Science.gov

Sample records for abiotic environmental variables

  1. Abiotic environmental factors influencing blowfly colonisation patterns in the field.

    PubMed

    George, Kelly A; Archer, Melanie S; Toop, Tes

    2013-06-10

    The accuracy of minimum post-mortem interval (mPMI) estimates usually hinges upon the ability of forensic entomologists to predict the conditions under which calliphorids will colonise bodies. However, there can be delays between death and colonisation due to poorly understood abiotic and biotic factors, hence the need for a mPMI. To quantify the importance of various meteorological and light-level factors, beef liver baits were placed in the field (Victoria, Australia) on 88 randomly selected days over 3 years in all seasons and observed every 60-90 min for evidence of colonisation. Baits were exposed during daylight, and the following parameters were measured: barometric pressure, light intensity, wind speed, ambient temperature, relative humidity and rainfall. Collected data were analysed using backward LR logistic regression to produce an equation of colonisation probability. This type of analysis removes factors with the least influence on colonisation in successive steps until all remaining variables significantly increase the accuracy of predicting colonisation presence or absence. Ambient temperature was a positive predictor variable (an increase in temperature increased the probability of calliphorid colonisation). Relative humidity was a negative predictor variable (an increase in humidity decreased the probability of calliphorid colonisation). Barometric pressure, light intensity, wind speed and rainfall did not enhance the accuracy of the probability model; however, analysis of species activity patterns suggests that heavy rainfall and strong wind speeds inhibit calliphorid colonisation.

  2. 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

  3. 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

  4. 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

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

    PubMed

    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

  6. 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.

  7. 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.

  8. Using abiotic variables to predict importance of sites for species representation.

    PubMed

    Albuquerque, Fabio; Beier, Paul

    2015-10-01

    In systematic conservation planning, species distribution data for all sites in a planning area are used to prioritize each site in terms of the site's importance toward meeting the goal of species representation. But comprehensive species data are not available in most planning areas and would be expensive to acquire. As a shortcut, ecologists use surrogates, such as occurrences of birds or another well-surveyed taxon, or land types defined from remotely sensed data, in the hope that sites that represent the surrogates also represent biodiversity. Unfortunately, surrogates have not performed reliably. We propose a new type of surrogate, predicted importance, that can be developed from species data for a q% subset of sites. With species data from this subset of sites, importance can be modeled as a function of abiotic variables available at no charge for all terrestrial areas on Earth. Predicted importance can then be used as a surrogate to prioritize all sites. We tested this surrogate with 8 sets of species data. For each data set, we used a q% subset of sites to model importance as a function of abiotic variables, used the resulting function to predict importance for all sites, and evaluated the number of species in the sites with highest predicted importance. Sites with the highest predicted importance represented species efficiently for all data sets when q = 25% and for 7 of 8 data sets when q = 20%. Predicted importance requires less survey effort than direct selection for species representation and meets representation goals well compared with other surrogates currently in use. This less expensive surrogate may be useful in those areas of the world that need it most, namely tropical regions with the highest biodiversity, greatest biodiversity loss, most severe lack of inventory data, and poorly developed protected area networks.

  9. 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.

  10. 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. PMID:25496258

  11. Inter-annual variability of carbon fluxes in temperate forest ecosystems: effects of biotic and abiotic factors

    NASA Astrophysics Data System (ADS)

    Chen, M.; Keenan, T. F.; Hufkens, K.; Munger, J. W.; Bohrer, G.; Brzostek, E. R.; Richardson, A. D.

    2014-12-01

    Carbon dynamics in terrestrial ecosystems are influenced by both abiotic and biotic factors. Abiotic factors, such as variation in meteorological conditions, directly drive biophysical and biogeochemical processes; biotic factors, referring to the inherent properties of the ecosystem components, reflect the internal regulating effects including temporal dynamics and memory. The magnitude of the effect of abiotic and biotic factors on forest ecosystem carbon exchange has been suggested to vary at different time scales. In this study, we design and conduct a model-data fusion experiment to investigate the role and relative importance of the biotic and abiotic factors for inter-annual variability of the net ecosystem CO2 exchange (NEE) of temperate deciduous forest ecosystems in the Northeastern US. A process-based model (FöBAAR) is parameterized at four eddy-covariance sites using all available flux and biometric measurements. We conducted a "transplant" modeling experiment, that is, cross- site and parameter simulations with different combinations of site meteorology and parameters. Using wavelet analysis and variance partitioning techniques, analysis of model predictions identifies both spatial variant and spatially invariant parameters. Variability of NEE was primarily modulated by gross primary productivity (GPP), with relative contributions varying from hourly to yearly time scales. The inter-annual variability of GPP and NEE is more regulated by meteorological forcing, but spatial variability in certain model parameters (biotic response) has more substantial effects on the inter-annual variability of ecosystem respiration (Reco) through the effects on carbon pools. Both the biotic and abiotic factors play significant roles in modulating the spatial and temporal variability in terrestrial carbon cycling in the region. Together, our study quantifies the relative importance of both, and calls for better understanding of them to better predict regional CO2

  12. 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

  13. 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.

  14. 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

  15. 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

  16. 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

  17. 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.

  18. The Role of Abiotic Environmental Conditions and Herbivory in Shaping Bacterial Community Composition in Floral Nectar

    PubMed Central

    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. PMID:24922317

  19. Plant core environmental stress response genes are systemically coordinated during abiotic stresses.

    PubMed

    Hahn, Achim; Kilian, Joachim; Mohrholz, Anne; Ladwig, Friederike; Peschke, Florian; Dautel, Rebecca; Harter, Klaus; Berendzen, Kenneth W; Wanke, Dierk

    2013-01-01

    Studying plant stress responses is an important issue in a world threatened by global warming. Unfortunately, comparative analyses are hampered by varying experimental setups. In contrast, the AtGenExpress abiotic stress experiment displays intercomparability. Importantly, six of the nine stresses (wounding, genotoxic, oxidative, UV-B light, osmotic and salt) can be examined for their capacity to generate systemic signals between the shoot and root, which might be essential to regain homeostasis in Arabidopsis thaliana. We classified the systemic responses into two groups: genes that are regulated in the non-treated tissue only are defined as type I responsive and, accordingly, genes that react in both tissues are termed type II responsive. Analysis of type I and II systemic responses suggest distinct functionalities, but also significant overlap between different stresses. Comparison with salicylic acid (SA) and methyl-jasmonate (MeJA) responsive genes implies that MeJA is involved in the systemic stress response. Certain genes are predominantly responding in only one of the categories, e.g., WRKY genes respond mainly non-systemically. Instead, genes of the plant core environmental stress response (PCESR), e.g., ZAT10, ZAT12, ERD9 or MES9, are part of different response types. Moreover, several PCESR genes switch between the categories in a stress-specific manner.

  20. Abiotic Limits for Germination of Sugarcane Seed in Relation to Environmental Spread.

    PubMed

    Pierre, J S; Rae, A L; Bonnett, G D

    2014-01-01

    Sugarcane is a vegetatively propagated crop and hence the production of seed and its fate in the environment has not been studied. The recent development of genetically modified sugarcane, with the aim of commercial production, requires a research effort to understand sugarcane reproductive biology. This study contributes to this understanding by defining the abiotic limits for sugarcane seed germination. Using seed from multiple genetic crosses, germination was measured under different light regimes (light and dark), temperatures (from 18 °C to 42 °C) and water potentials (from 0 MPa to -1 MPa); cardinal temperatures and base water potential of germination were estimated based on the rates of germination. We found that sugarcane seed could germinate over a broad range of temperatures (from 11 °C to 42 °C) with optima ranging from 27 °C to 36 °C depending on source of seed. Water potentials below -0.5 MPa halved the proportion of seed that germinated. By comparing these limits to the environmental conditions in areas where sugarcane grows and has the potential to produce seed, water, but not temperature, will be the main limiting factor for germination. This new information can be taken into account when evaluating any risk of weediness during the assessment of GM sugarcane.

  1. 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.

  2. 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. PMID:27122551

  3. 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.

  4. 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.

  5. Biotic and abiotic factors affecting stemflow variability in downy oak and Scots pine stands in Mediterranean conditions

    NASA Astrophysics Data System (ADS)

    Cayuela, Carles; Garcia-Estringana, Pablo; Latron, Jérôme; Llorens, Pilar

    2015-04-01

    Although stemflow is only a small portion of rainfall, it may represent an important local input of water and nutrients at the plant stem. Previous studies have shown that stemflow has a significant influence on hydrological and biogeochemical processes. Stemflow volume is affected by many biotic factors as species, age, branch or bark characteristics. Moreover, the seasonality of the rainfall regime in Mediterranean areas, which includes both frontal rainfall events and short convective storms, can add complexity to the rainfall-stemflow relationship. This work investigates stemflow dynamics and the influence of biotic and abiotic factors on stemflow rates in two Mediterranean stands during the leafed period - from May to October. The monitored stands are a Downy oak forest (Quercus pubescens) and a Scots pine forest (Pinus sylvestris), both located in the Vallcebre research catchments (NE Spain, 42° 12'N, 1° 49'E). The monitoring design of each plot consists of 7 stemflow rings connected to tipping-buckets, bulk rainfall measured in a nearby clearing and meteorological conditions above the canopies. All data were recorded at 5 min interval. Biometric characteristics of the measured trees were also measured. The analysis of 39 rainfall events (65% smaller than 10 mm) shows that stemflow accounted for less than 1% of the bulk rainfall in both stands. Results also show that, on average, the rainfall amount required for the start of the stemflow and the time delay between the beginning of the precipitation and the start of stemflow are higher in the Downy oak forest. As suggested by stemflow funneling ratios, these differences might be linked to the canopy structure and bark water storage capacity of the trees, indicating that during low magnitude events, oaks have more difficulty to reach storage capacity. The role of other biotic and abiotic parameters on stemflow variability in both stands is still under investigation.

  6. 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…

  7. 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

  8. 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

  9. Abiotic and biotic stressors causing equivalent mortality induce highly variable transcriptional responses in the soybean aphid.

    PubMed

    Enders, Laramy S; Bickel, Ryan D; Brisson, Jennifer A; Heng-Moss, Tiffany M; Siegfried, Blair D; Zera, Anthony J; Miller, Nicholas J

    2015-02-01

    Environmental stress affects basic organismal functioning and can cause physiological, developmental, and reproductive impairment. However, in many nonmodel organisms, the core molecular stress response remains poorly characterized and the extent to which stress-induced transcriptional changes differ across qualitatively different stress types is largely unexplored. The current study examines the molecular stress response of the soybean aphid (Aphis glycines) using RNA sequencing and compares transcriptional responses to multiple stressors (heat, starvation, and plant defenses) at a standardized stress level (27% adult mortality). Stress-induced transcriptional changes showed remarkable variation, with starvation, heat, and plant defensive stress altering the expression of 3985, 510, and 12 genes, respectively. Molecular responses showed little overlap across all three stressors. However, a common transcriptional stress response was identified under heat and starvation, involved with up-regulation of glycogen biosynthesis and molecular chaperones and down-regulation of bacterial endosymbiont cellular and insect cuticular components. Stressor-specific responses indicated heat affected expression of heat shock proteins and cuticular components, whereas starvation altered a diverse set of genes involved in primary metabolism, oxidative reductive processes, nucleosome and histone assembly, and the regulation of DNA repair and replication. Exposure to host plant defenses elicited the weakest response, of which half of the genes were of unknown function. This study highlights the need for standardizing stress levels when comparing across stress types and provides a basis for understanding the role of general vs. stressor specific molecular responses in aphids.

  10. Adhesive properties of environmental Vibrio alginolyticus strains to biotic and abiotic surfaces.

    PubMed

    Snoussi, Mejdi; Noumi, Emira; Cheriaa, Jihane; Usai, Donatella; Sechi, Leonardo Antonio; Zanetti, Stefania; Bakhrouf, Amina

    2008-10-01

    The ability of Vibrio alginolyticus strains isolated from a bathing and fishing area (Khenis, Centre of Tunisia) to adhere to both biotic and abiotic surfaces was evaluated in the present work. The biochemical, physiological and enzymatic activities of all strains was also investigated. Three morphotypes of V. alginolyticus were obtained on Congo red agar and only 14 strains produced black colonies. The majority of strains were able to degrade the skin mucus of both Sparus aurata and Dicentrarchus labrax fishes while the fish mucus preparation of these two specimens exhibits a high level of anti-V. alginolyticus strains. Adhesive properties were observed in 37.5% of the analyzed V. alginolyticus strains to Hep-2 cells and 50% to Caco-2 cells. All strains were able to form a purple pellicule on glass tube when they were stained with Crystal violet. Fifteen percent of V. alginolyticus strains (16/32) were strongly adhesive to polystyrene with a values ranging from 3.04 to 18.25 at 595 nm and only four strains were weak biofilm forming. V. alginolyticus bacterium possess a strong adhesive power to both biotic and inertes surfaces. These proprieties may allow to these strains to persist in this biotope in planctonic state or attached to both biotic and abiotic surfaces.

  11. 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.

  12. Environmental mapping based on spatial variability.

    PubMed

    Kovalevskaya, Nelley; Pavlov, Vladimir

    2002-01-01

    Environmental maps show the probable environmental states of different types of land use or development of landscape in a geographic context. Remotely sensed data are particularly efficient for environmental mapping in order to outline major environmental types. Multiple schemes of image classification used in environmental mapping are either traditionally statistical or heuristic. While the former methods do not take account of spatial variability in space and aerial data, the latter ones does not lend themselves to optimal solutions we present. Novel probabilistic models of piecewise-homogeneous images are used in environmental mapping to segment real images. The models consider both an image and a land cover map. Such a pair constitutes an example of a Markov random field specified by a joint Gibbs probability distribution of images and maps. Parameters of the model are estimated by using a stochastic approximation technique. Its convergence to the desired values is studied experimentally. Addition of spatial attributes appears to be necessary in most areas where the differences in spatial data between regions in the image occur. Experiments in generating the pairs of images and environmental maps and in segmenting the simulated as well as real images are discussed. PMID:12371162

  13. Biogeography of ectomycorrhizal fungi associated with alders (Alnus spp.) in relation to biotic and abiotic variables at the global scale.

    PubMed

    Põlme, Sergei; Bahram, Mohammad; Yamanaka, Takashi; Nara, Kazuhide; Dai, Yu Cheng; Grebenc, Tine; Kraigher, Hojka; Toivonen, Mika; Wang, Pi-Han; Matsuda, Yosuke; Naadel, Triin; Kennedy, Peter G; Kõljalg, Urmas; Tedersoo, Leho

    2013-06-01

    · Much of the macroecological information about microorganisms is confounded by the lack of standardized methodology, paucity of metadata and sampling effect of a particular substrate or interacting host taxa. · This study aims to disentangle the relative effects of biological, geographical and edaphic variables on the distribution of Alnus-associated ectomycorrhizal (ECM) fungi at the global scale by using comparable sampling and analysis methods. · Ribosomal DNA sequence analysis revealed 146 taxa of ECM fungi from 22 Alnus species across 96 sites worldwide. Use of spatial and phylogenetic eigenvectors along with environmental variables in model selection indicated that phylogenetic relations among host plants and geographical links explained 43 and 10%, respectively,in ECM fungal community composition, whereas soil calcium concentration positively influenced taxonomic richness. · Intrageneric phylogenetic relations among host plants and regional processes largely account for the global biogeographic distribution of Alnus-associated ECM fungi. The biogeography of ECM fungi is consistent with ancient host migration patterns from Eurasia to North America and from southern Europe to northern Europe after the last glacial maximum, indicating codispersal of hosts and their mycobionts.

  14. 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.

  15. 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. PMID

  16. 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.

  17. 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.

  18. Role of Environmental Variability in Evaluating Stressor Effects

    SciTech Connect

    Luoma, Samuel N.; Clements, Will; Dewitt, Ted; Gerritsen, Jeroen; Hatch, Audrey; Jepson, Paul; Reynoldson, Trefor; Thom, Ronald M.

    2001-12-03

    In this chapter, we discuss how environmental variability affects the exposure of organisms and ecological systems to stressors, and give guidance on how to understand influences of stressors. We consider the characteristics of environmental variability and issues relating to the measurement of environmental variation. We discuss how to select the optimal indicators of ecological response in a variable natural environment. Finally, we suggest some approaches to incorporate environmental variability into resource management. In all cases we employ examples and case studies throughout to illustrate principles.

  19. Assessing the influence of two environmental variables on microfossil stratigraphies

    NASA Astrophysics Data System (ADS)

    Trachsel, Mathias; Telford, Richard; Birks, John

    2014-05-01

    Biological assemblages are controlled by several environmental variables (e.g. temperature, precipitation, soil, etc.). Usually, the quantitative influence of several environmental variables on modern species assemblages is evaluated by assessing the influence of different variables on modern species assemblages by means of canonical correspondence analysis or related multivariate regression methods (e.g. Juggins 2013). For fossil assemblages, palaeoecologists have only recently started to assess the statistical influence of one environmental variable (Telford and Birks 2011) and have rarely attempted to assess the joint influence of different environmental variables. For this purpose, we propose a simple approach, generating synthetic variables with different proportions of two environmental variables and testing how much variation in the fossil data the reconstructions of these synthetic variables explain. We first applied this approach to simulated environmental and species data, and then applied the method to pollen data from two transects in Norway that both cover gradients from oceanic to continental sites. We found that our method was able to detect variables used to simulate species assemblages, differences in importance of these variables, and correlations between these variables. Applying the method to pollen data we find that pollen assemblages at coastal sites are mainly sensitive to past changes in July temperature, whereas inland continental sites are influenced by both July temperature and annual precipitation. References Juggins (2013) QSR 64, 20 - 32. Telford and Birks (2011) QSR 30, 1272 - 1278

  20. Biotic and abiotic variables affecting internalization and fate of Escherichia coli O157:H7 isolates in leafy green roots.

    PubMed

    Erickson, Marilyn C; Webb, Cathy C; Davey, Lindsey E; Payton, Alison S; Flitcroft, Ian D; Doyle, Michael P

    2014-06-01

    Preharvest internalization of Escherichia coli O157:H7 into the roots of leafy greens is a food safety risk because the pathogen may be systemically transported to edible portions of the plant. In this study, both abiotic (degree of soil moisture) and biotic (E. coli O157:H7 exposure, presence of Shiga toxin genes, and type of leafy green) factors were examined to determine their potential effects on pathogen internalization into roots of leafy greens. Using field soil that should have an active indigenous microbial community, internalized populations in lettuce roots were 0.8 to 1.6 log CFU/g after exposure to soil containing E. coli O157:H7 at 5.6 to 6.1 log CFU/g. Internalization of E. coli O157:H7 into leafy green plant roots was higher when E. coli O157:H7 populations in soil were increased to 7 or 8 log CFU/g or when the soil was saturated with water. No differences were noted in the extent to which internalization of E. coli O157:H7 occurred in spinach, lettuce, or parsley roots; however, in saturated soil, maximum levels in parsley occurred later than did those in spinach or lettuce. Translocation of E. coli O157:H7 from roots to leaves was rare; therefore, decreases observed in root populations over time were likely the result of inactivation within the plant tissue. Shiga toxin-negative (nontoxigenic) E. coli O157:H7 isolates were more stable than were virulent isolates in soil, but the degree of internalization of E. coli O157:H7 into roots did not differ between isolate type. Therefore, these nontoxigenic isolates could be used as surrogates for virulent isolates in field trials involving internalization.

  1. 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

  2. Environmental variables and evolution of xenobiotic catabolism in Bacteria.

    PubMed

    Seech, A G; Trevors, J T

    1991-03-01

    The use of microorganisms for remediation of contaminated soil and groundwater has been limited by our incomplete understanding of how environmental variables influence the activities of microorganisms. Recent research has increased our knowledge of the mechanisms whereby environmental variables can regulate microbial processes, including gene transfer and expression. This review examines factors that influence transfer of genetic material between bacteria in the environmental (evolution of genotypes) and utilization of genetic capabilities (expression of phenotypes).

  3. Relationship between macroinvertebrate fauna and environmental variables in small streams of the Dominican Republic.

    PubMed

    Soldner, Michael; Stephen, Ian; Ramos, Litay; Angus, Robert; Wells, N Claire; Grosso, Albania; Crane, Mark

    2004-02-01

    Field assessment methods for freshwater macroinvertebrates and water quality in tropical small-island states were assessed in the Dominican Republic. Macroinvertebrate samples were collected from 26 river sites within the Dominican Republic's Yaque del Norte river catchment. Environmental data on geographical, physical and chemical variables were also collected from each site. The Biological Monitoring Working Party score and total numbers of Ephemeroptera and Trichoptera were calculated for each site. Physico-chemical and biological data sets were ordinated by principal components analysis and non-parametric multi-dimensional scaling, and the biotic and abiotic data sets were correlated to determine the most influential factors determining site similarities. Macroinvertebrate assemblage structure was correlated with declining water quality: however, a high correlation between water quality and altitude confounded an unqualified interpretation of impairment.

  4. 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

  5. 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…

  6. 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.

  7. Limnoperna fortunei Dunker, 1857 larvae in different environments of a Neotropical floodplain: relationships of abiotic variables and phytoplankton with different stages of development.

    PubMed

    Ernandes-Silva, J; Ragonha, F H; Jati, S; Takeda, A M

    2016-02-01

    Limnoperna fortunei Dunker, 1857 is an Asian invasive freshwater bivalve. Although there need to contain their spread, studies about the biology of the larvae are scarce. We correlated the larval stages of L. fortunei with biotic factors such as phytoplankton and main abiotic variables in lotic environments of the Upper Paraná River floodplain. The four samples were taken quarterly during the year 2012. The Principal component analysis (PCA) showed only spatial differences, as did a Canonical Correspondence Analysis (CCA). High densities of larvae were recorded in all samples the Paraná River and Baía River only in December, especially those in their initial stage. In the biovolume of Class of algae, Bacillarophyceae showed the highest value, but Chlorophycea who was strongly correlated with the density of D-stage larvae. The large variety of phytoplankton, especially microplankton Chlorophyceae, high values of PO4, NH4 and temperature were positively correlated with high densities of D-stage larvae. We conclude that high temperature, and food availability, indicated by phytoplankton community, favored the reproduction of L. fortunei and enhance the ability of specie dispersion due to the increase in the emission of propagules. Therefore, studies that address the biology of golden mussel larvae should be performed in order to prevent its spread.

  8. 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.

  9. Relating design and environmental variables to reliability

    NASA Astrophysics Data System (ADS)

    Kolarik, William J.; Landers, Thomas L.

    The combination of space application and nuclear power source demands high reliability hardware. The possibilities of failure, either an inability to provide power or a catastrophic accident, must be minimized. Nuclear power experiences on the ground have led to highly sophisticated probabilistic risk assessment procedures, most of which require quantitative information to adequately assess such risks. In the area of hardware risk analysis, reliability information plays a key role. One of the lessons learned from the Three Mile Island experience is that thorough analyses of critical components are essential. Nuclear grade equipment shows some reliability advantages over commercial. However, no statistically significant difference has been found. A recent study pertaining to spacecraft electronics reliability, examined some 2500 malfunctions on more than 300 aircraft. The study classified the equipment failures into seven general categories. Design deficiencies and lack of environmental protection accounted for about half of all failures. Within each class, limited reliability modeling was performed using a Weibull failure model.

  10. 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. PMID:25499240

  11. [The pattern of variables predicting self-reported environmental behavior].

    PubMed

    Kannapin, O; Pawlik, K; Zinn, F

    1998-01-01

    Many of the changes observed in our environment today may be traced back to human action. In addition to a descriptive elaboration of possible predictor variables, the psychological analysis of environmental behavior is directed towards the identification of key variables and the structural relationships among these and behavior. Variables that are suitable to predict environmental behavior need to be identified. In this study, 215 subjects each were drawn from an urban and a rural sample; 85 further subjects were considered to be highly environmentally engaged. Thus the total sample population for this study included 515 subjects. Scales on acquisition of information, values, locus of control, attribution of responsibility, and environmental threat were administered to all subjects. A modified version of the protection-motivation theory formulated by Gardner and Stern (1996) served as a reference model. Simultaneous regression analysis revealed that scales specifically directed to the domain of environmental behavior are well suited to explain environmental actions, especially in the subset of highly engaged persons (R2 = .58). In contrast to both other groups, the acquisition of environmentally specific information was a strong predictor in this group. On the basis of these regression analyses, it is argued that additional predictors--along with the ones used in this study--must be taken into account in groups that do not display extraordinary engagement in environmental matters.

  12. Neural mechanisms for evaluating environmental variability in Caenorhabditis elegans

    PubMed Central

    Calhoun, Adam J.; Tong, Ada; Pokala, Navin; Fitzpatrick, James A. J.; Sharpee, Tatyana O.; Chalasani, Sreekanth H.

    2015-01-01

    Summary The ability to evaluate variability in the environment is vital for making optimal behavioral decisions. Here we show that Caenorhabditis elegans evaluates variability in its food environment and then modifies its future behavior accordingly. We derived a behavioral model that reveals a critical period over which information about the food environment is acquired and predicts future search behavior. We identified a pair of high-threshold sensory neurons that encode variability in food concentration and downstream dopamine-dependent circuitry that generates appropriate search behavior upon removal from food. Further, we show that CREB is required in a subset of interneurons and determines the timescale over which the variability is integrated. Interestingly, the variability circuit is a subset of a larger circuit driving search behavior, showing that learning directly modifies the very same neurons driving behavior. Our study reveals how a neural circuit decodes environmental variability to generate contextually appropriate decisions. PMID:25864633

  13. Sparse modeling of spatial environmental variables associated with asthma

    PubMed Central

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

    2014-01-01

    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 5–50 years over a three-year period. Each patient’s home address was geocoded to one of 3,456 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. PMID:25533437

  14. 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.

  15. 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. PMID:25533437

  16. 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.

  17. 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.

  18. 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…

  19. Environmental versus demographic variability in stochastic predator-prey models

    NASA Astrophysics Data System (ADS)

    Dobramysl, U.; Täuber, U. C.

    2013-10-01

    In contrast to the neutral population cycles of the deterministic mean-field Lotka-Volterra rate equations, including spatial structure and stochastic noise in models for predator-prey interactions yields complex spatio-temporal structures associated with long-lived erratic population oscillations. Environmental variability in the form of quenched spatial randomness in the predation rates results in more localized activity patches. Our previous study showed that population fluctuations in rare favorable regions in turn cause a remarkable increase in the asymptotic densities of both predators and prey. Very intriguing features are found when variable interaction rates are affixed to individual particles rather than lattice sites. Stochastic dynamics with demographic variability in conjunction with inheritable predation efficiencies generate non-trivial time evolution for the predation rate distributions, yet with overall essentially neutral optimization.

  20. 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

  1. 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.

  2. Transposons, environmental changes, and heritable induced phenotypic variability.

    PubMed

    Piacentini, Lucia; Fanti, Laura; Specchia, Valeria; Bozzetti, Maria Pia; Berloco, Maria; Palumbo, Gino; Pimpinelli, Sergio

    2014-08-01

    The mechanisms of biological evolution have always been, and still are, the subject of intense debate and modeling. One of the main problems is how the genetic variability is produced and maintained in order to make the organisms adaptable to environmental changes and therefore capable of evolving. In recent years, it has been reported that, in flies and plants, mutations in Hsp90 gene are capable to induce, with a low frequency, many different developmental abnormalities depending on the genetic backgrounds. This has suggested that the reduction of Hsp90 amount makes different development pathways more sensitive to hidden genetic variability. This suggestion revitalized a classical debate around the original Waddington hypothesis of canalization and genetic assimilation making Hsp90 the prototype of morphological capacitor. Other data have also suggested a different mechanism that revitalizes another classic debate about the response of genome to physiological and environmental stress put forward by Barbara McClintock. That data demonstrated that Hsp90 is involved in repression of transposon activity by playing a significant role in piwi-interacting RNA (piRNAs)-dependent RNA interference (RNAi) silencing. The important implication is that the fixed phenotypic abnormalities observed in Hsp90 mutants are probably related to de novo induced mutations by transposon activation. In this case, Hsp90 could be considered as a mutator. In the present theoretical paper, we discuss several possible implications about environmental stress, transposon, and evolution offering also a support to the concept of evolvability. PMID:24752783

  3. Transposons, environmental changes, and heritable induced phenotypic variability.

    PubMed

    Piacentini, Lucia; Fanti, Laura; Specchia, Valeria; Bozzetti, Maria Pia; Berloco, Maria; Palumbo, Gino; Pimpinelli, Sergio

    2014-08-01

    The mechanisms of biological evolution have always been, and still are, the subject of intense debate and modeling. One of the main problems is how the genetic variability is produced and maintained in order to make the organisms adaptable to environmental changes and therefore capable of evolving. In recent years, it has been reported that, in flies and plants, mutations in Hsp90 gene are capable to induce, with a low frequency, many different developmental abnormalities depending on the genetic backgrounds. This has suggested that the reduction of Hsp90 amount makes different development pathways more sensitive to hidden genetic variability. This suggestion revitalized a classical debate around the original Waddington hypothesis of canalization and genetic assimilation making Hsp90 the prototype of morphological capacitor. Other data have also suggested a different mechanism that revitalizes another classic debate about the response of genome to physiological and environmental stress put forward by Barbara McClintock. That data demonstrated that Hsp90 is involved in repression of transposon activity by playing a significant role in piwi-interacting RNA (piRNAs)-dependent RNA interference (RNAi) silencing. The important implication is that the fixed phenotypic abnormalities observed in Hsp90 mutants are probably related to de novo induced mutations by transposon activation. In this case, Hsp90 could be considered as a mutator. In the present theoretical paper, we discuss several possible implications about environmental stress, transposon, and evolution offering also a support to the concept of evolvability.

  4. 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

  5. Evaluating environmental flows under climate variability and change

    NASA Astrophysics Data System (ADS)

    Wilby, R.

    2012-04-01

    How much river flow is needed to ensure healthy freshwater ecosystems? This is a question that has exercised environmental managers for decades and one that is being made even harder by the prospect of anthropogenic climate change. The response requires balancing the long-term water demands of society with the needs of the environment in a sustainable and least cost way. Meeting these challenges will require more flexible water management systems and processes that recognise changing environmental limits, incentivise more environmentally-sensitive behaviours by water users and abstractors during times of water scarcity, and a move away from capital intensive, supply-side solutions. This talk evaluates the sensitivity of river flows to decadal variations in rainfall, abstraction amounts, licensing regime, and climate change. The overall objective is to determine how achievable abstraction volumes vary with different e-flow standards and water licensing regimes, under climate variability and change. The River Itchen in southern England has historically experienced unsustainable levels of water abstraction and is used as a test basin. The talk will consider the extent to which a 'smarter' approach to abstraction licensing could ensure that e-flow standards are met despite large uncertainty in the future climate, whilst having a minimal impact on security of water supplies.

  6. Confounding variables in the environmental toxicology of arsenic.

    PubMed

    Gebel, T

    2000-04-01

    Arsenic is one of the most important global environmental toxicants. For example, in regions of West Bengal and Inner Mongolia, more than 100000 persons are chronically exposed to well water often strongly contaminated with As. Unfortunately, a toxicologically safe risk assessment and standard setting, especially for long-term and low-dose exposures to arsenic, is not possible. One reason is that the key mechanism of arsenic's tumorigenicity still is not elucidated. Experimental data indicate that either DNA repair inhibition or DNA methylation status alteration may be causal explanations. Moreover, when comparing epidemiological data, it cannot be ruled out that the susceptibility to arsenic's carcinogenicity may be different between Mexican and Taiwanese people. Some other studies indicate that some Andean populations do not develop skin cancer after long-term exposure to As. It is not known yet how this resistance could be mediated. Finally, the situation is even more complicated when taking into consideration that there are several compounds suspected to modulate the chronic environmental toxicity of arsenic, variables that may either enhance or suppress the in vivo genotoxicity and carcinogenicity of the metalloid. Among them are nutritional factors like selenium and zinc as well as drinking water co-contaminants like antimony. Further, yet unidentified factors influencing the body burden and/or the excretion of arsenic are possibly prevailing: preliminary data from own human biomonitoring studies showed a peaking of As in urine samples of non-exposed people which was not caused by elevated exposure to As through seafood consumption. The relevance of these putative confounding variables cannot be finally evaluated yet. Further experimental as well as epidemiological studies are needed to answer these questions. This would help to conduct a toxicologically improved risk assessment, especially for low-dose and long-term exposures to arsenic.

  7. 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.

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

    PubMed Central

    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. PMID:26091266

  9. 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.

  10. 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.

  11. 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…

  12. 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...

  13. Effects of isolation and environmental variables on fish community structure in the Brazilian Amazon Madeira-Purus interfluve.

    PubMed

    Barros, D F; Albernaz, A L M; Zuanon, J; Espírito Santo, H M V; Mendonça, F P; Galuch, A V

    2013-08-01

    Due to the existence of terrestrial barriers to freshwater fish dispersion, it is believed that its distribution is strongly associated with historical factors related to the formation of the habitats they occupy. By the other hand, some studies reveal the influence of abiotic conditions (such as size of water bodies, pH, conductivity) on the composition of fish fauna occurring in small streams. This study aimed to investigate whether drainage basins, because catchment boundaries are potential barriers to fish dispersion, or the physical structure and physico-chemical characteristics of water have a greater influence on fish community structure in small streams. We sampled 22 streams belonging to five drainage basins in the Madeira-Purus interfluve. Fish were caught with dip nets and a small trawl, and data were simultaneously obtained on structural characteristics of the streams and physico-chemical characteristics of the water. Community composition was analyzed using Non-Metric Multidimensional Scaling (NMDS), and variables related to structural and physico-chemical characteristics were summarized by Principal Component Analysis (PCA). Two explanatory models relating faunal composition to environmental factors were constructed: the first using only continuous variables and the second including the drainage basin as a categorical variable. The Akaike Information Criterion (AIC) and AIC weight were used to select the best model. Although structural and physico-chemical variables significantly contributed to explaining faunal composition, the model including the drainage basin was clearly the better of the two models (more than 90% support in the data). The importance of drainage basins in structuring fish communities in streams may have significant consequences for conservation planning in these environments.

  14. 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.

  15. Assessment of environmental variables in Cauvery River and its tributaries.

    PubMed

    Mahadev, J; Srikantswamy, S; Gholami, Siamak; Ahmed, Syed Akheel

    2010-10-01

    This research paper pertains to the variation in water quality with special reference to physicochemical and biological parameters in Cauvery River and its tributaries in India over a period of 1 year. The quality of water in four streams of Cauvery River in Mysore, Mandya and Chamaraja Nagar districts, where many small scale sugar, paper industries and agricultural lands are located were analyzed. Sampling was carried out from Cauvery and its tributaries which were designated as stations 1, 2, 3 & 4 (all towards down streams of Cauvery River). The river water composition is increasingly dominated by PO4, NO3 Cl at stations 3 & 4 compared to stations 1 & 2. Significant spatial variations were observed in water level, transparency, turbidity, colour, DO, BOD, NO3, NO2 and total hardness among the physico-chemical parameters at the study locations. The DO level at stations 3 & 4 was lower than 5.0 mg/L, which is the recommended minimum allowable limit for aquatic life. 30 species of phytoplanktons were identified under five classes: viz, Chlorophyceae, Bacillariophyceae, Cyanophyceae, Euglenophyceae and Desmidaceae. About 20 algal species were recorded at station 1, 16 at station 2,13 species at station 3 and 14 species at station 4. The overall diversity and density of algae at four stations was significantly different. A posterior comparison revealed that stations 3 and 4 are the cause of significant difference. The chlorophyceae members, which dominated the algal community, were found to tolerate the effluent effect at stations land 2. Low algal diversity and negative impact on the biotic and abiotic environment were experienced at stations 3 and 4 throughout the duration of sampling, because of man made activities. PMID:22312799

  16. 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

  17. 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.

  18. Ecology of mesophilic Aeromonas spp. in aquatic environments of a temperate region and relationship with some biotic and abiotic environmental parameters.

    PubMed

    Chowdhury, M A; Yamanaka, H; Miyoshi, S; Shinoda, S

    1990-10-01

    The Ecology of mesophilic Aeromonas species has been investigated since January 1988 to examine their occurrence and distribution in aquatic environments of Okayama Prefecture. Water and plankton samples were quantitatively as well as qualitatively analyzed throughout the seasons from five selected stations including fresh, brackish, and saline environments. Analysis of variance and correlation coefficients among the biotic and abiotic parameters were sought. The organisms were found in all the environs with high densities through all the seasons. Plankton samples yielded higher counts of Aeromonas than the water samples in all the environs. Water temperature seemed to play a significant role on their growth during the winter months, however, no significant seasonal variation nor any correlation with fecal pollution were observed in most of the environments. A reciprocal relationship was seen with salt concentration in the saline environment. Among the currently recognized mesophilic species; A. caviae, A. hydrophila, A. sobria, and A. media were isolated with the predominance of anaerobic biovar. The present study reveals that Aeromonas are widely distributed in fresh, brackish and saline environments of this region. The study also reveals that Aeromonas are autochthonous members in aquatic ecosystems and are indigenous to these environs. Aeromonas species isolated from our environments were found to exhibit drug resistance potential which differed from that of isolates from diverse geographical locales. The high incidence of clinically significant Aeromonas species in this aquatic region could be of public health significance for the inhabitants of this region, as well as a challenge to their dependence on aquatic resources.

  19. 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...

  20. 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

  1. Variability of building environmental assessment tools on evaluating carbon emissions

    SciTech Connect

    Ng, S. Thomas Chen Yuan Wong, James M.W.

    2013-01-15

    With an increasing importance of sustainability in construction, more and more clients and designers employ building environmental assessment (BEA) tools to evaluate the environmental friendliness of their building facilities, and one important aspect of evaluation in the BEA models is the assessment of carbon emissions. However, in the absence of any agreed framework for carbon auditing and benchmarking, the results generated by the BEA tools might vary significantly which could lead to confusion or misinterpretation on the carbon performance of a building. This study thus aims to unveil the properties of and the standard imposed by the current BEA models on evaluating the life cycle carbon emissions. The analyses cover the (i) weighting of energy efficiency and emission levels among various environmental performance indicators; (ii) building life cycle stages in which carbon is taken into consideration; (iii) objectiveness of assessment; (iv) baseline set for carbon assessment; (v) mechanism for benchmarking the emission level; and (v) limitations of the carbon assessment approaches. Results indicate that the current BEA schemes focus primarily on operational carbon instead of the emissions generated throughout the entire building life cycle. Besides, the baseline and benchmark for carbon evaluation vary significantly among the BEA tools based on the analytical results of a hypothetical building. The findings point to the needs for a more transparent framework for carbon auditing and benchmarking in BEA modeling. - Highlights: Black-Right-Pointing-Pointer Carbon emission evaluation in building environmental assessment schemes are studied. Black-Right-Pointing-Pointer Simulative carbon emission is modeled for building environmental assessment schemes. Black-Right-Pointing-Pointer Carbon assessments focus primarily on operational stage instead of entire lifecycle. Black-Right-Pointing-Pointer Baseline and benchmark of carbon assessment vary greatly among BEA

  2. 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

  3. Circadian regulation of abiotic stress tolerance in plants.

    PubMed

    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.

  4. Roles of melatonin in abiotic stress resistance in plants.

    PubMed

    Zhang, Na; Sun, Qianqian; Zhang, Haijun; Cao, Yunyun; Weeda, Sarah; Ren, Shuxin; Guo, Yang-Dong

    2015-02-01

    In recent years melatonin has emerged as a research highlight in plant studies. Melatonin has different functions in many aspects of plant growth and development. The most frequently mentioned functions of melatonin are related to abiotic stresses such as drought, radiation, extreme temperature, and chemical stresses. This review mainly focuses on the regulatory effects of melatonin when plants face harsh environmental conditions. Evidence indicates that environmental stress can increase the level of endogenous melatonin in plants. Overexpression of the melatonin biosynthetic genes elevates melatonin levels in transgenic plants. The transgenic plants show enhanced tolerance to abiotic stresses. Exogenously applied melatonin can also improve the ability of plants to tolerate abiotic stresses. The mechanisms by which melatonin alleviates abiotic stresses are discussed.

  5. 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

  6. Response of Fish Communities to Various Environmental Variables across Multiple Spatial Scales

    PubMed Central

    Kwon, Yong-Su; Li, Fengqing; Chung, Namil; Bae, Mi-Jung; Hwang, Soon-Jin; Byoen, Myeong-Seop; Park, Sang-Jung; Park, Young-Seuk

    2012-01-01

    A better understanding of the relative importance of different spatial scale determinants on fish communities will eventually increase the accuracy and precision of their bioassessments. Many studies have described the influence of environmental variables on fish communities on multiple spatial scales. However, there is very limited information available on this topic for the East Asian monsoon region, including Korea. In this study, we evaluated the relationship between fish communities and environmental variables at multiple spatial scales using self-organizing map (SOM), random forest, and theoretical path models. The SOM explored differences among fish communities, reflecting environmental gradients, such as a longitudinal gradient from upstream to downstream, and differences in land cover types and water quality. The random forest model for predicting fish community patterns that used all 14 environmental variables was more powerful than a model using any single variable or other combination of environmental variables, and the random forest model was effective at predicting the occurrence of species and evaluating the contribution of environmental variables to that prediction. The theoretical path model described the responses of different species to their environment at multiple spatial scales, showing the importance of altitude, forest, and water quality factors to fish assemblages. PMID:23202766

  7. Personality and Sociodemographic Variables as Sources of Variation in Environmental Perception.

    ERIC Educational Resources Information Center

    Feimer, Nickolaus R.

    This research paper examines the relationship between individual differences in environmental perception, and variables which may be important in predicting, if not explaining those variations. The analyses reported were based upon an environmental perception research study previously conducted at the University of California at Berkeley during…

  8. 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…

  9. 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

  10. 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.

  11. Natural Variation in Abiotic Stress Responsive Gene Expression and Local Adaptation to Climate in Arabidopsis thaliana

    PubMed Central

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

    2014-01-01

    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. PMID:24850899

  12. Integrated biomarker responses of an estuarine invertebrate to high abiotic stress and decreased metal contamination.

    PubMed

    Rodrigues, Aurélie Pinto; Oliva-Teles, Teresa; Mesquita, Sofia Raquel; Delerue-Matos, Cristina; Guimarães, Laura

    2014-10-01

    An integrated chemical-biological effects monitoring was performed in 2010 and 2012 in two NW Iberian estuaries under different anthropogenic pressure. One is low impacted and the other is contaminated by metals. The aim was to verify the usefulness of a multibiomarker approach, using Carcinus maenas as bioindicator species, to reflect diminishing environmental contamination and improved health status under abiotic variation. Sampling sites were assessed for metal levels in sediments and C. maenas, water abiotic factors and biomarkers (neurotoxicity, energy metabolism, biotransformation, anti-oxidant defences, oxidative damage). High inter-annual and seasonal abiotic variation was observed. Metal levels in sediments and crab tissues were markedly higher in 2010 than in 2012 in the contaminated estuary. Biomarkers indicated differences between the study sites and seasons and an improvement of effects measured in C. maenas from the polluted estuary in 2012. Integrated Biomarker Response (IBR) index depicted sites with higher stress levels whereas Principal Component Analysis (PCA) showed associations between biomarker responses and environmental variables. The multibiomarker approach and integrated assessments proved to be useful to the early diagnosis of remediation measures in impacted sites. PMID:25314018

  13. Microbialite genetic diversity and composition relate to environmental variables.

    PubMed

    Centeno, Carla M; Legendre, Pierre; Beltrán, Yislem; Alcántara-Hernández, Rocío J; Lidström, Ulrika E; Ashby, Matthew N; Falcón, Luisa I

    2012-12-01

    Microbialites have played an important role in the early history of life on Earth. Their fossilized forms represent the oldest evidence of life on our planet dating back to 3500 Ma. Extant microbialites have been suggested to be highly productive and diverse communities with an evident role in the cycling of major elements, and in contributing to carbonate precipitation. Although their ecological and evolutionary importance has been recognized, the study of their genetic diversity is yet scanty. The main goal of this study was to analyse microbial genetic diversity of microbialites living in different types of environments throughout Mexico, including desert ponds, coastal lagoons and a crater-lake. We followed a pyrosequencing approach of hypervariable regions of the 16S rRNA gene. Results showed that microbialite communities were very diverse (H' = 6-7) and showed geographic variation in composition, as well as an environmental effect related to pH and conductivity, which together explained 33% of the genetic variation. All microbialites had similar proportions of major bacterial and archaeal phyla. PMID:22775797

  14. Abiotic immobilization/detoxification of recalcitrant organics

    SciTech Connect

    Whelan, G. ); Sims, R.C. )

    1990-11-01

    In contrast to many remedial techniques that simply transfer hazardous wastes from one part of the environment to another (e.g., off-site landfilling), in situ restoration may offer a safe and cost-effective solution through transformation (to less hazardous products) or destruction of recalcitrant organics. Currently, the US Environmental Protection Agency and US Department of Energy are encouraging research that addresses the development of innovative alternatives for hazardous-waste control. One such alternative is biotic and abiotic immobilization and detoxification of polynuclear aromatic hydrocarbons (PNAs) as associated with the soil humification process. This paper discusses (1) the possibility of using abiotic catalysis (with manganese dioxide) to polymerize organic substances; (2) aspects associated with the thermodynamics and kinetics of the process, and (3) a simple model upon which analyses may be based. 36 refs., 7 figs., 3 tabs.

  15. Regulation of Photosynthesis during Abiotic Stress-Induced Photoinhibition.

    PubMed

    Gururani, Mayank Anand; Venkatesh, Jelli; Tran, Lam Son Phan

    2015-09-01

    Plants as sessile organisms are continuously exposed to abiotic stress conditions that impose numerous detrimental effects and cause tremendous loss of yield. Abiotic stresses, including high sunlight, confer serious damage on the photosynthetic machinery of plants. Photosystem II (PSII) is one of the most susceptible components of the photosynthetic machinery that bears the brunt of abiotic stress. In addition to the generation of reactive oxygen species (ROS) by abiotic stress, ROS can also result from the absorption of excessive sunlight by the light-harvesting complex. ROS can damage the photosynthetic apparatus, particularly PSII, resulting in photoinhibition due to an imbalance in the photosynthetic redox signaling pathways and the inhibition of PSII repair. Designing plants with improved abiotic stress tolerance will require a comprehensive understanding of ROS signaling and the regulatory functions of various components, including protein kinases, transcription factors, and phytohormones, in the responses of photosynthetic machinery to abiotic stress. Bioenergetics approaches, such as chlorophyll a transient kinetics analysis, have facilitated our understanding of plant vitality and the assessment of PSII efficiency under adverse environmental conditions. This review discusses the current understanding and indicates potential areas of further studies on the regulation of the photosynthetic machinery under abiotic stress.

  16. 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

  17. 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.

  18. 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

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

    PubMed

    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

  20. Spatial Relationships between Polychaete Assemblages and Environmental Variables over Broad Geographical Scales

    PubMed Central

    Benedetti-Cecchi, Lisandro; Iken, Katrin; Konar, Brenda; Cruz-Motta, Juan; Knowlton, Ann; Pohle, Gerhard; Castelli, Alberto; Tamburello, Laura; Mead, Angela; Trott, Tom; Miloslavich, Patricia; Wong, Melisa; Shirayama, Yoshihisa; Lardicci, Claudio; Palomo, Gabriela; Maggi, Elena

    2010-01-01

    This study examined spatial relationships between rocky shore polychaete assemblages and environmental variables over broad geographical scales, using a database compiled within the Census of Marine Life NaGISA (Natural Geography In Shore Areas) research program. The database consisted of abundance measures of polychaetes classified at the genus and family levels for 74 and 93 sites, respectively, from nine geographic regions. We tested the general hypothesis that the set of environmental variables emerging as potentially important drivers of variation in polychaete assemblages depend on the spatial scale considered. Through Moran's eigenvector maps we indentified three submodels reflecting spatial relationships among sampling sites at intercontinental (>10000 km), continental (1000–5000 km) and regional (20–500 km) scales. Using redundancy analysis we found that most environmental variables contributed to explain a large and significant proportion of variation of the intercontinental submodel both for genera and families (54% and 53%, respectively). A subset of these variables, organic pollution, inorganic pollution, primary productivity and nutrient contamination was also significantly related to spatial variation at the continental scale, explaining 25% and 32% of the variance at the genus and family levels, respectively. These variables should therefore be preferably considered when forecasting large-scale spatial patterns of polychaete assemblages in relation to ongoing or predicted changes in environmental conditions. None of the variables considered in this study were significantly related to the regional submodel. PMID:20886075

  1. 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.

  2. Environmental variabilities and the distribution of octocorals and black corals in Hong Kong.

    PubMed

    Yeung, C W; Cheang, C C; Lee, M W; Fung, H L; Chow, W K; Ang, P

    2014-08-30

    A recent comprehensive survey covering 125 sites in Hong Kong waters recorded 29 soft coral species in 14 genera, 38 species of gorgonians in 19 genera and six species of black corals in two genera. Environmental variabilities based on water quality data collected by Hong Kong Environmental Protection Department were analyzed using multivariate statistics to find variables that are significantly correlated with coral distribution patterns. Eleven water quality zones with similar environmental variabilities were recognized, which could further be classified into five groups, namely Inner Bay, Outer Bay, Eastern, Western and Southern waters. LINKTREE analysis provided an overall trend indicating the importance of salinity, sediment and nutrient loadings in affecting octocoral and black coral distribution from west to east of Hong Kong waters, and from inner to outer bays. Furthermore, water turbidity and wave exposure could also affect the coral distribution patterns from north, northeast to southern waters. PMID:24434001

  3. 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. PMID:23724073

  4. Spatiotemporal Variability of Dimethylsulphoniopropionate on a Fringing Coral Reef: The Role of Reefal Carbonate Chemistry and Environmental Variability

    PubMed Central

    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. PMID:23724073

  5. 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.

  6. 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

  7. Predicting biotic interactions and their variability in a changing environment.

    PubMed

    Kadowaki, Kohmei; Barbera, Claire G; Godsoe, William; Delsuc, Frédéric; Mouquet, Nicolas

    2016-05-01

    Global environmental change is altering the patterns of biodiversity worldwide. Observation and theory suggest that species' distributions and abundances depend on a suite of processes, notably abiotic filtering and biotic interactions, both of which are constrained by species' phylogenetic history. Models predicting species distribution have historically mostly considered abiotic filtering and are only starting to integrate biotic interaction. However, using information on present interactions to forecast the future of biodiversity supposes that biotic interactions will not change when species are confronted with new environments. Using bacterial microcosms, we illustrate how biotic interactions can vary along an environmental gradient and how this variability can depend on the phylogenetic distance between interacting species. PMID:27220858

  8. 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.

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

    PubMed Central

    Medina, Iliana; Francis, Clinton D.

    2012-01-01

    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. PMID:22859557

  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. 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.

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

    PubMed

    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

  13. 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.

  14. Abiotic self-replication.

    PubMed

    Meyer, Adam J; Ellefson, Jared W; Ellington, Andrew D

    2012-12-18

    functions (including the replication of nucleic acids) to more competent protein enzymes would complete the journey from an abiotic world to the molecular biology we see today. PMID:22891822

  15. Abiotic self-replication.

    PubMed

    Meyer, Adam J; Ellefson, Jared W; Ellington, Andrew D

    2012-12-18

    functions (including the replication of nucleic acids) to more competent protein enzymes would complete the journey from an abiotic world to the molecular biology we see today.

  16. 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...

  17. Multivariate approach for studying interactions between environmental variables and microbial communities.

    PubMed

    Wang, Xinhui; Eijkemans, Marinus J C; Wallinga, Jacco; Biesbroek, Giske; Trzciński, Krzysztof; Sanders, Elisabeth A M; Bogaert, Debby

    2012-01-01

    To understand the role of human microbiota in health and disease, we need to study effects of environmental and other epidemiological variables on the composition of microbial communities. The composition of a microbial community may depend on multiple factors simultaneously. Therefore we need multivariate methods for detecting, analyzing and visualizing the interactions between environmental variables and microbial communities. We provide two different approaches for multivariate analysis of these complex combined datasets: (i) We select variables that correlate with overall microbiota composition and microbiota members that correlate with the metadata using canonical correlation analysis, determine independency of the observed correlations in a multivariate regression analysis, and visualize the effect size and direction of the observed correlations using heatmaps; (ii) We select variables and microbiota members using univariate or bivariate regression analysis, followed by multivariate regression analysis, and visualize the effect size and direction of the observed correlations using heatmaps. We illustrate the results of both approaches using a dataset containing respiratory microbiota composition and accompanying metadata. The two different approaches provide slightly different results; with approach (i) using canonical correlation analysis to select determinants and microbiota members detecting fewer and stronger correlations only and approach (ii) using univariate or bivariate analyses to select determinants and microbiota members detecting a similar but broader pattern of correlations. The proposed approaches both detect and visualize independent correlations between multiple environmental variables and members of the microbial community. Depending on the size of the datasets and the hypothesis tested one can select the method of preference.

  18. Interactions between environmental variables determine immunity in the Indian meal moth Plodia interpunctella.

    PubMed

    Triggs, Alison; Knell, Robert J

    2012-03-01

    1. Animals raised in good environmental conditions are expected to have more resources to invest in immunity than those raised in poor conditions. Variation in immune activity and parasite resistance in response to changes in environmental temperature, population density and food quality have been shown in many invertebrate species. 2. Almost all studies to date have examined the effects of individual variables in isolation. The aim of this study was to address whether environmental factors interact to produce synergistic effects on phenoloxidase (PO) activity and haemocyte count, both indicators of immune system activity. Temperature, food quality and density were varied in a fully factorial design for a total of eight treatment combinations. 3. Strong interactions between the three environmental variables led to the magnitude and in some cases the direction of the effect of most variables changing as the other environmental factors were altered. Overall, food quality had the most important and consistent influence, larvae raised on a good-quality diet having substantially higher PO activity in every case and substantially higher haemocyte counts in all treatments except unheated/low density. 4. When food quality was good, the larvae showed 'density-dependent prophylaxis': raising their investment in immunity when population density is high. When food quality was poor and the temperature low, however, those larvae raised at high densities invested less in immunity. 5. Increased temperature is often thought to lead to increased immune reactivity in ectotherms, but we found that the effect of temperature was strongly dependent on the values of other environmental variables. PO activity increased with temperature when larvae were raised on good food or when density was high, but when food was poor and density low, a higher temperature led to reduced PO activity. A higher temperature led to higher haemocyte counts when density was high and food quality was poor, but

  19. 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.

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

    PubMed

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

    2016-01-01

    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. PMID:27377748

  1. 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.

  2. 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

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

    PubMed

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

    2010-05-01

    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

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

    PubMed

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

    2010-05-01

    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.

  5. Linking environmental variability and fish performance: integration through the concept of scope for activity.

    PubMed

    Claireaux, Guy; Lefrançois, Christel

    2007-11-29

    Investigating the biological mechanisms linking environmental variability to fish production systems requires the disentangling of the interactions between habitat, environmental adaptation and fitness. Since the number of environmental variables and regulatory processes is large, straightening out the environmental influences on fish performance is intractable unless the mechanistic analysis of the 'fish-milieu' system is preceded by an understanding of the properties of that system. While revisiting the key points in our currently poorly integrated understanding of fish ecophysiology, we have highlighted the explanatory potential contained within Fry's (Fry 1947 Univ. Toronto Stud. Biol. Ser. 55, 1-62) concept of metabolic scope and categorization of environmental factors. These two notions constitute a pair of powerful tools for conducting an external (at the emerging property level) analysis of the environmental influences on fish, as well as an internal (mechanistic) examination of the behavioural, morphological and physiological processes involved. Using examples from our own and others work, we have tried to demonstrate that Fry's framework represents a valuable conceptual basis leading to a broad range of testable ecophysiological hypotheses.

  6. Interaction between microalgal species richness and environmental variables in Peringalkuthu Reservoir, Western Ghats, Kerala.

    PubMed

    Nasser, K M Mohamed; Sureshkumar, S

    2013-11-01

    Microalgae are the most diverse group of aquatic organisms and are the primary food source for animals of higher trophic levels in the aquatic food web. Biomonitoring the fresh water habitats in terms of phycological evaluation provide useful information about the pollution status of the water body. The present investigation aimed to delineate the interaction between microalgal species richness and environmental variables in Peringalkuthu Reservoir of Western Ghats, Kerala. Samples were collected during 2009-2011 for the analysis of environmental variables and microalgal community. Ninety four species of microalgae belonged to 42 genera under the classes Chlorophyceae, Desmidiaceae, Bacillariophyceae, Cyanophyceae and Euglenophycea were recorded from the samples. The dominant groups were desmids followed by diatoms. Factor analysis and multivariate analysis were applied to evaluate the extent of interaction between the microalgal species richness and the environmental variables. Temperature, total alkalinity, BOD, phosphate, silicate and chloride showed positive relationship with the species richness of the microalgae. While pH, total hardness, nitrate, fluoride, calcium and magnesium hinder the microalgal species richness. Elucidation of the interactions between microalgae and various environmental parameters suggested a control over the anthropogenic interventions to the reservoir to check the conversion of the lake oligotrophic to eutrophic condition. PMID:24555328

  7. Changes in free-living bacterial community diversity reflect the magnitude of environmental variability.

    PubMed

    Ortmann, Alice C; Ortell, Natalie

    2014-01-01

    A 2-year study was undertaken to compare patterns in the diversity of free-living bacteria in a river-dominated estuary and offshore, on the shelf, to determine whether changes in the free-living bacterial community could be related to differences in environmental seasonality and variability. Although the environmental conditions inshore were significantly more variable than those on the shelf and demonstrated clear seasonal patterns, there were no significant differences in the alpha diversity of the communities based on richness, evenness, or phylogenetic diversity. Comparison of communities using Bray-Curtis similarity indicated no significant differences in the magnitude of change between sequential samples from inshore and on the shelf. Seasonal differences were detected both inshore and on the shelf. However, analysis using the weighted UniFrac distance indicated significantly lower overall change between shelf samples with no significant seasonal differences. These findings suggest different patterns of change between the two sites. Inshore, changes in the relative abundance of distantly related bacterial species reflect the larger environmental variability, while on the shelf, changes in the relative abundance of closely related bacterial species or strains may result in a more functionally stable community. Thus, the magnitude of environmental change can alter patterns of bacterial diversity in marine systems.

  8. 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

  9. 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

  10. 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.

  11. Environmental and trait variability constrain community structure and the biodiversity-productivity relationship.

    PubMed

    Hodapp, Dorothee; Hillebrand, Helmut; Blasius, Bernd; Ryabov, Alexey B

    2016-06-01

    There is still considerable debate about which mechanisms drive the relationship between biodiversity and ecosystem function (BEF). Although most scientists agree on the existence of two underlying mechanisms, complementarity and selection, experimental studies keep producing contrasting results on the relative contributions of the two effects. We present a spatially explicit resource competition model and investigate how the strength of these effects is influenced by trait and environmental variability, resource distribution, and species pool size. Our results demonstrate that the increase of biomass production with increasing species numbers depends on the concurrence of environmental and trait variability: BEF relationships are stronger if functionally different species coexist in a landscape with heterogeneous resource supply. These large biodiversity effects arise from complementarity effects, whereas selection effects are maximized when broad trait ranges coincide with narrow ranges of resource supply ratios. Our results will therefore help to resolve the debate on complementarity and selection mechanisms.

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

    PubMed

    Victora, C G; Vaughan, J P; Kirkwood, B R; Martines, J C; Barcelos, L 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.

  13. 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.

  14. 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

  15. Optimising survey effort to monitor environmental variables: A case study using New Zealand kiwifruit orchards.

    PubMed

    MacLeod, Catriona J; Green, Peter; Tompkins, Daniel M; Benge, Jayson; Moller, Henrik

    2016-12-01

    Environmental monitoring is increasingly used to assess spatial and temporal trends in agricultural sustainability, and test the effectiveness of farm management policies. However, detecting changes in environmental variables is often technically and logistically challenging. To demonstrate how survey effort for environmental monitoring can be optimised, we applied the new statistical power analysis R package simr to pilot survey data. Specifically, we identified the amount of survey effort required to have an 80% chance of detecting specified trends (-1 to -4% pa) in 13 environmental variables on New Zealand kiwifruit orchards within an 11-year period. The variables assessed were related to soil status, agricultural pests (birds), or ecosystem composition (birds). Analyses were conducted on average values (for each orchard and year combination) to provide a consistent scale for comparison among variables. Survey frequency varied from annual (11 surveys) to every 5 years (3 surveys). Survey size was set at either 30, 60, 150 or 300 orchards. In broad terms, we show the power to detect a specified range of trends over an 11-year period in this sector is much higher for 'soil status' than for 'agricultural pest' or 'ecosystem composition'. Changes in one subset of native bird species (nectar-feeders) requiring a particularly high level of relative survey effort to detect with confidence. Monitoring soil status can thus be smaller and less frequent than those which also want to detect changes in agricultural pests or ecosystem composition (with the latter requiring the most effort) but will depend on the magnitude of changes that is meaningful to detect. This assessment thus allows kiwifruit industry in New Zealand to optimise survey design to the desired information, and provides a template for other industries to do likewise. Power analyses are now more accessible through the provision of the simr package, so deploying and integrating them into design and decision

  16. Optimising survey effort to monitor environmental variables: A case study using New Zealand kiwifruit orchards.

    PubMed

    MacLeod, Catriona J; Green, Peter; Tompkins, Daniel M; Benge, Jayson; Moller, Henrik

    2016-12-01

    Environmental monitoring is increasingly used to assess spatial and temporal trends in agricultural sustainability, and test the effectiveness of farm management policies. However, detecting changes in environmental variables is often technically and logistically challenging. To demonstrate how survey effort for environmental monitoring can be optimised, we applied the new statistical power analysis R package simr to pilot survey data. Specifically, we identified the amount of survey effort required to have an 80% chance of detecting specified trends (-1 to -4% pa) in 13 environmental variables on New Zealand kiwifruit orchards within an 11-year period. The variables assessed were related to soil status, agricultural pests (birds), or ecosystem composition (birds). Analyses were conducted on average values (for each orchard and year combination) to provide a consistent scale for comparison among variables. Survey frequency varied from annual (11 surveys) to every 5 years (3 surveys). Survey size was set at either 30, 60, 150 or 300 orchards. In broad terms, we show the power to detect a specified range of trends over an 11-year period in this sector is much higher for 'soil status' than for 'agricultural pest' or 'ecosystem composition'. Changes in one subset of native bird species (nectar-feeders) requiring a particularly high level of relative survey effort to detect with confidence. Monitoring soil status can thus be smaller and less frequent than those which also want to detect changes in agricultural pests or ecosystem composition (with the latter requiring the most effort) but will depend on the magnitude of changes that is meaningful to detect. This assessment thus allows kiwifruit industry in New Zealand to optimise survey design to the desired information, and provides a template for other industries to do likewise. Power analyses are now more accessible through the provision of the simr package, so deploying and integrating them into design and decision

  17. 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. PMID:27591515

  18. 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

  19. 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

  20. Environmental, dietary, demographic, and activity variables associated with biomarkers of exposure for benzene and lead.

    PubMed

    Roy, A; Georgopoulos, P G; Ouyang, M; Freeman, N; Lioy, P J

    2003-11-01

    Classification and regression tree methods represent a potentially powerful means of identifying patterns in exposure data that may otherwise be overlooked. Here, regression tree models are developed to identify associations between blood concentrations of benzene and lead and over 300 variables of disparate type (numerical and categorical), often with observations that are missing or below the quantitation limit. Benzene and lead are selected from among all the environmental agents measured in the NHEXAS Region V study because they are ubiquitous, and they serve as paradigms for volatile organic compounds (VOCs) and heavy metals, two classes of environmental agents that have very different properties. Two sets of regression models were developed. In the first set, only environmental and dietary measurements were employed as predictor variables, while in the second set these were supplemented with demographic and time-activity data. In both sets of regression models, the predictor variables were regressed on the blood concentrations of the environmental agents. Jack-knife cross-validation was employed to detect overfitting of the models to the data. Blood concentrations of benzene were found to be associated with: (a) indoor air concentrations of benzene; (b) the duration of time spent indoors with someone who was smoking; and (c) the number of cigarettes smoked by the subject. All these associations suggest that tobacco smoke is a major source of exposure to benzene. Blood concentrations of lead were found to be associated with: (a) house dust concentrations of lead; (b) the duration of time spent working in a closed workshop; and (c) the year in which the subject moved into the residence. An unexpected finding was that the regression trees identified time-activity data as better predictors of the blood concentrations than the measurements in environmental and dietary media.

  1. 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. PMID:23413702

  2. 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

  3. 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.

  4. Environmental vs. demographic variability in stochastic lattice predator-prey models

    NASA Astrophysics Data System (ADS)

    Tauber, Uwe C.

    2014-03-01

    In contrast to the neutral population cycles of the deterministic mean-field Lotka-Volterra rate equations, including spatial structure and stochastic noise in models for predator-prey interactions yields complex spatio-temporal structures associated with long-lived erratic population oscillations. Environmental variability in the form of quenched spatial randomness in the predation rates results in more localized activity patches. Population fluctuations in rare favorable regions in turn cause a remarkable increase in the asymptotic densities of both predators and prey. Very intriguing features are found when variable interaction rates are affixed to individual particles rather than lattice sites. Stochastic dynamics with demographic variability in conjunction with inheritable predation efficiencies generate non-trivial time evolution for the predation rate distributions, yet with overall essentially neutral optimization.

  5. Current perspectives in proteomic analysis of abiotic stress in Grapevines

    PubMed Central

    George, Iniga S.; Haynes, Paul A.

    2014-01-01

    Grapes are an important crop plant which forms the basis of a globally important industry. Grape and wine production is particularly vulnerable to environmental and climatic fluctuations, which makes it essential for us to develop a greater understanding of the molecular level responses of grape plants to various abiotic stresses. The completion of the initial grape genome sequence in 2007 has led to a significant increase in research on grapes using proteomics approaches. In this article, we discuss some of the current research on abiotic stress in grapevines, in the context of abiotic stress research in other plant species. We also highlight some of the current limitations in grapevine proteomics and identify areas with promising scope for potential future research. PMID:25538720

  6. 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.

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

    PubMed

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

    2013-07-01

    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.

  8. 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

  9. 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

  10. 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. PMID:26747986

  11. 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

  12. 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.

  13. 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...

  14. Polyamines and abiotic stress tolerance in plants.

    PubMed

    Gill, Sarvajeet Singh; Tuteja, Narendra

    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.

  15. 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

  16. 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

  17. 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.

  18. 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

  19. Hundred years of environmental change and phytoplankton ecophysiological variability archived in coastal sediments.

    PubMed

    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

  20. Omics for aquatic ecotoxicology: control of extraneous variability to enhance the analysis of environmental effects.

    PubMed

    Simmons, Denina B D; Benskin, Jonathan P; Cosgrove, John R; Duncker, Bernard P; Ekman, Drew R; Martyniuk, Christopher J; Sherry, James P

    2015-08-01

    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 be necessary to understand and control the main source(s) of variability to facilitate meaningful interpretation of such data. For instance, can variability in omics studies be addressed by changing the approach to study design and data analysis? Are there statistical methods that can be employed to correctly interpret omics data and make use of unattributed, inherent variability? The present study presents a review of experimental design and statistical considerations applicable to the use of omics methods in systems toxicology studies. In addition to highlighting potential sources that contribute to experimental variability, this review suggests strategies with which to reduce and/or control such variability so as to improve reliability, reproducibility, and ultimately the application of omics data for systems toxicology.

  1. Temporal variability and effect of environmental variables on airborne bacterial communities in an urban area of Northern Italy.

    PubMed

    Bertolini, Valentina; Gandolfi, Isabella; Ambrosini, Roberto; Bestetti, Giuseppina; Innocente, Elena; Rampazzo, Giancarlo; Franzetti, Andrea

    2013-07-01

    Despite airborne microorganisms representing a relevant fraction of atmospheric suspended particles, only a small amount of information is currently available on their abundance and diversity and very few studies have investigated the environmental factors influencing the structure of airborne bacterial communities. In this work, we used quantitative PCR and Illumina technology to provide a thorough description of airborne bacterial communities in the urban area of Milan (Italy). Forty samples were collected in 10-day sampling sessions, with one session per season. The mean bacterial abundance was about 10⁴ ribosomal operons per m³ of air and was lower in winter than in the other seasons. Communities were dominated by Actinobacteridae, Clostridiales, Sphingobacteriales and few proteobacterial orders (Burkholderiales, Rhizobiales, Sphingomonadales and Pseudomonadales). Chloroplasts were abundant in all samples. A higher abundance of Actinobacteridae, which are typical soil-inhabiting bacteria, and a lower abundance of chloroplasts in samples collected on cold days were observed. The variation in community composition observed within seasons was comparable to that observed between seasons, thus suggesting that airborne bacterial communities show large temporal variability, even between consecutive days. The structure of airborne bacterial communities therefore suggests that soil and plants are the sources which contribute most to the airborne communities of Milan atmosphere, but the structure of the bacterial community seems to depend mainly on the source of bacteria that predominates in a given period of time.

  2. 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...

  3. The relationship between species richness and community biomass: the importance of environmental variables

    USGS Publications Warehouse

    Gough, L.; Grace, J.B.; Taylor, K.L.

    1994-01-01

    Several studies have used plant community biomass to predict species richness with varying success. In this study we examined the relationship between species richness and biomass for 36 marsh communities from two different watersheds. In addition, we measured several environmental variables and estimated the potential richness (the total number of species known to be able to occur in a community type) for each community. Above ground living and dead biomass combined was found to be weakly correlated with species richness (R2=0.02). Instead, a multiple regression model based on elevation (R2=0.47), salinity (R2=0.30), soil organic matter (R2=0.18), and biomass was able to explain 82% of the variance in species richness. It was found that environmental conditions could explain 89% of the variation in potential richness. Biomass had no relation to potential richness. When used as a predictor variable, potential richness was found to explain 72% of the variation in realized (observed) richness and biomass explained an addition 9% of the variance in realized richness. This finding suggests that realized richness in our system was controlled primarily by environmental regulation of potential richness and secondarily by biomass (as an indicator of competition). Further examination of the data revealed that when sites exposed to extreme environmental conditons were eliminated from the analysis, biomass became the primary predictor of realized richness and potential richness was of secondary importance. We conclude that community biomass has a limited capacity to predict species richness across a broad range of habitat conditions. Of particular importance is the inability of biomass to indicate the effect of environmental factors and evolutionary history on the potential species richness at a site.

  4. 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.

  5. 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

  6. 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. PMID:27492078

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

    PubMed Central

    Ma, Bo; Ott, William; Josić, Krešimir; Bennett, Matthew R.

    2015-01-01

    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. PMID:26200924

  8. 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.

  9. Correlative changes in life-history variables in response to environmental change in a model organism.

    PubMed

    Smallegange, Isabel M; Deere, Jacques A; Coulson, Tim

    2014-06-01

    Global change alters the environment, including increases in the frequency of (un)favorable events and shifts in environmental noise color. However, how these changes impact the dynamics of populations, and whether these can be predicted accurately has been largely unexamined. Here we combine recently developed population modeling approaches and theory in stochastic demography to explore how life history, morphology, and average fitness respond to changes in the frequency of favorable environmental conditions and in the color of environmental noise in a model organism (an acarid mite). We predict that different life-history variables respond correlatively to changes in the environment, and we identify different life-history variables, including lifetime reproductive success, as indicators of average fitness and life-history speed across stochastic environments. Depending on the shape of adult survival rate, generation time can be used as an indicator of the response of populations to stochastic change, as in the deterministic case. This work is a useful step toward understanding population dynamics in stochastic environments, including how stochastic change may shape the evolution of life histories.

  10. Spatio-temporal analysis of the relationship between WNV dissemination and environmental variables in Indianapolis, USA

    PubMed Central

    Liu, Hua; Weng, Qihao; Gaines, David

    2008-01-01

    Background This study developed a multi-temporal analysis on the relationship between West Nile Virus (WNV) dissemination and environmental variables by using an integrated approach of remote sensing, GIS, and statistical techniques. WNV mosquito cases in seven months (April-October) of the six years (2002–2007) were collected in Indianapolis, USA. Epidemic curves were plotted to identify the temporal outbreaks of WNV. Spatial-temporal analysis and k-mean cluster analysis were further applied to determine the high-risk areas. Finally, the relationship between environmental variables and WNV outbreaks were examined by using Discriminant Analysis. Results The results show that the WNV epidemic curve reached its peak in August for all years in the study area except in 2007, where the peak was reached in July. WNV dissemination started from the central longitudinal corridor of the city and spread out to the east and west. Different years and seasons had different high-risk areas, but the southwest and southeast corners show the highest risk for WNV infection due to their high percentages of agriculture and water sources. Conclusion Major environmental factors contributing to the outbreak of WNV in Indianapolis were the percentages of agriculture and water, total length of streams, and total size of wetlands. This study provides important information for urban public health prevention and management. It also contributes to the optimization of mosquito control and arrangement of future sampling efforts. PMID:19094221

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. [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.

  17. 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.

  18. Environmental variability and the evolution of the glucocorticoid receptor (Nr3c1) in African starlings.

    PubMed

    Hofmeister, Natalie R; Rubenstein, Dustin R

    2016-10-01

    One of the primary ways that organisms cope with environmental change is through regulation of the hypothalamo-pituitary-adrenal (HPA) axis, the neuroendocrine system that controls reactions to stress. Variation in genes regulating the HPA axis - particularly the glucocorticoid receptor - may facilitate adaptation to changing climatic conditions by altering expression. Here we examine signatures of selection on the glucocorticoid receptor gene (Nr3c1) in African starlings that inhabit a range of environments, including those with variable climatic conditions. To investigate potential adaptive mechanisms underlying the vertebrate stress response, we sequence the Nr3c1 gene in 27 species of African starlings. Although we find some evidence of positive selection, substitution rate is negatively correlated with variance in precipitation. This suggests climatic cycling in sub-Saharan Africa may have resulted in lower substitution rates to maintain a successful coping strategy. When environmental conditions fluctuate rapidly, variation in the strength of purifying selection can explain evolutionary rate variation. PMID:27500971

  19. 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. PMID:17884159

  20. 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.

  1. 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.

  2. 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. PMID:27473110

  3. 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.

  4. 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.

  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. The temperature size rule in arthropods: independent of macro-environmental variables but size dependent.

    PubMed

    Klok, C Jaco; Harrison, Jon F

    2013-10-01

    Temperature is a key factor that affects the rates of growth and development in animals, which ultimately determine body size. Although not universal, a widely documented and poorly understood pattern is the inverse relationship between the temperature at which an ectothermic animal is reared and its body size (temperature size rule [TSR]). The proximate and ultimate mechanisms for the TSR remain unclear. To explore possible explanations for the TSR, we tested for correlations between the magnitude/direction of the TSR and latitude, temperature, elevation, habitat, availability of oxygen, capacity for flight, and taxonomic grouping in 98 species/populations of arthropods. The magnitude and direction of the TSR was not correlated with any of the macro-environmental variables we examined, supporting the generality of the TSR. However, body size affected the magnitude and direction of the TSR, with smaller arthropods more likely to demonstrate a classic TSR. Considerable variation among species exists in the TSR, suggesting either strong interactions with nutrition, or selection based on microclimatic or seasonal variation not captured in classic macro-environmental variables.

  7. Mapping grass communities based on multi-temporal Landsat TM imagery and environmental variables

    NASA Astrophysics Data System (ADS)

    Zeng, Yuandi; Liu, Yanfang; Liu, Yaolin; de Leeuw, Jan

    2007-06-01

    Information on the spatial distribution of grass communities in wetland is increasingly recognized as important for effective wetland management and biological conservation. Remote sensing techniques has been proved to be an effective alternative to intensive and costly ground surveys for mapping grass community. However, the mapping accuracy of grass communities in wetland is still not preferable. The aim of this paper is to develop an effective method to map grass communities in Poyang Lake Natural Reserve. Through statistic analysis, elevation is selected as an environmental variable for its high relationship with the distribution of grass communities; NDVI stacked from images of different months was used to generate Carex community map; the image in October was used to discriminate Miscanthus and Cynodon communities. Classifications were firstly performed with maximum likelihood classifier using single date satellite image with and without elevation; then layered classifications were performed using multi-temporal satellite imagery and elevation with maximum likelihood classifier, decision tree and artificial neural network separately. The results show that environmental variables can improve the mapping accuracy; and the classification with multitemporal imagery and elevation is significantly better than that with single date image and elevation (p=0.001). Besides, maximum likelihood (a=92.71%, k=0.90) and artificial neural network (a=94.79%, k=0.93) perform significantly better than decision tree (a=86.46%, k=0.83).

  8. 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.

  9. Impacts of environmental variability on desiccation rate, plastic responses and population dynamics of Glossina pallidipes.

    PubMed

    Kleynhans, E; Clusella-Trullas, S; Terblanche, J S

    2014-02-01

    Physiological responses to transient conditions may result in costly responses with little fitness benefits, and therefore, a trade-off must exist between the speed of response and the duration of exposure to new conditions. Here, using the puparia of an important insect disease vector, Glossina pallidipes, we examine this potential trade-off using a novel combination of an experimental approach and a population dynamics model. Specifically, we explore and dissect the interactions between plastic physiological responses, treatment-duration and -intensity using an experimental approach. We then integrate these experimental results from organismal water-balance data and their plastic responses into a population dynamics model to examine the potential relative fitness effects of simulated transient weather conditions on population growth rates. The results show evidence for the predicted trade-off for plasticity of water loss rate (WLR) and the duration of new environmental conditions. When altered environmental conditions lasted for longer durations, physiological responses could match the new environmental conditions, and this resulted in a lower WLR and lower rates of population decline. At shorter time-scales however, a mismatch between acclimation duration and physiological responses was reflected by reduced overall population growth rates. This may indicate a potential fitness cost due to insufficient time for physiological adjustments to take place. The outcomes of this work therefore suggest plastic water balance responses have both costs and benefits, and these depend on the time-scale and magnitude of variation in environmental conditions. These results are significant for understanding the evolution of plastic physiological responses and changes in population abundance in the context of environmental variability.

  10. 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

  11. Spatial structure of the abiotic environment and its association with sapling community structure and dynamics in a cloud forest

    NASA Astrophysics Data System (ADS)

    Mejía-Domínguez, Nancy R.; Meave, Jorge A.; Díaz-Ávalos, Carlos

    2012-03-01

    Analyzing the relationship between the spatial structures of environmental variables and of the associated seedling and sapling communities is crucial to understanding the regeneration processes in forest communities. The degree of spatial structuring (i.e., spatial autocorrelation) of environmental and sapling community variables in the cloud forest of Teipan, S Mexico, were analyzed at a 1-ha scale using geostatistical analysis; after fitting semivariogram models for each set of variables, the association between the two sets was examined through cross-variograms. Kriging maps of the sapling community variables (density, cover, species richness, and mortality and recruitment rates) were obtained through conditional simulation method. Canopy openness, total solar radiation, litter depth, soil temperature and soil moisture were spatially structured, as were sapling density, species richness and sapling mortality rate. Mean range in semivariograms for environmental and sapling community variables were 13.14 ± 3.67 and 12.68 ± 5.71 m (±SE), respectively. The spatial structure of litter depth was negatively associated with the spatial structures of sapling density, species richness, and sapling community cover; in turn, the spatial structure of soil moisture was positively associated with the spatial structure of recruitment rate. These associations of the spatial structures of abiotic and sapling community variables suggest that the regeneration processes in this cloud forest is driven by the existence of different microsites, largely characterized by litter depth variations, across which saplings of tree species encounter a range of opportunities for successful establishment and survival.

  12. 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

  13. 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

  14. 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. PMID:24689692

  15. Environmental variables and levels of exhaled carbon monoxide and carboxyhemoglobin in elderly people taking exercise.

    PubMed

    Salicio, Marcos Adriano; Mana, Viviane Aparecida Martins; Fett, Waléria Christiane Rezende; Gomes, Luciano Teixeira; Botelho, Clovis

    2016-04-01

    This article aims to analyze levels of exhaled carbon monoxide, carboxyhemoglobinand cardiopulmonary variables in old people practicing exercise in external environments, and correlate them with climate and pollution factors. Temporal ecological study with118 active elderly people in the city of Cuiabá, in the state of Mato Grosso, Brazil. Data were obtained on use of medication, smoking, anthropometric measurements, spirometry, peak flow, oxygen saturation, heart rate, exhaled carbon monoxide, carboxyhemoglobin, climate, number of farm fires and pollution. Correlations were found between on the one hand environmental temperature, relative humidity of the air and number of farmers' fires, and on the other hand levels of carbon monoxide exhaled and carboxyhemoglobin (p < 0.05).There was a correlation between heart rate and changes in environmental temperature, time of exposure to the sun and relative humidity (p < 0.05). In elderly people, environmental factors influence levels of exhaled carbon monoxide, carboxyhemoglobin and heart rate. There is thus a need for these to be monitored during exercise. The use of a carbon monoxide monitor to evaluate exposure to pollutants is suggested. PMID:27076001

  16. 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.

  17. 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.

  18. Environmental variables and levels of exhaled carbon monoxide and carboxyhemoglobin in elderly people taking exercise.

    PubMed

    Salicio, Marcos Adriano; Mana, Viviane Aparecida Martins; Fett, Waléria Christiane Rezende; Gomes, Luciano Teixeira; Botelho, Clovis

    2016-04-01

    This article aims to analyze levels of exhaled carbon monoxide, carboxyhemoglobinand cardiopulmonary variables in old people practicing exercise in external environments, and correlate them with climate and pollution factors. Temporal ecological study with118 active elderly people in the city of Cuiabá, in the state of Mato Grosso, Brazil. Data were obtained on use of medication, smoking, anthropometric measurements, spirometry, peak flow, oxygen saturation, heart rate, exhaled carbon monoxide, carboxyhemoglobin, climate, number of farm fires and pollution. Correlations were found between on the one hand environmental temperature, relative humidity of the air and number of farmers' fires, and on the other hand levels of carbon monoxide exhaled and carboxyhemoglobin (p < 0.05).There was a correlation between heart rate and changes in environmental temperature, time of exposure to the sun and relative humidity (p < 0.05). In elderly people, environmental factors influence levels of exhaled carbon monoxide, carboxyhemoglobin and heart rate. There is thus a need for these to be monitored during exercise. The use of a carbon monoxide monitor to evaluate exposure to pollutants is suggested.

  19. 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.

  20. 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.

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

    PubMed Central

    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.

    2015-01-01

    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 × 103 − 4 × 105 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. PMID:26247348

  2. 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. PMID:24044943

  3. Patterns in temporal variability of temperature, oxygen and pH along an environmental gradient in a coral reef.

    PubMed

    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

  4. Patterns in temporal variability of temperature, oxygen and pH along an environmental gradient in a coral reef.

    PubMed

    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.

  5. 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

  6. 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

  7. The role of transcriptional coactivator ADA2b in Arabidopsis abiotic stress responses

    PubMed Central

    Kaldis, Athanasios; Nikoloudi, Adriana; Tsementzi, Despoina

    2011-01-01

    Plant growth and crop production can be greatly affected by common environmental stresses such as drought, high salinity and low temperatures. Gene expression is affected by several abiotic stresses. Stress-inducible genes are regulated by transcription factors and epigenetic mechanisms such as histone modifications. In this mini-review, we have explored the role of transcriptional adaptor ADA2b in Arabidopsis responses to abiotic stress. ADA2b is required for the expression of genes involved in abiotic stress either by controlling H3 and H4 acetylation in the case of salt stress or affecting nucleosome occupancy in low temperatures response. PMID:21897124

  8. The role of transcriptional coactivator ADA2b in Arabidopsis abiotic stress responses.

    PubMed

    Vlachonasios, Konstantinos E; Kaldis, Athanasios; Nikoloudi, Adriana; Tsementzi, Despoina

    2011-10-01

    Plant growth and crop production can be greatly affected by common environmental stresses such as drought, high salinity and low temperatures. Gene expression is affected by several abiotic stresses. Stress-inducible genes are regulated by transcription factors and epigenetic mechanisms such as histone modifications. In this Mini-Review, we have explored the role of transcriptional adaptor ADA2b in Arabidopsis responses to abiotic stress. ADA2b is required for the expression of genes involved in abiotic stress either by controlling H3 and H4 acetylation in the case of salt stress or affecting nucleosome occupancy in low temperatures response.

  9. A FORTRAN technique for correlating a circular environmental variable with a linear physiological variable in the sugar maple.

    PubMed

    Pease, J M; Morselli, M F

    1987-01-01

    This paper deals with a computer program adapted to a statistical method for analyzing an unlimited quantity of binary recorded data of an independent circular variable (e.g. wind direction), and a linear variable (e.g. maple sap flow volume). Circular variables cannot be statistically analyzed with linear methods, unless they have been transformed. The program calculates a critical quantity, the acrophase angle (PHI, phi o). The technique is adapted from original mathematics [1] and is written in Fortran 77 for easier conversion between computer networks. Correlation analysis can be performed following the program or regression which, because of the circular nature of the independent variable, becomes periodic regression. The technique was tested on a file of approximately 4050 data pairs.

  10. Autoregressive modeling with state-space embedding vectors for damage detection under operational and environmental variability

    SciTech Connect

    Farrar, Charles; Figueiredo, Eloi; Todd, Michael; Flynn, Eric

    2010-01-01

    A nonlinear time series approach is presented to detect damage in systems by using a state-space reconstruction to infer the geometrical structure of a deterministic dynamical system from observed time series response at multiple locations. The unique contribution of this approach is using a Multivariate Autoregressive (MAR) model of a baseline condition to predict the state space, where the model encodes the embedding vectors rather than scalar time series. A hypothesis test is established that the MAR model will fail to predict future response if damage is present in the test condition, and this test is investigated for robustness in the context of operational and environmental variability. The applicability of this approach is demonstrated using acceleration time series from a base-excited 3-story frame structure.

  11. The stable isotopic composition of coral skeletons: control by environmental variables

    NASA Astrophysics Data System (ADS)

    Weil, Sandra M.; Buddemeier, Robert W.; Smith, Stephen V.; Kroopnick, Peter M.

    1981-07-01

    The reef corals Pocillopora damicornis and Montipora verrucosa were cultured under various controlled temperature and light conditions. The corals were analyzed for growth rate, tissue pigment content and skeletal 13C and 18O. Coral skeletal δ 13C values varied with light dose and correlated with changes in zooxanthellar pigment. The δ 13C values of skeletal aragonite seem to be modified by oxidation of photosynthetically produced organic matter. Functionally significant relationships between coral skeletal δ 18O values and temperature have been determined. The temperature coefficients of the δ 18O values [-4.4°C (%.) -1] are similar to the first order coefficient in the equilibrium paleotemperature equation, but the δ 18O values have taxonomically consistent offsets from equilibrium. The offsets may be attributed to the coral metabolism with slight but statistically significant differences between the two genera. Environmental and metabolic variables other than temperature have little or no effect on skeletal δ 18O.

  12. Genetic variability in environmental isolates of Legionella pneumophila from Comunidad Valenciana (Spain).

    PubMed

    Coscollá, Mireia; Gosalbes, María José; Catalán, Vicente; González-Candelas, Fernando

    2006-06-01

    Legionella pneumophila is associated to recurrent outbreaks in several Comunidad Valenciana (Spain) localities, especially in Alcoi, where social and climatic conditions seem to provide an excellent environment for bacterial growth. We have analysed the nucleotide sequences of three loci from 25 environmental isolates from Alcoi and nearby locations sampled over 3 years. The analysis of these isolates has revealed a substantial level of genetic variation, with consistent patterns of variability across loci, and comparable to that found in a large, European-wide sampling of clinical isolates. Among the tree loci studied, fliC showed the highest level of nucleotide diversity. The analysis of isolates sampled in different years revealed a clear differentiation, with samples from 2001 being significantly distinct from those obtained in 2002 and 2003. Furthermore, although linkage disequilibrium measures indicate a clonal nature for population structure in this sample, the presence of some recombination events cannot be ruled out.

  13. 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

  14. Socio-environmental variables and transmission risk of lymphatic filariasis in central and northern Mozambique.

    PubMed

    Manhenje, Isabel; Galán-Puchades, M Teresa; Fuentes, Màrius V

    2013-05-01

    Lymphatic filariasis (LF) is endemic in Mozambique, where it is caused by Wuchereria bancrofti with Culex quinquefasciatus as the main vector. It affects approximately 10% of the population (2 million) with about 16 million at risk. Prevalence rates in 40 out of 65 districts that together comprise the four endemic provinces Niassa, Cabo Delgado, Nampula and Zambezia were analysed with the aim of elucidating the socio-environmental variables influencing the transmission. The levels of prevalence were divided into six ranks and certain climatic, environmental and social factors were considered independent variables. A climadiagram was created and the LF risk and the water budget-based index were calculated for each district. Factors influencing the risk of the overall transmission and that of the provincial levels were established by discriminant analysis. The results show that LF transmission increased with mean maximum temperature and decreased with altitude. The almost constant annual temperature (especially in the tropical area), altitude, general economic conditions and predominant crop production (rice) were found to be responsible for the abundance and presence of the vector. However, despite the presence of the vector in the hinterland, presence and survival of the parasite were not found to be favoured there. The transmission risk was found to be highest in Zambezia, and consequently also the prevalence, while the situation in Niassa was the opposite. The conclusion is that temperature, altitude and the development/poverty index (particularly in the urban areas) have to be considered as transmission risk factors for LF in Mozambique. The extent of rice culturing probably also plays a role with respect to this infection.

  15. 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. PMID:24635043

  16. 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.

  17. Integrating Environmental and Socio-Economic Indicators of a Linked Catchment-Coastal System Using Variable Environmental Intensity

    NASA Astrophysics Data System (ADS)

    Dymond, John R.; Davie, Tim J. A.; Fenemor, Andrew D.; Ekanayake, Jagath C.; Knight, Ben R.; Cole, Anthony O.; de Oca Munguia, Oscar Montes; Allen, Will J.; Young, Roger G.; Basher, Les R.; Dresser, Marc; Batstone, Chris J.

    2010-09-01

    Can we develop land use policy that balances the conflicting views of stakeholders in a catchment while moving toward long term sustainability? Adaptive management provides a strategy for this whereby measures of catchment performance are compared against performance goals in order to progressively improve policy. However, the feedback loop of adaptive management is often slow and irreversible impacts may result before policy has been adapted. In contrast, integrated modelling of future land use policy provides rapid feedback and potentially improves the chance of avoiding unwanted collapse events. Replacing measures of catchment performance with modelled catchment performance has usually required the dynamic linking of many models, both biophysical and socio-economic—and this requires much effort in software development. As an alternative, we propose the use of variable environmental intensity (defined as the ratio of environmental impact over economic output) in a loose coupling of models to provide a sufficient level of integration while avoiding significant effort required for software development. This model construct was applied to the Motueka Catchment of New Zealand where several biophysical (riverine water quantity, sediment, E. coli faecal bacteria, trout numbers, nitrogen transport, marine productivity) models, a socio-economic (gross output, gross margin, job numbers) model, and an agent-based model were linked. An extreme set of land use scenarios (historic, present, and intensive) were applied to this modelling framework. Results suggest that the catchment is presently in a near optimal land use configuration that is unlikely to benefit from further intensification. This would quickly put stress on water quantity (at low flow) and water quality ( E. coli). To date, this model evaluation is based on a theoretical test that explores the logical implications of intensification at an unlikely extreme in order to assess the implications of likely growth

  18. Dynamical seasonal prediction using the global environmental multiscale model with a variable resolution modeling approach

    NASA Astrophysics Data System (ADS)

    Markovic, Marko; Lin, Hai; Winger, Katja

    2012-10-01

    In this work we evaluate seasonal forecasts performed with the global environmental multiscale model (GEM) using a variable resolution approach and with a high-resolution region over different geographical locations. Therefore, using two grid positions, one over North America and the other over the tropical Pacific-eastern Indian Ocean, we compare the seasonal predictions performed with the variable resolution approach with seasonal forecast performed with the uniform grid GEM model. For each model configuration, a ten-member ensemble forecast of 4 months is performed starting from the first of December of selected ENSO winters between 1982 and 2000. The sea surface temperature anomaly of the month preceding the forecast (November) is persisted throughout the forecast period. There is not enough evidence to indicate that a Stretch-Grid configuration has a clear advantage in seasonal prediction compared to a Uniform-Grid configuration. Forecasts with highly resolved grids placed over North America have more accurate seasonal mean anomalies and more skill in representing near surface temperature over the North American continent. For 500-hPa geopotential height, however, no configuration stands out to be consistently superior in forecasting the ENSO related seasonal mean anomalies and skill score.

  19. 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

  20. 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.

  1. 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

  2. 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. PMID:25885810

  3. 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

    2014-01-01

    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

  4. 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.

  5. 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

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

    PubMed

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

    2015-01-01

    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

  7. 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

  8. Polyamines in response to abiotic stress tolerance through transgenic approaches

    PubMed Central

    Pathak, Malabika Roy; Teixeira da Silva, Jaime A; Wani, Shabir H

    2014-01-01

    The distribution, growth, development and productivity of crop plants are greatly affected by various abiotic stresses. Worldwide, sustainable crop productivity is facing major challenges caused by abiotic stresses by reducing the potential yield in crop plants by as much as 70%. Plants can generally adapt to one or more environmental stresses to some extent. Physiological and molecular studies at transcriptional, translational, and transgenic plant levels have shown the pronounced involvement of naturally occurring plant polyamines (PAs), in controlling, conferring, and modulating abiotic stress tolerance in plants. PAs are small, low molecular weight, non-protein polycations at physiological pH, that are present in all living organisms, and that have strong binding capacity to negatively charged DNA, RNA, and different protein molecules. They play an important role in plant growth and development by controlling the cell cycle, acting as cell signaling molecules in modulating plant tolerance to a variety of abiotic stresses. The commonly known PAs, putrescine, spermidine, and spermine tend to accumulate together accompanied by an increase in the activities of their biosynthetic enzymes under a range of environmental stresses. PAs help plants to combat stresses either directly or by mediating a signal transduction pathway, as shown by molecular cloning and expression studies of PA biosynthesis-related genes, knowledge of the functions of PAs, as demonstrated by developmental studies, and through the analysis of transgenic plants carrying PA genes. This review highlights how PAs in higher plants act during environmental stress and how transgenic strategies have improved our understanding of the molecular mechanisms at play. PMID:24710064

  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. 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.

  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

    2016-01-01

    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

  12. Spatiotemporal environmental heterogeneity and the maintenance of the tailspot polymorphism in the variable platyfish (Xiphophorus variatus).

    PubMed

    Culumber, Zachary W; Tobler, Michael

    2016-02-01

    Genetic variation is critical for adaptive evolution. Despite its importance, there is still limited evidence in support of some prominent theoretical models explaining the maintenance of genetic polymorphism within populations. We examined 84 populations of Xiphophorus variatus, a livebearing fish with a genetic polymorphism associated with physiological performance, to test: (1) whether niche differentiation explains broad-scale maintenance of polymorphism, (2) whether polymorphism is maintained among populations by local adaptation and migration, or (3) whether heterogeneity in explicit environmental variables could be linked to levels of polymorphism within populations. We found no evidence of climatic niche differentiation that could generate or maintain broad geographic variation in polymorphism. Subsequently, hierarchical partitioning of genetic richness and partial mantel tests revealed that 76% of the observed genetic richness was partitioned within populations with no effect of geographic distance on polymorphism. These results strongly suggest a lack of migration-selection balance in the maintenance of polymorphism, and model selection confirmed a significant relationship between environmental heterogeneity and genetic richness within populations. Few studies have demonstrated such effects at this scale, and additional studies in other taxa should examine the generality of gene-by-environment interactions across populations to better understand the dynamics and scale of balancing selection. PMID:26748941

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. 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. PMID:24789391

  18. 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.

  19. 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

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

    PubMed

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

    2013-03-01

    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 results

  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. 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.

  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. 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

  5. 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

  6. 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

  7. 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.

  8. 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. PMID:26803396

  9. 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.

  10. 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.

  11. 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. PMID:25874412

  12. 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).

  13. Phenotyping for abiotic stress tolerance in maize.

    PubMed

    Masuka, Benhilda; Araus, Jose Luis; Das, Biswanath; Sonder, Kai; Cairns, Jill E

    2012-04-01

    The ability to quickly develop germplasm having tolerance to several complex polygenic inherited abiotic and biotic stresses combined is critical to the resilience of cropping systems in the face of climate change. Molecular breeding offers the tools to accelerate cereal breeding; however, suitable phenotyping protocols are essential to ensure that the much-anticipated benefits of molecular breeding can be realized. To facilitate the full potential of molecular tools, greater emphasis needs to be given to reducing the within-experimental site variability, application of stress and characterization of the environment and appropriate phenotyping tools. Yield is a function of many processes throughout the plant cycle, and thus integrative traits that encompass crop performance over time or organization level (i.e. canopy level) will provide a better alternative to instantaneous measurements which provide only a snapshot of a given plant process. Many new phenotyping tools based on remote sensing are now available including non-destructive measurements of growth-related parameters based on spectral reflectance and infrared thermometry to estimate plant water status. Here we describe key field phenotyping protocols for maize with emphasis on tolerance to drought and low nitrogen.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. Carbon isotope variations in a solar pond microbial mat: Role of environmental gradients as steering variables

    NASA Astrophysics Data System (ADS)

    Schidlowski, Manfred; Gorzawski, Hendrik; Dor, Inka

    1994-05-01

    A biogeochemical traverse is presented for a juvenile benthic mat covering the depth profile of an artificially stratified and eutrophicated hypersaline heliothermal pond with known gradients of temperature, salinity, pH, and light transmission. It can be shown that visual mat development depends primarily on temperature and salinity as main environmental steering variables whose increase with depth goes along with the attenuation and final disappearance of a visible microbial film in the pond's hypolimnic compartment. Recorded biogeochemical parameters (C org content, cell numbers, chlorophyll-a content) evidently reflect, as either biomass- or productivity-related index functions, the visually perceptible growth gradient of the microbial ecosystem along the pond slope. The observed coincidence of maxima in these index functions with maxima in δ13Corg clearly identifies high rates of primary productivity as the agent ultimately responsible for the generation of isotopically heavy ( 13C-enriched) biomass in these and related environments. Extreme demands placed on the local feeder pool of dissolved inorganic carbon by high rates of primary productivity entertained by the mat-forming microbenthos obviously give rise to severe CO 2 limitation, enforcing the operation of a diffusion-(supply-)limited assimilatory pathway with an isotopically indiscriminate metabolization of the available CO 2 resources.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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

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

    PubMed

    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 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

  6. 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

  7. 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. PMID:25101102

  8. 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

  9. 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…

  10. 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

  11. Abscisic Acid and Abiotic Stress Tolerance in Crop Plants.

    PubMed

    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

  12. Recent benthic foraminiferal assemblages and their relationship to environmental variables on the shoreface and inner shelf off Valencia (western Mediterranean).

    PubMed

    López-Belzunce, María; Blázquez, Ana M; Pretus, Joan Lluís

    2014-10-01

    The environmental variables that determine the distributions of benthic foraminiferal assemblages on the shoreface and inner shelf of the north of Valencia province (Western Mediterranean) are identified. The possible influence of variables such as water depth, distance from shore, hydrodynamics, substrate type, carbonate content, organic matter content and human activity is evaluated. Multivariate cluster-Q-type analysis and redundancy analysis (RDA) are used to identify the environmental variables that have the greatest influence on the assemblage distribution. The spatial distribution of the assemblages is closely associated with water depth and substrate. The diversity and abundance of foraminifera shells increase with depth and their conservation improves. The most common species in the study area are Ammonia beccarii, Rosalina globularis, Buccella granulata, Planorbulina mediterranensis, and Lobatula lobatula. The presence of wastewater in the study area has not polluted the foraminiferal assemblages (absence of anomalous shells). The direction of the discharge plume is a potential source of nutrients for deep water.

  13. 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

  14. 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

  15. Abiotic stress modifies the synthesis of alpha-tocopherol and beta-carotene in phytoplankton species.

    PubMed

    Häubner, Norbert; Sylvander, Peter; Vuori, Kristiina; Snoeijs, Pauline

    2014-08-01

    We performed laboratory experiments to investi-gate whether the synthesis of the antioxidants α-tocopherol (vitamin E) and β-carotene in phytoplankton depends on changes in abiotic factors. Cultures of Nodularia spumigena, Phaeodactylum tricornutum, Skeletonema costatum, Dunaliella tertiolecta, Prorocentrum cordatum, and Rhodomonas salina were incubated at different tempe-ratures, photon flux densities and salinities for 48 h. We found that abiotic stress, within natural ecological ranges, affects the synthesis of the two antioxidants in different ways in different species. In most cases antioxidant production was stimulated by increased abiotic stress. In P. tricornutum KAC 37 and D. tertiolecta SCCAP K-0591, both good producers of this compound, α-tocopherol accumulation was negatively affected by environmentally induced higher photosystem II efficiency (Fv /Fm ). On the other hand, β-carotene accumulation was positively affected by higher Fv /Fm in N. spumigena KAC 7, P. tricornutum KAC 37, D. tertiolecta SCCAP K-0591 and R. salina SCCAP K-0294. These different patterns in the synthesis of the two compounds may be explained by their different locations and functions in the cell. While α-tocopherol is heavily involved in the protection of prevention of lipid peroxidation in membranes, β-carotene performs immediate photo-oxidative protection in the antennae complex of photosystem II. Overall, our results suggest a high variability in the antioxidant pool of natural aquatic ecosystems, which can be subject to short-term temperature, photon flux density and salinity fluctuations. The antioxidant levels in natural phytoplankton communities depend on species composition, the physiological condition of the species, and their respective strategies to deal with reactive oxygen species. Since α-tocopherol and β-carotene, as well as many other nonenzymatic antioxidants, are exclusively produced by photo-synthetic organisms, and are required by higher

  16. Abiotic stress modifies the synthesis of alpha-tocopherol and beta-carotene in phytoplankton species.

    PubMed

    Häubner, Norbert; Sylvander, Peter; Vuori, Kristiina; Snoeijs, Pauline

    2014-08-01

    We performed laboratory experiments to investi-gate whether the synthesis of the antioxidants α-tocopherol (vitamin E) and β-carotene in phytoplankton depends on changes in abiotic factors. Cultures of Nodularia spumigena, Phaeodactylum tricornutum, Skeletonema costatum, Dunaliella tertiolecta, Prorocentrum cordatum, and Rhodomonas salina were incubated at different tempe-ratures, photon flux densities and salinities for 48 h. We found that abiotic stress, within natural ecological ranges, affects the synthesis of the two antioxidants in different ways in different species. In most cases antioxidant production was stimulated by increased abiotic stress. In P. tricornutum KAC 37 and D. tertiolecta SCCAP K-0591, both good producers of this compound, α-tocopherol accumulation was negatively affected by environmentally induced higher photosystem II efficiency (Fv /Fm ). On the other hand, β-carotene accumulation was positively affected by higher Fv /Fm in N. spumigena KAC 7, P. tricornutum KAC 37, D. tertiolecta SCCAP K-0591 and R. salina SCCAP K-0294. These different patterns in the synthesis of the two compounds may be explained by their different locations and functions in the cell. While α-tocopherol is heavily involved in the protection of prevention of lipid peroxidation in membranes, β-carotene performs immediate photo-oxidative protection in the antennae complex of photosystem II. Overall, our results suggest a high variability in the antioxidant pool of natural aquatic ecosystems, which can be subject to short-term temperature, photon flux density and salinity fluctuations. The antioxidant levels in natural phytoplankton communities depend on species composition, the physiological condition of the species, and their respective strategies to deal with reactive oxygen species. Since α-tocopherol and β-carotene, as well as many other nonenzymatic antioxidants, are exclusively produced by photo-synthetic organisms, and are required by higher

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

    PubMed Central

    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. PMID:26241328

  18. 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.

  19. Variability in alkaloid profiles in neotropical poison frogs (Dendrobatidae): genetic versus environmental determinants.

    PubMed

    Daly, J W; Secunda, S I; Garraffo, H M; Spande, T F; Wisnieski, A; Nishihira, C; Cover, J F

    1992-08-01

    Dendrobatid frogs produce a diverse set of alkaloids, whose profiles appear characteristic of frogs of each species or, in the case of variable species, of each population. In the case of one widespread species, Dendrobates auratus, alkaloid profiles in extracts of skin are markedly different in three populations, one from a Pacific island, Isla Taboga, Panama, one from central mountains in Panama, and the third from the Caribbean coast in Costa Rica. The first contains three major classes of dendrobatid alkaloids, the histrionicotoxins, the pumiliotoxin-A class and the decahydroquinolines. The second contains mainly histrionicotoxins, pumiliotoxin-A class alkaloids and one indolizidine. The third contains histrionicotoxins, a homopumiliotoxin, one decahydroquinoline, and a variety of indolizidines, quinolizidines and pyrrolizidines. Frogs from Isla Taboga or a nearby island were introduced into the Manoa Valley, Oahu, Hawaii, in 1932. Remarkably, although alkaloids of the pumiliotoxin-A class and one decahydroquinoline are still major constituents in skin extracts of Hawaiian frogs descended from the 1932 founding population, histrionicotoxins are absent and a novel tricyclic alkaloid is present. Offspring of wild-caught parents from Hawaii, Panama or Costa Rica raised in indoor terrariums on a diet of crickets and fruit flies do not contain detectable amounts of skin alkaloids. Offspring raised in large outside terrariums in Hawaii and fed mainly wild-caught termites and fruit flies do contain the same profile of alkaloids as their wild-caught parents in Hawaii, but at reduced levels. The genetic, environmental and dietary determinants of alkaloid profiles in dendrobatid frogs remain obscure, in particular the underlying cause for total absence in terrarium-reared frogs.

  20. 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.

  1. 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…

  2. Links between Transcription, Environmental Adaptation and Gene Variability in Escherichia coli: Correlations between Gene Expression and Gene Variability Reflect Growth Efficiencies.

    PubMed

    Feugeas, Jean-Paul; Tourret, Jerome; Launay, Adrien; Bouvet, Odile; Hoede, Claire; Denamur, Erick; Tenaillon, Olivier

    2016-10-01

    Gene expression is known to be the principle factor explaining how fast genes evolve. Highly transcribed genes evolve slowly because any negative impact caused by a particular mutation is magnified by protein abundance. However, gene expression is a phenotype that depends both on the environment and on the strains or species. We studied this phenotypic plasticity by analyzing the transcriptome profiles of four Escherichia coli strains grown in three different culture media, and explored how expression variability was linked to gene allelic diversity. Genes whose expression changed according to the media and not to the strains were less polymorphic than other genes. Genes for which transcription depended predominantly on the strain were more polymorphic than other genes and were involved in sensing and responding to environmental changes, with an overrepresentation of two-component system genes. Surprisingly, we found that the correlation between transcription and gene diversity was highly variable among growth conditions and could be used to quantify growth efficiency of a strain in a medium. Genetic variability was found to increase with gene expression in poor growth conditions. As such conditions are also characterized by down-regulation of all DNA repair systems, including transcription-coupled repair, we suggest that gene expression under stressful conditions may be mutagenic and thus leads to a variability in mutation rate among genes in the genome which contributes to the pattern of protein evolution.

  3. 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. PMID:23581698

  4. Influence of topographic and environmental variability on model uncertainty: a case study on snow and ground temperatures in mountain regions

    NASA Astrophysics Data System (ADS)

    Gubler, S.; Gruber, S.; Purves, R.; Endrizzi, S.

    2012-12-01

    A variety of physically based models to predict and understand the spatio-temporal behaviour of snow and ground temperatures have been developed in recent years. Model evaluation including the analysis of model uncertainty and validation is widely accepted as fundamental in enhancing trust in decisions that are based on model simulations. Due to constraints on resources or lack of distributed validation data, model evaluation is often restricted to one or few locations only, even if the model is applied to make predictions for large spatial areas and time periods. Thus, conclusions about model behaviour entail the tacit assumption that validation at one point can inform decisions about model performance in different environmental conditions. The effect of this assumption on model application and development when modeling phenomena in highly variable terrain or over large distances has rarely been studied. This study is focused on a sensitivity and uncertainty analysis of an energy and mass balance model that simulates snow and ground temperatures. It serves as a case study examining the role of topography and soil on parametric model uncertainty and sensitivity. A sensitivity analysis on individual parameters and a Monte Carlo based uncertainty study are performed at a variety of locations covering the range of topographic and environmental variability typically found in mountain regions. The results indicate that model uncertainties and sensitivities vary strongly under differing environmental conditions. This demonstrates that model evaluation (validation, sensitivity and uncertainty analyses) benefits strongly from the consideration of differing variables and, especially, the environmental variation of their behaviour.

  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. 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.

  7. 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

  8. Spatio-Temporal Environmental Correlation and Population Variability in Simple Metacommunities

    PubMed Central

    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. PMID:24023615

  9. 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

  10. AN ENVIRONMENTAL ASSESSMENT OF SENSOR-BASED VARIABLE-RATE NITROGEN MANAGEMENT IN CORN

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order to address the problem of nitrate contamination of surface and ground waters, various methods have been used to try to account for spatial variability of N within agricultural fields. One approach to account for this variability and thereby reduce nitrate pollution is in-season site-specif...

  11. 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

  12. Identification of Arabidopsis Candidate Genes in Response to Biotic and Abiotic Stresses Using Comparative Microarrays

    PubMed Central

    Sham, Arjun; Moustafa, Khaled; Al-Ameri, Salma; Al-Azzawi, Ahmed; Iratni, Rabah; AbuQamar, Synan

    2015-01-01

    Plants have evolved with intricate mechanisms to cope with multiple environmental stresses. To adapt with biotic and abiotic stresses, plant responses involve changes at the cellular and molecular levels. The current study was designed to investigate the effects of combinations of different environmental stresses on the transcriptome level of Arabidopsis genome using public microarray databases. We investigated the role of cyclopentenones in mediating plant responses to environmental stress through TGA (TGACG motif-binding factor) transcription factor, independently from jasmonic acid. Candidate genes were identified by comparing plants inoculated with Botrytis cinerea or treated with heat, salt or osmotic stress with non-inoculated or non-treated tissues. About 2.5% heat-, 19% salinity- and 41% osmotic stress-induced genes were commonly upregulated by B. cinerea-treatment; and 7.6%, 19% and 48% of genes were commonly downregulated by B. cinerea-treatment, respectively. Our results indicate that plant responses to biotic and abiotic stresses are mediated by several common regulatory genes. Comparisons between transcriptome data from Arabidopsis stressed-plants support our hypothesis that some molecular and biological processes involved in biotic and abiotic stress response are conserved. Thirteen of the common regulated genes to abiotic and biotic stresses were studied in detail to determine their role in plant resistance to B. cinerea. Moreover, a T-DNA insertion mutant of the Responsive to Dehydration gene (rd20), encoding for a member of the caleosin (lipid surface protein) family, showed an enhanced sensitivity to B. cinerea infection and drought. Overall, the overlapping of plant responses to abiotic and biotic stresses, coupled with the sensitivity of the rd20 mutant, may provide new interesting programs for increased plant resistance to multiple environmental stresses, and ultimately increases its chances to survive. Future research directions towards a

  13. 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

  14. 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

  15. Life span variation in 13 Drosophila species: a comparative study on life span, environmental variables and stress resistance.

    PubMed

    Wit, J; Loeschcke, V; Kellermann, V

    2015-10-01

    Recently, heterogeneity of the environment has been suggested as an important player in the evolution of life span variation. Established ageing theories propose that life span variation is the result of coevolution with other traits, such as stress resistance. This study aimed to compare these alternative hypotheses by examining the relationship between four environmental variables and different types of stress resistance traits with life span in 13 Drosophila species originating from tropical, subtropical and temperate environments (ecotypes). Average life span was found to differ significantly both between species and sexes, but only male life span correlated with the environment and cold resistance. While controlling for phylogeny, the environmental variable precipitation seasonality and resistance against cold-induced stress explained most variation in male life span. Furthermore, male life span varied between species in a manner represented by environmental variables linked to the different ecotypes, such that tropical species lived longer and were less cold resistant. The current results suggest that general mechanisms underlying stress resistance and life span are unlikely. In addition, our results point to the environment independently shaping variation in life span and cold resistance rather than genetic interactions.

  16. 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. PMID:26352857

  17. 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.

  18. ANNUAL REPORT FOR ENVIRONMENTAL MANAGEMENT SCIENCE PROGRAM PROJECT NUMBER 86598 COUPLED FLOW AND REACTIVITY IN VARIABLY SATURATED POROUS MEDIA

    SciTech Connect

    Palmer, Carl D.; Mattson, Earl D.; Smith, Robert W.

    2003-06-13

    Improved models of contaminant migration in heterogeneous, variably saturated porous media are required to better define the long-term stewardship requirements for U.S. Department of Energy (DOE) lands and to assist in the design of effective vadose zone barriers to contaminant migrations. The objective of our three-year project is to meet the DOE need by developing new experimental approaches to describe adsorption and transport of contaminants in heterogeneous, variably saturated media (i.e., the vadose zone). The research specifically addresses the behavior of strontium, a high priority DOE contaminant. However, the key benefit of this research is improved conceptual models of how all contaminants migrate through heterogeneous, variably-saturated, porous media. Research activities are driven by the hypothesis that the reactivity of variably saturated porous media is dependent on the moisture content of the medium and can be represented by a relatively simple function applicable over a range of scales, contaminants, and media. A key and novel aspect of our research is the use of the 2-meter radius geocentrifuge capabilities at the Idaho National Engineering and Environmental Laboratory (INEEL) to conduct unsaturated reactive transport experiments (Figure 1). The experimental approach using the geocentrifuge provides data in a much shorter time period than conventional methods allowing us to complete more experiments and explore a wider range of moisture contents. The vadose zone research being done in this project will demonstrate the utility of environmental geocentrifuge experimental approaches and their applicability to DOE's vadose research needs.

  19. 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

  20. 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. PMID:26218583

  1. Mesozooplankton assemblages and their relationship with environmental variables: a study case in a disturbed bay (Beagle Channel, Argentina).

    PubMed

    Biancalana, Florencia; Dutto, M Sofía; Berasategui, Anabela A; Kopprio, Germán; Hoffmeyer, Mónica S

    2014-12-01

    This study focused on the seasonal and spatial analysis of the mesozooplankton community in a human-impacted subantarctic bay in Argentina and aimed to detect assemblages associated with environmental variability. Mesozooplankton samples and environmental data were obtained in the Ushuaia Bay (UB) seasonally, from August 2004 to June 2005, and spatially, from coastal (more polluted), middle (less influenced) and open sea water (free polluted) sampling stations. Remarkable seasonal changes on the mesozooplankton community were observed. Nitrogenated nutrients, chlorophyll a, salinity and temperature were the prevailing environmental conditions likely associated with the different mesozooplankton assemblages found in the bay. The copepods Eurytemora americana, Acartia tonsa, Podon leuckarti and Nematoda were particularly observed on the northwest coast of the bay, characterized by the highest level of urban pollution, eutrophicated by sewage and freshwater inputs from the Encerrada Bay which is connected to it. The stations situated in the northeast area, mostly influenced by freshwater input from rivers and glacier melting, showed low mesozooplankton abundances and an important contribution of adventitious plankton. The copepods Ctenocalanus citer, Clausocalanus brevipes and Drepanopus forcipatus were mostly observed at the stations located near the Beagle Channel, characterized by open sea and free polluted waters. Our findings suggest that the variations observed in the mesozooplankton assemblages in the UB seem to be modulated by environmental variables associated with the anthropogenic influence, clearly detected on the coast of the bay. Certain opportunistic species such as A. tonsa and E. americana could be postulated as potential bioindicators of water quality in subantarctic coastal ecosystems.

  2. Patterns of tree growth in relation to environmental variability in the tropical dry deciduous forest at Mudumalai, southern India.

    PubMed

    Nath, Cheryl D; Dattaraja, H S; Suresh, H S; Joshi, N V; Sukumar, R

    2006-12-01

    Tree diameter growth is sensitive to environmental fluctuations and tropical dry forests experience high seasonal and inter-annual environmental variation. Tree growth rates in a large permanent plot at Mudumalai, southern India, were examined for the influences of rainfall and three intrinsic factors (size, species and growth form) during three 4-year intervals over the period 1988-2000. Most trees had lowest growth during the second interval when rainfall was lowest, and skewness and kurtosis of growth distributions were reduced during this interval. Tree diameter generally explained less than 10% of growth variation and had less influence on growth than species identity or time interval. Intraspecific variation was high, yet species identity accounted for up to 16% of growth variation in the community. There were no consistent differences between canopy and understory tree growth rates; however, a few subgroups of species may potentially represent canopy and understory growth guilds. Environmentally-induced temporal variations in growth generally did not reduce the odds of subsequent survival. Growth rates appear to be strongly influenced by species identity and environmental variability in the Mudumalai dry forest. Understanding and predicting vegetation dynamics in the dry tropics thus also requires information on temporal variability in local climate.

  3. 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.

  4. 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

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

    PubMed

    Ramakrishna, Akula; Ravishankar, Gokare Aswathanarayana

    2011-11-01

    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.

  6. Drought variability in the western Great Plains: Synoptic associations of environmental drought

    NASA Astrophysics Data System (ADS)

    Narey, Martha Adele

    This research defined environmental drought as persistent moisture deficit recorded as reduced annual ring widths in Ponderosa pines. Reconstructed Palmer Drought Severity Index (PDSI) values more negative than -2 indicated environmental drought in the western Great Plains (1790-1989). The study identified precedent mean growing-season 500-hecto-Pascal pressure-surface synoptic change associated with environmental drought from 1946 to 1989. Drought distribution patterns, growing-season mean- departure-from-average-geopotential-height patterns, and map comparison formed the basis for classifying droughts and evaluating changes in atmospheric pressure regime that produced them. The magnitude of environmental drought for any growing season was influenced by the mean pressure regime dominating the prior year's growing season and, more weakly, by that dominating the second-prior year's growing season. The net change over three growing seasons, as expressed by composite difference maps of mean departures from average geopotential height, determined whether the moisture deficit conditions persisted long enough to produce environmental drought. Ponderosa pine sampling indicated similarity of response to environmental drought by lower-elevation stands and that expected from all-elevation, many-species reconstructed PDSI. Local conditions and responses varied considerably. The reconstructed PDSI corresponded rather better with the instrument-measurement based PDSI (1895-1978) for locations where more trees of all species actually were present or nearby than for locations where trees were sparse or absent. Sixty-four years of environmental drought were identified for 1790 to 1989. Ten basic types of environmental drought were noted, with several subtypes separately identified. Those patterns of environmental drought distribution occurring during 1946-1989 were examined as outcomes of change in upper-atmosphere regime; seven basic synoptic regime types and several variants

  7. 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...

  8. 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

  9. Glycinebetaine and abiotic stress tolerance in plants

    PubMed Central

    Giri, Jitender

    2011-01-01

    The accumulation of osmolytes like glycinebetaine (GB) in cell is known to protect organisms against abiotic stresses via osmoregulation or osmoprotection. Transgenic plants engineered to produce GB accumulate very low concentration of GB, which might not be sufficient for osmoregulation. Therefore, other roles of GB like cellular macromolecule protection and ROS detoxification have been suggested as mechanisms responsible for abiotic stress tolerance in transgenic plants. In addition, GB influences expression of several endogenous genes in transgenic plants. The new insights gained about the mechanism of stress tolerance in GB accumulating transgenic plants are discussed. PMID:22057338

  10. 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.

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

    NASA Astrophysics Data System (ADS)

    Gengler, Sarah; Bogaert, Patrick

    2014-12-01

    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.

  12. 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.

  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. 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...

  15. Effects of `Environmental Chemistry' Elective Course Via Technology-Embedded Scientific Inquiry Model on Some Variables

    NASA Astrophysics Data System (ADS)

    Çalik, Muammer; Özsevgeç, Tuncay; Ebenezer, Jazlin; Artun, Hüseyin; Küçük, Zeynel

    2014-06-01

    The purpose of this study is to examine the effects of `environmental chemistry' elective course via Technology-Embedded Scientific Inquiry (TESI) model on senior science student teachers' (SSSTs) conceptions of environmental chemistry concepts/issues, attitudes toward chemistry, and technological pedagogical content knowledge (TPACK) levels. Within one group pre-test-post-test design, the study was conducted with 117 SSSTs (68 females and 49 males—aged 21-23 years) enrolled in an `environmental chemistry' elective course in the spring semester of 2011-2012 academic-years. Instruments for data collection comprised of Environmental Chemistry Conceptual Understanding Questionnaire, TPACK survey, and Chemistry Attitudes and Experiences Questionnaire. Significant increases in the SSSTs' conceptions of environmental chemistry concepts/issues, attitudes toward chemistry, and TPACK levels are attributed to the SSSTs learning how to use the innovative technologies in the contexts of the `environmental chemistry' elective course and teaching practicum. The study implies that the TESI model may serve a useful purpose in experimental science courses that use the innovative technologies. However, to generalize feasibility of the TESI model, it should be evaluated with SSSTs in diverse learning contexts.

  16. A method to combine non-probability sample data with probability sample data in estimating spatial means of environmental variables.

    PubMed

    Brus, D J; de Gruijter, J J

    2003-04-01

    In estimating spatial means of environmental variables of a region from data collected by convenience or purposive sampling, validity of the results can be ensured by collecting additional data through probability sampling. The precision of the pi estimator that uses the probability sample can be increased by interpolating the values at the nonprobability sample points to the probability sample points, and using these interpolated values as an auxiliary variable in the difference or regression estimator. These estimators are (approximately) unbiased, even when the nonprobability sample is severely biased such as in preferential samples. The gain in precision compared to the pi estimator in combination with Simple Random Sampling is controlled by the correlation between the target variable and interpolated variable. This correlation is determined by the size (density) and spatial coverage of the nonprobability sample, and the spatial continuity of the target variable. In a case study the average ratio of the variances of the simple regression estimator and pi estimator was 0.68 for preferential samples of size 150 with moderate spatial clustering, and 0.80 for preferential samples of similar size with strong spatial clustering. In the latter case the simple regression estimator was substantially more precise than the simple difference estimator.

  17. Biotic and abiotic degradation of CL-20 and RDX in soils.

    PubMed

    Crocker, Fiona H; Thompson, Karen T; Szecsody, James E; Fredrickson, Herbert L

    2005-01-01

    The caged cyclic nitramine 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) is a new explosive that has the potential to replace existing military explosives, but little is known about its environmental toxicity, transport, and fate. We quantified and compared the aerobic environmental fate of CL-20 to the widely used cyclic nitramine explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in surface and subsurface soil microcosms. Soil-free controls and biologically attenuated soil controls were used to separate abiotic processes from biologically mediated processes. Both abiotic and biological processes significantly degraded CL-20 in all soils examined. Apparent abiotic, first-order degradation rates (k) for CL-20 were not significantly different between soil-free controls (0.018 < k < 0.030 d(-1)) and biologically attenuated soil controls (0.003 < k < 0.277 d(-1)). The addition of glucose to biologically active soil microcosms significantly increased CL-20 degradation rates (0.068 < k < 1.22 d(-1)). Extents of mineralization of (14)C-CL-20 to (14)CO(2) in biologically active soil microcosms were 41.1 to 55.7%, indicating that the CL-20 cage was broken, since all carbons are part of the heterocyclic cage. Under aerobic conditions, abiotic degradation rates of RDX were generally slower (0 < k < 0.032 d(-1)) than abiotic CL-20 degradation rates. In biologically active soil microcosms amended with glucose aerobic RDX degradation rates varied between 0.010 and 0.474 d(-1). Biodegradation was a key factor in determining the environmental fate of RDX, while a combination of biotic and abiotic processes was important with CL-20. Our data suggest that CL-20 should be less recalcitrant than RDX in aerobic soils. PMID:16275722

  18. 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

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

    PubMed

    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

    2015-09-01

    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

  20. 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.

  1. Relationship between yearly fluctuations in Fusarium head blight intensity and environmental variables: a window-pane analysis.

    PubMed

    Kriss, A B; Paul, P A; Madden, L V

    2010-08-01

    Window-pane methodology was used to determine the length and starting time of temporal windows where environmental variables were associated with annual fluctuations of Fusarium head blight (FHB) intensity in wheat. Initial analysis involved FHB intensity observations for Ohio (44 years), with additional analyses for Indiana (36 years), Kansas (28 years), and North Dakota (23 years). Selected window lengths of 10 to 280 days were evaluated, with starting times from approximate crop maturity back to the approximate time of planting. Associations were quantified with Spearman rank correlation coefficients. Significance for a given variable (for any window starting time in a collection of starting times) was declared using the Simes' multiplicity adjustment; at individual time windows, significant correlations were declared when the individual (unadjusted) P values were <0.005. In all states, moisture- or wetness-related variables (e.g., daily average relative humidity [RH] and total daily precipitation) were found to be positively correlated with FHB intensity for multiple window lengths and starting times; however, the highest correlations were primarily for shorter-length windows (especially 15 and 30 days) at similar starting times during the final 60 days of the growing season, particularly near the time of anthesis. This period encompasses spore production, dispersal, and fungal colonization of wheat spikes. There was no evidence of significant correlations between FHB and temperature-only variables for any time window; however, variables that combined aspects of moisture or wetness with temperature (e.g., duration of temperature between 15 and 30 degrees C and RH > or = 80%) were positively correlated with FHB intensity. Results confirm that the intensity of FHB in a region depends, at least in part, on environmental conditions during relatively short, critical time periods for epidemic development. PMID:20626282

  2. Examine the potential of spatial downscaling of TRMM precipitation with environmental variables: An evaluation for the Ohio River Basin

    NASA Astrophysics Data System (ADS)

    Yoon, Y.; Beighley, E., II

    2014-12-01

    Accurately quantifying precipitation in both space and time is a central challenge in hydrologic modelling. Data products from the Tropical Rainfall Measuring Mission (TRMM) are commonly used as precipitation forcings in many models. TRMM provides 3-hr precipitation estimates at a near-global scale (-50◦ S to 50◦N) with a 0.25 degree spatial resolution. However, when applied in regional scale hydrologic models, the spatial resolution of the TRMM is often too coarse limiting our ability to simulate relevant hydrologic processes.This study focuses on addressing the science question: can we improve the spatial resolution of the TRMM using statistical downscaling with environmental variables derived from finer scale remote sensing data? The goal is to downscale the TRMM resolution from 0.25 degrees (25 km) to 0.05 degrees (about 5 km). In our approach, we first identify environmental variables (i.e., vegetation cover, topography, and temperature) that are related to the formation of or result from precipitation by exploring their statistical relationships with TRMM precipitation at varying temporal scales (i.e., daily, monthly, and yearly) using an analysis of variance in multiple regression. The MODIS vegetation index, MODIS leaf area index, and SPOT vegetation are examined as a proxy for vegetation. To represent the topography, the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) is used. MODIS land surface temperature are used for temperature. Second, we characterize a residual component, which cannot be explained by the statistical relationship between precipitation and environmental variables, to improve the accuracy of the downscaling results. For example, recent studies have shown that approximately 30-40% of the variability in annual precipitation cannot be explained by vegetation and elevation characteristics. According for this unexplained variability in statistical downscaling methods is a significant challenge. Here, we use a data

  3. 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.

  4. Stability of Intercellular Exchange of Biochemical Substances Affected by Variability of Environmental Parameters

    NASA Astrophysics Data System (ADS)

    Mihailović, Dragutin T.; Budinčević, Mirko; Balaž, Igor; Mihailović, Anja

    Communication between cells is realized by exchange of biochemical substances. Due to internal organization of living systems and variability of external parameters, the exchange is heavily influenced by perturbations of various parameters at almost all stages of the process. Since communication is one of essential processes for functioning of living systems it is of interest to investigate conditions for its stability. Using previously developed simplified model of bacterial communication in a form of coupled difference logistic equations we investigate stability of exchange of signaling molecules under variability of internal and external parameters.

  5. Relevance of proteomic investigations in plant abiotic stress physiology.

    PubMed

    Hakeem, Khalid Rehman; Chandna, Ruby; Ahmad, Parvaiz; Iqbal, Muhammad; Ozturk, Munir

    2012-11-01

    Plant growth and productivity are influenced by various abiotic stresses. Stressful conditions may lead to delays in seed germination, reduced seedling growth, and decreased crop yields. Plants respond to environmental stresses via differential expression of a subset of genes, which results in changes in omic compositions, such as transcriptome, proteome, and metabolome. Since the development of modern biotechnology, various research projects have been carried out to understand the approaches that plants have adopted to overcome environmental stresses. Advancements in omics have made functional genomics easy to understand. Since the fundamentals of classical genomics were unable to clear up confusion related to the functional aspects of the metabolic processes taking place during stress conditions, new fields have been designed and are known as omics. Proteomics, the analysis of genomic complements of proteins, has caused a flurry of activity in the past few years. It defines protein functions in cells and explains how those protein functions respond to changing environmental conditions. The ability of crop plants to cope up with the variety of environmental stresses depends on a number of changes in their proteins, which may be up- and downregulated as a result of altered gene expression. Most of these molecules display an essential function, either in the regulation of the response (e.g., components of the signal transduction pathway), or in the adaptation process (e.g., enzymes involved in stress repair and degradation of damaged cellular contents), allowing plants to recover and survive the stress. Many of these proteins are constitutively expressed under normal conditions, but when under stress, they undergo a modification of their expression levels. This review will explain how proteomics can help in elucidating important plant processes in response to various abiotic stresses.

  6. 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.

  7. 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

  8. Variability in oxidative degradation of charcoal: Influence of production conditions and environmental exposure

    NASA Astrophysics Data System (ADS)

    Ascough, P. L.; Bird, M. I.; Francis, S. M.; Thornton, B.; Midwood, A. J.; Scott, A. C.; Apperley, D.

    2011-05-01

    Charcoal is a key component of the Black Carbon (BC) continuum, where BC is characterized as a recalcitrant, fire-derived, polyaromatic material. Charcoal is an important source of palaeoenvironmental data, and of great interest as a potential carbon sink, due to its high apparent environmental stability. However, at least some forms of charcoal are clearly susceptible to environmental alteration and degradation over relatively short timescales. Although these processes have importance for the role of charcoal in global biogeochemistry, they remain poorly understood. Here we present results of an investigation into the susceptibility of a range of charcoal samples to oxidative degradation in acidified potassium dichromate. The study examines both freshly-produced charcoal, and charcoal exposed to environmental conditions for up to 50,000 years. We compare the proportion of carbon present in different forms between the samples, specifically with respect to the relative chemical resistance of these forms. This was undertaken in order to improve understanding of the post-depositional diagenetic changes affecting charcoal within environmental deposits. A wide range in chemical compositions are apparent both within and between the sample groups. In freshly-produced charcoal, material produced at 300 °C contains carbon with more labile forms than charcoal produced at ⩾400 °C, signifying a key chemical change over the 300-400 °C temperature range. Charcoal exposed to environmental depositional conditions is frequently composed of a highly carboxylated aromatic structure and contains a range of carbon fractions of varying oxidative resistance. These findings suggest that a significant number of the environmental charcoals have undergone post-depositional diagenetic alteration. Further, the data highlight the potential for the use of controlled progressive oxidative degradation as a method to characterize chemical differences between individual charcoal samples.

  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. 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. PMID:26910504

  11. 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.

  12. 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...

  13. 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...

  14. 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

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

    PubMed

    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

  16. 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.

  17. 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

  18. 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.

  19. ANNUAL REPORT FOR ENVIRONMENTAL MANAGEMENT SCIENCE PROGRAM PROJECT NUMBER 86598 COUPLED FLOW AND REACTIVITY IN VARIABLY SATURATED POROUS MEDIA

    SciTech Connect

    Palmer, Carl D.; Mattson, Earl D.; Smith, Robert W.

    2003-06-15

    Improved models of contaminant migration in heterogeneous, variably saturated porous media are required to better define the long-term stewardship requirements for U.S. Department of Energy (DOE) lands and to assist in the design of effective vadose-zone barriers to contaminant migrations. The objective of our three-year project is to meet the DOE need by developing new experimental approaches to describe adsorption and transport of contaminants in heterogeneous, variably saturated media (i.e., the vadose zone). The research specifically addresses the behavior of strontium, a high priority DOE contaminant. However, the key benefit of this research is improved conceptual models of how all contaminants migrate through heterogeneous, variably-saturated, porous media. Research activities are driven by the hypothesis that the reactivity of variably saturated porous media is dependent on the moisture content of the medium and can be represented by a relatively simple function applicable over a range of scales, contaminants, and media. A key and novel aspect of our research is the use of the 2-meter radius geocentrifuge capabilities at the Idaho National Laboratory (INL) to conduct unsaturated reactive transport experiments (Figure 1). The experimental approach using the geocentrifuge provides data in a much shorter time period than conventional methods allowing us to complete more experiments and explore a wider range of moisture contents. The vadose zone research being done in this project will demonstrate the utility of environmental geocentrifuge experimental approaches and their applicability to DOE’s vadose research needs.

  20. 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.

  1. ANNUAL REPORT FOR ENVIRONMENTAL MANAGEMENT SCIENCE PROGRAM PROJECT NUMBER 86598 COUPLED FLOW AND REACTIVITY IN VARIABLY SATURATED POROUS MEDIA

    SciTech Connect

    Palmer, Carl D.; Mattson, Earl D.; Smith, Robert W.

    2003-06-01

    Improved models of contaminant migration in heterogeneous, variably saturated porous media are required to better define the long-term stewardship requirements for U.S. Department of Energy (DOE) lands and to assist in the design of effective vadose zone barriers to contaminant migrations. The objective of our three-year project is to meet the DOE need by developing new experimental approaches to describe adsorption and transport of contaminants in heterogeneous, variably saturated media (i.e., the vadose zone). The research specifically addresses the behavior of strontium, a high priority DOE contaminant. However, the key benefit of this research is improved conceptual models of how all contaminants migrate through heterogeneous, variably-saturated, porous media. Research activities are driven by the hypothesis that the reactivity of variably saturated porous media is dependent on the moisture content of the medium and can be represented by a relatively simple function applicable over a range of scales, contaminants, and media. A key and novel aspect of our research is the use of the 2-meter radius geocentrifuge capabilities at the Idaho National Engineering and Environmental Laboratory (INEEL) to conduct unsaturated reactive transport experiments (Figure 1). The experimental approach using the geocentrifuge provides data in a much shorter time period than conventional methods allowing us to complete more experiments and explore a wider range of moisture contents. The vadose zone research being done in this project will demonstrate the utility of environmental geocentrifuge experimental approaches and their applicability to DOE's vadose research needs. This report summarizes our progress as of June 2003 in the first year of a three-year project.

  2. 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.

  3. Ageing in a variable habitat: environmental stress affects senescence in parasite resistance in St Kilda Soay sheep

    PubMed Central

    Hayward, Adam D.; Wilson, Alastair J.; Pilkington, Jill G.; Pemberton, Josephine M.; Kruuk, Loeske E. B.

    2009-01-01

    Despite widespread empirical evidence for a general deterioration in the majority of traits with advancing age, it is unclear whether the progress of senescence is chronologically determined, or whether factors such as environmental conditions experienced over the lifespan are more important. We explored the relative importance of ‘chronological’ and ‘environmental’ measures of age to changes in parasite resistance across the lifespan of free-living Soay sheep. Our results show that individuals experience an increase in parasite burden, as indicated by gastrointestinal helminth faecal egg count (FEC) with chronological age. However, chronological age fails to fully explain changes in FEC because a measure of environmental age, cumulative environmental stress, predicts an additional increase in FEC once chronological age has been accounted for. Additionally, we show that in females age-specific changes are dependent upon the environmental conditions experienced across individuals' life histories: increases in FEC with age were greatest among individuals that had experienced the highest degree of stress. Our results illustrate that chronological age alone may not always correspond to biological age, particularly in variable environments. In these circumstances, measures of age that capture the cumulative stresses experienced by an individual may be useful for understanding the process of senescence. PMID:19586947

  4. 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.

  5. 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

  6. Common environmental factors explain both ectomycorrhizal species diversity and pine regeneration variability in a post-fire Mediterranean forest.

    PubMed

    Buscardo, Erika; Freitas, Helena; Pereira, João Santos; De Angelis, Paolo

    2011-08-01

    Natural seedling regeneration and establishment after stand replacing wildfires is influenced by a series of environmental and biological constraints. In this study, we characterized the diversity and structure of the ectomycorrhizal (ECM) fungal community associated with post-fire naturally regenerated maritime pine saplings, and individuate the environmental factors responsible for fungal species distribution. We also identify the main environmental factors responsible for maritime pine regeneration variability and assessed the relation between saplings performance and ECM fungal diversity indices. Fungal species were identified by direct sequencing of internal transcribed spacer regions. Five years after the disturbance event, a total of 30 taxa colonized the pine saplings. The ECM fungal community was dominated by ruderal species of the genus Rhizopogon (present in almost half of the samples). Almost one third of the identified ECM fungal species belonged to the family Thelephoraceae. Typical k-selected species like Amanita pantherina, Boletus aestivalis, Lactarius chrysorrheus, and Russula densifolia were found on pine saplings collected in proximity of unburnt pine trees, in correspondence with low erosion extents. Pine regeneration varied throughout the study areas and was enhanced at higher elevations, in correspondence with moderate slopes, shallower soils, and a reduced cover of ericaceous shrubs and bare ground. These conditions were found in close proximity to patches of pine trees that survived the disturbance event and were previously characterized by a higher pre-fire pine biomass. Even though no correlations were found between saplings performance and ECM fungal diversity indices, common environmental factors (i.e., ericaceous shrub cover, extent of erosion, slope, and soil depth) were responsible for shaping the ECM fungal distribution and for describing most of the explained regeneration variability.

  7. 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. PMID:26163019

  8. 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.

  9. Determinants of temporal variability in NHEXAS-Maryland environmental concentrations, exposures, and biomarkers.

    PubMed

    Egeghy, Peter P; Quackenboss, James J; Catlin, Sandra; Ryan, P Barry

    2005-09-01

    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 regression models for lead, phenanthrene, and chlorpyrifos (including metabolites) in indoor air, dust, dermal wipes, and biological fluids. Significant predictors represented time-varying activities as well as unchanging housing and demographic factors. There was little overlap among the models, with predictors generally reflecting the diverse characteristics of the target compounds. We estimated between- and within-person variance components to evaluate the reliability of the measurements. While only one measurement of lead in blood or chlopyrifos in dust was needed for a dependable estimate of an individual's average level, three to eight measurements were needed for most other compound/exposure medium combinations because of considerable temporal variability. Measurements in biological fluids and dust were generally more consistent than those in indoor air. The significant covariates in the full models preferentially reduced the between-person variance component. Since the regression models explained only 1-37% of the within-person variance, the questionnaires in this study provided only modest insight into the factors responsible for the temporal variability in the contaminant levels.

  10. Reductive transformation of carbamazepine by abiotic and biotic processes.

    PubMed

    König, Anne; Weidauer, Cindy; Seiwert, Bettina; Reemtsma, Thorsten; Unger, Tina; Jekel, Martin

    2016-09-15

    The antiepileptic drug carbamazepine (CBZ) is ubiquitously present in the anthropogenic water cycle and is therefore of concern regarding the potable water supply. Despite of its persistent behavior in the aquatic environment, a redox dependent removal at bank filtration sites with anaerobic aquifer passage was reported repeatedly but not elucidated in detail yet. The reductive transformation of CBZ was studied, using abiotic systems (catalytic hydrogenation, electrochemistry) as well as biologically active systems (column systems, batch degradation tests). In catalytic hydrogenation CBZ is gradually hydrogenated and nine transformation products (TPs) were detected by liquid chromatography high-resolution mass spectrometry. 10,11-Dihydro-CBZ ((2H)-CBZ) was the major stable product in these abiotic, surface catalyzed reduction processes and turned out to be not a precursor of the more hydrogenated TPs. In the biotic reduction processes the formation of (2H)-CBZ alone could not explain the observed CBZ decline. There, also traces of (6H)-CBZ and (8H)-CBZ were formed by microbes under anaerobic conditions and four phase-II metabolites of reduced CBZ could be detected and tentatively identified. Thus, the spectrum of reduction products of CBZ is more diverse than previously thought. In environmental samples CBZ removal along an anaerobic soil passage was confirmed and (2H)-CBZ was determined at one of the sites.

  11. 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.

  12. Influence of Environmental Variables on the Distribution of Macrobenthos in the Han River Estuary, Korea

    NASA Astrophysics Data System (ADS)

    Yu, Ok Hwan; Lee, Hyung-Gon; Lee, Jae-Hac

    2012-12-01

    We compared environmental effects on the macrobenthic community of the Han River Estuary in summer, when freshwater input from the Han River increased, and in spring, when freshwater input decreased. Field samples were taken from the upper region of the Shingok reservoir to the southern area of Ganghwado at 18 sampling sites after rainy (August 2006) and dry (March 2007) seasons. Macrobenthic fauna were collected using a Van Veen Grab (0.025 m2 and 0.1 m2) and environmental factors were measured simultaneously. Dominant species of macrobenthic fauna and the macrobenthic community were divided into two areas, the area of the Han River with no salinity (< 0.1 psu) and the southern part of Ganghwado with salinity (> 20 psu). The dominant species Byblis japonicus appeared at Junruri in the dry season. The distributions of two polychaetes, Hediste japonica and Nephtys caeca, were divided into the lower and upper areas of the Singok submerged weir. BIO-ENV (the matching of biotic to environmental patterns) analysis revealed that salinity was the most important factor affecting macrobenthic communities in the Han River Estuary, with other factors such as sediment grain size, bottom dissolved oxygen, and total organic carbon of sediment being secondary.

  13. 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

  14. Cross-tolerance to biotic and abiotic stresses in plants: a focus on resistance to aphid infestation.

    PubMed

    Foyer, Christine H; Rasool, Brwa; Davey, Jack W; Hancock, Robert D

    2016-03-01

    Plants co-evolved with an enormous variety of microbial pathogens and insect herbivores under daily and seasonal variations in abiotic environmental conditions. Hence, plant cells display a high capacity to respond to diverse stresses through a flexible and finely balanced response network that involves components such as reduction-oxidation (redox) signalling pathways, stress hormones and growth regulators, as well as calcium and protein kinase cascades. Biotic and abiotic stress responses use common signals, pathways and triggers leading to cross-tolerance phenomena, whereby exposure to one type of stress can activate plant responses that facilitate tolerance to several different types of stress. While the acclimation mechanisms and adaptive responses that facilitate responses to single biotic and abiotic stresses have been extensively characterized, relatively little information is available on the dynamic aspects of combined biotic/abiotic stress response. In this review, we consider how the abiotic environment influences plant responses to attack by phloem-feeding aphids. Unravelling the signalling cascades that underpin cross-tolerance to biotic and abiotic stresses will allow the identification of new targets for increasing environmental resilience in crops.

  15. Cross-tolerance to biotic and abiotic stresses in plants: a focus on resistance to aphid infestation.

    PubMed

    Foyer, Christine H; Rasool, Brwa; Davey, Jack W; Hancock, Robert D

    2016-03-01

    Plants co-evolved with an enormous variety of microbial pathogens and insect herbivores under daily and seasonal variations in abiotic environmental conditions. Hence, plant cells display a high capacity to respond to diverse stresses through a flexible and finely balanced response network that involves components such as reduction-oxidation (redox) signalling pathways, stress hormones and growth regulators, as well as calcium and protein kinase cascades. Biotic and abiotic stress responses use common signals, pathways and triggers leading to cross-tolerance phenomena, whereby exposure to one type of stress can activate plant responses that facilitate tolerance to several different types of stress. While the acclimation mechanisms and adaptive responses that facilitate responses to single biotic and abiotic stresses have been extensively characterized, relatively little information is available on the dynamic aspects of combined biotic/abiotic stress response. In this review, we consider how the abiotic environment influences plant responses to attack by phloem-feeding aphids. Unravelling the signalling cascades that underpin cross-tolerance to biotic and abiotic stresses will allow the identification of new targets for increasing environmental resilience in crops. PMID:26936830

  16. 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.

  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. 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. PMID:26565796

  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. 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.

  1. 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.

  2. Environmental variability in the early rearing environment generates behaviourally flexible cod: implications for rehabilitating wild populations.

    PubMed

    Braithwaite, Victoria A; Salvanes, Anne G V

    2005-06-01

    The release of hatchery-reared fishes for restoring threatened and endangered populations is one of the most controversial issues in applied ecology. A central issue has been to determine whether releases cause extinction of local wild populations. This may arise either through domesticated or non-local fishes hybridizing with wild fishes, or through inappropriate behavioural interactions; for example, many hatchery fishes show exaggerated aggressive and competitive behaviour and out-compete wild counterparts. The impact of the impoverished hatchery environment in shaping behaviour is only now receiving attention. Attempts to counteract hatchery-related behavioural deficiencies have utilized intensive training programmes shortly before the fishes are released. However, we show here that simple exposure to variable spatial and foraging cues in the standard hatchery environment generates fishes with enhanced behavioural traits that are probably associated with improved survival in the wild. It appears that fishes need to experience a varying and changeable environment to learn and develop flexible behaviour. Using variable hatchery rearing environments to generate suitable phenotypes in combination with a knowledge of appropriate local genotypes, rehabilitation of wild fishes is likely to succeed, where to date it has largely failed.

  3. 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.

  4. 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. PMID:24367499

  5. 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

  6. Short-term environmental variability in cold-water coral habitat at Viosca Knoll, Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Davies, Andrew J.; Duineveld, Gerard C. A.; van Weering, Tjeerd C. E.; Mienis, Furu; Quattrini, Andrea M.; Seim, Harvey E.; Bane, John M.; Ross, Steve W.

    2010-02-01

    The Lophelia pertusa community at Viosca Knoll (VK826) is the most extensive found to date in the Gulf of Mexico. As part of a multi-disciplinary study, the physical setting of this area was described using benthic landers, CTD transects and remotely operated vehicle observations. The site was broadly characterised into three main habitats: (1) dense coral cover that resembles biogenic reef complexes, (2) areas of sediment, and (3) authigenic carbonate blocks with sparse coral and chemosynthetic communities. The coral communities were dominated by L. pertusa but also contained numerous solitary coral species. Over areas that contained L. pertusa, the environmental conditions recorded were similar to those associated with communities in the north-eastern Atlantic, with temperature (8.5-10.6 °C) and salinity (˜35) falling within the known species niche for L. pertusa. However, dissolved oxygen concentrations (2.7-2.8 ml l -1) and density ( σ Θ, 27.1-27.2 kg m -3) were lower and mass fluxes from sediment trap data appeared much higher (4002-4192 mg m -2 d -1). Yet, this species still appears to thrive in this region, suggesting that L. pertusa may not be as limited by lower dissolved oxygen concentrations as previously thought. The VK826 site experienced sustained eastward water flow of 10-30 cm s -1 over the 5-day measurement period but was also subjected to significant short-term variability in current velocity and direction. In addition, two processes were observed that caused variability in salinity and temperature; the first was consistent with internal waves that caused temperature variations of 0.8 °C over 5-11 h periods. The second was high-frequency variability (20-30 min periods) in temperature recorded only at the ALBEX site. A further pattern observed over the coral habitat was the presence of a 24 h diel vertical migration of zooplankton that may form part of a food chain that eventually reaches the corals. The majority of detailed studies concerning

  7. 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

  8. Mercury bioaccumulation in an estuarine predator: Biotic factors, abiotic factors, and assessments of fish health.

    PubMed

    Smylie, Meredith S; McDonough, Christopher J; Reed, Lou Ann; Shervette, Virginia R

    2016-07-01

    Estuarine wetlands are major contributors to mercury (Hg) transformation into its more toxic form, methylmercury (MeHg). Although these complex habitats are important, estuarine Hg bioaccumulation is not well understood. The longnose gar Lepisosteus osseus (L. 1758), an estuarine predator in the eastern United States, was selected to examine Hg processes due to its abundance, estuarine residence, and top predator status. This study examined variability in Hg concentrations within longnose gar muscle tissue spatially and temporally, the influence of biological factors, potential maternal transfer, and potential negative health effects on these fish. Smaller, immature fish had the highest Hg concentrations and were predominantly located in low salinity waters. Sex and diet were also important factors and Hg levels peaked in the spring. Although maternal transfer occurred in small amounts, the potential negative health effects to young gar remain unknown. Fish health as measured by fecundity and growth rate appeared to be relatively unaffected by Hg at concentrations in the present study (less than 1.3 ppm wet weight). The analysis of biotic and abiotic factors relative to tissue Hg concentrations in a single estuarine fish species provided valuable insight in Hg bioaccumulation, biomagnification, and elimination. Insights such as these can improve public health policy and environmental management decisions related to Hg pollution. PMID:27086072

  9. The thiamine content of phytoplankton cells is affected by abiotic stress and growth rate.

    PubMed

    Sylvander, Peter; Häubner, Norbert; Snoeijs, Pauline

    2013-04-01

    Thiamine (vitamin B1) is produced by many plants, algae and bacteria, but by higher trophic levels, it must be acquired through the diet. We experimentally investigated how the thiamine content of six phytoplankton species belonging to five different phyla is affected by abiotic stress caused by changes in temperature, salinity and photon flux density. Correlations between growth rate and thiamine content per cell were negative for the five eukaryotic species, but not for the cyanobacterium Nodularia spumigena. We demonstrate a high variability in thiamine content among phytoplankton species, with the highest content in N. spumigena. Salinity was the factor with the strongest effect, followed by temperature and photon flux density, although the responses varied between the investigated phytoplankton species. Our results suggest that regime shifts in phytoplankton community composition through large-scale environmental changes has the potential to alter the thiamine availability for higher trophic levels. A decreased access to this essential vitamin may have serious consequences for aquatic food webs. PMID:23263236

  10. 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

  11. 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.

  12. [Magnolia liliiflora whole-tree sap flow in response to multiple environmental variables in Beijing].

    PubMed

    Wang, Hua; Ouyang, Zhi-yun; Zheng, Hua; Ren, Yu-fen; Gao, Fu-yuan

    2011-03-01

    In order to clarify the environmental factors affecting the water use of typical urban tree species Magnolia liliflora, an investigation was conducted on the responses of M. liliiflora whole-tree sap flow to the air temperature, air relative humidity, radiation, wind speed, soil temperature and water content, and precipitation in Beijing from April to October, 2008. The eight environmental factors affecting M. liliiflora whole-tree sap flow could be divided into three categories, i.e., evaporative demand index, soil index, and precipitation index. The evaporative demand index (air temperature, air relative humidity, total radiation, wind speed, and vapor pressure deficit) could explain 60% of the variation in the sap flow of individual trees, which presented S-type change trend, i.e., the sap flow reached an asymptote where higher light and evaporative demands could not cause sap flow to increase further. Soil index (soil temperature and water content) and precipitation index (precipitation amount) had little influence on the sap flow.

  13. Genetic Structure of Bluefin Tuna in the Mediterranean Sea Correlates with Environmental Variables

    PubMed Central

    Riccioni, Giulia; Stagioni, Marco; Landi, Monica; Ferrara, Giorgia; Barbujani, Guido; Tinti, Fausto

    2013-01-01

    Background Atlantic Bluefin Tuna (ABFT) shows complex demography and ecological variation in the Mediterranean Sea. Genetic surveys have detected significant, although weak, signals of population structuring; catch series analyses and tagging programs identified complex ABFT spatial dynamics and migration patterns. Here, we tested the hypothesis that the genetic structure of the ABFT in the Mediterranean is correlated with mean surface temperature and salinity. Methodology We used six samples collected from Western and Central Mediterranean integrated with a new sample collected from the recently identified easternmost reproductive area of Levantine Sea. To assess population structure in the Mediterranean we used a multidisciplinary framework combining classical population genetics, spatial and Bayesian clustering methods and a multivariate approach based on factor analysis. Conclusions FST analysis and Bayesian clustering methods detected several subpopulations in the Mediterranean, a result also supported by multivariate analyses. In addition, we identified significant correlations of genetic diversity with mean salinity and surface temperature values revealing that ABFT is genetically structured along two environmental gradients. These results suggest that a preference for some spawning habitat conditions could contribute to shape ABFT genetic structuring in the Mediterranean. However, further studies should be performed to assess to what extent ABFT spawning behaviour in the Mediterranean Sea can be affected by environmental variation. PMID:24260341

  14. Potential Bud Bank Responses to Apical Meristem Damage and Environmental Variables: Matching or Complementing Axillary Meristems?

    PubMed Central

    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. PMID:24516587

  15. The impact of environmental enrichment on the outcome variability and scientific validity of laboratory animal studies.

    PubMed

    Bayne, K; Würbel, H

    2014-04-01

    It has been widely accepted for some time that species-appropriate environmental enrichment is important for the welfare of research animals, but its impact on research data initially received little attention. This has now changed, as the use of enrichment as one element of routine husbandry has expanded. In addition to its use in the care of larger research animals, such as nonhuman primates, it is now being used to improve the environments of small research animals, such as rodents, which are used in significantly greater numbers and in a wide variety of studies. Concern has been expressed that enrichment negatively affects both experimental validity and reproducibility. However, when a concise definition of enrichment is used, with a sound understanding of the biology and behaviour of the animal as well as the research constraints, it becomes clear that the welfare of research animals can be enhanced through environmental enrichment without compromising their purpose. Indeed, it is shown that the converse is true: the provision of suitable enrichment enhances the well-being of the animal, thereby refining the animal model and improving the research data. Thus, the argument is made that both the validity and reproducibility of the research are enhanced when proper consideration is given to the research animal's living environment and the animal's opportunities to express species-typical behaviours.

  16. 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.

  17. 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. PMID:24516587

  18. 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.

  19. 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.

  20. Effects of individual quality, reproductive success and environmental variability on survival of a long-lived seabird.

    PubMed

    Lescroël, Amélie; Dugger, Katie M; Ballard, Grant; Ainley, David G

    2009-07-01

    1. Heterogeneity in individual quality (i.e. individuals having different performance levels that are consistent throughout life) can drive the demography of iteroparous species, but quality in the context of environmental variability has rarely been evaluated. 2. We investigated the demographic responses of a long-lived seabird, the Adélie penguin (Pygoscelis adeliae), to contrasting environmental conditions as a function of reproductive success, breeding quality (BQ) and experience. A continuous index of BQ (BQI) was developed to reflect an individual's ability, relative to others, to produce viable offspring. 3. First, we assessed the relative importance of costs of reproduction vs. heterogeneity in quality by comparing survival and reproductive probabilities among deferred, successful and unsuccessful breeders under 'demanding' conditions using multistate capture-mark-recapture modelling. Then, we quantified the influence of BQI on adult survival among experienced breeders vs. the whole study population under both 'normal' and 'demanding' conditions. 4. Higher survival rates were exhibited by successful (74-76%) compared to unsuccessful breeders (64%); the former also more frequently reproduced successfully at year t + 1. 5. From 1997 to 2006, adult survival ranged from 64-79%, with BQI accounting for 91% of variability in the entire study population, but only 17% in experienced breeders. The weakened relationship between BQI and survival in experienced breeders supports the theory that selection during the first reproductive event accounts for a more homogeneous pool of experienced breeders. 6. No significant effect of environmental covariates on survival was evident, suggesting that what appeared to be demanding conditions were within the range that could be buffered by this species. 7. For the first time in seabirds, a quadratic relationship between adult survival and BQI showed that adult survival is shaped by both heterogeneity in quality and reproductive

  1. 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

    2014-01-01

    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.

  2. The contribution of genetic and environmental factors to quantitative variability of erythrocyte membrane proteins in primary hypotension.

    PubMed

    Ivanov, V P; Polonikov, A V; Solodilova, M A

    2005-01-01

    Our previous studies have shown that, compared with healthy individuals, patients with primary arterial hypotension (PAH) have significant quantitative changes in erythrocyte membrane proteins. The purpose of the present study was to evaluate the contribution made by genetic and environmental factors to quantitative variation of erythrocyte membrane proteins in PAH. We studied 109 hypotensive patients, 124 normotensive subjects, 222 of their first-degree relatives and 24 twin pairs by sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis. The decomposition of total phenotypic variance of erythrocyte membrane proteins to genetic and environmental components was performed on the basis of correlations among first-degree relatives by the least squares method. The genetic dominance and shared environmental factors were found to influence the variability of cytoskeletal membrane proteins whose contents were changed in PAH. Furthermore, variations in alpha-spectrin, actin and anion exchanger in hypotensives were substantially influenced by major gene and maternal effects. Ankyrin 2.1 and actin content was under the control of common underlying genes. Variations in membrane-associated glutathione-S-transferase and tropomyosin were predominantly affected by polygenes. These findings suggest that the putative major genes with pleiotropic effects appear to be involved in the control of quantitative disorders of erythrocyte membrane proteins in primary hypotension. PMID:15638825

  3. 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.

  4. 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.

  5. Abiotic stress tolerance and competition-related traits underlie phylogenetic clustering in soil bacterial communities.

    PubMed

    Goberna, Marta; Navarro-Cano, Jose A; Valiente-Banuet, Alfonso; García, Carlos; Verdú, Miguel

    2014-10-01

    Soil bacteria typically coexist with close relatives generating widespread phylogenetic clustering. This has been ascribed to the abiotic filtering of organisms with shared ecological tolerances. Recent theoretical developments suggest that competition can also explain the phylogenetic similarity of coexisting organisms by excluding large low-competitive clades. We propose that combining the environmental patterns of traits associated with abiotic stress tolerances or competitive abilities with phylogeny and abundance data, can help discern between abiotic and biotic mechanisms underlying the coexistence of phylogenetically related bacteria. We applied this framework in a model system composed of interspersed habitats of highly contrasted productivity and comparatively dominated by biotic and abiotic processes, i.e. the plant patch-gap mosaic typical of drylands. We examined the distribution of 15 traits and 3290 bacterial taxa in 28 plots. Communities showed a marked functional response to the environment. Conserved traits related to environmental stress tolerance (e.g. desiccation, formation of resistant structures) were differentially selected in either habitat, while competition related traits (e.g. organic C consumption, formation of nutrient-scavenging structures) prevailed under high resource availability. Phylogenetic clustering was stronger in habitats dominated by biotic filtering, suggesting that competitive exclusion of large clades might underlie the ecological similarity of co-occurring soil bacteria.

  6. 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.

  7. Biotic and Abiotic Degradation of CL-20 and RDX in Soils

    SciTech Connect

    Crocker, Fiona H.; Thompson, Karen T.; Szecsody, Jim E.; Fredrickson, Herbert L.

    2005-11-01

    The caged cyclic nitramine 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) is a new explosive that has the potential to replace existing military explosives, but little is known about its environmental toxicity, transport, and fate. We quantified and compared the aerobic environmental fate of CL-20 to the widely used cyclic nitramine explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in surface and subsurface soil microcosms. Soil-free controls and biologically mediated processes. Both abiotic and biological processes significantly degraded CL-20 in all soils examined. Apparent abiotic, first-order degradation rates (k) for CL-20 were not significantly different between soil-free controls (0.018 < k < 0.030 d-1) and biologically attenuated soil controls (0.003 abiotic degradation rates of RDX were generally slower (0 < k < 0.032 d-1) than abiotic CL-20 degradation rates. In biologically active soil microcosms amended with glucose aerobic RDX degradation rates varied between 0.010 and 0.474 d-1. Biodegradation was a key factor in determining the environmental fate of RDX, while a combination of biotic and abiotic processes was important with CL-20. Our data suggest that CL-20 should be less recalcitrant than RDX in aerobic soils.

  8. 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

  9. Coexistence of competitors in marine metacommunities: environmental variability, edge effects, and the dispersal niche.

    PubMed

    Aiken, Christopher M; Navarrete, Sergio A

    2014-08-01

    Theoretical studies have shown that coexistence between competitors can be favored in a spatially heterogeneous environment by a number of mechanisms, which ultimately allow the expression of persistent or transitory variation in species competitive abilities, colonization, or reproduction. Four distinctive paradigms to model metacommunities have been identified according to assumptions about the biology of the species and essential aspects of the environment. Missing from these are mechanisms of coexistence that can arise from the dispersal process itself without explicit spatial heterogeneity or biological trade-offs. These mechanisms have only recently received attention, but they may be common in marine communities and other systems in which dispersal is obligatory and modulated by the physical environment. We investigate coexistence in spatially homogeneous metacommunities where there is no partitioning of resources, no competition-colonization trade-off, and no possibility of source-sink dynamics. Coexistence is shown to be possible through three distinct mechanisms related to the dispersal process itself. Firstly, in a neutral scenario, inclusion of temporal variability in the connectivity matrix, emulating an intrinsic attribute of ocean character and other turbulent environments, can promote the invasion of an equally matched competitor and, in a hierarchical competition scenario, the persistence of an otherwise unviable, inferior competitor (the dispersal variability mechanism). Secondly, a sufficiently large difference in the shape of the time-independent dispersal kernels of the two species, which may result from differences in larval-release timing, buoyancy, or behavior, can produce stable coexistence in the center of their shared range (the dispersal-shape mechanism). Thirdly, asymmetry in the dispersal process due to biased advection renders the metapopulation model reactive, such that small variations in the upstream abundances can be sufficient

  10. 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

  11. Darwinian Dynamics of Intratumoral Heterogeneity: Not Solely Random Mutations but Also Variable Environmental Selection Forces.

    PubMed

    Lloyd, Mark C; Cunningham, Jessica J; Bui, Marilyn M; Gillies, Robert J; Brown, Joel S; Gatenby, Robert A

    2016-06-01

    Spatial heterogeneity in tumors is generally thought to result from branching clonal evolution driven by random mutations that accumulate during tumor development. However, this concept rests on the implicit assumption that cancer cells never evolve to a fitness maximum because they can always acquire mutations that increase proliferative capacity. In this study, we investigated the validity of this assumption. Using evolutionary game theory, we demonstrate that local cancer cell populations will rapidly converge to the fittest phenotype given a stable environment. In such settings, cellular spatial heterogeneity in a tumor will be largely governed by regional variations in environmental conditions, for example, alterations in blood flow. Model simulations specifically predict a common spatial pattern in which cancer cells at the tumor-host interface exhibit invasion-promoting, rapidly proliferating phenotypic properties, whereas cells in the tumor core maximize their population density by promoting supportive tissue infrastructures, for example, to promote angiogenesis. We tested model predictions through detailed quantitative image analysis of phenotypic spatial distribution in histologic sections of 10 patients with stage 2 invasive breast cancers. CAIX, GLUT1, and Ki67 were upregulated in the tumor edge, consistent with an acid-producing invasive, proliferative phenotype. Cells in the tumor core were 20% denser than the edge, exhibiting upregulation of CAXII, HIF-1α, and cleaved caspase-3, consistent with a more static and less proliferative phenotype. Similarly, vascularity was consistently lower in the tumor center compared with the tumor edges. Lymphocytic immune responses to tumor antigens also trended to higher level in the tumor edge, although this effect did not reach statistical significance. Like invasive species in nature, cancer cells at the leading edge of the tumor possess a different phenotype from cells in the tumor core. Our results suggest

  12. 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.

  13. 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. PMID:25446213

  14. Optical system design with variable working distance for monitoring of environmental contamination in infrared region

    NASA Astrophysics Data System (ADS)

    Romanova, G. E.; Zaitceva, A. S.

    2016-04-01

    The project is dedicated to a research and development of a compact optical system for an identification of dangerous substances in a surrounding environment using a spectrum of scattered laser radiation. There is a whole class of tasks for diagnostics of environments and substances which are solved by mobile systems on distances of 0.5 - 10 m from the object. The key feature of an optical system in this case is having the highest functionality, to meet this demands it should be able to work on variable distances and provide the minimal light spot. The purpose of the work is a research of the best possible initial system parameters and its components, designing of an optical system with minimum possible number of elements providing acceptable quality of the image in the required dimensions. An image quality criterion for such systems is the size of the light spot, which defines an operation speed of the system. Using the beam diameter and allowable system dimensions as initial parameters of the two components system, relations were found which helps to define optimal component parameters for future design. To provide the possibility of working on various distances the thickness between the components can be varied. An example of a two component system consisted of three lenses with spherical surfaces is presented. The system works with a laser with the wavelength of 0.785 μm and provides the light spot less than 2.3 mm for all working distances within the range of 2 - 5 m.

  15. Separating stressor influences from environmental variability: eight case studies from aquatic and terrestrial ecosystems

    SciTech Connect

    Luoma, Samuel N.; Clements, Will; Gerritsen, Jeroen; Hatch, Audrey; Jepson, Paul; Reynoldson, Trefor; Thom, Ronald M.

    2001-12-03

    It can be difficult to unambiguously establish the influences of a particular stressor or group of stressors in a complex ecosystem, except, perhaps, when the effects are extreme (Luoma and Carter, 1991). Yet this is a critical problem we face when attempting to understand the influences of human activities on ecosystems. Single experiments or studies are rarely adequate to establish cause and effect in complex ecosystems, and many of the individual approaches available to demonstrate stressor effects have important inadequacies. A multi-faceted body of work is usually at the center of most examples where stressor effects are explained. In this chapter seven case studies are presented where effects or influences of multiple stressors were explained and separated from natural variability. The goal of this chapter is to demonstrate that identification of stressor effects is tractable, although not necessarily simple; and to illustrate some specific strategies that have worked. We also present one case study where the quest for cause and effect is just beginning, to illustrate the range of challenges involved as a body of work begins to be established. The examples are from several different fields of ecology, they cover a variety of scales and a mix of disciplines.

  16. Trait-Based Community Assembly along an Elevational Gradient in Subalpine Forests: Quantifying the Roles of Environmental Factors in Inter- and Intraspecific Variability.

    PubMed

    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

  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. The determinants of actinic skin damage: problems of confounding among environmental and constitutional variables.

    PubMed

    Holman, C D; Evans, P R; Lumsden, G J; Armstrong, B K

    1984-09-01

    Constitutional and environmental determinants of actinic skin damage, assessed by cutaneous microtopography, were evaluated in 1,216 subjects attending the 1981 Busselton Health Survey in Western Australia. Increasing age, male sex, the tendency to burn on exposure to sunlight and outdoor occupation were found to have independent predictive value for the presence of actinic skin damage. Crude positive and inverse associations of actinic skin damage with several other factors were shown to arise from confounding. Effect measures for outdoor leisure pursuits and sunscreen use were underestimated due to inverse associations of these factors with older age, and inverse associations of high-exposure outdoor activities with poor skin response to sunlight. Associations of constitutional traits typical of fair individuals and sunscreen use with the tendency to burn resulted in overestimation of effect measures. Empirical relationships of actinic skin damage with certain leisure activities and with use of sunscreens were also confounded by sex. The results indicate a need for greater attention to confounding in nonexperimental skin cancer research.

  19. 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.

  20. Effects of environmental stimulation on biochemical and psychological variables in dementia.

    PubMed

    Karlsson, I; Bråne, G; Melin, E; Nyth, A L; Rybo, E

    1988-02-01

    The nursing care of a group of moderately demented patients (n = 11) in a nursing home was improved as a result of an education of the staff. Thus the patients were subjected to an increased emotional and intellectual stimulation during the ordinary daily care and participated in group sessions twice a week. In order to evaluate the effects of the treatment, psychological parameters and cerebrospinal fluid (CSF) HVA (homovanillic acid), 5-HIAA (5-hydroxyindole acetic acid) and HMPG (4-hydroxy, 3-metoxyphenylglucol) were quantified before and after a 2-month treatment period. A group of similar patients (n = 13) in another nursing home constituted a control group. The ratings of concentration, absent mindedness and recent memory showed a more favorable development in the treatment group than in the control group where an intellectual deterioration was evident. Restlessness was rated higher in the treatment group after the treatment period, while the psychological testings showed no significant changes between the groups. CSF HVA concentrations increased in the treatment group and decreased in the control group (P less than 0.05). No change was evident in 5-HIAA or HMPG concentrations in either group. The results suggest that environmental factors influence biochemical markers of transmitter activity which thus possibly may be of etiological importance in dementia. PMID:2452557

  1. 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.

  2. 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.

  3. The electric organ discharge of Brachyhypopomus pinnicaudatus. The effects of environmental variables on waveform generation.

    PubMed

    Caputi, A A; Silva, A C; Macadar, O

    1998-01-01

    The electric organ discharge of Brachyhypopomus pinnicaudatus was studied by recording (1) the discharge field potentials in water at different conductivities and temperatures and (2) the spatiotemporal pattern of electromotive forces of the equivalent source. An early deflection, head positive (P wave), and a late deflection, head negative (N wave), are the major components of the discharge, however a striking double positive peak is generated at the abdominal level. Comparisons of this species with other pulse gymnotids provide evidence for common patterns of organization of the electrogenic system: (1) There is a head-to-tail activation wave along the fish; (2) the electromotive force increases exponentially from head to tail, but it is differentially attenuated by the passive tissues in male and females; (3) the abdominal region generates a complex species-specific waveform, whereas the tail discharge is similar across species. In B. pinnicaudatus the electric organ discharge waveform is sensitive to endocrine and environmental stimuli. The effect of seasonal sex differences on electrogenic and passive tissue, the changes in impedance matching between the fish's body and the environment, and the modulation of membrane properties by temperature, are able to modify the EOD waveform. Since these factors change during the breeding season, their appropriate combination might be crucial for reproduction.

  4. Environmental variables affecting the distribution of POPs on Mt. Meru, Tanzania.

    PubMed

    Guazzoni, Niccolò; Comolli, Roberto; Binelli, Andrea; Tremolada, Paolo

    2013-08-01

    Tanzania is an equatorial country characterized by warm temperatures, which should increase the volatilization of persistent organic pollutants (POPs), but this scenario could be different in mountainous areas like Mount Meru, a volcano situated in the East African Rift (Tz). We collected soil samples along an altitudinal transect upto 4577 m a.s.l., reporting the first data about POP contamination in this area (DDX, HCHs, HCB and PCBs). The DDX contamination pattern in Mt. Meru shows levels slightly higher than those of other remote places with a strong increase in the metabolites/DDT historical trend, which is different from DDX, PCBs, HCHs and particularly HCB as this shows very low contamination levels. Back trajectory analysis allowed a discussion about putative contamination sources, while analysis of the environmental features (climatic and pedological) allowed us to discriminate their relative importance. The distribution of POPs shows a strong correlation with soil organic matter and vegetation. SOM-normalization evidenced altitudinal dependence according to cold condensation for PCBs and HCHs, while DDX are present in larger amounts in the agricultural area at the volcano foot. OM-normalized concentrations suggested also a possible role of the OM composition on the POPs' distribution.

  5. 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. PMID:26865733

  6. [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. PMID:25418656

  7. Environmental variables affecting the distribution of POPs on Mt. Meru, Tanzania.

    PubMed

    Guazzoni, Niccolò; Comolli, Roberto; Binelli, Andrea; Tremolada, Paolo

    2013-08-01

    Tanzania is an equatorial country characterized by warm temperatures, which should increase the volatilization of persistent organic pollutants (POPs), but this scenario could be different in mountainous areas like Mount Meru, a volcano situated in the East African Rift (Tz). We collected soil samples along an altitudinal transect upto 4577 m a.s.l., reporting the first data about POP contamination in this area (DDX, HCHs, HCB and PCBs). The DDX contamination pattern in Mt. Meru shows levels slightly higher than those of other remote places with a strong increase in the metabolites/DDT historical trend, which is different from DDX, PCBs, HCHs and particularly HCB as this shows very low contamination levels. Back trajectory analysis allowed a discussion about putative contamination sources, while analysis of the environmental features (climatic and pedological) allowed us to discriminate their relative importance. The distribution of POPs shows a strong correlation with soil organic matter and vegetation. SOM-normalization evidenced altitudinal dependence according to cold condensation for PCBs and HCHs, while DDX are present in larger amounts in the agricultural area at the volcano foot. OM-normalized concentrations suggested also a possible role of the OM composition on the POPs' distribution. PMID:23807727

  8. 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.

  9. 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. PMID:25974943

  10. 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

  11. Developmental models for estimating ecological responses to environmental variability: structural, parametric, and experimental issues.

    PubMed

    Moore, Julia L; Remais, Justin V

    2014-03-01

    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 non-linear 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 versus 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.

  12. 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).

  13. 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

  14. 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.

  15. 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.

  16. 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.

  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. 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

  19. 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

  20. 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.

  1. [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.

  2. 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

  3. Agricultural, socioeconomic and environmental variables as risks for human verotoxigenic Escherichia coli (VTEC) infection in Finland

    PubMed Central

    2011-01-01

    Background Verotoxigenic E. coli (VTEC) is the cause of severe gastrointestinal infection especially among infants. Between 10 and 20 cases are reported annually to the National Infectious Disease Register (NIDR) in Finland. The aim of this study was to identify explanatory variables for VTEC infections reported to the NIDR in Finland between 1997 and 2006. We applied a hurdle model, applicable for a dataset with an excess of zeros. Methods We enrolled 131 domestically acquired primary cases of VTEC between 1997 and 2006 from routine surveillance data. The isolated strains were characterized by virulence type, serogroup, phage type and pulsed-field gel electrophoresis. By applying a two-part Bayesian hurdle model to infectious disease surveillance data, we were able to create a model in which the covariates were associated with the probability for occurrence of the cases in the logistic regression part and the magnitude of covariate changes in the Poisson regression part if cases do occur. The model also included spatial correlations between neighbouring municipalities. Results The average annual incidence rate was 4.8 cases per million inhabitants based on the cases as reported to the NIDR. Of the 131 cases, 74 VTEC O157 and 58 non-O157 strains were isolated (one person had dual infections). The number of bulls per human population and the proportion of the population with a higher education were associated with an increased occurrence and incidence of human VTEC infections in 70 (17%) of 416 of Finnish municipalities. In addition, the proportion of fresh water per area, the proportion of cultivated land per area and the proportion of low income households with children were associated with increased incidence of VTEC infections. Conclusions With hurdle models we were able to distinguish between risk factors for the occurrence of the disease and the incidence of the disease for data characterised by an excess of zeros. The density of bulls and the proportion of

  4. 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

  5. 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

  6. 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

  7. Autophagy, a Conserved Mechanism for Protein Degradation, Responds to Heat, and Other Abiotic Stresses in Capsicum annuum L.

    PubMed

    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.

  8. 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

  9. 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

  10. 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.

  11. [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.

  12. [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. PMID:27396104

  13. [Association of sardine fishery, Sardinella aurita (Teleostei: Clupeidae) and environmental variability of the coastal upwelling ecosystem of Nueva Esparta, Venezuela].

    PubMed

    Gonzźlez, Leo W; Euán, Jorge; Eslava, Nora; Suniaga, Jesús

    2007-03-01

    The present research is an analysis of Spanish sardine fishing (Sardinella aurita) associated with some climatic and meteorologic parameters of the ecosystem from El Morro Nueva Esparta, Venezuela. The catch and environmental data from the area were taken in the period 1996-2000. Catch data as a function of wind speed, sea surface temperature, air temperature and rain were analyzed by means of simple lineal regression and multiple models. We found a positive correlation of catch with wind speed, and a negative correlation with sea surface temperature, air temperature, and rain. The multiple regression model with intercept had a poor fit, therefore, we made a model without intercept, which improve greatly the fit. A selection of the variables using the forward procedure verified that the independent variables "wind speed" and "air temperature" have a significant relation with catch (p < 0.001) at real time. This method suggests that sea surface temperature and rain have little influence on the catch, and suggests a major availability of resources in the months with low air temperature and the highest wind speed (January-June). Rev. PMID:18457137

  14. 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. PMID:22639119

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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. PMID:26720156

  20. Effects of environmental enrichment and voluntary exercise on neurogenesis, learning and memory, and pattern separation: BDNF as a critical variable?

    PubMed

    Bekinschtein, Pedro; Oomen, Charlotte A; Saksida, Lisa M; Bussey, Timothy J

    2011-07-01

    Adult-generated neurons in the dentate gyrus of the hippocampus have been the focus of many studies concerned with learning and memory (L&M). It has been shown that procedures like environmental enrichment (EE) or voluntary physical exercise (Vex) can increase neurogenesis (NG) and also enhance L&M. It is tempting to conclude that improvements in L&M are due to the increased NG; that is, a causal relationship exists between enhancement of NG and enhancement of L&M. However, it remains unclear whether the L&M enhancement observed after these treatments is causally dependent on the increase in newborn neurons in the dentate gyrus. It remains a possibility that some unspecified change--a "third variable"--brought about by EE and/or Vex could be a causal determinant of both NG and L&M. We suggest that this third variable could be neurotrophic and/or plasticity-related factors such as BDNF. Indeed, both EE and Vex can induce expression of such proteins, and BDNF in particular has long been linked with L&M. In addition, we argue that a very likely source of variation in previous experiments was the load on "pattern separation", a process that keeps similar memories distinct, and in which NG has been shown to be critically involved. To attempt to bring these ideas together, we present preliminary evidence that BDNF is also required for pattern separation, which strengthens the case for BDNF as a candidate third variable. Other ways in which BDNF might be involved are also discussed.

  1. 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

  2. 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

  3. Chromium Stable Isotope Fractionation During Abiotic Reduction of Hexavalent Chromium

    NASA Astrophysics Data System (ADS)

    Kitchen, J. W.; Johnson, T. M.; Bullen, T. D.

    2004-12-01

    Chromium, a common surface water and ground water contaminant, occurs as Cr(VI), which is soluble and toxic, and Cr(III), which is insoluble and less toxic. Reduction of Cr(VI) to Cr(III) is often the most important reaction controlling attenuation of Cr plumes, and Cr stable isotope (53Cr/52Cr) measurements show great promise as indicators of this reaction. Cr(VI) reduction involves a kinetic isotope effect; lighter isotopes react at greater rates and heavier isotopes become increasingly enriched in the remaining Cr(VI) with increasing extent of reduction. If the size of this effect can be constrained well, then precise estimates of reduction are possible. Cr(VI) reduction can be mediated by microbes, or may occur abiotically in the presence of Fe(II) and a variety of organic compounds. A recent study of bacterial reduction of Cr(VI) under low electron donor conditions yielded a Cr isotope fractionation factor of 1000lnα = 4.1 ± 0.2. A previous study of abiotic reduction indicated a fractionation factor of 1000lnα = 3.4 ± 0.2, but this work was limited to 3 experiments. The present study provides a more detailed look at Cr isotope fractionation induced by abiotic Cr(VI) reduction by: Fe(II); mandelic acid with alumina and goethite catalysts; and humic substances. Reduction occurred slowly, over days or weeks. The fractionation factor for the organic reductants (all at pH=4), including two surface-catalyzed mandelic acid reactions, two fulvic reactions, and one humic reaction,- was 1000lnα = 3.0 ± 0.4, with no statistically significant differences between experiments. The fractionation factors for the Fe(II) experiments were 4.7 ± 0.3, 3.7 ± 0.2, and 2.9 ± 0.2 for pH = 4, 5, and 6, respectively. Further work is necessary to better constrain this pH dependence and to determine if it occurs with the organic reductants. The overall variability in the size of the Cr isotope fractionation during Cr(VI) reduction translates into a moderate level of uncertainty

  4. Survival in macaroni pengu