Sökning: "food web dynamics"

Visar resultat 21 - 25 av 59 avhandlingar innehållade orden food web dynamics.

  1. 21. Disturbances in food webs : Importance of species interactions from an ecological and evolutionary perspective

    Författare :Anna Åkesson; Anna Eklöf; György Barabas; Vasilis Dakos; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : Biodiversity loss is occurring globally at an unprecedented pace. This is not only followed by ethical concerns; it also affects all levels of an ecosystem, with wide-spread implications for ecosystem functioning, services and human well-being. LÄS MER

  3. 22. The aquatic microbial food web and occurence of predation-resistant and potentially pathogenic bacteria, such as Francisella tularensis

    Författare :Johanna Thelaus; Agneta Andersson; Mats Forsman; Farooq Azam; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; bacteria; protozoa; ecology; predation; nutrient-availability; microbial food web; model; predation-resistance; Francisella; reservoir; biofilm formation; Freshwater ecology; Limnisk ekologi;

    Sammanfattning : All natural aquatic systems harbour a vast variety of microorganisms. In the aquatic microbial food web, the larger microorganisms (i.e. protozoa) feed on the smaller microorganisms (i. LÄS MER

  4. 23. Climate-induced changes : Its effects on plankton food webs from the Baltic Sea

    Författare :Claudia Romero-Oliva; Edna Graneli; Linnéuniversitetet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Climate-induced changes; temperature; acidification; marine food web; natural plankton community; spring; summer; Baltic Sea; Marine ecology; Marin ekologi; Akvatisk ekologi; Aquatic Ecology;

    Sammanfattning : The Earth’s climate is determined different processes occurring in the atmosphere, land and ocean.Anthropogenic activities (mainly combustion of fossil fuels) have increased since the 1950’s, andthus the concentration of greenhouse gases that are warming up the planet. LÄS MER

  5. 24. Non-indigenous zooplankton : the role of predatory cladocerans and of copepods in trophic dynamics

    Författare :Marc Andersen Borg; Fredrik Wulff; Markku Viitasalo; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Acartia tonsa; Bythotrephes longimanus; Cercopagis pengoi; egg production; fitness; food web changes; ingestion rates; invasive species; metabolic balance; mortality; non-indigenous zooplankton; predation impact; salinity tolerance; stable isotopes; Marine ecology; Marin ekologi; marin ekologi; Marine Ecology;

    Sammanfattning : Human-mediated introductions of non-indigenous species now threaten to homogenize the biota of the Globe, causing huge economic and ecological damage. This thesis studies the ecological role of 3 invasive planktonic crustaceans, the omnivorous copepod Acartia tonsa (western Atlantic and Indo-Pacific) and the predatory cladocerans, Cercopagis pengoi (Ponto-Caspian) and Bythotrephes longimanus (Eurasian). LÄS MER

  7. 25. Top-down and bottom-up effects in a Fennoscandian tundra community

    Författare :Doris Grellmann; Lars Ericson; Lauri Oksanen; Richard Inouye; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; consumer-resource interactions; exclosures; food web dynamics; grey-sided voles; lemmings; NPK-fertilization; plant defences; reindeer; soil microbes; vertebrate grazing;

    Sammanfattning : The objective of this thesis was to investigate the effects of mammalian grazers, such as microtine rodents and reindeer, (top-down effects) and nutrient availability (bottom- up effects) on the plant community of a tundra heath.I conducted a large-scale fertilization experiment and studied the impact of grazers using exclosures. LÄS MER