Sökning: "trophic level effect"

Visar resultat 11 - 15 av 33 avhandlingar innehållade orden trophic level effect.

  1. 11. Ecological effects of pesticides in freshwater model ecosystems

    Författare :Lina Wendt-Rasch; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; marine biology; aquatic ecology; limnology; Marinbiologi; Hydrobiology; community; zooplankton; algae; herbicide; insecticide; pesticide mixture; macrophytes; cypermethrin; metsulfuron-methyl; risk assessment; pesticides; microcosms; limnologi; akvatisk ekologi;

    Sammanfattning : In this thesis I have investigated the effects of pesticide exposure on the ecosystem level using various types of experimental ecosystems, i.e. microcosms. The direct effect of exposure to cyperemthrin, a pyretroid insecticide, was a rapid decrease of crustancean zooplankton in enclosures in a lake. LÄS MER

  3. 12. Thiamine dynamics in the pelagic food web of the Baltic Sea

    Författare :Peter Sylvander; Snoeijs Pauline; Anders Bignert; Dale C Honeyfield; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Thiamine; Vitamin B1; Baltic Sea; M74; marin ekologi; Marine Ecology;

    Sammanfattning : Thiamine (vitamin B1) is involved in several basal metabolic processes. It is an essential compound for many organisms and in aquatic systems it is mainly produced by phytoplankton and prokaryotes and transferred to higher trophic levels through grazing and predation. LÄS MER

  4. 13. Species extinctions in food webs : local and regional processes

    Författare :Anna Eklöf; Bo Ebenman; Peter Münger; Marcel Holyoak; Linköpings universitet; []
    Nyckelord :Extinction; food web; metacommunity; dispersal; species loss; migration; habitat fragmentation; connectance; NATURAL SCIENCES; NATURVETENSKAP;

    Sammanfattning : Loss of biodiversity is one of the most severe threats to the ecosystems of the world. The major causes behind the high population and species extinction rates are anthropogenic activities such as overharvesting of natural populations, pollution, climate change and destruction and fragmentation of natural habitats. LÄS MER

  5. 14. Food webs and the distribution of body sizes

    Författare :Tomas Jonsson; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : Many ecologically relevant life-history traits of organisms, (such as generation time and ingestion rate) are significantly correlated to body size. Since these individual and species characteristics can affect the interactions between the species in a community, it is possible that the distribution of body sizes (in communities) can affect different properties of foodwebs as well. LÄS MER

  7. 15. Food selection and fitness optimisation in insects

    Författare :Helene Bracht Jörgensen; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; food preference; nested PCR; fungal DNA; växtparasitologi; plant parasitology; Entomology; Entomologi; fungi; seeds; ground beetles; collembolans;

    Sammanfattning : To optimise fitness is a continuous process which assists species survival in changing environments. Choosing an optimal diet is an essential part of the optimisation process and a key element of optimal foraging theory. LÄS MER