Sökning: "food web dynamics"
Visar resultat 6 - 10 av 59 avhandlingar innehållade orden food web dynamics.
6. Complexity and Change in a Simple Food Web : Studies in the Baltic Sea (FAO Area 27.IIId)
Sammanfattning : An influence at one trophic level can result in dynamic impacts also on other components of a food web. These dynamics are known as trophic cascades, and can be both top-down and bottom-up. After a near-collapse of the Baltic cod Gadus morhua stock in the 1980s, its main prey sprat Sprattus sprattus increased dramatically. LÄS MER
7. Dynamics of astaxanthin, tocopherol (Vitamin E) and thiamine (Vitamin B1) in the Baltic Sea ecosystem : Bottom-up effects in an aquatic food web
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
8. Mysid growth, stable isotope fractionation, and energetics : implications for food web studies
Sammanfattning : Field data, stable isotope analyses of the Baltic Sea food web structure,and experimental studies of the functional response indicate that theomnivorous crustacean Mysis mixta (Crustacea, Mysidacea) has no distinct trophic position, but can potentially affect plankton communitystructure and compete with herring and sprat for the zooplankton. Toevaluate field data on mysid body constituents, abundance and populationstructure, and that of their potentialprey, basic knowledge of feeding behaviour, growth mechanisms, andreproductive capabilities are required. LÄS MER
9. Species extinctions in food webs : local and regional processes
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
10. Food Web Ecology -- individual life-histories and ecological processes shape complex communities
Sammanfattning : This thesis sets out a food web framework for size-structured populations. The framework enables an ecological approach to food web modelling as the individual life-history from birth, through maturation, and ultimately death is explicitly resolved with the use of bioenergetics based on individual body size. LÄS MER
