Research Casper van Leeuwen mosaicResearch  

Human impact increasingly leads to loss of pristine habitats and their rich plant and animal communities. To reverse this trend via effective conservation and restoration, we need to understand which species can respond to changing conditions and by which mechanisms (e.g. adaptation, spatial escape). My research vision is to understand the ecological functioning of aquatic ecosystems, so we can preserve and restore our natural ecosystems based on science-based knowledge. 

I study freshwater ecosystems, because they are understudied and it is a realm with strong conflicts between ecosystem services and biota. My research focusses on three core components in wetland ecosystems: (1) the movement and physiology of higher trophic levels of the food web (birds, fish), (2) the distributions and communities of lower trophic levels (plants, invertebrates, plankton), and (3) the impact of environmental conditions on organisms at various spatial scales. For an understanding at the ecosystem level, I integratively study multiple trophic levels of wetland food webs, ranging from plants to zooplankton and fish to birds. First, I aim to understand how ecosystem functioning depends on movements of higher trophic levels such as dispersal and migration. What are the consequences of the presence or absence of these higher trophic levels, and what attracts these birds and fish to select certain habitats? Second, how do movement of these birds and fish affect the occurence of lower trophic levels, via zoochory, changes in predation rates, grazing pressure or nutrient deposition? Third, how do both higher and lower trophic levels respond to changes in abiotic conditions in ecosystems, and how does their interaction change?

Examples of research topics embedded in my research are the dispersal of plant seeds and aquatic invertebrates by larger animals and water flows, aquatic food web restoration via engineering approaches, the impact of hydropower dams on fish communities, restoration of fen ecosystems in relation to nutrients, impact of temperature rise on plant-animal interactions, and range expansions of invasive species. Methodologically, I combine detailed laboratory experiments with large-scale fieldwork. I track adult fish and birds by telemetry and GPS techniques, apply stable isotope analyses on food webs, population genetic analyses on populations at large spatial scales, search for temporal trends in long-term data, and perform field experiments on multiple trophic levels of the aquatic food web.

Please contact me in case you are interested in collaborating!

Fieldwork at Marker Wadden