Sökning: "perch"

Visar resultat 6 - 10 av 76 avhandlingar innehållade ordet perch.

1. 6. Ecology and Evolution of Adaptive Morphological Variation in Fish Populations

   Författare :Richard Svanbäck; Peter Eklöv; Lennart Persson; Beren Robinson; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; competition; functional morphology; individual specialization; inter-individual variation; intra-population variation; morphological variation; ontogeny; Perca fluviatilis; perch; phenotypic plasticity; predation; trade-offs; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi;

   Sammanfattning : The work in this thesis deals with the ecology and evolution of adaptive individual variation. Ecologists have long used niche theory to describe the ecology of a species as a whole, treating conspecific individuals as ecological equivalent. LÄS MER

3. 7. Local adaptive pigmentation in Asellus aquaticus -effects of UV-radiation and predation regime

   Författare :Jonas Johansson; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Marinbiologi; limnology; aquatic ecology; marine biology; Hydrobiology; Ekologi; Ecology; damselfly; perch; UV-avoidance; isopod; anti-predator traits; evolution; selective predation; limnologi; akvatisk ekologi; Animal ecology; Djurekologi;

   Sammanfattning : Pigmentation in the freshwater isopod Asellus aquaticus differed between two habitats. Asellus were lighter pigmented in stands of submerged stonewort vegetation, than in nearby reed stands. Moreover, Asellus pigmentation became lighter with time in recently established stonewort stands. LÄS MER

4. 8. Development of GC-HRMS procedures for determination of naturally occuring polar compounds in various environmental applications

   Författare :Bodil Widell; Dag Broman; Caroline Leck; Joan Grimalt; Stockholms universitet; []
   Nyckelord :GC-HRMS; steroid hormones; amino acids; perch; size-resolved aerosol; Arctic; NATURAL SCIENCES; NATURVETENSKAP; Applied Environmental Science; tillämpad miljövetenskap;

   Sammanfattning : The overall objectives of this dissertation were to gain further understanding of the two following environmentally significant issues: (i) Determination of natural steroid hormones in blood plasma from perch (Perca fluviatilis) during a reproductive cycle and to evaluate the possibility of using the steroid composition as a biomarker for early signs of endocrine disruptive effects. (ii) Determination of dissolved free amino acids in size resolved airborne particles collected over the Arctic pack ice area (>80°N) in summer and to study their overall relationship with the ocean surface microlayer as a potential source. LÄS MER

5. 9. Biological Diversity of Fish and Bacteria in Space and Time

   Författare :Henrik Ragnarsson; Peter Eklöv; Kerstin Holmgren; Göran Englund; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; species richness; fish; lake; biogeography; glacial; colonization; metacommunity; speciation; perch; bacteria; diversity; Ekologi;

   Sammanfattning : Biological diversity is controlled by an array of factors and processes all active at different spatial and temporal scales. Regional factors control what species are available to occur locally, whereas the local factors determine what species are actually capable of colonizing the locality. LÄS MER

7. 10. Does fish health matter? The Utility of Biomarkers in Fish for Environmental Assessment

   Författare :Niklas Hanson; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biomarkers; Fish; Environmental monitoring; Ecological risk assessment; Rainbow trout; Perch;

   Sammanfattning : Two common strategies to assess exposure to environmental toxicants are to measure chemical concentrations in the environment and to examine the presence of certain species that are known to be sensit... merive to pollution. LÄS MER