Sökning: "Lake"

Visar resultat 21 - 25 av 566 avhandlingar innehållade ordet Lake.

  1. 21. Bottom-up and top-down regulation of heterogeneous lake food webs

    Författare :Fernando Chaguaceda; Peter Eklöv; Kristin Scharnweber; Lars Tranvik; Blake Matthews; Uppsala universitet; []
    Nyckelord :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;

    Sammanfattning : 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. LÄS MER

  3. 22. Biogeochemical evidences of human intervention in a shallow lake, Zeekoevlei, South Africa

    Författare :Supriyo Das; Joyanto Routh; Michael R. Talbot; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; lake; primary productivity; biomarkers; stable isotopes; trace elements; phosphorus; Earth sciences; Geovetenskap; geokemi; Geochemistry;

    Sammanfattning : This thesis describes a multi-parameter biogeochemical investigation in a shallow hyper-eutrophic freshwater coastal lake, Zeekoevlei, in South Africa. The predominance of autochthonous algal-derived organic matter in lake sediments is indicated by low C/N, high H/C ratios and δ13Corganic values. LÄS MER

  4. 23. The role of benthic macrofauna in nitrogen cycling in eutrophic lake sediment

    Författare :Jonas Martin Svensson; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; nitrogen retention; nitrous oxide; oligochaetes; chironomids; mineralisation; nitrification; denitrification; eutrophic; sediment; lake; Macrofauna; nitrogen cycling; fish reduction.; Ecology; Ekologi;

    Sammanfattning : This thesis concerns the role of sediment-living macrobenthos in the cycling of nitrogen species and nitrogen transformation in eutrophic freshwater sediments. In my thesis I have, employing 15N-isotope techniques in laboratory experiments, shown the importance of infaunal chironomid larvae and oligochaetes on denitrification in eutrophic lake sediments. LÄS MER

  5. 24. Lake sediments around the Antarctic Peninsula : archives of climatic and environmental changes

    Författare :Rolf Zale; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Lake sediments; Antarctic Peninsula; radiocarbon dating; climatic and environmental changes; sediment chemistry; naturgeografi; Physical Geography;

    Sammanfattning : Lakes and lake sediments from four areas around the Antarctic Peninsula are described.The concentrations of trace metals in sediment are found to be a useful tool in distinguishing between the different sedimentary phases during a transition from marine to limnic environment. LÄS MER

  7. 25. The River-lake Nilotes : politics of an African tribal group

    Författare :Per Säfholm; Uppsala universitet; []
    Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Sociology; Sociologi;

    Sammanfattning : .... LÄS MER