in Brazil in recent decades has generated concerns about its environmental impacts. To assess these impacts, two representative chains supplying soybeans to Europe were identified: Center West (CW) and Southern (SO) Brazil. Each supply chain was analyzed using Life Cycle Assessment methodology. We considered different levels of use of chemical and organic fertilizers, pesticides and machinery, different distances for transportation of inputs and different yield levels. Because transportation contributed strongly to environmental impacts, a detailed study was performed to identify the routes used to transport soybeans to seaports. Additionally, we considered different levels of land occupation and land transformation to represent the impact of deforestation in the CW region. Environmental impacts were calculated for 1000 kg of soybean up to and including the delivery to Europe at the seaport in Rotterdam, at 13% humidity. Overall results showed that the impacts are greater for CW than for SO for all impact categories studied, including acidification (7.7 and 5.3 kg SO(2) eq., respectively), climate change (959 and 510 kg CO(2) eq.), cumulative energy demand (12,634 and 6,999 MJ) and terrestrial ecotoxicity (4.9 and 3.1 kg 1,4-DCB eq.), except eutrophication and land occupation. The same trend was observed for the crop-production stage. Efforts to reduce chemical fertilizers and diesel consumption can reduce CO(2) emissions. Although deforestation for crop production has decreased in recent years, the contribution of deforestation to climate change and cumulative energy demand remains significant. In the CW scenario deforestation contributed 29% to climate change and 20% to cumulative energy demand. Results also showed that although there are different transportation options in Brazil, the current

  15. The estimation of soil parameters using observations on crop biophysical variables and the crop model STICS improve the predictions of agro environmental variables.

    NASA Astrophysics Data System (ADS)

    Varella, H.-V.

    2009-04-01

    Dynamic crop models are very useful to predict the behavior of crops in their environment and are widely used in a lot of agro-environmental work. These models have many parameters and their spatial application require a good knowledge of these parameters, especially of the soil parameters. These parameters can be estimated from soil analysis at different points but this is very costly and requires a lot of experimental work. Nevertheless, observations on crops provided by new techniques like remote sensing or yield monitoring, is a possibility for estimating soil parameters through the inversion of crop models. In this work, the STICS crop model is studied for the wheat and the sugar beet and it includes more than 200 parameters. After a previous work based on a large experimental database for calibrate parameters related to the characteristics of the crop, a global sensitivity analysis of the observed variables (leaf area index LAI and absorbed nitrogen QN provided by remote sensing data, and yield at harvest provided by yield monitoring) to the soil parameters is made, in order to determine which of them have to be estimated. This study was made in different climatic and agronomic conditions and it reveals that 7 soil parameters (4 related to the water and 3 related to the nitrogen) have a clearly influence on the variance of the observed variables and have to be therefore estimated. For estimating these 7 soil parameters, a Bayesian data assimilation method is chosen (because of available prior information on these parameters) named Importance Sampling by using observations, on wheat and sugar beet crop, of LAI and QN at various dates and yield at harvest acquired on different climatic and agronomic conditions. The quality of parameter estimation is then determined by comparing the result of parameter estimation with only prior information and the result with the posterior information provided by the Bayesian data assimilation method. The result of the

  16. Precision agriculture: introduction to the spatial and temporal variability of environmental quality.

    PubMed

    Bouma, J

    1997-01-01

    Precision agriculture aims at adjusting and fine-tuning land and crop management to the needs of plants within heterogeneous fields. Production aspects have to be balanced against environmental threshold values and modern information technology has made it possible to devise operational field systems. A reactive approach is described, using yield maps and sensors. A proactive approach uses simulation modelling of plant growth and solute fluxes to predict optimal timing of management practices. Precision agriculture, combining both approaches, is seen as making a major contribution towards the development of sustainable agricultural production systems.

  17. Characterization of Chlorinated Aliphatic Hydrocarbons and Environmental Variables in a Shallow Groundwater in Shanghai Using Kriging Interpolation and Multifactorial Analysis

    PubMed Central

    Lu, Qiang; Luo, Qi Shi; Li, Hui; Liu, Yong Di; Gu, Ji Dong; Fei Lin, Kuang

    2015-01-01

    CAHs, as a cleaning solvent, widely contaminated shallow groundwater with the development of manufacturing in China's Yangtze River Delta. This study focused on the distribution of CAHs, and correlations between CAHs and environmental variables in a shallow groundwater in Shanghai, using kriging interpolation and multifactorial analysis. The results showed that the overall CAHs plume area (above DIV) was approximately 9,000 m2 and located in the 2–4 m underground, DNAPL was accumulated at an area of approximately 1,400 m2 and located in the 6-8m sandy silt layer on the top of the muddy silty clay. Heatmap of PPC for CAHs and environmental variables showed that the correlation between “Fe2+” and most CAHs such as “1,1,1-TCA”, “1,1-DCA”, “1,1-DCE” and “%TCA” were significantly positive (p<0.001), but “%CA” and/or “%VC” was not, and “Cl-” was significantly positive correlated with “1,1-DCA” and “1,1-DCE” (p<0.001). The PCA demonstrated that the relative proportions of CAHs in groundwater were mostly controlled by the sources and the natural attenuation. In conclusion, the combination of geographical and chemometrics was helpful to establishing an aerial perspective of CAHs and identifying reasons for the accumulation of toxic dechlorination intermediates, and could become a useful tool for characterizing contaminated sites in general. PMID:26565796

  18. Effects of vegetation, a clay cap and environmental variables on 222Rn fluence rate from reclaimed U mill tailings.

    PubMed

    Morris, R C; Fraley, L

    1989-04-01

    We measured 222Rn fluence rate and several environmental variables on two plots with U mill tailings buried beneath 30 cm of overburden and 20 cm of topsoil. An additional 30 cm of clay covered the tailings on one plot and each plot was subdivided into bare soil and vegetated subplots. We used linear correlation, two-way ANOVA and stepwise multiple regression to analyze the effects of the plot characteristics and the environmental variables on 222Rn fluence rate. The most important effect on 222Rn fluence rates from these plots was the combination of a clay cap and a vegetated surface. The mean annual fluence rate from the plot having both of these characteristics (520 +/- 370 mBq m-2 s-1) was over three times that of the vegetated plot without a clay cap (170 +/- 130 mBq m-2 s-1) and 18 times that of the bare plot with a clay cap (29 +/- 13 mBq m-2 s-1). The interaction effect may have been due to the growth of roots in the moist clay and active transport of dissolved 222Rn to the surface in water. This speculation is supported by the observation that on vegetated plots with a clay cap, moisture in the clay enhanced the fluence rate.

  19. Characterization of Chlorinated Aliphatic Hydrocarbons and Environmental Variables in a Shallow Groundwater in Shanghai Using Kriging Interpolation and Multifactorial Analysis.

    PubMed

    Lu, Qiang; Luo, Qi Shi; Li, Hui; Liu, Yong Di; Gu, Ji Dong; Lin, Kuang Fei; Fei Lin, Kuang

    2015-01-01

    CAHs, as a cleaning solvent, widely contaminated shallow groundwater with the development of manufacturing in China's Yangtze River Delta. This study focused on the distribution of CAHs, and correlations between CAHs and environmental variables in a shallow groundwater in Shanghai, using kriging interpolation and multifactorial analysis. The results showed that the overall CAHs plume area (above DIV) was approximately 9,000 m(2) and located in the 2-4 m underground, DNAPL was accumulated at an area of approximately 1,400 m(2) and located in the 6-8m sandy silt layer on the top of the muddy silty clay. Heatmap of PPC for CAHs and environmental variables showed that the correlation between "Fe(2+)" and most CAHs such as "1,1,1-TCA", "1,1-DCA", "1,1-DCE" and "%TCA" were significantly positive (p<0.001), but "%CA" and/or "%VC" was not, and "Cl-" was significantly positive correlated with "1,1-DCA" and "1,1-DCE" (p<0.001). The PCA demonstrated that the relative proportions of CAHs in groundwater were mostly controlled by the sources and the natural attenuation. In conclusion, the combination of geographical and chemometrics was helpful to establishing an aerial perspective of CAHs and identifying reasons for the accumulation of toxic dechlorination intermediates, and could become a useful tool for characterizing contaminated sites in general.

  20. The environmental variables that impact human decomposition in terrestrially exposed contexts within Canada.

    PubMed

    Cockle, Diane Lyn; Bell, Lynne S

    2017-03-01

    Little is known about the nature and trajectory of human decomposition in Canada. This study involved the examination of 96 retrospective police death investigation cases selected using the Canadian ViCLAS (Violent Crime Linkage Analysis System) and sudden death police databases. A classification system was designed and applied based on the latest visible stages of autolysis (stages 1-2), putrefaction (3-5) and skeletonisation (6-8) observed. The analysis of the progression of decomposition using time (Post Mortem Interval (PMI) in days) and temperature accumulated-degree-days (ADD) score found considerable variability during the putrefaction and skeletonisation phases, with poor predictability noted after stage 5 (post bloat). The visible progression of decomposition outdoors was characterized by a brown to black discolouration at stage 5 and remnant desiccated black tissue at stage 7. No bodies were totally skeletonised in under one year. Mummification of tissue was rare with earlier onset in winter as opposed to summer, considered likely due to lower seasonal humidity. It was found that neither ADD nor the PMI were significant dependent variables for the decomposition score with correlations of 53% for temperature and 41% for time. It took almost twice as much time and 1.5 times more temperature (ADD) for the set of cases exposed to cold and freezing temperatures (4°C or less) to reach putrefaction compared to the warm group. The amount of precipitation and/or clothing had a negligible impact on the advancement of decomposition, whereas the lack of sun exposure (full shade) had a small positive effect. This study found that the poor predictability of onset and the duration of late stage decomposition, combined with our limited understanding of the full range of variables which influence the speed of decomposition, makes PMI estimations for exposed terrestrial cases in Canada unreliable, but also calls in question PMI estimations elsewhere.

  1. Multi-scale responses of scattering layers to environmental variability in Monterey Bay, California

    NASA Astrophysics Data System (ADS)

    Urmy, Samuel S.; Horne, John K.

    2016-07-01

    A 38 kHz upward-facing echosounder was deployed on the seafloor at a depth of 875 m in Monterey Bay, CA, USA (36° 42.748‧N, 122° 11.214‧W) from 27 February 2009 to 18 August 2010. This 18-month record of acoustic backscatter was compared to oceanographic time series from a nearby data buoy to investigate the responses of animals in sound-scattering layers to oceanic variability at seasonal and sub-seasonal time scales. Pelagic animals, as measured by acoustic backscatter, moved higher in the water column and decreased in abundance during spring upwelling, attributed to avoidance of a shoaling oxycline and advection offshore. Seasonal changes were most evident in a non-migrating scattering layer near 500 m depth that disappeared in spring and reappeared in summer, building to a seasonal maximum in fall. At sub-seasonal time scales, similar responses were observed after individual upwelling events, though they were much weaker than the seasonal relationship. Correlations of acoustic backscatter with oceanographic variability also differed with depth. Backscatter in the upper water column decreased immediately following upwelling, then increased approximately 20 days later. Similar correlations existed deeper in the water column, but at increasing lags, suggesting that near-surface productivity propagated down the water column at 10-15 m d-1, consistent with sinking speeds of marine snow measured in Monterey Bay. Sub-seasonal variability in backscatter was best correlated with sea-surface height, suggesting that passive physical transport was most important at these time scales.

  2. miRNAs: Major modulators for crop growth and development under abiotic stresses.

    PubMed

    Noman, Ali; Fahad, Shah; Aqeel, Muhammad; Ali, Usman; Amanullah; Anwar, Sumera; Baloch, Shahbaz Khan; Zainab, Madiha

    2017-02-25

    Cumulatively, biotic and abiotic stresses of various magnitudes can decrease the production of crops by 70%. miRNAs have emerged as a genetic tool with enormous potential that can be exploited to understand stress tolerance at the molecular level and eventually regulate stress in crops. Plant miRNA targets frequently fit into diverse families of TFs that control the expression of genes related to a certain trait. As key machinery in gene regulatory networks, it is agreed that a broad understanding of miRNAs will greatly increase our understanding of plant responses to environmental stresses. miRNA-led stress regulatory networks are being considered as novel tools for the development of abiotic stress tolerance in crops. At this time, we need to expand our knowledge about the modulatory role of miRNAs during environmental fluctuations. It has become exceedingly clear that with increased understanding of the role of miRNAs during stress, the techniques for using miRNA-mediated gene regulation to enhance plant stress tolerance will become more effective and reliable. In this review we present: (1) miRNAs as a potential avenue for the modulation of abiotic stresses, and (2) summarize the research progress regarding plant responses to stress. Current progress is explained through discussion of the identification and validation of several miRNAs that enhance crop tolerance of salinity, drought, etc., while missing links on different aspects of miRNAs related to abiotic stress tolerance are noted.

  3. Jasmonate signaling in plant development and defense response to multiple (a)biotic stresses.

    PubMed

    Santino, Angelo; Taurino, Marco; De Domenico, Stefania; Bonsegna, Stefania; Poltronieri, Palmiro; Pastor, Victoria; Flors, Victor

    2013-07-01

    Plants frequently live in environments characterized by the presence of simultaneous and different stresses. The intricate and finely tuned molecular mechanisms activated by plants in response to abiotic and biotic environmental factors are not well understood, and less is known about the integrative signals and convergence points activated by plants in response to multiple (a)biotic stresses. Phytohormones play a key role in plant development and response to (a)biotic stresses. Among these, one of the most important signaling molecules is an oxylipin, the plant hormone jasmonic acid. Oxylipins are derived from oxygenation of polyunsaturated fatty acids. Jasmonic acid and its volatile derivative methyl jasmonate have been considered for a long time to be the bioactive forms due to their physiological effects and abundance in the plant. However, more recent studies showed unambiguously that they are only precursors of the active forms represented by some amino acid conjugates. Upon developmental or environmental stimuli, jasmonates are synthesized and accumulate transiently. Upon perception, jasmonate signal transduction process is finely tuned by a complex mechanism comprising specific repressor proteins which in turn control a number of transcription factors regulating the expression of jasmonate responsive genes. We discuss the latest discoveries about the role of jasmonates in plants resistance mechanism against biotic and abiotic stresses. Finally, the deep interplay of different phytohormones in stresses signaling will be also discussed.

  4. Unraveling the role of fungal symbionts in plant abiotic stress tolerance

    PubMed Central

    Singh, Lamabam Peter

    2011-01-01

    Fungal symbionts have been found to be associated with every plant studied in the natural ecosystem, where they colonize and reside entirely or partially in the internal tissues of their host plant. Fungal endophytes can express/form a range of different lifestyle/relationships with different host including symbiotic, mutualistic, commensalistic and parasitic in response to host genotype and environmental factors. In mutualistic association fungal endophyte can enhance growth, increase reproductive success and confer biotic and abiotic stress tolerance to its host plant. Since abiotic stress such as, drought, high soil salinity, heat, cold, oxidative stress and heavy metal toxicity is the common adverse environmental conditions that affect and limit crop productivity worldwide. It may be a promising alternative strategy to exploit fungal endophytes to overcome the limitations to crop production brought by abiotic stress. There is an increasing interest in developing the potential biotechnological applications of fungal endophytes for improving plant stress tolerance and sustainable production of food crops. Here we have described the fungal symbioses, fungal symbionts and their role in abiotic stress tolerance. A putative mechanism of stress tolerance by symbionts has also been covered. PMID:21512319

  5. The Baltic Sea: Geophysical and geochemical properties of Holocene sediment sequences as indicators of past environmental variability

    NASA Astrophysics Data System (ADS)

    Lenz, Conny; Reinholdsson, Maja; Zillén, Lovisa; Conley, Daniel J.; Snowball, Ian

    2010-05-01

    The Baltic Sea has undergone large environmental changes since the retreat of the Weischselian Ice-sheet. In the Late Glacial Period and the early Holocene these changes were most likely caused by natural environmental changes (i.e. changes in the morphology and depths of the Baltic basin and the sills). In more recent time anthropogenic impacts have become more important as a possible and likely cause for changes. During the whole Holocene period climate variability played an important role. However, the relative importance between humans and nature is largely unknown. Here we present the results of a combined geophysical and geochemical study on selected sediment sequences from the Baltic Sea within the two BONUS (Baltic Organisations Network For Funding Science) funded projects HYPER (HYPoxia mitigation for Baltic Sea Ecosystem Restoration) and Baltic GAS (GAS storage and effects of climate change and eutrophication). The over-all aim of these projects is to understand large-scale Baltic Sea ecosystem responses to environmental, climate and anthropogenic forcing. During two Baltic Sea research cruises in 2009 long sediment cores from 8 different locations were recovered. We present preliminary results from one site (LL19) located in the north central Baltic Proper at 169 m water depth. The Littorina Sea sediment record (i.e. the last c. 8000 years) is characterised by alternating periods of homogenised sediments (indicative of oxic conditions) and laminated sediments (indicative of hypoxic/anoxic conditions). Mineral magnetic properties illustrate clear changes between laminated and non-laminated sections of the core. The concentration of ferrimagnetic minerals, as revealed by initial magnetic susceptibility (χ) and saturation isothermal remanent magnetization (SIRM) is variable. The laminated sections in particular show high concentrations and to reveal the origin of the ferrimagnetic signal additional magnetic properties were measured, specifically the

  6. Histone variants and chromatin assembly in plant abiotic stress responses.

    PubMed

    Zhu, Yan; Dong, Aiwu; Shen, Wen-Hui

    2013-01-01

    Genome organization into nucleosomes and higher-order chromatin structures has profound implications for the regulation of gene expression, DNA replication and repair. The structure of chromatin can be remodeled by several mechanisms; among others, nucleosome assembly/disassembly and replacement of canonical histones with histone variants constitute important ones. In this review, we provide a brief description on the current knowledge about histone chaperones involved in nucleosome assembly/disassembly and histone variants in Arabidopsis thaliana. We discuss recent advances in revealing crucial functions of histone chaperones, nucleosome assembly/disassembly and histone variants in plant response to abiotic stresses. It appears that chromatin structure remodeling may provide a flexible, global and stable means for the regulation of gene transcription to help plants more effectively cope with environmental stresses. This article is part of a Special Issue entitled: Histone chaperones and chromatin assembly.

  7. The Tropical Cyclone Response to Structural and Temporal Variability in the Environmental Wind Profile

    NASA Astrophysics Data System (ADS)

    Onderlinde, Matthew J.

    The aim of this dissertation is to attain a better understanding of how tropical cyclones (TCs) respond to variations in the three-dimensional environmental wind field. Much attention has been given to the impact of environmental wind shear in the 850 -- 200 hPa layer on tropical cyclones. However, even with the same magnitude of shear, helicity in this layer can vary significantly. A new parameter is presented, the tropical cyclone-relative environmental helicity (TCREH). Positive TCREH leads to a tilted storm that enhances local storm scale helicity in regions of convection within the TC. Initially we proposed that this enhanced local scale helicity may allow for more robust and longer lasting convection which is more effective at generating latent heat and subsequent TC intensification. Further investigation shows that this is a secondary influence on TC intensity and that variations in the azimuthal and radial position of convection in the TC play a stronger role. Vertical tilt of the vortex is often attributed to wind shear. Different values of helicity modulate this tilt and certain tilt configurations are more favorable for development or intensification than others, suggesting that mean positive environmental helicity is more favorable for development and intensification than mean negative helicity. Idealized modeling simulations demonstrate the impact of environmental helicity on TC development and intensification. Results show that wind profiles with the same 850-200 hPa wind shear but different values of helicity lead to different rates of development. TCREH also is computed from Era-Interim reanalysis (1979 -- 2011) and GFS analyses (2004 -- 2011) to determine if a significant signal exists between TCREH and TC intensification. Mean annular helicity is averaged over various time periods and correlated with the TC intensity change during those periods. Results suggest a weak but statistically significant correlation between environmental helicity and TC

  8. Environmentally induced changes in correlated responses to selection reveal variable pleiotropy across a complex genetic network.

    PubMed

    Sikkink, Kristin L; Reynolds, Rose M; Cresko, William A; Phillips, Patrick C

    2015-05-01

    Selection in novel environments can lead to a coordinated evolutionary response across a suite of characters. Environmental conditions can also potentially induce changes in the genetic architecture of complex traits, which in turn could alter the pattern of the multivariate response to selection. We describe a factorial selection experiment using the nematode Caenorhabditis remanei in which two different stress-related phenotypes (heat and oxidative stress resistance) were selected under three different environmental conditions. The pattern of covariation in the evolutionary response between phenotypes or across environments differed depending on the environment in which selection occurred, including asymmetrical responses to selection in some cases. These results indicate that variation in pleiotropy across the stress response network is highly sensitive to the external environment. Our findings highlight the complexity of the interaction between genes and environment that influences the ability of organisms to acclimate to novel environments. They also make clear the need to identify the underlying genetic basis of genetic correlations in order understand how patterns of pleiotropy are distributed across complex genetic networks.

  9. The spatial patterns of soil respiration regulated by biological and environmental variables along a precipitation gradient

    NASA Astrophysics Data System (ADS)

    Xu, W.; Li, X.; Liu, W.; Li, L.; Hou, L.; Shi, H.; Xia, J.; Liu, D.; Zhang, H.; Chen, Y.; Cai, W.; Fu, Y.; Yuan, W.

    2015-12-01

    Precipitation is a key environmental factor in determining ecosystem structure and function. Knowledge of how soil respiration responds to climate change (precipitation etc.) and human activities (grazing, clipping etc.) is crucial for assessing the impacts of climate change on terrestrial ecosystems and for improving model simulations and predictions of future global C cycling in response to human activities. In this study, we examined the spatial patterns of soil respiration along a precipitation gradient from 176.7 mm to 398.1 mm. Our results showed that soil respiration increased linearly with increasing mean annual precipitation. The increasing trend was similar to the trends of shoot biomass, litter biomass and soil total C content along the precipitation gradient. Root biomass was described by quadratic curves along the increasing precipitation gradient and may result from the tradeoff of environmental regulation and carbon allocation. Our results indicated that precipitation was the primary controlling factor in determining the spatial pattern of soil respiration. The linear/nonlinear relationships in this study describing the variations of the ecosystem carbon process with precipitation could be useful for model development, parameterization and validation at the regional scale to improve predictions of how the carbon process in grasslands responds to climate change, land use and grassland management.

  10. Potential bud bank responses to apical meristem damage and environmental variables: matching or complementing axillary meristems?

    PubMed

    Klimešová, Jitka; Malíková, Lenka; Rosenthal, Jonathan; Šmilauer, Petr

    2014-01-01

    Soil nutrients, dormant axillary meristem availability, and competition can influence plant tolerance to damage. However, the role of potential bud banks (adventitious meristems initiated only after injury) is not known. Examining Central European field populations of 22 species of short-lived monocarpic herbs exposed to various sources of damage, we hypothesized that: (1) with increasing injury severity, the number of axillary branches would decrease, due to axillary meristem limitation, whereas the number of adventitious shoots (typically induced by severe injury) would increase; (2) favorable environmental conditions would allow intact plants to branch more, resulting in stronger axillary meristem limitation than in unfavorable conditions; and (3) consequently, adventitious sprouting would be better enabled in favorable than unfavorable conditions. We found strong support for the first hypothesis, only limited support for the second, and none for the third. Our results imply that whereas soil nutrients and competition marginally influence plant tolerance to damage, potential bud banks enable plants to overcome meristem limitation from severe damage, and therefore better tolerate it. All the significant effects were found in intraspecific comparisons, whereas interspecific differences were not found. Monocarpic plants with potential bud banks therefore represent a distinct strategy occupying a narrow environmental niche. The disturbance regime typical for this niche remains to be examined, as do the costs associated with the banks of adventitious and axillary reserve meristems.

  11. [Environmental and genetic variables related with alterations in language acquisition in early childhood].

    PubMed

    Moriano-Gutierrez, A; Colomer-Revuelta, J; Sanjuan, J; Carot-Sierra, J M

    2017-01-01

    Introduccion. Los problemas en la correcta adquisicion del lenguaje se han estudiado mucho, pero con escasas conclusiones globales; a ello contribuye la variabilidad individual, la existencia de diferentes medidas para evaluar el lenguaje y a que en su desarrollo participa una compleja red de factores geneticos y ambientales. Objetivo. Revisar las variables ambientales y geneticas que se han investigado hasta la actualidad, para comprender mejor las causas de los trastornos especificos del lenguaje y crear nuevas evidencias que faciliten la elaboracion de sistemas de deteccion precoz de estos trastornos. Desarrollo. Dentro de las variables ambientales relacionadas con peor desarrollo en el lenguaje infantil estan el sexo masculino, un nivel educacional maternal bajo, una historia familiar de problemas en el lenguaje o problemas psiquiatricos, los problemas perinatales y los problemas de salud en la infancia. El bilinguismo parece ser un factor protector. El temperamento y el lenguaje tienen relacion. Dentro de los factores geneticos existen ya varios genes especificos asociados con el lenguaje, dos de ellos con una influencia mayor en su adquisicion fisiologica: FOXP2 y CNTNAP2. Los otros genes mas relacionados con trastornos especificos del lenguaje son ATP2C2, CMIP, ROBO2, ZNF277 y NOP9. Conclusiones. La clave para entender el desarrollo de los trastornos especificos del lenguaje radica en llegar a comprender el verdadero papel que desempeñan los genes en la ontogenia, regulando los diferentes procesos de desarrollo y como este papel se ve modulado por el ambiente.

  12. High frequency variability of environmental drivers determining benthic community dynamics in headwater streams.

    PubMed

    Snell, M A; Barker, P A; Surridge, B W J; Large, A R G; Jonczyk, J; Benskin, C McW H; Reaney, S; Perks, M T; Owen, G J; Cleasby, W; Deasy, C; Burke, S; Haygarth, P M

    2014-07-01

    Headwater streams are an important feature of the landscape, with their diversity in structure and associated ecological function providing a potential natural buffer against downstream nutrient export. Phytobenthic communities, dominated in many headwaters by diatoms, must respond to physical and chemical parameters that can vary in magnitude within hours, whereas the ecological regeneration times are much longer. How diatom communities develop in the fluctuating, dynamic environments characteristic of headwaters is poorly understood. Deployment of near-continuous monitoring technology in sub-catchments of the River Eden, NW England, provides the opportunity for measurement of temporal variability in stream discharge and nutrient resource supply to benthic communities, as represented by monthly diatom samples collected over two years. Our data suggest that the diatom communities and the derived Trophic Diatom Index, best reflect stream discharge conditions over the preceding 18-21 days and Total Phosphorus concentrations over a wider antecedent window of 7-21 days. This is one of the first quantitative assessments of long-term diatom community development in response to continuously-measured stream nutrient concentration and discharge fluctuations. The data reveal the sensitivity of these headwater communities to mean conditions prior to sampling, with flow as the dominant variable. With sufficient understanding of the role of antecedent conditions, these methods can be used to inform interpretation of monitoring data, including those collected under the European Water Framework Directive and related mitigation efforts.

  13. Sinking jelly-carbon unveils potential environmental variability along a continental margin.

    PubMed

    Lebrato, Mario; Molinero, Juan-Carlos; Cartes, Joan E; Lloris, Domingo; Mélin, Frédéric; Beni-Casadella, Laia

    2013-01-01

    Particulate matter export fuels benthic ecosystems in continental margins and the deep sea, removing carbon from the upper ocean. Gelatinous zooplankton biomass provides a fast carbon vector that has been poorly studied. Observational data of a large-scale benthic trawling survey from 1994 to 2005 provided a unique opportunity to quantify jelly-carbon along an entire continental margin in the Mediterranean Sea and to assess potential links with biological and physical variables. Biomass depositions were sampled in shelves, slopes and canyons with peaks above 1000 carcasses per trawl, translating to standing stock values between 0.3 and 1.4 mg C m(2) after trawling and integrating between 30,000 and 175,000 m(2) of seabed. The benthopelagic jelly-carbon spatial distribution from the shelf to the canyons may be explained by atmospheric forcing related with NAO events and dense shelf water cascading, which are both known from the open Mediterranean. Over the decadal scale, we show that the jelly-carbon depositions temporal variability paralleled hydroclimate modifications, and that the enhanced jelly-carbon deposits are connected to a temperature-driven system where chlorophyll plays a minor role. Our results highlight the importance of gelatinous groups as indicators of large-scale ecosystem change, where jelly-carbon depositions play an important role in carbon and energy transport to benthic systems.

  14. Sinking Jelly-Carbon Unveils Potential Environmental Variability along a Continental Margin

    PubMed Central

    Lebrato, Mario; Molinero, Juan-Carlos; Cartes, Joan E.; Lloris, Domingo; Mélin, Frédéric; Beni-Casadella, Laia

    2013-01-01

    Particulate matter export fuels benthic ecosystems in continental margins and the deep sea, removing carbon from the upper ocean. Gelatinous zooplankton biomass provides a fast carbon vector that has been poorly studied. Observational data of a large-scale benthic trawling survey from 1994 to 2005 provided a unique opportunity to quantify jelly-carbon along an entire continental margin in the Mediterranean Sea and to assess potential links with biological and physical variables. Biomass depositions were sampled in shelves, slopes and canyons with peaks above 1000 carcasses per trawl, translating to standing stock values between 0.3 and 1.4 mg C m2 after trawling and integrating between 30,000 and 175,000 m2 of seabed. The benthopelagic jelly-carbon spatial distribution from the shelf to the canyons may be explained by atmospheric forcing related with NAO events and dense shelf water cascading, which are both known from the open Mediterranean. Over the decadal scale, we show that the jelly-carbon depositions temporal variability paralleled hydroclimate modifications, and that the enhanced jelly-carbon deposits are connected to a temperature-driven system where chlorophyll plays a minor role. Our results highlight the importance of gelatinous groups as indicators of large-scale ecosystem change, where jelly-carbon depositions play an important role in carbon and energy transport to benthic systems. PMID:24367499

  15. Influence of PAHs among other coastal environmental variables on total and PAH-degrading bacterial communities.

    PubMed

    Sauret, Caroline; Tedetti, Marc; Guigue, Catherine; Dumas, Chloé; Lami, Raphaël; Pujo-Pay, Mireille; Conan, Pascal; Goutx, Madeleine; Ghiglione, Jean-François

    2016-03-01

    We evaluated the relative impact of anthropogenic polycyclic aromatic hydrocarbons (PAHs) among biogeochemical variables on total, metabolically active, and PAH bacterial communities in summer and winter in surface microlayer (SML) and subsurface seawaters (SSW) across short transects along the NW Mediterranean coast from three harbors, one wastewater effluent, and one nearshore observatory reference site. At both seasons, significant correlations were found between dissolved total PAH concentrations and PAH-degrading bacteria that formed a gradient from the shore to nearshore waters. Accumulation of PAH degraders was particularly high in the SML, where PAHs accumulated. Harbors and wastewater outfalls influenced drastically and in a different way the total and active bacterial community structure, but they only impacted the communities from the nearshore zone (<2 km from the shore). By using direct multivariate statistical analysis, we confirmed the significant effect of PAH concentrations on the spatial and temporal dynamic of total and active communities in this area, but this effect was putted in perspective by the importance of other biogeochemical variables.

  16. Temporal dynamics of biotic and abiotic drivers of litter decomposition.

    PubMed

    García-Palacios, Pablo; Shaw, E Ashley; Wall, Diana H; Hättenschwiler, Stephan

    2016-05-01

    Climate, litter quality and decomposers drive litter decomposition. However, little is known about whether their relative contribution changes at different decomposition stages. To fill this gap, we evaluated the relative importance of leaf litter polyphenols, decomposer communities and soil moisture for litter C and N loss at different stages throughout the decomposition process. Although both microbial and nematode communities regulated litter C and N loss in the early decomposition stages, soil moisture and legacy effects of initial differences in litter quality played a major role in the late stages of the process. Our results provide strong evidence for substantial shifts in how biotic and abiotic factors control litter C and N dynamics during decomposition. Taking into account such temporal dynamics will increase the predictive power of decomposition models that are currently limited by a single-pool approach applying control variables uniformly to the entire decay process.

  17. Landrace Germplasm for Improving Yield and Abiotic Stress Adaptation.

    PubMed

    Dwivedi, Sangam L; Ceccarelli, Salvatore; Blair, Matthew W; Upadhyaya, Hari D; Are, Ashok K; Ortiz, Rodomiro

    2016-01-01

    Plant landraces represent heterogeneous, local adaptations of domesticated species, and thereby provide genetic resources that meet current and new challenges for farming in stressful environments. These local ecotypes can show variable phenology and low-to-moderate edible yield, but are often highly nutritious. The main contributions of landraces to plant breeding have been traits for more efficient nutrient uptake and utilization, as well as useful genes for adaptation to stressful environments such as water stress, salinity, and high temperatures. We propose that a systematic landrace evaluation may define patterns of diversity, which will facilitate identifying alleles for enhancing yield and abiotic stress adaptation, thus raising the productivity and stability of staple crops in vulnerable environments.

  18. Effects of environmental variables on surface temperature of breeding adult female northern elephant seals, Mirounga angustirostris, and pups.

    PubMed

    Codde, Sarah A; Allen, Sarah G; Houser, Dorian S; Crocker, Daniel E

    2016-10-01

    Pinnipeds spend extended periods of time on shore during breeding, and some temperate species retreat to the water if exposed to high ambient temperatures. However, female northern elephant seals (Mirounga angustirostris) with pups generally avoid the water, presumably to minimize risks to pups or male harassment. Little is known about how ambient temperature affects thermoregulation of well insulated females while on shore. We used a thermographic camera to measure surface temperature (Ts) of 100 adult female elephant seals and their pups during the breeding season at Point Reyes National Seashore, yielding 782 thermograms. Environmental variables were measured by an onsite weather station. Environmental variables, especially solar radiation and ambient temperature, were the main determinants of mean and maximum Ts of both females and pups. An average of 16% of the visible surface of both females and pups was used as thermal windows to facilitate heat loss and, for pups, this area increased with solar radiation. Thermal window area of females increased with mean Ts until approximately 26°C and then declined. The Ts of both age classes were warmer than ambient temperature and had a large thermal gradient with the environment (female mean 11.2±0.2°C; pup mean 14.2±0.2°C). This large gradient suggests that circulatory adjustments to bypass blubber layers were sufficient to allow seals to dissipate heat under most environmental conditions. We observed the previously undescribed behavior of females and pups in the water and determined that solar radiation affected this behavior. This may have been possible due to the calm waters at the study site, which reduced the risk of neonates drowning. These results may predict important breeding habitat features for elephant seals as solar radiation and ambient temperatures change in response to changing climate.

  19. Effects of seasonal meteorological variables on E. coli persistence in livestock faeces and implications for environmental and human health

    PubMed Central

    Oliver, David M.; Page, Trevor

    2016-01-01

    Agriculture contributes significant volumes of livestock faeces to land. Understanding how faecal microbes respond to shifts in meteorological patterns of contrasting seasons is important in order to gauge how environmental (and human health) risks may alter under a changing climate. The aim of this study was to: (i) quantify the temporal pattern of E. coli growth within dairy faeces post defecation; and (ii) derive E. coli seasonal population change profiles associated with contrasting environmental drivers. Evaluation of the die-off dynamics of E. coli revealed that a treatment mimicking drought and warming conditions significantly enhanced persistence relative to E. coli in faeces that were exposed to field conditions, and that this pattern was consistent across consecutive years. The internal temperature of faeces was important in driving the rate of change in the E. coli population in the immediate period post defecation, with most E. coli activity (as either die-off or growth) occurring at low dry matter content. This study highlighted that the use of seasonal E. coli persistence profiles should be approached with caution when modelling environmental and human health risks given the increased likelihood of atypical seasonal meteorological variables impacting on E. coli growth and die-off. PMID:27845409

  20. Effects of seasonal meteorological variables on E. coli persistence in livestock faeces and implications for environmental and human health

    NASA Astrophysics Data System (ADS)

    Oliver, David M.; Page, Trevor

    2016-11-01

    Agriculture contributes significant volumes of livestock faeces to land. Understanding how faecal microbes respond to shifts in meteorological patterns of contrasting seasons is important in order to gauge how environmental (and human health) risks may alter under a changing climate. The aim of this study was to: (i) quantify the temporal pattern of E. coli growth within dairy faeces post defecation; and (ii) derive E. coli seasonal population change profiles associated with contrasting environmental drivers. Evaluation of the die-off dynamics of E. coli revealed that a treatment mimicking drought and warming conditions significantly enhanced persistence relative to E. coli in faeces that were exposed to field conditions, and that this pattern was consistent across consecutive years. The internal temperature of faeces was important in driving the rate of change in the E. coli population in the immediate period post defecation, with most E. coli activity (as either die-off or growth) occurring at low dry matter content. This study highlighted that the use of seasonal E. coli persistence profiles should be approached with caution when modelling environmental and human health risks given the increased likelihood of atypical seasonal meteorological variables impacting on E. coli growth and die-off.

  1. Effects of seasonal meteorological variables on E. coli persistence in livestock faeces and implications for environmental and human health.

    PubMed

    Oliver, David M; Page, Trevor

    2016-11-15

    Agriculture contributes significant volumes of livestock faeces to land. Understanding how faecal microbes respond to shifts in meteorological patterns of contrasting seasons is important in order to gauge how environmental (and human health) risks may alter under a changing climate. The aim of this study was to: (i) quantify the temporal pattern of E. coli growth within dairy faeces post defecation; and (ii) derive E. coli seasonal population change profiles associated with contrasting environmental drivers. Evaluation of the die-off dynamics of E. coli revealed that a treatment mimicking drought and warming conditions significantly enhanced persistence relative to E. coli in faeces that were exposed to field conditions, and that this pattern was consistent across consecutive years. The internal temperature of faeces was important in driving the rate of change in the E. coli population in the immediate period post defecation, with most E. coli activity (as either die-off or growth) occurring at low dry matter content. This study highlighted that the use of seasonal E. coli persistence profiles should be approached with caution when modelling environmental and human health risks given the increased likelihood of atypical seasonal meteorological variables impacting on E. coli growth and die-off.

  2. Remote-sensing reflectance determinations in the coastal ocean environment: impact of instrumental characteristics and environmental variability.

    PubMed

    Toole, D A; Siegel, D A; Menzies, D W; Neumann, M J; Smith, R C

    2000-01-20

    Three independent ocean color sampling methodologies are compared to assess the potential impact of instrumental characteristics and environmental variability on shipboard remote-sensing reflectance observations from the Santa Barbara Channel, California. Results indicate that under typical field conditions, simultaneous determinations of incident irradiance can vary by 9-18%, upwelling radiance just above the sea surface by 8-18%, and remote-sensing reflectance by 12-24%. Variations in radiometric determinations can be attributed to a variety of environmental factors such as Sun angle, cloud cover, wind speed, and viewing geometry; however, wind speed is isolated as the major source of uncertainty. The above-water approach to estimating water-leaving radiance and remote-sensing reflectance is highly influenced by environmental factors. A model of the role of wind on the reflected sky radiance measured by an above-water sensor illustrates that, for clear-sky conditions and wind speeds greater than 5 m/s, determinations of water-leaving radiance at 490 nm are undercorrected by as much as 60%. A data merging procedure is presented to provide sky radiance correction parameters for above-water remote-sensing reflectance estimates. The merging results are consistent with statistical and model findings and highlight the importance of multiple field measurements in developing quality coastal oceanographic data sets for satellite ocean color algorithm development and validation.

  3. Exploring chemical variables in Ligustrum lucidum Ait. F. tricolor (rehd.) Rehd. in relation to air pollutants and environmental conditions

    SciTech Connect

    Pignata, M.L.; Canas, M.S.; Carreras, H.A.; Orellana, L.

    1997-09-01

    A diagnostic study was done on Ligustrum lucidum Ait. f. tricolor (Rehd.) Rehd. in relation to atmospheric pollutants in Cordoba city, Argentina. The study area receives regional Pollutants and was categorized taking into account traffic level, industrial density, type of industry, location of the sample point in relation to the street corner, treeless condition, and topographic level. Dried weight/fresh weight ratio (DW/FW) and specific leaf area (SLA) were calculated, and concentrations of chlorophylls, carotenoids, total sulfur, soluble proteins, malondialdehyde (MDA), and hydroperoxy conjugated dienes (HPCD) were determined in leaf samples. Sulfur content correlates positively with traffic density and SLA correlates negatively with some combinations of the categorical variables; MDA correlates positively with topographic level and total protein concentration correlates negatively with treeless condition. On the basis of our results, traffic, location of trees, type of industry, situation of a tree with respect to others, and topographic level are the environmental variables to bear in mind when selecting analogous sampling points in a passive monitoring program. An approximation to predict tree injury may be obtained by measuring DW/FW ratio, proteins, pigments, HPCD, and MDA as they are responsible for the major variability of data.

  4. Kinetics of Abiotic Uranium(VI) Reduction by Sulfide

    NASA Astrophysics Data System (ADS)

    Hyun, S.; Davis, J. A.; Hayes, K. F.

    2010-12-01

    Uranium(VI) reduction is an important process affecting the radionuclide’s fate under sulfate reducing conditions. In this work, kinetics of abiotic U(VI) reduction by dissolved sulfide was studied using a batch reactor. The effects of solution pH, dissolved carbonate, Ca(II), U(VI), and S(-II) concentration on the reduction kinetics were tested. The ranges of these experimental variables were designed to cover the variation in groundwater chemistry observed at the Old Rifle uranium mill tailings site (Colorado, USA). Dissolved U concentration was monitored as a function of time using inductively coupled plasma-mass spectrometry to measure the rate of U(VI) reduction. Solid phase reduction products were identified using X-ray diffraction, transmission electron microscopy, and X-ray absorption spectroscopy. The results showed that changes in the experimental variables significantly affected U(VI) reduction kinetics by dissolved sulfide. U(VI) reduction occurred under circumneutral pH while no reduction was observed under alkaline conditions. The reduction rate was slowed by increased dissolved carbonate concentration. One solid phase reduction product was identified as nanoscale uraninite (UO2+x(s)). Thermodynamic modeling showed that the dissolved U(VI) aqueous species changed as a function of solution conditions correlated with the change in the reduction rate. These results show that U(VI) aqueous speciation is important in determining abiotic U(VI) reduction kinetics by dissolved sulfide. This study also illustrates the potential importance of dissolved sulfide in field-scale modeling of U reactive transport, and is expected to contribute to the understanding of long-term effects of biostimulation on U transport at the Rifle site.

  5. Relationship among environmental quality variables, housing variables, and residential needs: a secondary analysis of the relationship among indoor, outdoor, and personal air (RIOPA) concentrations database

    NASA Astrophysics Data System (ADS)

    Garcia, Fausto; Shendell, Derek G.; Madrigano, Jaime

    2017-03-01

    Retrospective descriptive secondary analyses of data from relationships of indoor, outdoor, and personal air (RIOPA) study homes (in Houston, Texas; Los Angeles County, California; and, Elizabeth, New Jersey May 1999-February 2001) were conducted. Data included air exchange rates, associations between indoor and outdoor temperature and humidity, and calculated apparent temperature and humidex. Analyses examined if study homes provided optimum thermal comfort for residents during both heating and cooling seasons when compared to current American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) Standards 62/62.1 and 55. Results suggested outdoor temperature, humidex, and apparent temperature during the cooling season potentially served as indicators of indoor personal exposure to parameters of thermal comfort. Outdoor temperatures, humidex, and apparent temperature during the cooling season had statistically significant predictive abilities in predicting indoor temperature. During the heating season, only humidex in Texas and combined data across study states were statistically significant, but with weaker to moderate predicative ability. The high degree of correlation between outdoor and indoor environmental variables provided support for the validity of epidemiologic studies of weather relying on temporal comparisons. Results indicated most RIOPA study residents experienced thermal comfort; however, many values indicated how several residents may have experienced some discomfort depending on clothing and indoor activities. With climate change, increases in temperature are expected, with more days of extreme heat and humidity and, potentially harsher, longer winters. Homes being built or modernized should be created with the appropriate guidelines to provide comfort for residents daily and in extreme weather events.

  6. Relationship among environmental quality variables, housing variables, and residential needs: a secondary analysis of the relationship among indoor, outdoor, and personal air (RIOPA) concentrations database.

    PubMed

    Garcia, Fausto; Shendell, Derek G; Madrigano, Jaime

    2017-03-01

    Retrospective descriptive secondary analyses of data from relationships of indoor, outdoor, and personal air (RIOPA) study homes (in Houston, Texas; Los Angeles County, California; and, Elizabeth, New Jersey May 1999-February 2001) were conducted. Data included air exchange rates, associations between indoor and outdoor temperature and humidity, and calculated apparent temperature and humidex. Analyses examined if study homes provided optimum thermal comfort for residents during both heating and cooling seasons when compared to current American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) Standards 62/62.1 and 55. Results suggested outdoor temperature, humidex, and apparent temperature during the cooling season potentially served as indicators of indoor personal exposure to parameters of thermal comfort. Outdoor temperatures, humidex, and apparent temperature during the cooling season had statistically significant predictive abilities in predicting indoor temperature. During the heating season, only humidex in Texas and combined data across study states were statistically significant, but with weaker to moderate predicative ability. The high degree of correlation between outdoor and indoor environmental variables provided support for the validity of epidemiologic studies of weather relying on temporal comparisons. Results indicated most RIOPA study residents experienced thermal comfort; however, many values indicated how several residents may have experienced some discomfort depending on clothing and indoor activities. With climate change, increases in temperature are expected, with more days of extreme heat and humidity and, potentially harsher, longer winters. Homes being built or modernized should be created with the appropriate guidelines to provide comfort for residents daily and in extreme weather events.

  7. Relationship among environmental quality variables, housing variables, and residential needs: a secondary analysis of the relationship among indoor, outdoor, and personal air (RIOPA) concentrations database

    NASA Astrophysics Data System (ADS)

    Garcia, Fausto; Shendell, Derek G.; Madrigano, Jaime

    2016-08-01

    Retrospective descriptive secondary analyses of data from relationships of indoor, outdoor, and personal air (RIOPA) study homes (in Houston, Texas; Los Angeles County, California; and, Elizabeth, New Jersey May 1999-February 2001) were conducted. Data included air exchange rates, associations between indoor and outdoor temperature and humidity, and calculated apparent temperature and humidex. Analyses examined if study homes provided optimum thermal comfort for residents during both heating and cooling seasons when compared to current American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) Standards 62/62.1 and 55. Results suggested outdoor temperature, humidex, and apparent temperature during the cooling season potentially served as indicators of indoor personal exposure to parameters of thermal comfort. Outdoor temperatures, humidex, and apparent temperature during the cooling season had statistically significant predictive abilities in predicting indoor temperature. During the heating season, only humidex in Texas and combined data across study states were statistically significant, but with weaker to moderate predicative ability. The high degree of correlation between outdoor and indoor environmental variables provided support for the validity of epidemiologic studies of weather relying on temporal comparisons. Results indicated most RIOPA study residents experienced thermal comfort; however, many values indicated how several residents may have experienced some discomfort depending on clothing and indoor activities. With climate change, increases in temperature are expected, with more days of extreme heat and humidity and, potentially harsher, longer winters. Homes being built or modernized should be created with the appropriate guidelines to provide comfort for residents daily and in extreme weather events.

  8. Unexpected Genomic Variability in Clinical and Environmental Strains of the Pathogenic Yeast Candida parapsilosis

    PubMed Central

    Pryszcz, Leszek P.; Németh, Tibor; Gácser, Attila; Gabaldón, Toni

    2013-01-01

    Invasive candidiasis is the most commonly reported invasive fungal infection worldwide. Although Candida albicans remains the main cause, the incidence of emerging Candida species, such as C. parapsilosis is increasing. It has been postulated that C. parapsilosis clinical isolates result from a recent global expansion of a virulent clone. However, the availability of a single genome for this species has so far prevented testing this hypothesis at genomic scales. We present here the sequence of three additional strains from clinical and environmental samples. Our analyses reveal unexpected patterns of genomic variation, shared among distant strains, that argue against the clonal expansion hypothesis. All strains carry independent expansions involving an arsenite transporter homolog, pointing to the existence of directional selection in the environment, and independent origins of the two clinical isolates. Furthermore, we report the first evidence for the existence of recombination in this species. Altogether, our results shed new light onto the dynamics of genome evolution in C. parapsilosis. PMID:24259314

  9. The ecophysiology of sulfur isotope fractionation by sulfate reducing bacteria in response to variable environmental conditions

    NASA Astrophysics Data System (ADS)

    Leavitt, W.; Bradley, A. S.; Johnston, D. T.; Pereira, I. A. C.; Venceslau, S.; Wallace, C.

    2014-12-01

    Microbial sulfate reducers (MSR) drive the Earth's biogeochemical sulfur cycle. At the heart of this energy metabolism is a cascade of redox transformations coupling organic carbon and/or hydrogen oxidation to the dissimilatory reduction of sulfate to sulfide. The sulfide produced is depleted in the heavier isotopes of sulfur relative to sulfate. The magnitude of discrimination (fractionation) depends on: i) the cell-specific sulfate reduction rate (csSRR, Kaplan & Rittenberg (1964) Can. J. Microbio.; Chambers et al. (1975) Can. J. Microbio; Sim et al. (2011) GCA; Leavitt et al. (2013) PNAS), ii) the ambient sulfate concentration (Harrison & Thode (1958) Research; Habicht et al. (2002) Science; Bradley et al. in review), iii) both sulfate and electron donor availability, or iv) an intrinsic physiological limitation (e.g. cellular division rate). When neither sulfate nor electron donor limits csSRR a more complex function relates the magnitude of isotope fractionation to cell physiology and environmental conditions. In recent and on-going work we have examined the importance of enzyme-specific fractionation factors, as well as the influence of electron donor or electron acceptor availability under carefully controlled culture conditions (e.g. Leavitt et al. (2013) PNAS). In light of recent advances in MSR genetics and biochemistry we utilize well-characterized mutant strains, along with a continuous-culture methodology (Leavitt et al. (2013) PNAS) to further probe the fractionation capacity of this metabolism under controlled physiological conditions. We present our latest findings on the magnitude of S and D/H isotope fractionation in both wild type and mutant strains. We will discuss these in light of recent theoretical advances (Wing & Halevy (2014) PNAS), examining the mode and relevance of MSR isotope fractionation in the laboratory to modern and ancient environmental settings, particularly anoxic marine sediments.

  10. Micronuclei in neonates and children: effects of environmental, genetic, demographic and disease variables

    PubMed Central

    Holland, Nina; Fucic, Alexandra; Merlo, Domenico Franco; Sram, Radim; Kirsch-Volders, Micheline

    2011-01-01

    Children may be more susceptible to the effects of the environmental exposure and medical treatments than adults; however, limited information is available about the differences in genotoxic effects in children by age, sex and health status. Micronucleus (MN) assay is a well established method of monitoring genotoxicity, and this approach is thoroughly validated for adult lymphocytes by the Human Micronucleus Biomonitoring project (HUMN.org). Similar international undertaking is in progress for exfoliated buccal cells. Most of the MN studies in children are focused on analyses of lymphocytes but in the recent years, more investigators are interested in using exfoliated cells from the oral cavity and other cell types that can be collected non-invasively, which is particularly important in paediatric cohorts. The baseline MN frequency is relatively low in newborns and its assessment requires large cohorts and cell sample counts. Available results are mostly consistent in conclusion that environmental pollutants and radiation exposures lead to the increase in the MN frequency in children. Effects of medical treatments are less clear, and more studies are needed to optimise the doses and minimise genotoxicity without compromising therapy outcomes. Despite the recent progress in MN assay in children, more studies are warranted to establish the relationship between MN in lymphocytes and exfoliated cells, to clarify sex, age and genotype differences in baseline MN levels and the changes in response to genotoxicants. One of the most important types of MN studies in children are prospective cohorts that will help to clarify the predictive value of MN and other cytome end points for cancer and other chronic diseases of childhood and adulthood. Emerging ‘omic’ and other novel molecular technologies may shed light on the molecular mechanisms and biological pathways associated with the MN levels in children. PMID:21164182

  11. Organismal climatology: analyzing environmental variability at scales relevant to physiological stress.

    PubMed

    Helmuth, Brian; Broitman, Bernardo R; Yamane, Lauren; Gilman, Sarah E; Mach, Katharine; Mislan, K A S; Denny, Mark W

    2010-03-15

    Predicting when, where and with what magnitude climate change is likely to affect the fitness, abundance and distribution of organisms and the functioning of ecosystems has emerged as a high priority for scientists and resource managers. However, even in cases where we have detailed knowledge of current species' range boundaries, we often do not understand what, if any, aspects of weather and climate act to set these limits. This shortcoming significantly curtails our capacity to predict potential future range shifts in response to climate change, especially since the factors that set range boundaries under those novel conditions may be different from those that set limits today. We quantitatively examine a nine-year time series of temperature records relevant to the body temperatures of intertidal mussels as measured using biomimetic sensors. Specifically, we explore how a 'climatology' of body temperatures, as opposed to long-term records of habitat-level parameters such as air and water temperatures, can be used to extrapolate meaningful spatial and temporal patterns of physiological stress. Using different metrics that correspond to various aspects of physiological stress (seasonal means, cumulative temperature and the return time of extremes) we show that these potential environmental stressors do not always occur in synchrony with one another. Our analysis also shows that patterns of animal temperature are not well correlated with simple, commonly used metrics such as air temperature. Detailed physiological studies can provide guidance to predicting the effects of global climate change on natural ecosystems but only if we concomitantly record, archive and model environmental signals at appropriate scales.

  12. An exploration of the relationships between microalgae biomass growth and related environmental variables.

    PubMed

    Ramaraj, Rameshprabu; Tsai, David Dah-Wei; Chen, Paris Honglay

    2014-06-05

    Algal community plays critical roles as the primary producer and as a major biotic component in the nutrient/energy cycle in aquatic ecosystems. The potential of fresh water algal biomass to mitigate global problems of food and energy and its significance as a carbon sink have been recognized. In this study, with a view to decreasing the cost of producing algal biomass for various purposes, the natural medium of unsupplemented freshwater was applied to mimic the real world to produce algal biomass. The relevant physicochemical variables in the improvised algal growth environment were analyzed and monitored, to investigate the algal growth mechanism. The simple regression analysis showed the applicability of the unsupplemented natural medium with sufficient natural nutrition for algal biomass production. The multiple linear analyses explained the complexity of the mimicked freshwater mixed-algal community in the laboratory. The laboratory results obtained in the present study also provide better insights that improve our understanding of the natural algal growth characteristics.

  13. Regional precipitation variability in East Asia related to climate and environmental factors during 1979-2012

    NASA Astrophysics Data System (ADS)

    Deng, Yinyin; Gao, Tao; Gao, Huiwang; Yao, Xiaohong; Xie, Lian

    2014-07-01

    This paper studies the inter-annual precipitation variations in different regions of East Asia from oceans to interior areas in China during 1979 - 2012. The results computed by Empirical Orthogonal Functions (EOF) demonstrate that the annual precipitation changes are mainly related to the El Niño-Southern Oscillation, East Asian summer monsoon and aerosols. We also found that the increased Sea surface temperature (SST) could explain the precipitation changes over the Northwest Pacific in the dry season (Oct. - May) and the East China Sea and the South China Sea in the rainy season (Jun. - Sep.). The precipitation changes over the ocean unexplained by SST were likely due to the water vapor transport dominated by dynamic factors. With the increased SST, the moisture transported from oceans to interior land was likely redistributed and caused the complicated regional variability of precipitation. Moreover, the impacts of aerosols on cloud and precipitation varied with different pollution levels and different seasons.

  14. Regional precipitation variability in East Asia related to climate and environmental factors during 1979-2012.

    PubMed

    Deng, Yinyin; Gao, Tao; Gao, Huiwang; Yao, Xiaohong; Xie, Lian

    2014-07-17

    This paper studies the inter-annual precipitation variations in different regions of East Asia from oceans to interior areas in China during 1979 - 2012. The results computed by Empirical Orthogonal Functions (EOF) demonstrate that the annual precipitation changes are mainly related to the El Niño-Southern Oscillation, East Asian summer monsoon and aerosols. We also found that the increased Sea surface temperature (SST) could explain the precipitation changes over the Northwest Pacific in the dry season (Oct. - May) and the East China Sea and the South China Sea in the rainy season (Jun. - Sep.). The precipitation changes over the ocean unexplained by SST were likely due to the water vapor transport dominated by dynamic factors. With the increased SST, the moisture transported from oceans to interior land was likely redistributed and caused the complicated regional variability of precipitation. Moreover, the impacts of aerosols on cloud and precipitation varied with different pollution levels and different seasons.

  15. Environmental Variability, Bowhead Whale Distributions, and Inupiat Subsistence Whaling in the Coastal Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Ashjian, C. J.; Campbell, R. G.; George, J. C.; Moore, S. E.; Okkonen, S. R.; Sherr, B. F.; Sherr, E. B.

    2006-12-01

    The annual migration of bowhead whales (Balaena mysticetus) past Barrow, Alaska has provided subsistence hunting opportunities to Native whalers for centuries. Bowheads regularly feed along the Arctic coast near Barrow in autumn, presumably to utilize recurrent aggregations of their zooplankton prey (e.g., copepods, euphausiids). Oceanographic field-sampling on the narrow continental shelf near Barrow and in Elson Lagoon was conducted during mid-August to mid-September of 2005 and 2006 to describe the different water mass types and plankton communities, to identify exchange of water and material between the shelf and lagoon and offshore, and to identify biological and physical mechanisms of plankton aggregation. High spatial resolution profiles of temperature, salinity, fluorescence, optical backscatter, and C-DOM were collected using an Acrobat undulating towed vehicle in the lagoon and across the shelf from near-shore to the ~150 m isobath. Discrete sampling for nutrients, chlorophyll a, and phytoplankton, and microzooplankton and mesozooplankton abundance and composition was conducted in distinct water types and across frontal boundaries identified from the high-resolution data. The distributions of bowhead whales were documented using aerial surveys. Inter-annual and shorter-term (days to weeks) variability in the distribution of water masses and intrinsic biological properties was observed. Distinct hydrographic and biological-chemical regions were located across the shelf that may contribute to the formation of bowhead whale prey aggregations. The lagoon system is an important interface between the ocean and land and may be critical to the formation of nearshore bowhead whale prey aggregations. Results from the field sampling will be coupled to biological-physical modeling and retrospective analyses to understand the response of this complex environment-whale-human system to climate variability.

  16. Identifying environmental variables explaining genotype-by-environment interaction for body weight of rainbow trout (Onchorynchus mykiss): reaction norm and factor analytic models

    PubMed Central

    2014-01-01

    Background Identifying the relevant environmental variables that cause GxE interaction is often difficult when they cannot be experimentally manipulated. Two statistical approaches can be applied to address this question. When data on candidate environmental variables are available, GxE interaction can be quantified as a function of specific environmental variables using a reaction norm model. Alternatively, a factor analytic model can be used to identify the latent common factor that explains GxE interaction. This factor can be correlated with known environmental variables to identify those that are relevant. Previously, we reported a significant GxE interaction for body weight at harvest in rainbow trout reared on three continents. Here we explore their possible causes. Methods Reaction norm and factor analytic models were used to identify which environmental variables (age at harvest, water temperature, oxygen, and photoperiod) may have caused the observed GxE interaction. Data on body weight at harvest was recorded on 8976 offspring reared in various locations: (1) a breeding environment in the USA (nucleus), (2) a recirculating aquaculture system in the Freshwater Institute in West Virginia, USA, (3) a high-altitude farm in Peru, and (4) a low-water temperature farm in Germany. Akaike and Bayesian information criteria were used to compare models. Results The combination of days to harvest multiplied with daily temperature (Day*Degree) and photoperiod were identified by the reaction norm model as the environmental variables responsible for the GxE interaction. The latent common factor that was identified by the factor analytic model showed the highest correlation with Day*Degree. Day*Degree and photoperiod were the environmental variables that differed most between Peru and other environments. Akaike and Bayesian information criteria indicated that the factor analytical model was more parsimonious than the reaction norm model. Conclusions Day*Degree and

  17. Trait-Based Community Assembly along an Elevational Gradient in Subalpine Forests: Quantifying the Roles of Environmental Factors in Inter- and Intraspecific Variability

    PubMed Central

    Luo, Ya-Huang; Liu, Jie; Tan, Shao-Lin; Cadotte, Marc William; Wang, Yue-Hua; Xu, Kun; Li, De-Zhu; Gao, Lian-Ming

    2016-01-01

    Understanding how communities respond to environmental variation is a central goal in ecology. Plant communities respond to environmental gradients via intraspecific and/or interspecific variation in plant functional traits. However, the relative contribution of these two responses to environmental factors remains poorly tested. We measured six functional traits (height, leaf thickness, specific leaf area (SLA), leaf carbon concentration (LCC), leaf nitrogen concentration (LNC) and leaf phosphorus concentration (LPC)) for 55 tree species occurring at five elevations across a 1200 m elevational gradient of subalpine forests in Yulong Mountain, Southwest China. We examined the relative contribution of interspecific and intraspecific traits variability based on community weighted mean trait values and functional diversity, and tested how different components of trait variation respond to different environmental axes (climate and soil variables). Species turnover explained the largest amount of variation in leaf morphological traits (leaf thickness and SLA) across the elevational gradient. However, intraspecific variability explained a large amount of variation (49.3%–76.3%) in three other traits (height, LNC and LPC) despite high levels of species turnover. The detection of limiting similarity in community assembly was improved when accounting for both intraspecific and interspecific variability. Different components of trait variation respond to different environmental axes, especially soil water content and climatic variables. Our results indicate that intraspecific variation is critical for understanding community assembly and evaluating community response to environmental change. PMID:27191402

  18. Behavioral profile of adults with Prader-Willi syndrome: correlations with individual and environmental variables

    PubMed Central

    2013-01-01

    Background Maladaptive behavior has been reported as a phenotypical feature in Prader–Willi syndrome (PWS). It severely limits social adaptation and the quality of life of children and adults with the syndrome. Different factors have been linked with the intensity and form of these behavioral disturbances but there is no consensus about the cause. Consequently, there is still controversy regarding management strategies and there is a need for new data. Methods The behavior of 100 adults with PWS attending a dedicated center was assessed using the Developmental Behavior Checklist for Adults (DBC-A) and the PWS-specific Hyperphagia Questionnaire. The DBC-A was completed separately by trained caregivers at the center and relatives or caregivers in a natural setting. Genotype, gender, age, degree of obesity and cognitive impairment were analyzed as variables with a hypothetical influence on behavioral features. Results Patients showed a relatively high rate of behavioral disturbances other than hyperphagia. Disruptive and social relating were the highest scoring DBC-A subscales whereas anxiety/antisocial and self-absorbed were the lowest. When hospital caregiver and natural caregiver scores were compared, scores for the latter were higher for all subscales except for disruptive and anxiety/antisocial. These effects of institutional management were underlined. In the DBC-A, 22 items have descriptive indications of PWS behavior and were used for further comparisons and correlation analysis. In contrast to previous reports, rates of disturbed behavior were lower in patients with a deletion genotype. However, the behavioral profile was similar for both genotypes. No differences were found in any measurement when comparing type I and type II deletions. The other analyzed variables showed little relevance. Conclusions Significant rates of behavioral disorders were highlighted and their typology described in a large cohort of adults with PWS. The deletion genotype was

  19. Environmental and management impacts on temporal variability of soil hydraulic properties

    NASA Astrophysics Data System (ADS)

    Bodner, G.; Scholl, P.; Loiskandl, W.; Kaul, H.-P.

    2012-04-01

    Soil hydraulic properties underlie temporal changes caused by different natural and management factors. Rainfall intensity, wet-dry cycles, freeze-thaw cycles, tillage and plant effects are potential drivers of the temporal variability. For agricultural purposes it is important to determine the possibility of targeted influence via management. In no-till systems e.g. root induced soil loosening (biopores) is essential to counteract natural soil densification by settling. The present work studies two years of temporal evolution of soil hydraulic properties in a no-till crop rotation (durum wheat-field pea) with two cover crops (mustard and rye) having different root systems (taproot vs. fibrous roots) as well as a bare soil control. Soil hydraulic properties such as near-saturated hydraulic conductivity, flow weighted pore radius, pore number and macroporosity are derived from measurements using a tension infiltrometer. The temporal dynamics are then analysed in terms of potential driving forces. Our results revealed significant temporal changes of hydraulic conductivity. When approaching saturation, spatial variability tended to dominate over the temporal evolution. Changes in near-saturated hydraulic conductivity were mainly a result of changing pore number, while the flow weighted mean pore radius showed less temporal dynamic in the no-till system. Macroporosity in the measured range of 0 to -10 cm pressure head ranged from 1.99e-4 to 8.96e-6 m3m-3. The different plant coverage revealed only minor influences on the observed system dynamics. Mustard increased slightly the flow weighted mean pore radius, being 0.090 mm in mustard compared to 0.085 mm in bare soil and 0.084 mm in rye. Still pore radius changes were of minor importance for the overall temporal dynamics. Rainfall was detected as major driving force of the temporal evolution of structural soil hydraulic properties at the site. Soil hydraulic conductivity in the slightly unsaturated range (-7 cm to -10

  20. Reconstruction of Centennial and Millennial-scale Climate and Environmental Variability during the Holocene in the Central Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Rolland, N.; Porinchu, D.; MacDonald, G.; Moser, K.

    2007-12-01

    The Arctic and sub-Arctic regions are experiencing dramatic changes in surface temperature, sea-ice extent, glacial melt, river discharge, soil carbon storage and snow cover. According to the IPCC high latitude regions are expected to warm between 4°C and 7°C over the next 100 years. The magnitude of warming and the rate at which it occurs will dwarf any previous warming episodes experienced by latitude regions over the last 11,000 years. It is critical that we improve our understanding of how the Arctic and sub-Arctic regions responded to past periods of warming, especially in light of the changes these regions will be experiencing over the next 100 years. One of the lines of evidence increasingly utilized in multi-proxy paleolimnological research is the Chironomidae (Insecta: Diptera). Also known as non-biting midge flies, chironomids are ubiquitous, frequently the most abundant insects found in freshwater ecosystems and very sensitive to environmental conditions. This research uses Chironomidae to quantitatively characterize climate and environmental conditions of the continental interior of Arctic Canada during the Holocene. Spanning four major vegetation zones (boreal forest, forest-tundra, birch tundra and herb tundra), the surface samples of 80 lakes recovered from the central Canadian Arctic were used to assess the relationship of 22 environmental variables with the chironomid distribution. Redundancy analysis (RDA) identified four variables, total Kjeldahl nitrogen (TKN), pH, summer surface water temperature (SSWT) and depth, which best explain the variance in the distribution of chironomids within these ecoregions. In order to provide new quantitative estimates of SSWT, a 1-component weighted average partial least square (WA-PLS) model was developed (r2jack = 0.76, RMSEP = 1.42°C) and applied downcore in two low arctic continental Nunavut lakes located approximately 50 km and 200 km north of modern treeline. This robust midge-inferred temperature

  1. Mechanisms of phytoplankton adaptation to environmental variability in a shelf ecosystem

    NASA Astrophysics Data System (ADS)

    Barlow, R.; Lamont, T.; Britz, K.; Sessions, H.

    2013-11-01

    Phytoplankton absorption, pigments and active fluorescence were investigated at five focus sites in a shelf region during summer and winter to elucidate the adaptation of communities to changing environmental conditions. We determined that the availability of nutrients and changing irradiance were the key drivers of phytoplankton growth and photoacclimation in an ecosystem influenced by a warm western boundary current. Diatoms dominated the communities in the winter, while mixed diatom-flagellate populations generally prevailed in summer. Prokaryotes were dominant in the surface layer at one site where warm water flowed onto the shelf. Diatom and flagellate communities were associated with cooler, lower salinity water and prokaryotes with warm, higher salinity water. Populations appeared not be nutrient stressed and actively drew down silicates and nitrates, with nitrates being rapidly utilized resulting in low ambient nitrate levels in the upper water column. The phytoplankton acclimated to changing irradiance conditions by increasing the quantum yield of photochemistry with decreasing irradiance and adjusting the absorption of light by accessory pigments. Prokaryote dominated communities had high chlorophyll-specific absorption coefficients, and a high proportion of spectral absorption by chlorophyll a and photoprotective carotenoids. Diatoms had low chlorophyll-specific absorption and elevated absorption by photosynthetic carotenoids and chlorophyll c. Although flagellate-dominated communities had intermediate chlorophyll-specific absorption, their proportion of absorption by photosynthetic carotenoids and chlorophyll c was similar to the diatoms.

  2. [Environmental pollution, climate variability and climate change: a review of health impacts on the Peruvian population].

    PubMed

    Gonzales, Gustavo F; Zevallos, Alisson; Gonzales-Castañeda, Cynthia; Nuñez, Denisse; Gastañaga, Carmen; Cabezas, César; Naeher, Luke; Levy, Karen; Steenland, Kyle

    2014-01-01

    This article is a review of the pollution of water, air and the effect of climate change on the health of the Peruvian population. A major air pollutant is particulate matter less than 2.5 μ (PM 2.5). In Lima, 2,300 premature deaths annually are attributable to this pollutant. Another problem is household air pollution by using stoves burning biomass fuels, where excessive indoor exposure to PM 2.5 inside the household is responsible for approximately 3,000 annual premature deaths among adults, with another unknown number of deaths among children due to respiratory infections. Water pollution is caused by sewage discharges into rivers, minerals (arsenic) from various sources, and failure of water treatment plants. In Peru, climate change may impact the frequency and severity of El Niño Southern Oscillation (ENSO), which has been associated with an increase in cases of diseases such as cholera, malaria and dengue. Climate change increases the temperature and can extend the areas affected by vector-borne diseases, have impact on the availability of water and contamination of the air. In conclusion, Peru is going through a transition of environmental risk factors, where traditional and modern risks coexist and infectious and chronic problems remain, some of which are associated with problems of pollution of water and air.

  3. Regional Genetic Structure and Environmental Variables Influence our Conservation Approach for Feather Heads (Ptilotus macrocephalus).

    PubMed

    Ahrens, Collin W; James, Elizabeth A

    2016-05-01

    Continued alterations to the Australian environment compromise the long-term viability of many plant species. We investigate the population genetics of Ptilotus macrocephalus, a perennial herb that occurs in 2 nationally endangered communities on the Victorian Volcanic Plain Bioregion (VVP), Australia, to answer key questions regarding regional differentiation and to guide conservation strategies. We evaluate genetic structure and diversity within and among 17 P. macrocephalus populations from 3 regions of southeastern Australia using 17 microsatellite markers developed de novo. Genetic structure was present in P. macrocephalus between the 3 regions but not at the population level. Environmental factors, namely temperature and precipitation, significantly explained differentiation between the North region and the other 2 regions indicating isolation by environment. Within regions, genetic structure currently shows a high level of gene flow and genetic variation. Our results suggest that within-region gene flow does not reflect current habitat fragmentation in southeastern Australia whereas temperature and precipitation are likely to be responsible for the differentiation detected among regions. Climate change may severely impact P. macrocephalus on the VVP and test its evolutionary resilience. We suggest taking a proactive conservation approach to improve long-term viability by sourcing material for restoration to assist gene flow to the VVP region to promote an increased adaptive capacity.

  4. Mass change, environmental variability and female fertility in wild Propithecus verreauxi.

    PubMed

    Richard, A F; Dewar, R E; Schwartz, M; Ratsirarson, J

    2000-10-01

    Accurate estimates of mass and size are important in a wide range of research questions in population and evolutionary biology, and yet such data are still rare for wild primates. This study presents detailed longitudinal data from a large population of wild indriids, and demonstrates links between fluctuations in body mass, environmental cycles, and reproduction. Understanding these links is a necessary step toward explaining the function and evolution of distinctive features of lemur biology and behavior. During the first 12 years of an ongoing study of the sifaka, Propithecus verreauxi verreauxi, at Beza Mahafaly in southwest Madagascar, 320 animals were captured and weighed throughout the year. Adult males and females exhibit seasonal cycles of mass loss, with females losing significantly more mass than males. In 2 drought years this pattern was especially pronounced. Compared to lighter females, females who were heavier at the time of the mating season were more likely to give birth in the following birth season. By showing (1) seasonally greater mass loss in reproductive females compared to males, particularly in drought years, (2) a close link between female mass and fertility, and (3) an uncoupling of the periods of highest body mass and of gestation and lactation, these results suggest that energy acquisition and storage are critically important in the life history strategies of female sifaka, and that "capital breeding" may be a feature of sifaka reproductive strategies.

  5. Environmental and climactic effects of chlorophyll-a variability around Iceland using reconstructed satellite data fields

    NASA Astrophysics Data System (ADS)

    McGinty, Niall; Guðmundsson, Kristinn; Ágústsdóttir, Kristín; Marteinsdóttir, Gudrún

    2016-11-01

    While remotely sensed data greatly improves the spatial and temporal resolution of ocean surface data, many data gaps still exist, particularly in northern latitude regions. We addressed this issue by reconstructing 8-day chl-a, sea surface temperature (SST) and photosynthetically available radiation (PAR) between 1998 and 2013. Direct matchups between the interpolated and in-situ chlorophyll-a data showed stronger correlations when both data types were combined although very little variation was found for the root mean square error across space and time. Chl-a shows a strong periodicity in the south and a weak periodicity in seasonal cycle in the north. Where periodicity is strong we found that correlations with the local environmental conditions were also the strongest. Wavelet coherence patterns showed that the phase correlation between SST, chl-a and NAO was dominated by an annual periodicity in the trends although the chl-a-NAO relationship was only significant after 2005. Ten regions were defined based on the k-means clustering of chl-a. Mean spring anomalies and the phenological timing of chl-a were defined for each region. The main drivers of spring anomalies were mean SST and PAR values while the spring timing was strongly correlated with the timing of MLD and PAR reaching threshold levels.

  6. A Wearable Patch to Enable Long-Term Monitoring of Environmental, Activity and Hemodynamics Variables

    PubMed Central

    Etemadi, Mozziyar; Inan, Omer T.; Heller, J. Alex; Hersek, Sinan; Klein, Liviu; Roy, Shuvo

    2015-01-01

    We present a low power multi-modal patch designed for measuring activity, altitude (based on high-resolution barometric pressure), a single-lead electrocardiogram, and a tri-axial seismocardiogram (SCG). Enabled by a novel embedded systems design methodology, this patch offers a powerful means of monitoring the physiology for both patients with chronic cardiovascular diseases, and the general population interested in personal health and fitness measures. Specifically, to the best of our knowledge, this patch represents the first demonstration of combined activity, environmental context, and hemodynamics monitoring, all on the same hardware, capable of operating for longer than 48 hours at a time with continuous recording. The three-channels of SCG and one-lead ECG are all sampled at 500 Hz with high signal-to-noise ratio, the pressure sensor is sampled at 10 Hz, and all signals are stored to a microSD card with an average current consumption of less than 2 mA from a 3.7 V coin cell (LIR2450) battery. In addition to electronic characterization, proof-of-concept exercise recovery studies were performed with this patch, suggesting the ability to discriminate between hemodynamic and electrophysiology response to light, moderate, and heavy exercise. PMID:25974943

  7. A Wearable Patch to Enable Long-Term Monitoring of Environmental, Activity and Hemodynamics Variables.

    PubMed

    Etemadi, Mozziyar; Inan, Omer T; Heller, J Alex; Hersek, Sinan; Klein, Liviu; Roy, Shuvo

    2016-04-01

    We present a low power multi-modal patch designed for measuring activity, altitude (based on high-resolution barometric pressure), a single-lead electrocardiogram, and a tri-axial seismocardiogram (SCG). Enabled by a novel embedded systems design methodology, this patch offers a powerful means of monitoring the physiology for both patients with chronic cardiovascular diseases, and the general population interested in personal health and fitness measures. Specifically, to the best of our knowledge, this patch represents the first demonstration of combined activity, environmental context, and hemodynamics monitoring, all on the same hardware, capable of operating for longer than 48 hours at a time with continuous recording. The three-channels of SCG and one-lead ECG are all sampled at 500 Hz with high signal-to-noise ratio, the pressure sensor is sampled at 10 Hz, and all signals are stored to a microSD card with an average current consumption of less than 2 mA from a 3.7 V coin cell (LIR2450) battery. In addition to electronic characterization, proof-of-concept exercise recovery studies were performed with this patch, suggesting the ability to discriminate between hemodynamic and electrophysiology response to light, moderate, and heavy exercise.

  8. Predicting the distribution of canine leishmaniasis in western Europe based on environmental variables.

    PubMed

    Franco, Ana O; Davies, Clive R; Mylne, Adrian; Dedet, Jean-Pierre; Gállego, Montserrat; Ballart, Cristina; Gramiccia, Marina; Gradoni, Luigi; Molina, Ricardo; Gálvez, Rosa; Morillas-Márquez, Francisco; Barón-López, Sergio; Pires, Carlos Alves; Afonso, Maria Odete; Ready, Paul D; Cox, Jonathan

    2011-12-01

    The domestic dog is the reservoir host of Leishmania infantum, the causative agent of zoonotic visceral leishmaniasis endemic in Mediterranean Europe. Targeted control requires predictive risk maps of canine leishmaniasis (CanL), which are now explored. We databased 2187 published and unpublished surveys of CanL in southern Europe. A total of 947 western surveys met inclusion criteria for analysis, including serological identification of infection (504, 369 dogs tested 1971-2006). Seroprevalence was 23 2% overall (median 10%). Logistic regression models within a GIS framework identified the main environmental predictors of CanL seroprevalence in Portugal, Spain, France and Italy, or in France alone. A 10-fold cross-validation approach determined model capacity to predict point-values of seroprevalence and the correct seroprevalence class (<5%, 5-20%, >20%). Both the four-country and France-only models performed reasonably well for predicting correctly the <5% and >20% seroprevalence classes (AUC >0 70). However, the France-only model performed much better for France than the four-country model. The four-country model adequately predicted regions of CanL emergence in northern Italy (<5% seroprevalence). Both models poorly predicted intermediate point seroprevalences (5-20%) within regional foci, because surveys were biased towards known rural foci and Mediterranean bioclimates. Our recommendations for standardizing surveys would permit higher-resolution risk mapping.

  9. Quality of environmental impact statements and variability of scrutiny by reviewers

    SciTech Connect

    Peterson, Kaja

    2010-04-15

    Adequate provision of information is essential for decision making. This paper provides the results of the quality assessment of Environmental Impact Statements (EIS), documents prescribed by EIA Directive (337/85/EEC). The assessment was completed by several categories of reviewers in Estonia, which has been an EU member state since 2004. The quality assessment of EIS was based on the EC Guidance on EIS Review (2001). Firstly, the quality assessment of 50 randomly selected EIS was carried out by a single reviewer. Secondly, the individual grading among 24 independent reviewers of a single EIS was tested. Thirdly, a comparison of the results of 15 individual and 5 group assessments of the same EIS was conducted. The results from the quality assessment of the selected EIS demonstrate a satisfactory level of information provided for decision making; 68% of the sample EIS were positively graded. However, more than half of the 50 EIS were graded as 'just satisfactory'. Comparison between the individual and group assessment of the same EIS demonstrates that the group assessment is more critical than the individual assessment. This possibly results from a wider technical expertise and balancing of subjective values and perspectives among group members. Arguably, the current practice of EIA competent authorities assessing the quality of EIS with individuals could be revised. We discuss the effect of the group assessment on expanding the narrow technical expertise and the subjectivity of a single expert.

  10. Relationship between environmental variables and CH4 fluxes in sub-Boreal peatlands

    NASA Astrophysics Data System (ADS)

    Pypker, T. G.; Moore, P. A.; Waddington, J. M.; Chimner, R. A.; Hribljan, J. A.

    2012-12-01

    Peatlands are a critical component in the global carbon (C) cycle because they have been slowly sequestering atmospheric greenhouse gases as peat since the last glaciation. Today, soil C stocks in peatlands are estimated to represent 224 to 455 Pg, equal to 12-30% of the global soil C pool. At present, peatlands are estimated to sequester 76 Tg C yr-1. The flux of C from peatlands is likely to respond to climate change, thereby influencing atmospheric C concentrations. We explored the relationship between ecosystem CO2 exchange, CH4 emissions and weather from May to November 2011 using the eddy covariance method. The peatland was located in the Seney National Wildlife Refuge in the Upper Peninsula of Michigan. During the study period, CO2 and CH4 fluxes ranged between -7.7 to 3.44 g CO2 m-2 d-1 and 0.01 to 0.21 nmol CH4 m-2 d-1, respectively. Both CO2 uptake and CH4 losses peaked in early July and were lowest in early May and late September. To better understand the environmental mechanisms controlling CH4 emissions, changes in CH4 fluxes were related to changes in temperature, precipitation, water table height and CO2 uptake.

  11. Environmental enrichment and cafeteria diet attenuate the response to chronic variable stress in rats.

    PubMed

    Zeeni, N; Bassil, M; Fromentin, G; Chaumontet, C; Darcel, N; Tome, D; Daher, C F

    2015-02-01

    Exposure to an enriched environment (EE) or the intake of a highly palatable diet may reduce the response to chronic stress in rodents. To further explore the relationships between EE, dietary intake and stress, male Sprague-Dawley rats were fed one of two diets for 5 weeks: high carbohydrate (HC) or "cafeteria" (CAF) (Standard HC plus a choice of highly palatable cafeteria foods: chocolate, biscuits, and peanut butter). In addition, they were either housed in empty cages or cages with EE. After the first two weeks, half of the animals from each group were stressed daily using a chronic variable stress (CVS) paradigm, while the other half were kept undisturbed. Rats were sacrificed at the end of the 5-week period. The effects of stress, enrichment and dietary intake on animal adiposity, serum lipids, and stress hormones were analyzed. Results showed an increase in intra-abdominal fat associated with the CAF diet and an increase in body weight gain associated with both the CAF diet and EE. Furthermore, the increase in ACTH associated with CVS was attenuated in the presence of EE and the CAF diet independently while the stress-induced increase in corticosterone was reduced by the combination of EE and CAF feeding. The present study provides evidence that the availability of a positive environment combined to a highly palatable diet increases resilience to the effects of CVS in rats. These results highlight the important place of palatable food and supportive environments in reducing central stress responses.

  12. Analysis of climatic and environmental variables associated with the occurrence of West Nile virus in Morocco.

    PubMed

    Calistri, Paolo; Ippoliti, Carla; Candeloro, Luca; Benjelloun, Abdennasser; El Harrak, Mehdi; Bouchra, Belkadi; Danzetta, Maria Luisa; Di Sabatino, Daria; Conte, Annamaria

    2013-07-01

    West Nile disease (WND) is one of the most widespread mosquito-borne infectious diseases in the World. In Morocco the first WND cases were reported in equines in 1996. After an apparent epidemiological silence, WND re-occurred in 2003 and in 2010, when the disease was reported in equines living in the central and north-western part of the country. Eco-climatic variables are known to influence the mosquito presence and abundance and, therefore, the probability of occurrence of mosquito-borne infections. The remote sensed values of Land Surface Temperature (LST), Normalised Difference Vegetation Index (NDVI) and rainfall registered from 2001 to 2010 were evaluated for a possible association with the occurrence of WND cases in 2003 and in 2010. In the zones where WND cases occurred, NDVI values recorded in 2003 and 2010, from June to November, were significantly higher than those registered during the same months in the rest of the decade. Rainfall data showed higher peaks in 2003 and 2010, when the number of days with extreme rainfall was significantly higher during 1-2 months before the occurrence of WND cases. Temperature does not seem to play an important role in Moroccan epidemiological conditions.

  13. Species Assemblages in Saltmarsh Ponds in Western Iceland in Relation to Environmental Variables

    NASA Astrophysics Data System (ADS)

    Ingólfsson, Agnar

    1994-03-01

    The fauna and flora of 63 saltmarsh ponds in western Iceland were investigated. Forty-five taxa were identified. A DECORANA analysis of presence/absence of species showed salinities to be the chief determinants of species composition. Salinities were highly variable, but minimum salinities appeared to be most critical, although maximum salinities as well as elevation of ponds had additional significant effects. The majority of the species are marine species, most of which are commonly found under fully marine conditions. Minimum salinities experienced can therefore be expected to be particularly critical for such species. Some species were shown to have a distinct modal abundance pattern with the mode at intermediate salinities. Species richness was positively related to salinities. A shift in composition of dominant angiosperms indicating a reduction in salinities had taken place between 1977-78 and 1991. The species composition of the ponds shows similarities to that of estuaries although significant differences can be seen. The species composition also shows similarities to that recorded from saltmarsh ponds in Britain, Netherlands and Germany

  14. Regional precipitation variability in East Asia related to climate and environmental factors during 1979-2012

    PubMed Central

    Deng, Yinyin; Gao, Tao; Gao, Huiwang; Yao, Xiaohong; Xie, Lian

    2014-01-01

    This paper studies the inter-annual precipitation variations in different regions of East Asia from oceans to interior areas in China during 1979 – 2012. The results computed by Empirical Orthogonal Functions (EOF) demonstrate that the annual precipitation changes are mainly related to the El Niño-Southern Oscillation, East Asian summer monsoon and aerosols. We also found that the increased Sea surface temperature (SST) could explain the precipitation changes over the Northwest Pacific in the dry season (Oct. – May) and the East China Sea and the South China Sea in the rainy season (Jun. – Sep.). The precipitation changes over the ocean unexplained by SST were likely due to the water vapor transport dominated by dynamic factors. With the increased SST, the moisture transported from oceans to interior land was likely redistributed and caused the complicated regional variability of precipitation. Moreover, the impacts of aerosols on cloud and precipitation varied with different pollution levels and different seasons. PMID:25033387

  15. Linking bovine tuberculosis on cattle farms to white-tailed deer and environmental variables using Bayesian hierarchical analysis

    USGS Publications Warehouse

    Walter, William D.; Smith, Rick; Vanderklok, Mike; VerCauterren, Kurt C.

    2014-01-01

    Bovine tuberculosis is a bacterial disease caused by Mycobacterium bovis in livestock and wildlife with hosts that include Eurasian badgers (Meles meles), brushtail possum (Trichosurus vulpecula), and white-tailed deer (Odocoileus virginianus). Risk-assessment efforts in Michigan have been initiated on farms to minimize interactions of cattle with wildlife hosts but research onM. bovis on cattle farms has not investigated the spatial context of disease epidemiology. To incorporate spatially explicit data, initial likelihood of infection probabilities for cattle farms tested for M. bovis, prevalence of M. bovis in white-tailed deer, deer density, and environmental variables for each farm were modeled in a Bayesian hierarchical framework. We used geo-referenced locations of 762 cattle farms that have been tested for M. bovis, white-tailed deer prevalence, and several environmental variables that may lead to long-term survival and viability of M. bovis on farms and surrounding habitats (i.e., soil type, habitat type). Bayesian hierarchical analyses identified deer prevalence and proportion of sandy soil within our sampling grid as the most supported model. Analysis of cattle farms tested for M. bovisidentified that for every 1% increase in sandy soil resulted in an increase in odds of infection by 4%. Our analysis revealed that the influence of prevalence of M. bovis in white-tailed deer was still a concern even after considerable efforts to prevent cattle interactions with white-tailed deer through on-farm mitigation and reduction in the deer population. Cattle farms test positive for M. bovis annually in our study area suggesting that the potential for an environmental source either on farms or in the surrounding landscape may contributing to new or re-infections with M. bovis. Our research provides an initial assessment of potential environmental factors that could be incorporated into additional modeling efforts as more knowledge of deer herd

  16. Autophagy, a Conserved Mechanism for Protein Degradation, Responds to Heat, and Other Abiotic Stresses in Capsicum annuum L.

    PubMed Central

    Zhai, Yufei; Guo, Meng; Wang, Hu; Lu, Jinping; Liu, Jinhong; Zhang, Chong; Gong, Zhenhui; Lu, Minghui

    2016-01-01

    Abiotic stresses negatively affect plants growth and development by inducing protein denaturation, and autophagy degrades the damaged proteins to alleviate their toxicity, however, little is known about the involvement of autophagy in pepper (Capsicum annuum L.) tolerances to abiotic stresses. In this study, we identified autophagy-related gene (ATG) members in the whole genome of pepper by HMM method and analyzed their expression profiles in response to heat and other abiotic stresses by quantitative real-time PCR. The results showed that the CaATG contained 15 core ATG members including 29 ATG proteins with their respective conserved functional domains, involving the whole process of autophagy. Under normal environmental condition, the expression of CaATG genes showed tissue- and developmental stage-specific patterns, while under abiotic stresses of salt, drought, heat, cold and carbohydrate starvation, the accumulation of autophagosome punctate increased and the expression level of CaATG genes changed with stress type-dependent pattern, which indicates the linkage of autophagy in pepper response to abiotic stresses. After treated with heat stress, both the number of up-regulated CaATG genes and the increment of autophagosome punctate were higher in pepper thermotolerant line R9 than those in thermosensitive line B6, implying an association of autophagy with heat tolerance. In addition, CaATG6 was predicted to interact with CaHSP90 family members. Our study suggests that autophagy is connected to pepper tolerances to heat and other abiotic stresses. PMID:26904087

  17. Covariance of bacterioplankton composition and environmental variables in a temperate delta system

    USGS Publications Warehouse

    Stepanauskas, R.; Moran, M.A.; Bergamaschi, B.A.; Hollibaugh, J.T.

    2003-01-01

    We examined seasonal and spatial variation in bacterioplankton composition in the Sacramento-San Joaquin River Delta (CA) using terminal restriction fragment length polymorphism (T-RFLP) analysis. Cloned 16S rRNA genes from this system were used for putative identification of taxa dominating the T-RFLP profiles. Both cloning and T-RFLP analysis indicated that Actinobacteria, Verrucomicrobia, Cytophaga-Flavobacterium and Proteobacteria were the most abundant bacterioplankton groups in the Delta. Despite the broad variety of sampled habitats (deep water channels, lakes, marshes, agricultural drains, freshwater and brackish areas), and the spatial and temporal differences in hydrology, temperature and water chemistry among the sampling campaigns, T-RFLP electropherograms from all samples were similar, indicating that the same bacterioplankton phylotypes dominated in the various habitats of the Delta throughout the year. However, principal component analysis (PCA) and partial least-squares regression (PLS) of T-RFLP profiles revealed consistent grouping of samples on a seasonal, but not a spatial, basis. ??-Proteobacteria related to Ralstonia, Actinobacteria related to Microthrix, and ??-Proteobacteria identical to the environmental Clone LD12 had the highest relative abundance in summer/fall T-RFLP profiles and were associated with low river flow, high pH, and a number of optical and chemical characteristics of dissolved organic carbon (DOC) indicative of an increased proportion of phytoplankton-produced organic material as opposed to allochthonous, terrestrially derived organic material. On the other hand, Geobacter-related ??-Proteobacteria showed a relative increase in abundance in T-RFLP analysis during winter/spring, and probably were washed out from watershed soils or sediment. Various phylotypes associated with the same phylogenetic division, based on tentative identification of T-RFLP fragments, exhibited diverse seasonal patterns, suggesting that ecological

  18. Geochemical variables as plausible aetiological cofactors in the incidence of some common environmental diseases in Africa

    NASA Astrophysics Data System (ADS)

    Davies, T. C.

    2013-03-01

    Over the last two decades, there has been a rapid growth in research in the field of medical geology around the world, and we continue to encounter “new” and important correlations between certain environmental health conditions and factors related to our interactions with geological materials and processes. A review of the possible role of geochemical factors such as the circulation of Mg, Se and F and the physico-chemical composition of volcanic soil particles, on the aetiology of some common diseases in Africa, is presented. Such studies till now, have tended to emphasise only the deleterious health impacts due to geoenvironmental factors. This is justifiable, since a proper understanding of the negative health impacts has contributed significantly towards improvement in diagnosis and therapy. But there are also beneficial effects accrued from judiciously exploiting geological materials and processes, exemplified in this review, by the several important medical applications of African clays, the therapeutic gains associated with hot springs, and balneology of peat deposits. The criticality of the “optimal range” of intake for the nutrient elements Mg, Se and F in metabolic processes is also emphasised, and illustrations given of illnesses such as cardiovascular disorders and various cancers (all major causes of mortality in Africa) that can possibly occur on either side of this range. It is hoped that this review would help generate ideas for the formulation of experimental studies that take into account the role of the geochemical environment, in an attempt to establish precisely the obscure aetiology of some of the diseases treated, and uncover new pathways in their pathogenesis.

  19. Developmental models for estimating ecological responses to environmental variability: structural, parametric, and experimental issues

    PubMed Central

    Moore, Julia L

    2014-01-01

    Developmental models that account for the metabolic effect of temperature variability on poikilotherms, such as degree-day models, have been widely used to study organism emergence, range and development, particularly in agricultural and vector-borne disease contexts. Though simple and easy to use, structural and parametric issues can influence the outputs of such models, often substantially. Because the underlying assumptions and limitations of these models have rarely been considered, this paper reviews the structural, parametric, and experimental issues that arise when using degree-day models, including the implications of particular structural or parametric choices, as well as assumptions that underlie commonly used models. Linear and nonlinear developmental functions are compared, as are common methods used to incorporate temperature thresholds and calculate daily degree-days. Substantial differences in predicted emergence time arose when using linear vs. non-linear developmental functions to model the emergence time in a model organism. The optimal method for calculating degree-days depends upon where key temperature threshold parameters fall relative to the daily minimum and maximum temperatures, as well as the shape of the daily temperature curve. No method is shown to be universally superior, though one commonly used method, the daily average method, consistently provides accurate results. The sensitivity of model projections to these methodological issues highlights the need to make structural and parametric selections based on a careful consideration of the specific biological response of the organism under study, and the specific temperature conditions of the geographic regions of interest. When degree-day model limitations are considered and model assumptions met, the models can be a powerful tool for studying temperature-dependent development. PMID:24443079

  20. Responses of coastal ecosystems to environmental variability in emerging countries from the Americas

    NASA Astrophysics Data System (ADS)

    Muniz, Pablo; Calliari, Danilo; Giménez, Luis; Defeo, Omar

    2015-12-01

    Coastal ecosystems supply critical ecological services and benefits to human society (Barbier et al., 2011). Nearly 38% of the global monetary value of annual ecosystem services arises from estuaries, seagrass and algal beds, coral reefs and shelf ecosystems (Costanza et al., 1997). However, these ecosystems are being increasingly affected by multiple drivers acting simultaneously at several spatial and temporal scales (Lotze et al., 2006; Hoegh-Guldberg and Bruno, 2010). Climate change (temperature increase, sea level rise, ocean acidification), human activities (e.g. land use/cover change, pollution, overexploitation, translocation of species), and extreme natural events (storms, floods, droughts) are the most important drivers degrading the resilience of coastal systems. Such factors operate on individual level processes, leading organisms away from their niches (Steinberg, 2013) or modifying rates and phenology (Giménez, 2011; Mackas et al., 2012, Deutsch et al., 2015). All of these influence ecosystem level processes, causing changes in species composition, diversity losses and deterioration of ecosystem functions (Worm et al., 2006; Defeo et al., 2009; Doney et al., 2011; Dornelas et al., 2014). The rate of change in habitats, species distributions and whole ecosystems has accelerated over the past decades as shown, for example, in the increase in the frequency of events of coastal hypoxia (Diaz and Rosenberg, 2008,Vaquer-Sunyer and Duarte, 2008), extensive translocation of species by global shipping (Seebens et al., 2013), and in ecosystem regime shifts (Möllmann et al., 2015 and references therein). Some coastal areas have been transformed into novel ecosystems with physical and biological characteristics outside their natural range of variability (Cloern et al., 2015) while others are likely to become sink areas, limiting the migration of marine species away from warming habitats (Burrows et al., 2014).

  1. Foraging movements of great frigatebirds from Aldabra Island: Relationship with environmental variables and interactions with fisheries

    NASA Astrophysics Data System (ADS)

    Weimerskirch, Henri; Corre, Matthieu Le; Kai, Emilie Tew; Marsac, Francis

    2010-07-01

    Great Frigatebirds ( Fregata minor) are large tropical seabirds that rely primarily on sub-surface predators such as tunas or cetaceans to capture their prey. We studied the foraging movements of 14 Great Frigatebirds breeding on Aldabra Island (9.4°S, 46.4°E), the largest colony in the Indian Ocean. This colony is located at more than 500 km from the main fishing grounds of a very important industrial purse-seine fishery targeting surface-dwelling tunas. Despite their slow flight speeds (16 km h -1), frigatebirds are able to forage at more than 1000 km from the colonies when breeding, using 2500-4750 km long foraging loops over oceanic waters. All trips were directed to the north of the island up to the equator. Foraging bouts, indicated by reduced flight speeds, were rare and located throughout the trips. Foraging spots tended to be more frequent on higher surface chlorophyll concentration and in association with some cyclonic vortices. However, mesoscale activity is relatively weak between Aldabra and the equator and the chlorophyll variability is mostly the result of wind-mixing processes during the southwest monsoon. These results suggest that frigatebirds forage for widely distributed resources to the north of Aldabra. The northernmost foraging bouts were located in the vicinity of the purse-seine fishing grounds, but without a significant overlap between frigatebirds and tuna fleets. The results of the study are compared with those from another population at Europa Island (22.3°S, 40.3°E) where birds were foraging on predictable features, the edge of cyclonic eddies that are marked in the Mozambique Channel. We discuss the consequences of the reliance of populations on contrasted oceanographic conditions on foraging strategies and on the evolution of life histories in these long-lived animals in a changing climate, as well as the possible effects of overfishing on frigatebird populations.

  2. Exposure to environmental tobacco smoke and risk of antenatal depression: application of latent variable modeling.

    PubMed

    Mbah, Alfred K; Salihu, Hamisu M; Dagne, Getachew; Wilson, Ronee E; Bruder, Karen

    2013-08-01

    This study sought to determine the impact of passive smoking on the risk for depressive symptoms during pregnancy. In this prospective study, 236 pregnant women were recruited at less than 20 weeks of gestation from a university-affiliated obstetric clinic from November 2009 through July 2011. Tobacco use/exposure was measured using questionnaire and confirmed by salivary cotinine analysis. The Edinburgh Perinatal Depression Scale (EPDS) was employed to capture perinatal depressive symptomatology. Traditionally, a cutoff of 13 is utilized to indicate depressive symptoms in the perinatal population. However, this approach is vulnerable to measurement errors that are inherent in assessing depression using cutoff points. Therefore, in this analysis, we apply a flexible approach (latent variable modeling) that accounts for measurement errors thereby reducing bias in the estimates of association. Significant differences were observed in the mean EPDS scores across non-smokers (mean ± SD = 4.8 ± 4.8), passive smokers (5.3 ± 5.5) and active smokers (7.4 ± 6.1) [p value = 0.02]. For each itemized response of the EPDS, passive smokers demonstrated an increased risk for depressive symptoms with the greatest risk exhibited by items 8 and 9 of the questionnaire (feeling sad or miserable and feeling unhappy [and]crying, respectively). In addition, for each item of the EPDS, a dose-response pattern was revealed with non-smokers having the least risk of depressive symptoms during pregnancy and active smokers having the greatest risk. Women who are exposed to secondhand smoke are at elevated risk for depressive symptoms during pregnancy.

  3. Environmental responses of the Northeast Antarctic Peninsula to the Holocene climate variability

    NASA Astrophysics Data System (ADS)

    Barbara, Loïc.; Crosta, Xavier; Leventer, Amy; Schmidt, Sabine; Etourneau, Johan; Domack, Eugene; Massé, Guillaume

    2016-01-01

    In this study, we present a unique high-resolution Holocene record of oceanographic and climatic change based on analyses of diatom assemblages combined with biomarker data from a sediment core collected from the Vega Drift, eastern Antarctic Peninsula (EAP). These data add to the climate framework already established by high-resolution marine sedimentary records from the Palmer Deep, western Antarctic Peninsula (WAP). Heavy sea ice conditions and reduced primary productivity were observed prior to 7.4 ka B.P. in relation with the proximity of the glacial ice melt and calving. Subsequent Holocene oceanographic conditions were controlled by the interactions between the Westerlies-Antarctic Circumpolar Current (ACC)-Weddell Gyre dynamics. A warm period characterized by short seasonal sea ice duration associated with a southern shift of both ACC and Westerlies field persisted until 5 ka B.P. This warm episode was then followed by climate deterioration during the middle-to-late Holocene (5 to 1.9 ka B.P.) with a gradual increase in annual sea ice duration triggered by the expansion of the Weddell Gyre and a strong oceanic connection from the EAP to the WAP. Increase of benthic diatom species during this period was indicative of more summer/autumn storms, which was consistent with changes in synoptic atmospheric circulation and the establishment of low- to high-latitude teleconnections. Finally, the multicentennial scale variability of the Weddell Gyre intensity and storm frequency during the late Holocene appeared to be associated with the increased El Niño-Southern Oscillation frequency.

  4. Environmental Variability and Fluctuation of Coccidioidomycosis (Valley Fever) In California: Based on a New Framework Involving Fungal Life Cycle

    NASA Astrophysics Data System (ADS)

    Jia, S.; Okin, G. S.; Shafir, S. C.

    2013-12-01

    Coccidioidomycosis (valley fever), caused by inhalation of spores from pathogenic fungus includingCoccidiodes immitis (C. immitis) and Coccidioides posadasii (C. posadasii), is a disease endemic to arid regions in the southwest US, as well as parts of Central and South America. With a projected increase of drought in this region, an improved understanding of environmental factors behind the outbreaks of coccidioidomycosis will enable the prediction of coccidioidomycosis in a changing climate regime. Previous research shows the infections correlate with climate conditions including precipitation, temperature, and dust. However, most studies focus only on the environmental conditions of fungus growth, which is the first stage in the fungal life cycle. In contrast, we extend the analysis to the following two stages in the life cycle, arthrospore formation and dispersal, to form a better model to predict the disease outbreaks. Besides climate conditions, we use relative spectral mixture analysis (RSMA) based on MODIS MOD43 nadir BRDF adjusted reflectance (NBAR) data to derive the relative dynamics of green vegetation, non-photosynthetic vegetation and bare soil coverage as better indicators of soil moisture, which is important for arthospore formation and dispersal. After detecting the hotspots of disease outbreaks, we correlate seasonal incidence from 2000 to 2010 with the environmental variables zero to eight seasons before to obtain candidates for stepwise regression. Regression result shows a seasonal difference in the leading explanatory variables. Such difference indicates the different seasonal main influential process from fungal life cycle. C. immitis (fungus responsible for coccidioidomycosis outbreaks in California) growth explains outbreaks in winter and fall better than other two stages in the life cycle, while arthospore formation is more responsible for spring and summer outbreaks. As the driest season, summer has the largest area related with arthospore

  5. Negative effects of heterospecific pollen receipt vary with abiotic conditions: ecological and evolutionary implications

    PubMed Central

    Celaya, Ileana N.; Arceo-Gómez, Gerardo; Alonso, Conchita; Parra-Tabla, Víctor

    2015-01-01

    Background and Aims Studies that have evaluated the effects of heterospecific pollen (HP) receipt on plant reproductive success have generally overlooked the variability of the natural abiotic environment in which plants grow. Variability in abiotic conditions, such as light and water availability, has the potential to affect pollen–stigma interactions (i.e. conspecific pollen germination and performance), which will probably influence the effects of HP receipt. Thus, a more complete understanding of the extent, strength and consequences of plant–plant interactions via HP transfer requires better consideration of the range of abiotic conditions in which these interactions occur. This study addresses this issue by evaluating the effects of two HP donors (Tamonea curassavica and Angelonia angustifolia) on the reproductive success of Cuphea gaumeri, an endemic species of the Yucatan Peninsula. Methods Mixed (conspecific pollen and HP) and pure (conspecific pollen only) hand-pollinations were conducted under varying conditions of water and light availability in a full factorial design. Reproductive success was measured as the number of pollen tubes that reached the bottom of the style. Key Results Only one of the two HP donors had a significant effect on C. gaumeri reproductive success, but this effect was dependent on water and light availability. Specifically, HP receipt caused a decrease in pollen tube growth, but only when the availability of water, light or both was low, and not when the availability of both resources was high. Conclusions The results show that the outcome of interspecific post-pollination interactions via HP transfer can be context-dependent and vary with abiotic conditions, thus suggesting that abiotic effects in natural populations may be under-estimated. Such context-dependency could lead to spatial and temporal mosaics in the ecological and evolutionary consequences of post-pollination interactions. PMID:26199385

  6. [Community structure of sponges (Porifera) in three reefs at Morrocoy National Park, Venezuela and its correspondence with some environmental variables].

    PubMed

    Romero, Marco A; Villamizar, Estrella; Malaver, Nora

    2013-09-01

    Sponges have an important ecological role in coral reef ecosystems. However, when compared to other benthic Phyla, it has been little researched. This research was focused in the variability of the community structure of sponges in three locations at Morrocoy National Park (Cayo Sombrero, Playa Mero and Punta Brava) exposed to different environmental conditions (transparency and currents intensity) and affected in different degree of severity by a mass mortality event in 1996. A total of 15 transects (10 m long and 1 m wide) were evaluated in three strata (between 3 and 15 m depth) in each site, where all the individuals were counted by species. Relative abundance by species, diversity and evenness were calculated. Locations showed differences respect turbidity, wave and current intensity. 27 species were found in Morrocoy; Cayo Sombrero (23), Playa Mero (18) and Punta Brava (15). Agelas sceptrum, Amphimedon erina and Niphates erecta were the most common in first location; Niphates erecta and Dysidea etheria in Playa Mero and Dysidea etheria, Niphates erecta and Amphimedon erina in Punta Brava. The species composition showed statistical differences between all three locations; Cayo Sombrero resulted the most diverse and even, followed by Playa Mero and Punta Brava. According to Sorensen Similarity Index results, Cayo Sombrero and Playa Mero were more similar, while Punta Brava resulted the most different. The variability in environmental conditions and the differential mass mortality effects of 1996 in all three reefs, were probably the main causes of the differences between their sponge communities. Nevertheless, we cannot conclude about the weight of these factors.

  7. Fish assemblages and environmental variables associated with hard-rock mining in the Coeur d'Alene River basin, Idaho

    USGS Publications Warehouse

    Maret, Terry R.; MacCoy, Dorene E.

    2002-01-01

    As part of the U.S. Geological Survey's National Water Quality Assessment Program, fish assemblages, environmental variables, and associated mine densities were evaluated at 18 test and reference sites during the summer of 2000 in the Coeur d'Alene and St. Regis river basins in Idaho and Montana. Multimetric and multivariate analyses were used to examine patterns in fish assemblages and the associated environmental variables representing a gradient of mining intensity. The concentrations of cadmium (Cd), lead (Pb), and zinc (Zn) in water and streambed sediment found at test sites in watersheds where production mine densities were at least 0.2 mines/km2 (in a 500-m stream buffer) were significantly higher than the concentrations found at reference sites. Many of these metal concentrations exceeded Ambient Water Quality Criteria (AWQC) and the Canadian Probable Effect Level guidelines for streambed sediment. Regression analysis identified significant relationships between the production mine densities and the sum of Cd, Pb, and Zn concentrations in water and streambed sediment (r2 = 0.69 and 0.66, respectively; P < 0.01). Zinc was identified as the primary metal contaminant in both water and streambed sediment. Eighteen fish species in the families Salmonidae, Cottidae, Cyprinidae, Catostomidae, Centrarchidae, and Ictaluridae were collected. Principal components analysis of 11 fish metrics identified two distinct groups of sites corresponding to the reference and test sites, predominantly on the basis of the inverse relationship between percent cottids and percent salmonids (r = -0.64; P < 0.05). Streams located downstream from the areas of intensive hard-rock mining in the Coeur d'Alene River basin contained fewer native fish and lower abundances as a result of metal enrichment, not physical habitat degradation. Typically, salmonids were the predominant species at test sites where Zn concentrations exceeded the acute AWQC. Cottids were absent at these sites, which

  8. Environmental variability drives rapid and dramatic changes in nutrient limitation of tropical macroalgae with different ecological strategies

    NASA Astrophysics Data System (ADS)

    Clausing, Rachel J.; Fong, Peggy

    2016-06-01

    Nitrogen (N) or phosphorus (P) limits primary productivity in nearly every ecosystem worldwide, yet how limitation changes over time, particularly in connection to variation in environmental drivers, remains understudied. We evaluated temporal and species-specific variability in the relative importance of N and P limitation among tropical macroalgae in two-factor experiments conducted twice after rains and twice after dry conditions to explore potential linkages to environmental drivers. We studied three common macroalgal species with varying ecological strategies: a fast-growing opportunist, Dictyota bartayresiana; and two calcifying species likely to be slower growing, Galaxaura fasciculata and Padina boryana. On the scale of days to weeks, nutrient responses ranged among and within species from no limitation to increases in growth by 20 and 40 % over controls in 3 d with N and P addition, respectively. After light rain or dry conditions, Dictyota grew rapidly (up to ~60 % in 3 d) with little indication of nutrient limitation, while Padina and Galaxaura shifted between N, P, or no limitation. All species grew slowly or lost mass after a large storm, presumably due to unfavorable conditions on the reef prior to the experiment that limited nutrient uptake. Padina and Galaxaura both became nutrient limited 3 d post-storm, while Dictyota did not. These results suggest that differing capabilities for nutrient uptake and storage dictate the influence of nutrient history and thus drive nutrient responses and, in doing so, may allow species with differing ecological strategies to coexist in a fluctuating environment. Moreover, the great variability in species' responses indicates that patterns of nutrient limitation are more complex than previously recognized, and generalizations about N versus P limitation of a given system may not convey the inherent complexity in governing conditions and processes.

  9. The quantitative response of wheat vernalization to environmental variables indicates that vernalization is not a response to cold temperature.

    PubMed

    Allard, Vincent; Veisz, Ottó; Kõszegi, Béla; Rousset, Michel; Le Gouis, Jacques; Martre, Pierre

    2012-01-01

    The initiation of flowering is a crucial trait that allows temperate plants to flower in the favourable conditions of spring. The timing of flowering initiation is governed by two main mechanisms: vernalization that defines a plant's requirement for a prolonged exposure to cold temperatures; and photoperiod sensitivity defining the need for long days to initiate floral transition. Genetic variability in both vernalization and photoperiod sensitivity largely explains the adaptability of cultivated crop plants such as bread wheat (Triticum aestivum L.) to a wide range of climatic conditions. The major genes controlling wheat vernalization (VRN1, VRN2, and VRN3) and photoperiod sensitivity (PPD1) have been identified, and knowledge of their interactions at the molecular level is growing. However, the quantitative effects of temperature and photoperiod on these genes remain poorly understood. Here it is shown that the distinction between the temperature effects on organ appearance rate and on vernalization sensu stricto is crucial for understanding the quantitative effects of the environmental signal on wheat flowering. By submitting near isogenic lines of wheat differing in their allelic composition at the VRN1 locus to various temperature and photoperiod treatments, it is shown that, at the whole-plant level, the vernalization process has a positive response to temperature with complex interactions with photoperiod. In addition, the phenotypic variation associated with the presence of different spring homoeoalleles of VRN1 is not induced by a residual vernalization requirement. The results demonstrate that a precise definition of vernalization is necessary to understand and model temperature and photoperiod effects on wheat flowering. It is suggested that this definition should be used as the basis for gene expression studies and assessment of functioning of the wheat flowering gene network, including an explicit account of the quantitative effect of environmental

  10. Dynamic Conceptual Model of Sediment Fluxes Underlying Numerical Modelling of Spatial and Temporal Variability and Adjustment to Environmental Change

    NASA Astrophysics Data System (ADS)

    Hooke, J.

    2015-12-01

    It is essential that a strong conceptual model underlies numerical modelling of basin fluxes and is inclusive of all factors and routeways through the system. Even under stable environmental conditions river fluxes in large basins vary spatially and temporally. Spatial variations arise due to location in the basin, relation to sources and connectivity, and due to morphology, boundary resistance and hydraulics of successive reaches. Temporal variations at a range of scales, from seasonal to decadal, occur within averaged 'stable' conditions, which produce changes in morphology and flux and subsequent feedback effects. Sediment flux in a reach can differ between similar peak magnitude events, depending on duration, season, connectivity and supply state, and existing morphology. Autogenic processes such as channel pattern and position changes, vegetation changes, and floodplain cyclicity also take place within the system. The major drivers of change at decadal-centennial timescales are assumed to be climate, land use cover and practices, and direct catchment and channel modification. Different parts of the system will have different trajectories of adjustment, depending on their location and spatial relation to connectivity within the system and on the reach morphological and resistance characteristics. These will govern the rate and extent of transmission of changes. The changes will also be influenced by the occurrence and sequence of flow events and their feedback effects, in relation to changing thresholds produced by the response to the environmental changes. It is essential that the underlying dynamics and inherent variability are recognised in numerical modelling and river management and that spatial sequencing of changes and their feedbacks are incorporated. The challenge is to produce quantifiable relations of the rate or propagation of changes through a basin given spatial variability of reach characteristics, under dynamic flow scenarios.

  11. Assessment of Inter-Individual and Geographic Variability in Human Exposure to Fine Particulate Matter in Environmental Tobacco Smoke

    PubMed Central

    Cao, Y; Frey, HC

    2010-01-01

    Environmental tobacco smoke (ETS) is a major contributor to indoor human exposures to fine particulate matter of 2.5 microns or smaller (PM2.5). The Stochastic Human Exposure and Dose Simulation for Particulate Matter (SHEDS-PM) model developed by the US Environmental Protection Agency estimates distributions of outdoor and indoor PM2.5 exposure for a specified population based on ambient concentrations and indoor emissions sources. A critical assessment was conducted of the methodology and data used in SHEDS-PM for estimation of indoor exposure to ETS. For the residential microenvironment, SHEDS uses a mass-balance approach which is comparable to best practices. The default inputs in SHEDS-PM were reviewed and more recent and extensive data sources were identified. Sensitivity analysis was used to determine which inputs should be prioritized for updating. Data regarding the proportion of smokers and “other smokers,” and cigarette emission rate were found to be important. SHEDS-PM does not currently account for in-vehicle ETS exposure; however, in-vehicle ETS-related PM2.5 levels can exceed those in residential microenvironments by a factor of 10 or more. Therefore, a mass-balance based methodology for estimating in-vehicle ETS PM2.5 concentration is evaluated. Recommendations are made regarding updating of input data and algorithms related to ETS exposure in the SHEDS-PM model. Inter-individual variability for ETS exposure was quantified. Geographic variability in ETS exposure was quantified based on the varying prevalence of smokers in five selected locations in the U.S. PMID:21039708

  12. Biofilm formation and persistence on abiotic surfaces in the context of food and medical environments.

    PubMed

    Abdallah, Marwan; Benoliel, Corinne; Drider, Djamel; Dhulster, Pascal; Chihib, Nour-Eddine

    2014-07-01

    The biofilm formation on abiotic surfaces in food and medical sectors constitutes a great public health concerns. In fact, biofilms present a persistent source for pathogens, such as Pseudomonas aeruginosa and Staphylococcus aureus, which lead to severe infections such as foodborne and nosocomial infections. Such biofilms are also a source of material deterioration and failure. The environmental conditions, commonly met in food and medical area, seem also to enhance the biofilm formation and their resistance to disinfectant agents. In this regard, this review highlights the effect of environmental conditions on bacterial adhesion and biofilm formation on abiotic surfaces in the context of food and medical environment. It also describes the current and emergent strategies used to study the biofilm formation and its eradication. The mechanisms of biofilm resistance to commercialized disinfectants are also discussed, since this phenomenon remains unclear to date.

  13. Evolution and Adaptation of Wild Emmer Wheat Populations to Biotic and Abiotic Stresses.

    PubMed

    Huang, Lin; Raats, Dina; Sela, Hanan; Klymiuk, Valentina; Lidzbarsky, Gabriel; Feng, Lihua; Krugman, Tamar; Fahima, Tzion

    2016-08-04

    The genetic bottlenecks associated with plant domestication and subsequent selection in man-made agroecosystems have limited the genetic diversity of modern crops and increased their vulnerability to environmental stresses. Wild emmer wheat, the tetraploid progenitor of domesticated wheat, distributed along a wide range of ecogeographical conditions in the Fertile Crescent, has valuable "left behind" adaptive diversity to multiple diseases and environmental stresses. The biotic and abiotic stress responses are conferred by series of genes and quantitative trait loci (QTLs) that control complex resistance pathways. The study of genetic diversity, genomic organization, expression profiles, protein structure and function of biotic and abiotic stress-resistance genes, and QTLs could shed light on the evolutionary history and adaptation mechanisms of wild emmer populations for their natural habitats. The continuous evolution and adaptation of wild emmer to the changing environment provide novel solutions that can contribute to safeguarding food for the rapidly growing human population.

  14. Functional ecology of saltglands in shorebirds: Flexible responses to variable environmental conditions

    USGS Publications Warehouse

    Gutierrez, J.S.; Dietz, M.W.; Masero, J.A.; Gill, R.E.; Dekinga, Anne; Battley, Phil F.; Sanchez-Guzman, J. M.; Piersma, Theunis

    2012-01-01

    Birds of marine environments have specialized glands to excrete salt, the saltglands. Located on the skull between the eyes, the size of these organs is expected to reflect their demand, which will vary with water turnover rates as a function of environmental (heat load, salinity of prey and drinking water) and organismal (energy demand, physiological state) factors. On the basis of inter- and intraspecific comparisons of saltgland mass (m sg) in 29 species of shorebird (suborder Charadrii) from saline, fresh and mixed water habitats, we assessed the relative roles of organism and environment in determining measured m sg species. The allometric exponent, scaling dry m sg to shorebird total body mass (m b), was significantly higher for coastal marine species (0??88, N=19) than for nonmarine species (0??43, N=14). Within the marine species, those ingesting bivalves intact had significantly higher m sg than species eating soft-bodied invertebrates, indicating that seawater contained within the shells added to the salt load. In red knots (Calidris canutus), dry m sg varied with monthly averaged ambient temperature in a U-shaped way, with the lowest mass at 12??5??C. This probably reflects increased energy demand for thermoregulation at low temperatures and elevated respiratory water loss at high temperatures. In fuelling bar-tailed godwits (Limosa lapponica), dry m sg was positively correlated with intestine mass, an indicator of relative food intake rates. These findings suggest once more that saltgland masses vary within species (and presumably individuals) in relation to salt load, that is a function of energy turnover (thermoregulation and fuelling) and evaporative water needs. Our results support the notion that m sg is strongly influenced by habitat salinity, and also by factors influencing salt load and demand for osmotically free water including ambient temperature, prey type and energy intake rates. Saltglands are evidently highly flexible organs. The small

  15. Influence of environmental variables in the efficiency of phage therapy in aquaculture.

    PubMed

    Silva, Yolanda J; Costa, Liliana; Pereira, Carla; Cunha, Ângela; Calado, Ricardo; Gomes, Newton C M; Almeida, Adelaide

    2014-09-01

    Aquaculture facilities worldwide continue to experience significant economic losses because of disease caused by pathogenic bacteria, including multidrug-resistant strains. This scenario drives the search for alternative methods to inactivate pathogenic bacteria. Phage therapy is currently considered as a viable alternative to antibiotics for inactivation of bacterial pathogens in aquaculture systems. While phage therapy appears to represent a useful and flexible tool for microbiological decontamination of aquaculture effluents, the effect of physical and chemical properties of culture waters on the efficiency of this technology has never been reported. The present study aimed to evaluate the effect of physical and chemical properties of aquaculture waters (e.g. pH, temperature, salinity and organic matter content) on the efficiency of phage therapy under controlled experimental conditions in order to provide a basis for the selection of the most suitable protocol for subsequent experiments. A bioluminescent genetically transformed Escherichia coli was selected as a model microorganism to monitor real-time phage therapy kinetics through the measurement of bioluminescence, thus avoiding the laborious and time-consuming conventional method of counting colony-forming units (CFU). For all experiments, a bacterial concentration of ≈ 10(5) CFU ml(-1) and a phage concentration of ≈ 10(6-8) plaque forming unit ml(-1) were used. Phage survival was not significantly affected by the natural variability of pH (6.5-7.4), temperature (10-25 °C), salinity (0-30 g NaCl l(-1) ) and organic matter concentration of aquaculture waters in a temperate climate. Nonetheless, the efficiency of phage therapy was mostly affected by the variation of salinity and organic matter content. As the effectiveness of phage therapy increases with water salt content, this approach appears to be a suitable choice for marine aquaculture systems. The success of phage therapy may also be enhanced in

  16. Influence of environmental variables in the efficiency of phage therapy in aquaculture

    PubMed Central

    Silva, Yolanda J; Costa, Liliana; Pereira, Carla; Cunha, Ângela; Calado, Ricardo; Gomes, Newton C M; Almeida, Adelaide

    2014-01-01

    Aquaculture facilities worldwide continue to experience significant economic losses because of disease caused by pathogenic bacteria, including multidrug-resistant strains. This scenario drives the search for alternative methods to inactivate pathogenic bacteria. Phage therapy is currently considered as a viable alternative to antibiotics for inactivation of bacterial pathogens in aquaculture systems. While phage therapy appears to represent a useful and flexible tool for microbiological decontamination of aquaculture effluents, the effect of physical and chemical properties of culture waters on the efficiency of this technology has never been reported. The present study aimed to evaluate the effect of physical and chemical properties of aquaculture waters (e.g. pH, temperature, salinity and organic matter content) on the efficiency of phage therapy under controlled experimental conditions in order to provide a basis for the selection of the most suitable protocol for subsequent experiments. A bioluminescent genetically transformed Escherichia coli was selected as a model microorganism to monitor real-time phage therapy kinetics through the measurement of bioluminescence, thus avoiding the laborious and time-consuming conventional method of counting colony-forming units (CFU). For all experiments, a bacterial concentration of ≈ 105 CFU ml−1 and a phage concentration of ≈ 106–8 plaque forming unit ml−1 were used. Phage survival was not significantly affected by the natural variability of pH (6.5–7.4), temperature (10–25°C), salinity (0–30 g NaCl l−1) and organic matter concentration of aquaculture waters in a temperate climate. Nonetheless, the efficiency of phage therapy was mostly affected by the variation of salinity and organic matter content. As the effectiveness of phage therapy increases with water salt content, this approach appears to be a suitable choice for marine aquaculture systems. The success of phage therapy may also be enhanced in

  17. Stone temperature and moisture variability under temperate environmental conditions: Implications for sandstone weathering

    NASA Astrophysics Data System (ADS)

    McAllister, Daniel; Warke, Patricia; McCabe, Stephen

    2017-03-01

    Temperature and moisture conditions are key drivers of stone weathering processes in both natural and built environments. Given their importance in the breakdown of stone, a detailed understanding of their temporal and spatial variability is central to understanding present-day weathering behaviour and for predicting how climate change may influence the nature and rates of future stone decay. Subsurface temperature and moisture data are reported from quarry fresh Peakmoor Sandstone samples exposed during summer (June-July) and late autumn/early winter (October-December) in a mid-latitude, temperate maritime environment. These data demonstrate that the subsurface thermal response of sandstone comprises numerous short-term (minutes), low magnitude fluctuations superimposed upon larger-scale diurnal heating and cooling cycles with distinct aspect-related differences. The short-term fluctuations create conditions in the outer 5-10 mm of stone that are much more 'energetic' in comparison to the more subdued thermal cycling that occurs deeper within the sandstone samples. Data show that moisture dynamics are equally complex with a near-surface region (5-10 mm) in which frequent moisture cycling takes place and this, combined with the thermal dynamism exhibited by the same region, may have significant implications for the nature and rate of weathering activity. Data indicate that moisture input from rainfall, particularly when it is wind-driven, can travel deep into the stone where it can prolong the time of wetness. This most often occurs during wetter winter months when moisture input is high and evaporative loss is low but can happen at any time during the year when the hydraulic connection between near-surface and deeper regions of the stone is disrupted with subsequent loss of moisture from depth slowing as it becomes reliant on vapour diffusion alone. These data illustrate the complexity of temperature and moisture conditions in sandstone exposed to the 'moderate

  18. Abiotic Formation of Methyl Halides in the Terrestrial Environment

    NASA Astrophysics Data System (ADS)

    Keppler, F.

    2011-12-01

    Methyl chloride and methyl bromide are the most abundant chlorine and bromine containing organic compounds in the atmosphere. Since both compounds have relatively long tropospheric lifetimes they can effectively transport halogen atoms from the Earth's surface, where they are released, to the stratosphere and following photolytic oxidation form reactive halogen gases that lead to the chemical destruction of ozone. Methyl chloride and methyl bromide account for more than 20% of the ozone-depleting halogens delivered to the stratosphere and are predicted to grow in importance as the chlorine contribution to the stratosphere from anthropogenic CFCs decline. Today methyl chloride and methyl bromide originate mainly from natural sources with only a minor fraction considered to be of anthropogenic origin. However, until as recently as 2000 most of the methyl chloride and methyl bromide input to the atmosphere was considered to originate from the oceans, but investigations in recent years have clearly demonstrated that terrestrial sources such as biomass burning, wood-rotting fungi, coastal salt marshes, tropical vegetation and organic matter degradation must dominate the atmospheric budgets of these trace gases. However, many uncertainties still exist regarding strengths of both sources and sinks, as well as the mechanisms of formation of these naturally occurring halogenated gases. A better understanding of the atmospheric budget of both methyl chloride and methyl bromide is therefore required for reliable prediction of future ozone depletion. Biotic and abiotic methylation processes of chloride and bromide ion are considered to be the dominant pathways of formation of these methyl halides in nature. In this presentation I will focus on abiotic formation processes in the terrestrial environment and the potential parameters that control their emissions. Recent advances in our understanding of the abiotic formation pathway of methyl halides will be discussed. This will

  19. Dynamic regulation of partner abundance mediates response of reef coral symbioses to environmental change.

    PubMed

    Cunning, R; Vaughan, N; Gillette, P; Capo, T R; Matté, J L; Baker, A C

    2015-05-01

    Regulating partner abunclance may allow symmotic organisms to mediate interaction outcomes, facilitating adaptive responses to environmental change. To explore the capacity for-adaptive regulation in an ecologically important endosymbiosis, we studied the population dynamics of symbiotic algae in reef-building corals under different abiotic contexts. We found high natural variability in symbiont abundance in corals across reefs, but this variability converged to different symbiont-specific abundances when colonies were maintained under constant conditions. When conditions changed seasonally, symbiont abundance readjusted to new equilibria. We explain these patterns using an a priori model of symbiotic costs and benefits to the coral host, which shows that the observed changes in symbiont abundance are consistent with the maximization of interaction benefit under different environmental conditions. These results indicate that, while regulating symbiont abundance helps hosts sustain maximum benefit in a dynamic environment, spatiotemporal variation in abiotic factors creates a broad range of symbiont abundances (and interaction outcomes) among corals that may account for observed natural variability in performance (e.g., growth rate) and stress tolerance (e.g., bleaching susceptibility). This cost or benefit framework provides a new perspective on the dynamic regulation of reef coral symbioses and illustrates that the dependence of interaction outcomes on biotic and abiotic contexts may be important in understanding how diverse mutualisms respond to environmental change.

  20. Human and Bovine Viruses and Bacteria at Three Great Lakes Beaches: Environmental Variable Associations and Health Risk.

    PubMed

    Corsi, Steven R; Borchardt, Mark A; Carvin, Rebecca B; Burch, Tucker R; Spencer, Susan K; Lutz, Michelle A; McDermott, Colleen M; Busse, Kimberly M; Kleinheinz, Gregory T; Feng, Xiaoping; Zhu, Jun

    2016-01-19

    Waterborne pathogens were measured at three beaches in Lake Michigan, environmental factors for predicting pathogen concentrations were identified, and the risk of swimmer infection and illness was estimated. Waterborne pathogens were detected in 96% of samples collected at three Lake Michigan beaches in summer, 2010. Samples were quantified for 22 pathogens in four microbial categories (human viruses, bovine viruses, protozoa, and pathogenic bacteria). All beaches had detections of human and bovine viruses and pathogenic bacteria indicating influence of multiple contamination sources at these beaches. Occurrence ranged from 40 to 87% for human viruses, 65-87% for pathogenic bacteria, and 13-35% for bovine viruses. Enterovirus, adenovirus A, Salmonella spp., Campylobacter jejuni, bovine polyomavirus, and bovine rotavirus A were present most frequently. Variables selected in multiple regression models used to explore environmental factors that influence pathogens included wave direction, cloud cover, currents, and water temperature. Quantitative Microbial Risk Assessment was done for C. jejuni, Salmonella spp., and enteroviruses to estimate risk of infection and illness. Median infection risks for one-time swimming events were approximately 2 × 10(-5), 8 × 10(-6), and 3 × 10(-7) [corrected] for C. jejuni, Salmonella spp., and enteroviruses, respectively. Results highlight the importance of investigating multiple pathogens within multiple categories to avoid underestimating the prevalence and risk of waterborne pathogens.

  1. Human and bovine viruses and bacteria at three Great Lakes beaches: Environmental variable associations and health risk

    USGS Publications Warehouse

    Corsi, Steven R.; Borchardt, Mark A.; Carvin, Rebecca B.; Burch, Tucker R; Spencer, Susan K.; Lutz, Michelle A.; McDermott, Colleen M.; Busse, Kimberly M.; Kleinheinz, Gregory; Feng, Xiaoping; Zhu, Jun

    2016-01-01

    Waterborne pathogens were measured at three beaches in Lake Michigan, environmental factors for predicting pathogen concentrations were identified, and the risk of swimmer infection and illness was estimated. Waterborne pathogens were detected in 96% of samples collected at three Lake Michigan beaches in summer, 2010. Samples were quantified for 22 pathogens in four microbial categories (human viruses, bovine viruses, protozoa, and pathogenic bacteria). All beaches had detections of human and bovine viruses and pathogenic bacteria indicating influence of multiple contamination sources at these beaches. Occurrence ranged from 40 to 87% for human viruses, 65–87% for pathogenic bacteria, and 13–35% for bovine viruses. Enterovirus, adenovirus A, Salmonella spp., Campylobacter jejuni, bovine polyomavirus, and bovine rotavirus A were present most frequently. Variables selected in multiple regression models used to explore environmental factors that influence pathogens included wave direction, cloud cover, currents, and water temperature. Quantitative Microbial Risk Assessment was done for C. jejuni, Salmonella spp., and enteroviruses to estimate risk of infection and illness. Median infection risks for one-time swimming events were approximately 3 × 10–5, 7 × 10–9, and 3 × 10–7 for C. jejuni, Salmonella spp., and enteroviruses, respectively. Results highlight the importance of investigating multiple pathogens within multiple categories to avoid underestimating the prevalence and risk of waterborne pathogens.

  2. Environmental forcing does not lead to diel or synoptic variability in carbon isotope content of forest soil respiration

    NASA Astrophysics Data System (ADS)

    Bowling, D. R.; Egan, J. E.; Hall, S. J.; Risk, D. A.

    2014-12-01

    Recent studies have highlighted fluctuations in the carbon isotope content (d13C) of CO2 produced by soil respiration. These fluctuations have been correlated with diel cycles of environmental forcing (e.g., soil temperature), or with synoptic weather events (e.g., rain events and pressure-induced ventilation). We used an extensive suite of observations to examine these phenomena over two months in a subalpine forest in Colorado, USA (the Niwot Ridge AmeriFlux site). Measurements included automated soil respiration chambers and automated measurements of the soil gas profile. We found 1) no diel change in the d13C of the soil surface flux or the CO2 produced in the soil (despite strong diel change in surface flux rate), 2) no change in d13C following wetting (despite a significant increase in soil flux rate), and 3) no evidence of pressure-induced ventilation of the soil. Measurements of the d13C of surface CO2 flux agreed closely with the isotopic composition of soil CO2 production calculated using soil profile measurements. Temporal variation in the d13C of surface flux was relatively minor and unrelated to measured environmental variables. Deep in the soil profile, results conform to established theory regarding diffusive soil gas transport and isotopic fractionation, and suggest that sampling soil gas at a depth of several tens of centimeters is a simple and effective way to assess the mean d13C of the surface flux.

  3. Circumpolar analysis of the Adélie Penguin reveals the importance of environmental variability in phenological mismatch.

    PubMed

    Youngflesh, Casey; Jenouvrier, Stephanie; Li, Yun; Ji, Rubao; Ainley, David G; Ballard, Grant; Barbraud, Christophe; Delord, Karine; Dugger, Katie M; Emmerson, Louise M; Fraser, William R; Hinke, Jefferson T; Lyver, Phil O'B; Olmastroni, Silvia; Southwell, Colin J; Trivelpiece, Susan G; Trivelpiece, Wayne Z; Lynch, Heather J

    2017-04-01

    Evidence of climate-change-driven shifts in plant and animal phenology have raised concerns that certain trophic interactions may be increasingly mismatched in time, resulting in declines in reproductive success. Given the constraints imposed by extreme seasonality at high latitudes and the rapid shifts in phenology seen in the Arctic, we would also expect Antarctic species to be highly vulnerable to climate-change-driven phenological mismatches with their environment. However, few studies have assessed the impacts of phenological change in Antarctica. Using the largest database of phytoplankton phenology, sea-ice phenology, and Adélie Penguin breeding phenology and breeding success assembled to date, we find that, while a temporal match between Penguin breeding phenology and optimal environmental conditions sets an upper limit on breeding success, only a weak relationship to the mean exists. Despite previous work suggesting that divergent trends in Adélie Penguin breeding phenology are apparent across the Antarctic continent, we find no such trends. Furthermore, we find no trend in the magnitude of phenological mismatch, suggesting that mismatch is driven by interannual variability in environmental conditions rather than climate-change-driven trends, as observed in other systems. We propose several criteria necessary for a species to experience a strong climate-change-driven phenological mismatch, of which several may be violated by this system.

  4. Condition of larval red snapper (Lutjanus campechanus) relative to environmental variability and the Deepwater Horizon oil spill

    NASA Astrophysics Data System (ADS)

    Hernandez, F. J., Jr.; Filbrun, J. E.; Fang, J.; Ransom, J. T.

    2016-09-01

    The Deepwater Horizon oil spill (DWHOS) spatially and temporally overlapped with the spawning of many fish species, including Red Snapper, one of the most economically important reef fish in the Gulf of Mexico. To investigate potential impacts of the DWHOS on larval Red Snapper, data from a long-term ichthyoplankton survey off the coast of Alabama were used to examine: (1) larval abundances among pre-impact (2007-2009), impact (2010), and post-impact (2011, 2013) periods; (2) proxies for larval condition (size-adjusted morphometric relationships and dry weight) among the same periods; and (3) the effects of background environmental variation on larval condition. We found that larval Red Snapper were in poorer body condition during 2010, 2011, and 2013 as compared to the 2007-2009 period, a trend that was strongly (and negatively) related to variation in Mobile Bay freshwater discharge. However, larvae collected during and after 2010 were in relatively poor condition even after accounting for variation in freshwater discharge and other environmental variables. By contrast, no differences in larval abundance were detected during these survey years. Taken together, larval supply did not change relative to the timing of the DWHOS, but larval condition was negatively impacted. Even small changes in condition can affect larval survival, so these trends may have consequences for recruitment of larvae to juvenile and adult life stages.

  5. Assessing the risk for dengue fever based on socioeconomic and environmental variables in a geographical information system environment.

    PubMed

    Khormi, Hassan M; Kumar, Lalit

    2012-05-01

    An important option in preventing the spread of dengue fever (DF) is to control and monitor its vector (Aedes aegypti) as well as to locate and destroy suitable mosquito breeding environments. The aim of the present study was to use a combination of environmental and socioeconomic variables to model areas at risk of DF. These variables include clinically confirmed DF cases, mosquito counts, population density in inhabited areas, total populations per district, water access, neighbourhood quality and the spatio-temporal risk of DF based on the average, weekly frequency of DF incidence. Out of 111 districts investigated, 17 (15%), covering a total area of 121 km2, were identified as of high risk, 25 (22%), covering 133 km2, were identified as of medium risk, 18 (16%), covering 180 km2, were identified as of low risk and 51 (46%), covering 726 km2, were identified as of very low risk. The resultant model shows that most areas at risk of DF were concentrated in the central part of Jeddah county, Saudi Arabia. The methods used can be implemented as routine procedures for control and prevention. A concerted intervention in the medium- and high-risk level districts identified in this study could be highly effective in reducing transmission of DF in the area as a whole.

  6. Relation of desert pupfish abundance to selected environmental variables in natural and manmade habitats in the Salton Sea basin

    USGS Publications Warehouse

    Martin, B.A.; Saiki, M.K.

    2005-01-01

    We assessed the relation between abundance of desert pupfish, Cyprinodon macularius, and selected biological and physicochemical variables in natural and manmade habitats within the Salton Sea Basin. Field sampling in a natural tributary, Salt Creek, and three agricultural drains captured eight species including pupfish (1.1% of the total catch), the only native species encountered. According to Bray-Curtis resemblance functions, fish species assemblages differed mostly between Salt Creek and the drains (i.e., the three drains had relatively similar species assemblages). Pupfish numbers and environmental variables varied among sites and sample periods. Canonical correlation showed that pupfish abundance was positively correlated with abundance of western mosquitofish, Gambusia affinis, and negatively correlated with abundance of porthole livebearers, Poeciliopsis gracilis, tilapias (Sarotherodon mossambica and Tilapia zillii), longjaw mudsuckers, Gillichthys mirabilis, and mollies (Poecilia latipinnaandPoecilia mexicana). In addition, pupfish abundance was positively correlated with cover, pH, and salinity, and negatively correlated with sediment factor (a measure of sediment grain size) and dissolved oxygen. Pupfish abundance was generally highest in habitats where water quality extremes (especially high pH and salinity, and low dissolved oxygen) seemingly limited the occurrence of nonnative fishes. This study also documented evidence of predation by mudsuckers on pupfish. These findings support the contention of many resource managers that pupfish populations are adversely influenced by ecological interactions with nonnative fishes. ?? Springer 2005.

  7. [Dynamics of sap flow density in stems of typical desert shrub Calligonum mongolicum and its responses to environmental variables].

    PubMed

    Xu, Shi-qin; Ji, Xi-bin; Jin, Bo-wen

    2016-02-01

    Independent measurements of stem sap flow in stems of Calligonum mongolicum and environmental variables using commercial sap flow gauges and a micrometeorological monitoring system, respectively, were made to simulate the variation of sap flow density in the middle range of Hexi Corridor, Northwest China during June to September, 2014. The results showed that the diurnal process of sap flow density in C. mongolicum showed a broad unimodal change, and the maximum sap flow density reached about 30 minutes after the maximum of photosynthetically active radiation (PAR) , while about 120 minutes before the maximum of temperature and vapor pressure deficit (VPD). During the studying period, sap flow density closely related with atmosphere evapor-transpiration demand, and mainly affected by PAR, temperature and VPD. The model was developed which directly linked the sap flow density with climatic variables, and good correlation between measured and simulated sap flow density was observed in different climate conditions. The accuracy of simulation was significantly improved if the time-lag effect was taken into consideration, while this model underestimated low and nighttime sap flow densities, which was probably caused by plant physiological characteristics.

  8. Unveiling the Redox Control of Plant Reproductive Development during Abiotic Stress

    PubMed Central

    Zinta, Gaurav; Khan, Asif; AbdElgawad, Hamada; Verma, Vipasha; Srivastava, Ashish Kumar

    2016-01-01

    Plants being sessile in nature are often challenged to various abiotic stresses including temperature fluctuations, water supply, salinity, and nutrient availability. Exposure of plants to such environmental perturbations result in the formation of reactive oxygen species (ROS) in cells. To scavenge ROS, enzymatic and molecular antioxidants are produced at a cellular level. ROS act as a signaling entity at lower concentrations maintaining normal growth and development, but if their levels increase beyond certain threshold, they produce toxic effects in plants. Some developmental stages, such as development of reproductive organs are more sensitive to abiotic stress than other stages of growth. As success of plant reproductive development is directly correlated with grain yield, stresses coinciding with reproductive phase results in the higher yield losses. In this article, we summarize the redox control of plant reproductive development, and elaborate how redox homeostasis is compromised during abiotic stress exposure. We highlight why more emphasis should be given to understand redox control of plant reproductive organ development during abiotic stress exposure96to engineer crops with better crop yield. We specifically discuss the role of ROS as a signaling molecule and its cross-talk with other signaling molecules such as hormones and sugars. PMID:27379102

  9. Survival in macaroni penguins and the relative importance of different drivers: individual traits, predation pressure and environmental variability.

    PubMed

    Horswill, Catharine; Matthiopoulos, Jason; Green, Jonathan A; Meredith, Michael P; Forcada, Jaume; Peat, Helen; Preston, Mark; Trathan, Phil N; Ratcliffe, Norman

    2014-09-01

    Understanding the demographic response of free-living animal populations to different drivers is the first step towards reliable prediction of population trends. Penguins have exhibited dramatic declines in population size, and many studies have linked this to bottom-up processes altering the abundance of prey species. The effects of individual traits have been considered to a lesser extent, and top-down regulation through predation has been largely overlooked due to the difficulties in empirically measuring this at sea where it usually occurs. For 10 years (2003-2012), macaroni penguins (Eudyptes chrysolophus) were marked with subcutaneous electronic transponder tags and re-encountered using an automated gateway system fitted at the entrance to the colony. We used multistate mark-recapture modelling to identify the different drivers influencing survival rates and a sensitivity analysis to assess their relative importance across different life stages. Survival rates were low and variable during the fledging year (mean = 0·33), increasing to much higher levels from age 1 onwards (mean = 0·89). We show that survival of macaroni penguins is driven by a combination of individual quality, top-down predation pressure and bottom-up environmental forces. The relative importance of these covariates was age specific. During the fledging year, survival rates were most sensitive to top-down predation pressure, followed by individual fledging mass, and finally bottom-up environmental effects. In contrast, birds older than 1 year showed a similar response to bottom-up environmental effects and top-down predation pressure. We infer from our results that macaroni penguins will most likely be negatively impacted by an increase in the local population size of giant petrels. Furthermore, this population is, at least in the short term, likely to be positively influenced by local warming. More broadly, our results highlight the importance of considering multiple causal effects across

  10. Ecohydrological responses of dense canopies to environmental variability: 2. Role of acclimation under elevated CO2

    NASA Astrophysics Data System (ADS)

    Drewry, D. T.; Kumar, P.; Long, S.; Bernacchi, C.; Liang, X.-Z.; Sivapalan, M.

    2010-12-01

    The ability to accurately predict land-atmosphere exchange of mass, energy, and momentum over the coming century requires the consideration of plant biochemical, ecophysiological, and structural acclimation to modifications of the ambient environment. Amongst the most important environmental changes experienced by terrestrial vegetation over the last century has been the increase in ambient carbon dioxide (CO2) concentrations, with a projected doubling in CO2 from preindustrial levels by the middle of this century. This change in atmospheric composition has been demonstrated to significantly alter a variety of leaf and plant properties across a range of species, with the potential to modify land-atmosphere interactions and their associated feedbacks. Free Air Carbon Enrichment (FACE) technology has provided significant insight into the functioning of vegetation in natural conditions under elevated CO2, but remains limited in its ability to quantify the exchange of CO2, water vapor, and energy at the canopy scale. This paper addresses the roles of ecophysiological, biochemical, and structural plant acclimation on canopy-scale exchange of CO2, water vapor, and energy through the application of a multilayer canopy-root-soil model (MLCan) capable of resolving changes induced by elevated CO2 through the canopy and soil systems. Previous validation of MLCan flux estimates were made for soybean and maize in the companion paper using a record of six growing seasons of eddy covariance data from the Bondville Ameriflux site. Observations of leaf-level photosynthesis, stomatal conductance, and surface temperature collected at the SoyFACE experimental facility in central Illinois provide a basis for examining the ability of MLCan to capture vegetation responses to an enriched CO2 environment. Simulations of control (370 [ppm]) and elevated (550 [ppm]) CO2 environments allow for an examination of the vertical variation and canopy-scale responses of vegetation states and fluxes

  11. Molecular method for the characterization of Coxiella burnetii from clinical and environmental samples: variability of genotypes in Spain

    PubMed Central

    2012-01-01

    Background Coxiella burnetii is a highly clonal microorganism which is difficult to culture, requiring BSL3 conditions for its propagation. This leads to a scarce availability of isolates worldwide. On the other hand, published methods of characterization have delineated up to 8 different genomic groups and 36 genotypes. However, all these methodologies, with the exception of one that exhibited limited discriminatory power (3 genotypes), rely on performing between 10 and 20 PCR amplifications or sequencing long fragments of DNA, which make their direct application to clinical samples impracticable and leads to a scarce accessibility of data on the circulation of C. burnetii genotypes. Results To assess the variability of this organism in Spain, we have developed a novel method that consists of a multiplex (8 targets) PCR and hybridization with specific probes that reproduce the previous classification of this organism into 8 genomic groups, and up to 16 genotypes. It allows for a direct characterization from clinical and environmental samples in a single run, which will help in the study of the different genotypes circulating in wild and domestic cycles as well as from sporadic human cases and outbreaks. The method has been validated with reference isolates. A high variability of C. burnetii has been found in Spain among 90 samples tested, detecting 10 different genotypes, being those adaA negative associated with acute Q fever cases presenting as fever of intermediate duration with liver involvement and with chronic cases. Genotypes infecting humans are also found in sheep, goats, rats, wild boar and ticks, and the only genotype found in cattle has never been found among our clinical samples. Conclusions This newly developed methodology has permitted to demonstrate that C. burnetii is highly variable in Spain. With the data presented here, cattle seem not to participate in the transmission of C. burnetii to humans in the samples studied, while sheep, goats, wild

  12. Stress ecology in fucus: abiotic, biotic and genetic interactions.

    PubMed

    Wahl, Martin; Jormalainen, Veijo; Eriksson, Britas Klemens; Coyer, James A; Molis, Markus; Schubert, Hendrik; Dethier, Megan; Karez, Rolf; Kruse, Inken; Lenz, Mark; Pearson, Gareth; Rohde, Sven; Wikström, Sofia A; Olsen, Jeanine L

    2011-01-01

    Stress regimes defined as the synchronous or sequential action of abiotic and biotic stresses determine the performance and distribution of species. The natural patterns of stress to which species are more or less well adapted have recently started to shift and alter under the influence of global change. This was the motivation to review our knowledge on the stress ecology of a benthic key player, the macroalgal genus Fucus. We first provide a comprehensive review of the genus as an ecological model including what is currently known about the major lineages of Fucus species with respect to hybridization, ecotypic differentiation and speciation; as well as life history, population structure and geographic distribution. We then review our current understanding of both extrinsic (abiotic/biotic) and intrinsic (genetic) stress(es) on Fucus species and how they interact with each other. It is concluded that (i) interactive stress effects appear to be equally distributed over additive, antagonistic and synergistic categories at the level of single experiments, but are predominantly additive when averaged over all studies in a meta-analysis of 41 experiments; (ii) juvenile and adult responses to stress frequently differ and (iii) several species or particular populations of Fucus may be relatively unaffected by climate change as a consequence of pre-adapted ecotypes that collectively express wide physiological tolerences. Future research on Fucus should (i) include additional species, (ii) include marginal populations as models for responses to environmental stress; (iii) assess a wider range of stress combinations, including their temporal fluctuations; (iv) better differentiate between stress sensitivity of juvenile versus adult stages; (v) include a functional genomic component in order to better integrate Fucus' ecological and evolutionary responses to stress regimes and (vi) utilize a multivariate modelling approach in order to develop and understand interaction

  13. An experimental test of the role of environmental temperature variability on ectotherm molecular, physiological and life-history traits: implications for global warming.

    PubMed

    Folguera, Guillermo; Bastías, Daniel A; Caers, Jelle; Rojas, José M; Piulachs, Maria-Dolors; Bellés, Xavier; Bozinovic, Francisco

    2011-07-01

    Global climate change is one of the greatest threats to biodiversity; one of the most important effects is the increase in the mean earth surface temperature. However, another but poorly studied main characteristic of global change appears to be an increase in temperature variability. Most of the current analyses of global change have focused on mean values, paying less attention to the role of the fluctuations of environmental variables. We experimentally tested the effects of environmental temperature variability on characteristics associated to the fitness (body mass balance, growth rate, and survival), metabolic rate (VCO(2)) and molecular traits (heat shock protein expression, Hsp70), in an ectotherm, the terrestrial woodlouse Porcellio laevis. Our general hypotheses are that higher values of thermal amplitude may directly affect life-history traits, increasing metabolic cost and stress responses. At first, results supported our hypotheses showing a diversity of responses among characters to the experimental thermal treatments. We emphasize that knowledge about the cellular and physiological mechanisms by which animals cope with environmental changes is essential to understand the impact of mean climatic change and variability. Also, we consider that the studies that only incorporate only mean temperatures to predict the life-history, ecological and evolutionary impact of global temperature changes present important problems to predict the diversity of responses of the organism. This is because the analysis ignores the complexity and details of the molecular and physiological processes by which animals cope with environmental variability, as well as the life-history and demographic consequences of such variability.

  14. Comprehensive structural, interaction and expression analysis of CBL and CIPK complement during abiotic stresses and development in rice.

    PubMed

    Kanwar, Poonam; Sanyal, Sibaji K; Tokas, Indu; Yadav, Akhilesh K; Pandey, Amita; Kapoor, Sanjay; Pandey, Girdhar K

    2014-08-01

    Calcium ion is involved in diverse physiological and developmental pathways. One of the important roles of calcium is a signaling messenger, which regulates signal transduction in plants. CBL (calcineurin B-like protein) is one of the calcium sensors that specifically interact with a family of serine-threonine protein kinases designated as CBL-interacting protein kinases (CIPKs). The coordination of these two gene families defines complexity of the signaling networks in several stimulus-response-coupling during various environmental stresses. In Arabidopsis, both of these gene families have been extensively studied. To understand in-depth mechanistic interplay of CBL-CIPK mediated signaling pathways, expression analysis of entire set of CBL and CIPK genes in rice genome under three abiotic stresses (salt, cold and drought) and different developmental stages (3-vegetative stages and 11-reproductive stages) were done using microarray expression data. Interestingly, expression analysis showed that rice CBLs and CIPKs are not only involved in the abiotic stress but their significant role is also speculated in the developmental processes. Chromosomal localization of rice CBL and CIPK genes reveals that only OsCBL7 and OsCBL8 shows tandem duplication among CBLs whereas CIPKs were evolved by many tandem as well as segmental duplications. Duplicated OsCIPK genes showed variable expression pattern indicating the role of gene duplication in the extension and functional diversification of CIPK gene family in rice. Arabidopsis SOS3/CBL4 related genes in rice (OsCBL4, OsCBL5, OsCBL7 and OsCBL8) were employed for interaction studies with rice and Arabidopsis CIPKs. OsCBLs and OsCIPKs are not only found structurally similar but likely to be functionally equivalent to Arabidopsis CBLs and CIPKs genes since SOS3/CBL4 related OsCBLs interact with more or less similarly to rice and Arabidopsis CIPKs and exhibited an interaction pattern comparable with Arabidopsis SOS3/CBL4.

  15. Formation of singlet oxygen and protection against its oxidative damage in Photosystem II under abiotic stress.

    PubMed

    Pospíšil, Pavel; Prasad, Ankush

    2014-08-01

    Photosystem II (PSII) is exposed to various abiotic stresses associated with adverse environmental conditions such as high light, heat, heavy metals or mechanical injury. Distinctive functional response to adverse environmental conditions is formation of singlet oxygen ((1)O2). In this review, recent progress on mechanistic principles on (1)O2 formation under abiotic stresses is summarized. Under high light, (1)O2 is formed by excitation energy transfer from triplet chlorophylls to molecular oxygen formed by the spin conversion via photosensitization Type II reaction in the PSII antenna complex or by the recombination of (1)[P680(+)Pheo(-)] radical pair in the PSII reaction center. Apart from well-described (1)O2 formation by excitation energy transfer, (1)O2 formation by decomposition of dioxetane and tetroxide is summarized as a potential source of (1)O2 in PSII under heat, heavy metals and mechanical stress. The description of mechanistic principles on (1)O2 formation under abiotic stress allows us to understand how plants respond to adverse environmental conditions in vivo.

  16. Integrating ecology and physiology of root-hemiparasitic interaction: interactive effects of abiotic resources shape the interplay between parasitism and autotrophy.

    PubMed

    Těšitel, Jakub; Těšitelová, Tamara; Fisher, James P; Lepš, Jan; Cameron, Duncan D

    2015-01-01

    Root hemiparasites are green photosynthetic plants, which parasitically acquire resources from host xylem. Mineral nutrients and water, two principal below-ground abiotic resources, were assumed to affect the interaction between hemiparasites and their hosts. The shape of these effects and the underlying physiological mechanisms have, however, remained unclear. We conducted a glasshouse experiment with root-hemiparasitic Rhinanthus alectorolophus, in which we manipulated the availability of mineral nutrients and water. Biomass production and Chl fluorescence of the hemiparasites and hosts were recorded, together with proportion of host-derived carbon in hemiparasite biomass. The abiotic resources had profound interactive effects on the performance of both the hemiparasite and the hosts, as well as the balance of above-ground biomass between them. These effects were mainly based on an increase of growth and photosynthetic efficiency under high nutrient concentrations, on the hemiparasite's ability to induce strong water stress on the hosts if water is limiting, and on release of the host from parasitism by simultaneous abundance of both resources. Hemiparasitism is a highly variable interaction, in which environmental conditions affect both the parasitic and autotrophic (and thus competitive) components. A hemiparasite's own photosynthesis plays a crucial role in the assimilation of parasitized mineral resources and their transformation into growth and fitness.

  17. Soluble sugars—Metabolism, sensing and abiotic stress

    PubMed Central

    Rosa, Mariana; Prado, Carolina; Podazza, Griselda; Interdonato, Roque; González, Juan A; Hilal, Mirna

    2009-01-01

    Plants are autotrophic and photosynthetic organisms that both produce and consume sugars. Soluble sugars are highly sensitive to environmental stresses, which act on the supply of carbohydrates from source organs to sink ones. Sucrose and hexoses both play dual functions in gene regulation as exemplified by the upregulation of growth-related genes and downregulation of stress-related genes. Although coordinately regulated by sugars, these growth- and stress-related genes are upregulated or downregulated through HXK-dependent and/or HXK-independent pathways. Sucrose-non-fermenting-1- (SNF1-) related protein pathway, analogue to the protein kinase (SNF-) yeast-signalling pathway, seems also involved in sugar sensing and transduction in plants. However, even if plants share with yeast some elements involved in sugar sensing, several aspects of sugar perception are likely to be peculiar to higher plants. In this paper, we have reviewed recent evidences how plants sense and respond to environmental factors through sugar-sensing mechanisms. However, we think that forward and reverse genetic analysis in combination with expression profiling must be continued to uncover many signalling components, and a full biochemical characterization of the signalling complexes will be required to determine specificity and cross-talk in abiotic stress signalling pathways. PMID:19816104

  18. Effects of biotic and abiotic factors on phenotypic partitioning of wing morphology and development in Sclerodermus pupariae (hymenoptera: bethylidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wing phenotype polymorphism is commonly observed in insects, yet little is known about the influence of environmental cues on the development or expression of the alternative phenotypes. Here, we examined the effects of biotic and abiotic factors including temperature, photoperiod, light intensity,...

  19. Linear free energy relationships for the biotic and abiotic reduction of nitroaromatic compounds.

    PubMed

    Luan, Fubo; Gorski, Christopher A; Burgos, William D

    2015-03-17

    Nitroaromatic compounds (NACs) are ubiquitous environmental contaminants that are susceptible to biological and abiotic reduction. Prior works have found that for the abiotic reduction of NACs, the logarithm of the NACs’ rate constants correlate with one-electron reduction potential values of the NACs (EH,NAC1) according to linear free energy relationships (LFERs). Here, we extend the application of LFERs to the bioreduction of NACs and to the abiotic reduction of NACs by bioreduced (and pasteurized) iron-bearing clay minerals. A linear correlation (R2=0.96) was found between the NACs’ bioreduction rate constants (kobs) and EH,NAC1 values. The LFER slope of log kobs versus EH,NAC1/(2.303RT/F) was close to one (0.97), which implied that the first electron transfer to the NAC was the rate-limiting step of bioreduction. LFERs were also established between NAC abiotic reduction rate constants by bioreduced iron-bearing clay minerals (montmorillonite SWy-2 and nontronite NAu-2). The second-order NAC reduction rate constants (k) by bioreduced SWy-2 and NAu-2 were well correlated to EH,NAC1 (R2=0.97 for both minerals), consistent with bioreduction results. However, the LFER slopes of log k versus EH,NAC1/(2.303RT/F) were significantly less than one (0.48–0.50) for both minerals, indicating that the first electron transfer to the NAC was not the rate-limiting step of abiotic reduction. Finally, we demonstrate that the rate of 4-acetylnitrobenzene reduction by bioreduced SWy-2 and NAu-2 correlated to the reduction potential of the clay (EH,clay, R2=0.95 for both minerals), indicating that the clay reduction potential also influences its reactivity.

  20. MicroRNAs As Potential Targets for Abiotic Stress Tolerance in Plants

    PubMed Central

    Shriram, Varsha; Kumar, Vinay; Devarumath, Rachayya M.; Khare, Tushar S.; Wani, Shabir H.

    2016-01-01

    The microRNAs (miRNAs) are small (20–24 nt) sized, non-coding, single stranded riboregulator RNAs abundant in higher organisms. Recent findings have established that plants assign miRNAs as critical post-transcriptional regulators of gene expression in sequence-specific manner to respond to numerous abiotic stresses they face during their growth cycle. These small RNAs regulate gene expression via translational inhibition. Usually, stress induced miRNAs downregulate their target mRNAs, whereas, their downregulation leads to accumulation and function of positive regulators. In the past decade, investigations were mainly aimed to identify plant miRNAs, responsive to individual or multiple environmental factors, profiling their expression patterns and recognizing their roles in stress responses and tolerance. Altered expressions of miRNAs implicated in plant growth and development have been reported in several plant species subjected to abiotic stress conditions such as drought, salinity, extreme temperatures, nutrient deprivation, and heavy metals. These findings indicate that miRNAs may hold the key as potential targets for genetic manipulations to engineer abiotic stress tolerance in crop plants. This review is aimed to provide recent updates on plant miRNAs, their biogenesis and functions, target prediction and identification, computational tools and databases available for plant miRNAs, and their roles in abiotic stress-responses and adaptive mechanisms in major crop plants. Besides, the recent case studies for overexpressing the selected miRNAs for miRNA-mediated enhanced abiotic stress tolerance of transgenic plants have been discussed. PMID:27379117

  1. Generation of RNA in abiotic conditions.

    NASA Astrophysics Data System (ADS)

    di Mauro, Ernesto

    Generation of RNA in abiotic conditions. Ernesto Di Mauro Dipartimento di Genetica Bi-ologia Molecolare, Universit` "Sapienza" Roma, Italy. a At least four conditions must be satisfied for the spontaneous generation of (pre)-genetic poly-mers: 1) availability of precursors that are activated enough to spontaneously polymerize. Preliminary studies showed that (a) nucleic bases and acyclonucleosides can be synthesized from formamide H2NCOH by simply heating with prebiotically available mineral catalysts [last reviewed in (1)], and that b) nucleic bases can be phosphorylated in every possible posi-tion [2'; 3'; 5'; cyclic 2',3'; cyclic 3',5' (2)]. The higher stability of the cyclic forms allows their accumulation. 2) A polymerization mechanism. A reaction showing the formation of RNA polymers starting from prebiotically plausible precursors (3',5' cyclic GMP and 3', 5'cyclic AMP) was recently reported (3). Polymerization in these conditions is thermodynamically up-hill and an equilibrium is attained that limits the maximum length of the polymer produced to about 40 nucleotides for polyG and 100 nucleotides for polyA. 3) Ligation of the synthesized oligomers. If this type of reaction could occur according to a terminal-joining mechanism and could generate canonical 3',5' phosphodiester bonds, exponential growth would be obtained of the generated oligomers. This type of reaction has been reported (4) , limited to homogeneous polyA sequences and leading to the production of polyA dimers and tetramers. What is still missing are: 4) mechanisms that provide the proof of principle for the generation of sequence complexity. We will show evidence for two mechanisms providing this proof of principle for simple complementary sequences. Namely: abiotic sequence complementary-driven terminal ligation and sequence-complementary terminal growth. In conclusion: all the steps leading to the generation of RNA in abiotic conditions are satisfied. (1) R Saladino, C Crestini, F

  2. High-frequency analysis of the complex linkage between soil CO(2) fluxes, photosynthesis and environmental variables.

    PubMed

    Martin, Jonathan G; Phillips, Claire L; Schmidt, Andres; Irvine, James; Law, Beverly E

    2012-01-01

    High-frequency soil CO(2) flux data are valuable for providing new insights into the processes of soil CO(2) production. A record of hourly soil CO(2) fluxes from a semi-arid ponderosa pine stand was spatially and temporally deconstructed in attempts to determine if variation could be explained by logical drivers using (i) CO(2) production depths, (ii) relationships and lags between fluxes and soil temperatures, or (iii) the role of canopy assimilation in soil CO(2) flux variation. Relationships between temperature and soil fluxes were difficult to establish at the hourly scale because diel cycles of soil fluxes varied seasonally, with the peak of flux rates occurring later in the day as soil water content decreased. Using a simple heat transport/gas diffusion model to estimate the time and depth of CO(2) flux production, we determined that the variation in diel soil CO(2) flux patterns could not be explained by changes in diffusion rates or production from deeper soil profiles. We tested for the effect of gross ecosystem productivity (GEP) by minimizing soil flux covariance with temperature and moisture using only data from discrete bins of environmental conditions (±1 °C soil temperature at multiple depths, precipitation-free periods and stable soil moisture). Gross ecosystem productivity was identified as a possible driver of variability at the hourly scale during the growing season, with multiple lags between ~5, 15 and 23 days. Additionally, the chamber-specific lags between GEP and soil CO(2) fluxes appeared to relate to combined path length for carbon flow (top of tree to chamber center). In this sparse and heterogeneous forested system, the potential link between CO(2) assimilation and soil CO(2) flux may be quite variable both temporally and spatially. For model applications, it is important to note that soil CO(2) fluxes are influenced by many biophysical factors, which may confound or obscure relationships with logical environmental drivers and act at

  3. Endocrinology of year-round reproduction in a highly seasonal habitat: environmental variability in testosterone and glucocorticoids in baboon males

    PubMed Central

    Gesquiere, Laurence R.; Onyango, Patrick O.; Alberts, Susan C.; Altmann, Jeanne

    2010-01-01

    In conditions characterized by energetic constraints, such as in periods of low food availability, some trade-offs between reproduction and self-maintenance may be necessary; even year-round breeders may then be forced to exhibit some reproductive seasonality. Prior research has largely focused on female reproduction and physiology, and few studies have evaluated the impact of environmental factors on males. Here we assessed the effects of season and ambient temperatures on fecal glucocorticoid (fGC) and testosterone (fT) levels in male baboons in Amboseli, Kenya. The Amboseli basin is a highly challenging, semi-arid tropical habitat that is characterized by strongly seasonal patterns of rainfall and by high ambient temperatures. We previously reported that female baboons were impacted by these challenging environmental conditions. We ask here whether male baboons in the same environment and groups as females exhibit similar physiological effects. We found that after accounting for male age and individual variability, males exhibited higher fGC levels and lower fT levels during the dry season than during the wet season. Furthermore, fT but not fGC levels were lower in months of high average daily maximum temperatures, suggesting a direct impact of heat on testes. Our results demonstrate that male baboons, like females, experience ecological stress that alters their reproductive physiology. The impact of the environment on male reproduction deserves more attention both in its own right and because alteration in male physiology may contribute to the reduction in female fertility observed in challenging environments. PMID:20721938

  4. Cell wall remodeling under abiotic stress

    PubMed Central

    Tenhaken, Raimund

    2015-01-01

    Plants exposed to abiotic stress respond to unfavorable conditions on multiple levels. One challenge under drought stress is to reduce shoot growth while maintaining root growth, a process requiring differential cell wall synthesis and remodeling. Key players in this process are the formation of reactive oxygen species (ROS) and peroxidases, which initially cross-link phenolic compounds and glycoproteins of the cell walls causing stiffening. The function of ROS shifts after having converted all the peroxidase substrates in the cell wall. If ROS-levels remain high during prolonged stress, OH°-radicals are formed which lead to polymer cleavage. In concert with xyloglucan modifying enzymes and expansins, the resulting cell wall loosening allows further growth of stressed organs. PMID:25709610

  5. Paleolimnological reconstruction of environmental variability during the Late Pleistocene and Holocene in the south-east Baltic region

    NASA Astrophysics Data System (ADS)

    Kublitskiy, Iurii; Subetto, Dmitriy; Druzhinina, Olga; Kulkova, Marianna; Arslanov, Khikmatula

    2016-04-01

    The main goal of our research is the high-resolution reconstruction of environmental and climatic changes in SE Baltic region since the Last Glacial Maximum by palaeolimnological data. The 6 objects - lakes and peat-bogs, were studied since 2009 in the Kaliningrad region, Russian Federation. According to palaeolimnological studies of bottom sediments of the Kamyshovoe Lake (N 54°22,6`; E22°42,8`, 189 m a.s.l.), located in the Vishtynets Highland, the south-east part of Kaliningrad district, the environmental and climatic changes after the late glacial have been reconstructed. At that moment the radiocarbon and loss-on-ignition (LOI) data, geochemistry and diatom analysis for the whole sediment core, and pollen analyze for the bottom part of the core have been completed. According to the pollen data the Alleröd interstadial starts at 13 200 cal. yrs BP and is marked by the rising of birch and pine pollen. The transition to the Younger Dryas around 12 700 cal. yrs BP corresponds with the development of patches of shrublands in which light-demanding species, such as juniper, flourished and communities of steppe herbs. The late Preboreal is marked by the appearance of Populus and an increase of the role of grasses in the vegetation cover 11 300-11 100 cal. yrs BP (Druzinina et al., 2015). The Holocene climatic zones have been identified by LOI and geochemistry analyses. The Boreal period started about 10 200 cal. yrs BP, Atlantic around 9100 cal. yrs BP, Subboreal 5800 cal. yrs BP, and Subatlantic 3200 cal. yrs BP (Kublitskiy et al., 2015). During the conference the new palaeolimnological data of environmental variability during the late Pleistocene and Holocene in SE Baltic region will be presented. Acknowledgements The investigations have been granted by the Russian Fund for Basic Research (12-05-33013, 13-05-41457, 15-35-50721). References Druzhinina, O., Subetto, D., Stančikaitė, M., Vaikutienė, G., Kublitsky, J., Arslanov, Kh., 2015. Sediment record from the

  6. Dissemination of antibiotic resistance genes in representative broiler feedlots environments: identification of indicator ARGs and correlations with environmental variables.

    PubMed

    He, Liang-Ying; Liu, You-Sheng; Su, Hao-Chang; Zhao, Jian-Liang; Liu, Shuang-Shuang; Chen, Jun; Liu, Wang-Rong; Ying, Guang-Guo

    2014-11-18

    fexA, fexB, cfr, sul1, tetW, tetO, tetS: R = 0.52-0.71) and some environmental parameters (e.g., TOC, TN, TP, NH3-N with fexA, fexB, cfr, sul1, tetW, tetO, tetQ, tetS: R = 0.53-0.87) (p < 0.01). Further redundancy analysis demonstrated that the distribution and transportation of ARGs from the boiler feedlots to the receiving environments were correlated with environmental variables. The findings highlight the contribution of some chemicals such as antibiotics and metals to the development of ARGs in broiler feedlots environments; and the observed ARG dissemination mechanism in the broiler feedlots facilitates the development of effective mitigation measures.

  7. Survival in macaroni penguins and the relative importance of different drivers: individual traits, predation pressure and environmental variability

    PubMed Central

    Horswill, Catharine; Matthiopoulos, Jason; Green, Jonathan A; Meredith, Michael P; Forcada, Jaume; Peat, Helen; Preston, Mark; Trathan, Phil N; Ratcliffe, Norman

    2014-01-01

    Understanding the demographic response of free-living animal populations to different drivers is the first step towards reliable prediction of population trends. Penguins have exhibited dramatic declines in population size, and many studies have linked this to bottom-up processes altering the abundance of prey species. The effects of individual traits have been considered to a lesser extent, and top-down regulation through predation has been largely overlooked due to the difficulties in empirically measuring this at sea where it usually occurs. For 10 years (2003–2012), macaroni penguins (Eudyptes chrysolophus) were marked with subcutaneous electronic transponder tags and re-encountered using an automated gateway system fitted at the entrance to the colony. We used multistate mark–recapture modelling to identify the different drivers influencing survival rates and a sensitivity analysis to assess their relative importance across different life stages. Survival rates were low and variable during the fledging year (mean = 0·33), increasing to much higher levels from age 1 onwards (mean = 0·89). We show that survival of macaroni penguins is driven by a combination of individual quality, top-down predation pressure and bottom-up environmental forces. The relative importance of these covariates was age specific. During the fledging year, survival rates were most sensitive to top-down predation pressure, followed by individual fledging mass, and finally bottom-up environmental effects. In contrast, birds older than 1 year showed a similar response to bottom-up environmental effects and top-down predation pressure. We infer from our results that macaroni penguins will most likely be negatively impacted by an increase in the local population size of giant petrels. Furthermore, this population is, at least in the short term, likely to be positively influenced by local warming. More broadly, our results highlight the importance of considering multiple causal

  8. Abiotic Organic Chemistry in Hydrothermal Systems.

    NASA Astrophysics Data System (ADS)

    Simoneit, B. R.; Rushdi, A. I.

    2004-12-01

    Abiotic organic chemistry in hydrothermal systems is of interest to biologists, geochemists and oceanographers. This chemistry consists of thermal alteration of organic matter and minor prebiotic synthesis of organic compounds. Thermal alteration has been extensively documented to yield petroleum and heavy bitumen products from contemporary organic detritus. Carbon dioxide, carbon monoxide, ammonia and sulfur species have been used as precursors in prebiotic synthesis experiments to organic compounds. These inorganic species are common components of hot spring gases and marine hydrothermal systems. It is of interest to further test their reactivities in reductive aqueous thermolysis. We have synthesized organic compounds (lipids) in aqueous solutions of oxalic acid, and with carbon disulfide or ammonium bicarbonate at temperatures from 175-400° C. The synthetic lipids from oxalic acid solutions consisted of n-alkanols, n-alkanoic acids, n-alkyl formates, n-alkanones, n-alkenes and n-alkanes, typically to C30 with no carbon number preferences. The products from CS2 in acidic aqueous solutions yielded cyclic thioalkanes, alkyl polysulfides, and thioesters with other numerous minor compounds. The synthesis products from oxalic acid and ammonium bicarbonate solutions were homologous series of n-alkyl amides, n-alkyl amines, n-alkanes and n-alkanoic acids, also to C30 with no carbon number predominance. Condensation (dehydration) reactions also occur under elevated temperatures in aqueous medium as tested by model reactions to form amide, ester and nitrile bonds. It is concluded that the abiotic formation of aliphatic lipids, condensation products (amides, esters, nitriles, and CS2 derivatives (alkyl polysulfides, cyclic polysulfides) is possible under hydrothermal conditions and warrants further studies.

  9. Environmental Controls on Multi-Scale Soil Nutrient Variability in the Tropics: the Importance of Land-Cover Change

    NASA Astrophysics Data System (ADS)

    Holmes, K. W.; Kyriakidis, P. C.; Chadwick, O. A.; Matricardi, E.; Soares, J. V.; Roberts, D. A.

    2003-12-01

    The natural controls on soil variability and the spatial scales at which correlation exists among soil and environmental variables are critical information for evaluating the effects of deforestation. We detect different spatial scales of variability in soil nutrient levels over a large region (hundreds of thousands of km2) in the Amazon, analyze correlations among soil properties at these different scales, and evaluate scale-specific relationships among soil properties and the factors potentially driving soil development. Statistical relationships among physical drivers of soil formation, namely geology, precipitation, terrain attributes, classified soil types, and land cover derived from remote sensing, were included to determine which factors are related to soil biogeochemistry at each spatial scale. Surface and subsurface soil profile data from a 3000 sample database collected in Rond“nia, Brazil, were used to investigate patterns in pH, phosphorus, nitrogen, organic carbon, effective cation exchange capacity, calcium, magnesium, potassium, aluminum, sand, and clay in this environment grading from closed canopy tropical forest to savanna. We focus on pH in this presentation for simplicity, because pH is the single most important soil characteristic for determining the chemical environment of higher plants and soil microbial activity. We determined four spatial scales which characterize integrated patterns of soil chemistry: less than 3 km; 3 to 10 km; 10 to 68 km; and from 68 to 550 km (extent of study area). Although the finest observable scale was fixed by the field sampling density, the coarser scales were determined from relationships in the data through coregionalization modeling, rather than being imposed by the researcher. Processes which affect soils over short distances, such as land cover and terrain attributes, were good predictors of fine scale spatial components of nutrients; processes which affect soils over very large distances, such as

  10. Holocene climate and environmental variability based on benthic foraminifera and sediments from the inner shelf of the southeastern Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Tapiero, I.; Almogi-Labin, A.; Benjamini, C.

    2003-04-01

    Deep-sea sedimentary successions are generally the best marine records for reconstruction of climate variability. Nearshore successions should be more suitable as they respond better to changes in fluvial input more directly linked to climate. We present here a high resolution study of two excellently preserved ˜7 m long vibrocores taken at 33 and 37 m water depth off the southern and central parts of the Israeli coast, distally located relative to the delta of the Nile River. Unlike the deep sea record, these successions directly record aspects of Nile discharge history tracking climate variability of east equatorial and NE Africa. Sand fraction, carbonate content, and benthic foraminiferal assemblages form the database for recording the environmental changes in these shallow water sediments, dated by AMS 14C. Findings show that during the Holocene, two different climatic regimes predominated, separated by a transitional period of ˜1000 y. Between 8.4 and 6.3-6.7 kyBP the climate was relatively humid with small seasonal fluctuations. From 6.3-6.7 to 5.5 kyBP the climate regime changed from humid to semi-arid, a transition apparently accompanied by increased periodic storm activity in the eastern Mediterranean. From 5.5 kyBP to the present, the climate become drier and seasonality was more pronounced. Sedimentation rates during the early Holocene were high, exceeding 140 cm/1000 y, indicating enhanced hydrological activity in the southeastern Mediterranean and at the headwaters of the Nile River. During the late Holocene, sedimentation rates decreased drastically to below 60 cm/1000 y, reflecting reduced hydrological activity and increasing aridity in the region. The benthic foraminiferal record shows at first high abundance, diversity and equitability, suggesting that nutrient flux and concomitant productivity was higher during the early Holocene with relatively stable food supply to the sediment. This assemblage was almost entirely replaced at 5.5 kyBP by a low

  11. The intraspecific variability of short- and long-term carbon allocation, turnover and fluxes under different environmental conditions

    NASA Astrophysics Data System (ADS)

    Wegener, Frederik; Beyschlag, Wolfram; Werner, Christiane

    2014-05-01

    allocation to different tissues and respiration. The results give valuable new information to understand the total plant C balance and to characterize its intraspecific variability due to environmental factors.