Sökning: "phytoplankton"

Visar resultat 16 - 20 av 186 avhandlingar innehållade ordet phytoplankton.

1. 16. Phytoplankton in Lake Hjälmaren

   Författare :Eva Willén; Uppsala universitet; []
   Nyckelord :NATURAL SCIENCES; NATURVETENSKAP;

   Sammanfattning : .... LÄS MER

3. 17. Pigment and Thiamine Dynamics in Marine Phytoplankton and Copepods

   Författare :Ingrid Wänstrand; Pauli Snoeijs; Marianne Pedersén; Helmut Hillebrandt; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biology; phytoplankton composition; pigments; chemotaxonomy; inorganic nutrients; pelagic copepods; grazing; astaxanthin; thiamine; mesocosm experiments; marine food webs; eutrophication; Baltic Sea; Biologi; Biology; Biologi;

   Sammanfattning : Based on a field study and several mesocosm experiments, I evaluated the use of pigments as chemotaxonomical biomarkers for phytoplankton community composition in the Baltic Sea and I examined effects of inorganic nutrients on the dynamics of carotenoids and thiamine (vitamin B1) at the phytoplankton–copepod level in marine pelagic food webs. My results show that HPLC pigment analysis combined with CHEMTAX data processing was an accurate alternative to microscopic analysis of Baltic Sea phytoplankton. LÄS MER

4. 18. Phytoplankton defense mechanisms against grazing : the role of grazing infochemicals

   Författare :Veronica Lundgren; Edna Granéli; Takeshi Yasumoto; Aaron Barkoh; Linnéuniversitetet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Akvatisk ekologi; Aquatic Ecology;

   Sammanfattning : Many phytoplankton species have evolved a variety of different defenses to decrease losses from grazing; morphological features, changes in life-history/behavior, and production of toxins. These defenses may be associated with costs. Therefore, some phytoplankton only express the defense when needed, i.e. LÄS MER

5. 19. Dynamics of astaxanthin, tocopherol (Vitamin E) and thiamine (Vitamin B1) in the Baltic Sea ecosystem : Bottom-up effects in an aquatic food web

   Författare :Norbert Häubner; Pauli Snoeijs; Jon Ågren; Rhena Schumann; Markku Viitasalo; Uppsala universitet; []
   Nyckelord :Baltic Sea; carotenoids; astaxanthin; tocopherols; Vitamin E; thiamine; Vitamin B1; pelagic food web; eutrophication; M74; phytoplankton; zooplankton; sprat; Sprattus sprattus balticus; herring; Clupea harengus; salmon; Salmo salar; cod; Gadus morhua; High Performance Liquid Chromatography HPLC ; electrochemical detection ECD ;

   Sammanfattning : The thesis combines laboratory experiments and field expeditions to study production, transfer and consumption of non-enzymatic antioxidants and thiamine in an aquatic food web. In particular, I (1) documented spatial and seasonal variation of tocopherols and carotenoids in the Baltic Sea pelagic food web, and (2) examined the effects of abiotic and biotic factors on tocopherol, carotenoid and thiamine concentrations in phytoplankton, zooplankton and fish. LÄS MER

7. 20. Direct and indirect effects of fish predation and excretion in aquatic food webs

   Författare :José Luiz Attayde; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; marine biology; Hydrobiology; zooplankton; resilience; predation; phytoplankton; nutrient enrichment; nutrient recycling; interaction strength; herbivory; food webs; food chain; excretion; fish; detritus; detritivory; aquatic ecology; limnology; Marinbiologi; limnologi; akvatisk ekologi; Ecology; Ekologi;

   Sammanfattning : The aim of this thesis was to elucidate the mechanisms by which planktivorous fish can affect planktonic communities in lakes and how they may affect benthic communities through their effects on planktonic communities. In a laboratory experiment, nutrients released by fish increased algal biomass and altered phytoplankton community structure, suggesting that fish can affect phytoplankton by directly releasing nutrients. LÄS MER