"Quantifying trophic relationships, habitat use and fish movements in freshwater ecosystems"

点击翻译按钮获取中文摘要

The movement and trophic interaction of animals are key variables that structure food webs and ecosystems. With increasing stress being placed on aquatic ecosystems, it has become very important to understand the underlying mechanisms that structure ecosystems so that effective management and conservation plans can be developed. This is of particular relevance in the Great Lakes, where invasive species, nutrients, climate change and habitat destruction have compromised the function and health of a system that holds 20% of the world's freshwater and supports more than 40% of Canadian's population. Quantifying trophic interactions and habitat use are often very difficult, particularly in aquatic systems that are hard to observe. My research will use a combination of chemical tracers and acoustic telemetry to quantify the influence of temperature, prey density and top predators on fish movement and trophic relationships in a semi-controlled pond system and in bays of Lake Ontario. We seek to explore the hypotheses, and quantify relationships, that food web structure and community dynamics are influenced by direct (consumption) and indirect (behavior changes) interactions with predators and prey density across a range of temperatures. The chemical tracers that will be employed in this project, particularly stable isotopes and fatty acids, have become widely applied tools for ecological studies. Unfortunately, the underlying mechanisms that determine the dynamics of these tracers are poorly understood. Through controlled-laboratory studies using different tissues, body sizes and temperatures, we will quantify the turnover rates of stable isotopes and fatty acids in fish. The results of these lab experiments will be applied to pond and lake studies and will improve our ability to apply these tracers to ecological questions. My research directly addresses pressing issues for Great Lakes ecosystem health and the application of chemical tracers and acoustic telemetry, but also contributes to our fundamental understanding of how ecosystems and food webs function.