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Showing 1 to 20 of 176 for “"Trophic levels"”.
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Trace Metal Concentrations across Trophic Levels in Cotton Fields of Xinjiang Province, China
<p>Trace metals become concentrated in urban and peri-urban soils with the use of agricultural practices and industrial emissions. Fertilizers, liming, sewage sludge, and irrigation water contain metals which accumulate in agricultural fields and pose a risk to humans and wildlife. Coal plants and …
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The transfer of heavy metals through trophic levels and their toxicity effects on organisms including humans
… have led to the accumulation of metals through trophic levels. During visits to Blanchdown Wood, Devon, UK and Snailbeach, Shropshire, UK, samples were collected to examine the effects of the spoil tips on the surrounding ecosystem. Samples of vegetation, soil and animal materials were extracted …
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Parallel and Nonparallel Patterns of Genetic Co-Differentiation: Evidence for Host Associated Differentiation Among Trophic Levels of the Oak Gall Wasp System
… In this work, we ask if HAD cascades to higher trophic levels in parasitoids of an insect herbivore that expresses HAD. Belonocnema treatae (Hymenoptera: Cynipidae) induces galls on three species of live oak (Quercus) across the southern USA. Both HAD and geography structure genomic variation …
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Stable carbon and nitrogen isotope ratios in the shallow-water cape hake, merluccius capensis (castelnau) as indicators of trophic position and diet on the west and south coasts of South Africa
13C/12C and 15N/14N were used to indicate the trophic levels of the shallow-water Cape hake, Merluccius capensis (Castelnau) at three sites on the west coast of South Africa, and five sites on the south coast. Gut content analyses show only the very recent diet of hake, therefore stable carbon and …
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Stability and Dynamics of Resource Consumer Ecosystems
… ecosystems (ecosystems with two trophic levels). Beginning with geometric analyses of small systems, we uncovered a critical instability arising from a mismatch between resources that promote growth (defined as niches) and those predominantly consumed. This instability emerges …
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FACTORS AFFECTING MERCURY BIOMAGNIFICATION IN RIVERINE FOOD WEBS IN THE ROCKY MOUNTAINS: CLARK FORK RIVER BASIN, MONTANA, U.S.A.
… in mercury concentration in three riverine trophic levels (aquatic invertebrates, fish, and osprey). I find that the mercury concentrations of low trophically positioned species, like aquatic invertebrates, are extremely dependent on mercury source concentrations (p=0.0143). While, species …
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FACTORS AFFECTING MERCURY BIOMAGNIFICATION IN RIVERINE FOOD WEBS IN THE ROCKY MOUNTAINS: CLARK FORK RIVER BASIN, MONTANA, U.S.A.
… in mercury concentration in three riverine trophic levels (aquatic invertebrates, fish, and osprey). I find that the mercury concentrations of low trophically positioned species, like aquatic invertebrates, are extremely dependent on mercury source concentrations (p=0.0143). While, species …
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Ecological and Trophic Distribution of Pesticides in Lack Poinsett, South Dakota
Ecological and trophic distributions of chlorinated hydrocarbon residues in Lake Poinsett, South Dakota were studies. Components of the ecosystem analyzed were water, bottom sediment, zooplankton, benthic algae, crayfish, aquatic insects and fish. Concentrations of aldrin, DDD, DDE, DDT, dieldrin, …
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An Isotopic Examination of Cave, Spring and Epigean Trophic Structures in Mammoth Cave National Park
… ISOTOPIC EXAMINATION OF CAVE, SPRING AND EPIGEAN TROPHIC STRUCTURES IN MAMMOTH CAVE NATIONAL PARK</p> <p>Name: Zacchaeus Greg Compson Date: October 15, 2004 Pages: 56</p> <p>Directed by: Philip Lienesch, Doug McElroy, Michael Stokes and Richard Bowker</p> <p>Department of Biology Western Kentucky …
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Community composition, migration and trophic positions of micronekton in two biogeochemical provinces of the South West Indian Ocean
… province, copepods were chosen as baseline in trophic level estimations. Feeding regime and size were shown to influence the trophic position of micronekon. In the ISSG, carnivores (fishes and squids) and omnivores (crustaceans) had higher δ 15 N values and trophic positions than filter feeder …
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Organic Matter Dynamics and Trophic Structure in Karst Groundwater
… should be important energy sources to higher trophic levels in the aquifer. The ecosystem expansion and contraction model, originally developed to describe surface streams, may be a good descriptor of spatial and temporal patterns of microbial films in karst aquifers. The process of leaf and …
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Invasive fish effects on the invertebrate constituents of wetland communities
… show that these two species occupy similar trophic levels; however p-values suggest these tissues are not highly alike. When comparing δ15N among stickleback and duck blood samples we see these two species occupy significantly different trophic levels. However, sticklebacks appear to be …
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Over-Winter Mortality Of Gizzard Shad (Dorosoma Cepedianum) In Oneida Lake, New York
… species and have ecosystem-level effects on all trophic levels of aquatic ecosystems. Oneida Lake has been the focus of a long-term data set across several trophic levels and provides the ideal location to study over-winter mortality in fishes. In Chapter 1, I provide a review of current methods …
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Hydrological and ecological observations along the eastern Beaufort Sea coast of Alaska
… stable C and N isotopic analysis to determine trophic structure and assess dependence of fauna on terrestrial (CT) vs. marine sources of carbon, with particular focus on animals widely used by local subsistence hunters. Our mixing model results suggest that terrestrial carbon (CT) may be …
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Trophic dynamics in Australian seagrass beds : unravelling linkages from nutrients to fish
The study of food webs and trophic dynamics has been a major endeavour for biologists for over half a century. The major aim of trophic ecology has been to explain the complex structures and interaction of food webs using simple models and generalities. A key debate in this research field has been …
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Interannual variability in Indian Ocean surface waters and tuna-environment relationships : filling the gaps with a coupled bio-physical ocean model
… basin-scale controls on productivity and higher trophic levels. A lack of in situ data, especially for mid and upper trophic-level organisms, has commonly limited to small spatiotemporal scales, investigations into environmental control of biological systems. These data gaps are increasingly …
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Host use, mutualism and parasitism in the Lycaeides butterfly complex
… in this group is interactions with other trophic levels. In the second chapter, interactions with mutualistic ants and parasitoids were investigated in the context of current adaptation to a new host, alfalfa, within one of the species previously studied, L. melissa. Over the course of two …
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Benthic microalgae on the Louisiana inner continental shelf: biomass, distribution, and contribution to benthic food-webs
… The contribution of microalgae to higher trophic levels was also examined. Three sandy shoals and surrounding muddy sediments with depths ranging from 4 to 20 m were studied. Light levels (< 1 to 30% of surface PAR) were sufficient for benthic photosynthesis although likely limiting at …
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