Search results for "ravinnonotto"

Ultraviolet cues in fruit-frugivore interactions

2002

All diurnal birds studied so far, many reptiles, amphibians, fish and some rodents are able to detect near-ultraviolet light (UV; 320-400 nm) invisible to humans. In many animals, UV cues have been found to play a role in foraging and mate choice. As many fruits reflect UV light, frugivores sensitive to UV may also use these cues in foraging. Fruit colours and their contrast with background coloration may attract frugivores. In this thesis, I studied the fruit colour preferences of both redwings (Turdus iliacus) and small rodents (house mice, Mus musculus and bank vole, Clethrionomys glareolus).

Ecology, fisheries and management of wild brown trout populations in boreal inland waters

2010

Eutrophication of aquatic ecosystems is an increasing problem, especially threatening small and shallow freshwater lakes. While the extreme inputs of nutrients (phosphorus and nitrogen) can nowadays be reduced and controlled rather efficiently, additional measures to reverse eutrophication may be needed. These often involve biomanipulation, typically mass removal of cyprinid fish. However, the success of biomanipulations has many times been limited or short lived. The reasons for this are not well known, perhaps because the more subtle impacts of biomanipulation on the ecosystem-wide processes of lakes have not been thoroughly studied. Natural abundance stable isotopes may provide a cost-ef…

Effects of fumonisin B1 on performance of juvenile Baltic salmon (Salmo salar)

2013

Fumonisin B1 is a mycotoxin produced by fungi of the genus Fusarium that frequently occurs on maize (Zea mays) and feeds containing it. The use of plant-based protein sources in feeds designed for aquaculture has increased due to their low costs compared with fishmeal. This trend has resulted in a global increase in feed formulations contaminated with mycotoxins, producing economical losses in aquaculture industry. The topic also causes concerns because of the potential health consequences that aquaculture products could have on human consumers. FB1 mainly disrupts sphingolipid metabolism and also has immune suppressive effects. Fish mycotoxicosis produces a wide range of symptoms from poor…

Pohjaeläinten ravinnonkäyttö keskisuomalaisessa luusuakoskessa isotooppianalyysin avulla arvioituna

2009

The variable position of Arctic charr (Salvelinus alpinus (L.)) in subarctic lake food webs

2013

A New Method to Reconstruct Quantitative Food Webs and Nutrient Flows from Isotope Tracer Addition Experiments

2020

Understanding how nutrients flow through food webs is central in ecosystem ecology. Tracer addition experiments are powerful tools to reconstruct nutrient flows by adding an isotopically enriched element into an ecosystem and tracking its fate through time. Historically, the design and analysis of tracer studies have varied widely, ranging from descriptive studies to modeling approaches of varying complexity. Increasingly, isotope tracer data are being used to compare ecosystems and analyze experimental manipulations. Currently, a formal statistical framework for analyzing such experiments is lacking, making it impossible to calculate the estimation errors associated with the model fit, the…