Search for dissertations about: "food abundance"

Showing result 16 - 20 of 154 swedish dissertations containing the words food abundance.

2. 16. The role of allelopathy in microbial food webs

   Author : Astrid Weissbach; Catherine Legrand; Ellen Van Donk; Linnéuniversitetet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Microbial food web; Allelopathy; Alexandrium tamarense; Prymnesium parvum; Infochemicals; marine plankton community; Freshwater ecology; Limnisk ekologi; Akvatisk ekologi; Aquatic Ecology;

   Abstract : Phytoplankton produce allelochemicals; excreted chemical substances that are affecting other microorganisms in their direct environment.In my thesis, I investigated strain specific variability in the expression of allelochemicals of the harmful flagellate Prymnesium parvum, that is euryhaline but mainly bloom forming in brackish water. READ MORE

4. 17. Mysid growth, stable isotope fractionation, and energetics : implications for food web studies

   Author : Elena Gorokhova; Ora Johansson; Stockholms universitet; []
   Keywords : Systems Ecology; systemekologi;

   Abstract : Field data, stable isotope analyses of the Baltic Sea food web structure,and experimental studies of the functional response indicate that theomnivorous crustacean Mysis mixta (Crustacea, Mysidacea) has no distinct trophic position, but can potentially affect plankton communitystructure and compete with herring and sprat for the zooplankton. Toevaluate field data on mysid body constituents, abundance and populationstructure, and that of their potentialprey, basic knowledge of feeding behaviour, growth mechanisms, andreproductive capabilities are required. READ MORE

5. 18. Bottom-up and top-down regulation of heterogeneous lake food webs

   Author : Fernando Chaguaceda; Peter Eklöv; Kristin Scharnweber; Lars Tranvik; Blake Matthews; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; food webs; resource coupling; ontogenetic diet shifts; resource specialization; bottom-up; top-down; browning; eutrophication; lake; mesocosms; fatty acids; apparent competition; Biology with specialization in Limnology; Biologi med inriktning mot limnologi;

   Abstract : Food webs are networks of organisms linked by trophic interactions that regulate the responses of ecosystems to environmental change. Such regulation is a result of the effects of resources on the abundance of their consumers (i.e. bottom-up effects) and/or the influence of consumers on the abundance of their resources (i. READ MORE

6. 19. Mechanisms structuring the pelagic microbial food web : Importance of resource and predation

   Author : Kristina Samuelsson; Agneta Andersson; Christiane Lancelot; Umeå universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Ecology; pelagic microbial food web; bacteria; flagellates; ciliates; phytoplankton; mixotrophy; nutrient status; predation limitation; resource limitation; Baltic Sea; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi;

   Abstract : Temporal and spatial variations of pelagic microorganisms in the northern Baltic Sea were studied, as well as factors influencing their abundance and growth rates. Three main questions were asked 1) How does increased productivity influence the structure of the microbial food web? 2) Does predation limitation vary between trophic levels? 3) What is the relative importance of resource and predation limitation at different trophic levels?A field study in the northern Baltic Sea showed that dominating protozoa, flagellates and ciliates, increased with increasing primary productivity from north to south. READ MORE

7. 20. Food Web Ecology -- individual life-histories and ecological processes shape complex communities

   Author : Martin Hartvig; Evolutionär ekologi; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; food web; community ecology; community assembly; size-structure; life-history omnivory; ontogeny; trophic interactions; trait based model; topology; emergent organisation; size-spectrum;

   Abstract : This thesis sets out a food web framework for size-structured populations. The framework enables an ecological approach to food web modelling as the individual life-history from birth, through maturation, and ultimately death is explicitly resolved with the use of bioenergetics based on individual body size. READ MORE