Sökning: "trophic cascades"

Visar resultat 11 - 15 av 21 avhandlingar innehållade orden trophic cascades.

1. 11. The influence of trophic polymorphisms on habitat coupling in aquatic food webs

   Författare :Maria H. K. Marklund; Peter Eklöv; R. Svanbäck; Pierre Magnan; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biology with specialization in Limnology; Biologi med inriktning mot limnologi;

   Sammanfattning : Trophic cascades, together with other indirect interactions are important aspects in shaping the composition and abundance of species in the food web. Theoretically, movement of energy between systems, and coupling between habitats by mobile predators have been suggested as being important for food web stability and evenness. LÄS MER

3. 12. The importance of predation in benthic stream communities

   Författare :Jonas Dahl; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Ekologi; Ecology; invertebrate predators; vertebrate predators; Predation; streams;

   Sammanfattning : There has been considerable debate whether or not predators has any significant effects on prey densities in streams. This thesis examines the importance of predation in stream communities. I have conducted both field and laboratory studies where I have studied how both vertebrate and invertebrate predators affects benthic prey. LÄS MER

4. 13. Mechanisms structuring the pelagic microbial food web : Importance of resource and predation

   Författare :Kristina Samuelsson; Agneta Andersson; Christiane Lancelot; Umeå universitet; []
   Nyckelord :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;

   Sammanfattning : 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. LÄS MER

5. 14. Dynamics of ecological communities in variable environments : local and spatial processes

   Författare :Linda Kaneryd; Bo Ebenman; Peter Münger; Michael S. Fowler; Linköpings universitet; []
   Nyckelord :;

   Sammanfattning : The ecosystems of the world are currently facing a variety of anthropogenic perturbations, such as climate change, fragmentation and destruction of habitat, overexploitation of natural resources and invasions of alien species. How the ecosystems will be affected is not only dependent on the direct effects of the perturbations on individual species but also on the trophic structure and interaction patterns of the ecological community. LÄS MER

7. 15. The role of crustacean zooplankton in pelagic nutrient cycling

   Författare :Tobias Vrede; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biology; nutrients; freshwaters; food web; Cladocera; Calanoida; stoichiometry; Biologi; Biology; Biologi; limnologi; Limnology;

   Sammanfattning : Herbivorous crustacean zooplankton link phytoplankton and other microorganisms withhigher trophic levels in pelagic food webs. Crustaceans show little intraspecificvariation in somatic C:N:P elemental ratios, which may have implications for theregulation of zooplankton growth and for nutrient cycling. LÄS MER