Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 34 for “"food web structure"”.
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Effects of water color on food web structure in freshwater lakes
… of water color, fish, and Chaoborus on the food web structure under controlled conditions, and (2) analyzed the food webs of two lakes that were similar in morphology and fish assemblage, but strongly differed in water color. Regression and canonical correspondence analysis confirmed my …
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Agricultural intensification, biological pest control and spatio-temporal changes in food web structure
Die Intensivierung der Landwirtschaft ist einer der Hauptauslöser von Verlusten in der Agrarbiodiversität und damit verbundenen Ökosystemfunktionen wie der biologischen Kontrolle. Sie beeinflusst dadurch indirekt auch die landwirtschaftliche Produktionsleistung. Durch die Intensivierung der …
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Carbon flow and food web structure in the mesopelagic zone of the North Atlantic Ocean
… the euphotic zone and the deep ocean through food web interactions and carbon flow pathways. In this dissertation, I use carbon compound-specific stable carbon isotope analysis of amino acids (CSIA-AA) and DNA gut metabarcoding methodologies to provide a broad ecological outlook on mesopelagic …
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Carbon flow and food web structure in the mesopelagic zone of the North Atlantic Ocean
… the euphotic zone and the deep ocean through food web interactions and carbon flow pathways. In this dissertation, I use carbon compound-specific stable carbon isotope analysis of amino acids (CSIA-AA) and DNA gut metabarcoding methodologies to provide a broad ecological outlook on mesopelagic …
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Spatial habitat variation in a Great Plains river: effects on the fish assemblage and food web structure
… spatial variation in fish assemblage and food web structure in the Kansas River, USA in relation to habitat changes. Fishes were collected at ten sites throughout the Kansas River for assessing assemblage structure in summer 2007 using fish community metrics and at 3 sites in 2006 for food …
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Influence of Food Web Structure and Environmental Conditions on Walleye Stocking Success in Two South Dakota Impoundments
… prey abundance to explore differences in Walleye food habits and growth (Chapter 1), 2) compare growth and condition of adult Walleye in relation to their food habits and trophic position (Chapter 2), 3) compare survival and growth of stocked juvenile Walleye as related to abiotic and biotic …
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Changes in food web structure and energy flow in kelp forest ecosystems on the south-west coast of South Africa following the invasion of Jasus lalandii
… in a complete change in the benthic community structure, changing from one state dominated by herbivores and encrusting algae, to another state dominated by lobsters, sessile species, kelp and understory foliose algae. Using the trophic modelling software Ecopath with Ecosim, baseline models of …
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The influence of spatiotemporal variation in food web models
… and prey availability. Consequently, aquatic food webs are dynamic, and relationships between species are perpetually changing as organisms and primary producer communities adapt to current environmental conditions both in time and space. Despite this knowledge however, many food web studies …
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Diet and trophic relationships of fishes from the nearshore of the Bay of Quinte and Kingston Basin, Lake Ontario
… In Chapter 3, I investigated differences in food web structure in these two habitats, and observed a general increase in trophic positions in the Kingston Basin. Diet as revealed by stomach contents and stable isotopes, and relative contribution of terrestrial versus pelagic primary …
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Small scale hydrogeomorphic features influence macroinvertebrate food webs in two Great Plains rivers
Food resources that support river food webs and food web structure have been shown to be influenced by hydrogeomorphology, and its influence on food webs has been gaining support with ecologists over the years. I analyzed the influence of local hydrogeomorphic variables on the structure and …
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Trophic model-generated indicators of the southern Benguela ecosystem for communicating with fisheries managers
… of the model outputs signify a change in the food web structure of the southern Benguela ecosystem.
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Trophic Dynamic Interactions in a Temperate Karst River
… waters. This research compared macroinvertebrate food web structure between riverine reaches with contrasting underlying karst topography, nutrient levels, and Cladophora cover during summer 2012 and autumn 2013. Recent work in these reaches found a high correlation between Cladophora cover and …
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Fire disturbance belowground: untangling consequences for soil food webs and organic matter
… ecosystem services including the provisioning of food and fiber, decomposition and nutrient cycling, water filtration, and the maintenance of terrestrial biodiversity. These complex belowground communities, and therefore the ecosystem processes they regulate, are increasingly threatened by fire …
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Influence of riparian forest and agricultural land use on community structure and ecosystem function in headwater streams
… years to explore temporal patterns in community structure and ecosystem function related to land use, instream habitat, and water quality parameters. While there were significant seasonal and annual differences, relationships among streams within different land use groups remained relatively …
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Ecological consequences of non-native parasites for native UK fishes.
… on hosts (individuals to populations), and on food web structure. The three non-native parasite: host systems were Ergasilus briani and roach Rutilus rutilus and common bream Abramis brama, Bothriocephalus acheilognathi and common carp Cyprinus carpio, and Anguillicoides crassus and the …
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Assessing the effect of feather wear on carbon and nitrogen stable isotope ratios, and the use of stable isotopes to determine predator diets in the Namibian Islands marine protected area
… research to tackle problems such as delineating food web structure or tracing the migratory origins of various organisms. This thesis first tested the widely accepted assumption that SI ratios are fixed in an inert tissue, and then used the SI approach to infer the food web structure, from a …
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Algal resource depression by macro-invertebrate herbivores in a chalk stream: An empirical approach
… are therefore important components of stream food webs. However there is relatively little empirical data quantifying the strength of these algal-herbivore interactions, or how these vary with herbivore identity, size, and biofilm physiognomy. Interactions across a diverse herbivore guild were …
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Unifying ecosystem concepts and mercury biomagnification in an estuarine environment using stable isotopes (delta-carbon-13 and delta nitrogen-15).
… and used to show the relationship between food web structure and patterns of mercury biomagnification. On a delta13C and delta15N basis, three different sources of energy were identified: terrestrial carbon, in situ estuarine primary production, and marine phytoplankton. Isotopically …
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Mercury concentration and aquatic food web alterations associated with zebra mussel invasion in Minnesota lakes
… and increased benthic energy reliance of food webs. However, the effects of zebra mussels vary among lakes, and few opportunities exist to examine lake ecosystems and food webs pre- and post- zebra mussel invasion. Furthermore, recent evidence has suggested that Dreissenid mussels may …
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