Search for dissertations about: "trophic level"

Showing result 6 - 10 of 66 swedish dissertations containing the words trophic level.

  2. 6. Consumption patterns and excretion in aquatic food websenrichment

    Author : Anders Persson; Enhet akvatisk ekologi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Hydrobiology; trophic interactions; translocation; biomanipulation; enrichment; phosphorus; model; marine biology; aquatic ecology; limnology; Marinbiologi; limnologi; akvatisk ekologi;

    Abstract : This thesis links biogeochemical cycling to classical ecology. Predictions derived from food chain theory, based on Lotka-Volterra type of interactions, were tested in aquatic environments with the main hypothesis that consumers affect lower levels of organization by both predation and excretion of limiting nutrients. READ MORE

  4. 7. Complexity and Change in a Simple Food Web : Studies in the Baltic Sea (FAO Area 27.IIId)

    Author : Henrik Österblom; Sture Hansson; Robert W Furness; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Avian cholera; Bottom-up; Bycatch; Clupea harengus; Ecosystem; Food web; Gadus morhua; Halichoerus grypus; Regime shift; Sprattus sprattus; Top-down; Trophic cascade; Uria aalge; Marine ecology; Marin ekologi;

    Abstract : An influence at one trophic level can result in dynamic impacts also on other components of a food web. These dynamics are known as trophic cascades, and can be both top-down and bottom-up. After a near-collapse of the Baltic cod Gadus morhua stock in the 1980s, its main prey sprat Sprattus sprattus increased dramatically. READ MORE

  5. 8. Anthropogenic Disturbances and Shifts in Tropical Seagrass Ecosystems

    Author : Johan S. Eklöf; Nils Kautsky; Patrik Rönnbäck; Teresa Alcoverro; Stockholms universitet; []
    Keywords : Aquaculture; feedback mechanisms; Kenya; management; overgrazing; regime shift; resilience; seagrass; seaweed farming; sea urchins; Tanzania; trophic cascades; Zanzibar; NATURAL SCIENCES; NATURVETENSKAP; Marine Ecotoxicology; marin ekotoxikologi;

    Abstract : Seagrasses constitute the basis for diverse and productive ecosystems worldwide. In East Africa, they provide important ecosystem services (e.g. fisheries) but are potentially threatened by increasing resource use and lack of enforced management regulations. READ MORE

  6. 9. Broadening the perspective on seafood production: Life cycle thinking and fisheries management

    Author : Sara Hornborg; Göteborgs universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; LCA; Nephrops; fuel use; Eastern Baltic cod; fisheries management; threatened species; trophic indicators;

    Abstract : Decisions made by fisheries managers strongly influence the overall resource use and environmental impacts associated with the seafood product from capture fisheries. These findings come from Life Cycle Assessments (LCA), a method that aims at quantifying all relevant resource use and environmental impacts throughout the life cycle of a product. READ MORE

  7. 10. Interactions between gray-sided voles (Clethrionomys rufocanus) and vegetation in the Fennoscandian tundra

    Author : Jonas Dahlgren; Lauri Oksanen; Johan Olofsson; John Terborgh; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; gray-sided voles; tundra vegetation; trophic cascades; plant-herbivore interactions; bilberry; plant communities; herbivory; plant resistance; Terrestrial ecology; Terrestisk ekologi;

    Abstract : I have, in this thesis, studied the interactions between gray-sided voles (Clethrionomys rufocanus) and tundra vegetation, on islands in, and mainland sites close to the lake Iešjávri, in northern Norway. As isolated islands are virtually free of predation, I have been able to compare plant-herbivore interactions in the presence and absence of predators. READ MORE