Food web ecology
Anthropogenic activities continue to impact the functioning and the biodiversity of freshwater ecosystems worldwide. With most of these activities now co-occurring, ecosystems are facing pressures from multiple stressors. The spatial or temporal co-occurrence of stressors may produce synergistic, antagonistic or additive ecological effects and thus influencing several biological compartments of freshwater ecosystems. Such novel effects are notoriously difficult to quantify using biodiversity-based assessment approaches, as they ignore interactions among biological compartments. Furthermore, classical approaches assume that the presence of a desired level of diversity also implies good ecosystem functioning but this assumption is often not met under realistic conditions. Hence, freshwater managers are becoming increasingly aware that classical assessment needs to be complemented by novel approaches that consider functional targets including ecosystem processes. The study of food webs provides a promising approach as food webs explicitly consider ecosystems functions to be mediated by biological communities and thus link classical, taxonomically grounded research with fluxes of organic matter.
Our research focuses on how human perturbations affect food web topology and consumer-resource interactions of lotic ecosystems. Building on that, we are working on indicators to assess the functional status of lotic ecosystems and to inform management authorities on how to mitigate human impacts on ecosystem material cycling. Our work involves a significant field component, including large-scale as well as field mesocosm studies. We use a range of techniques but primarily combine stable isotopes, mixing model analysis and estimates of ecosystem productivity and respiration to quantify organic matter fluxes.
Head of the research group: Dr. Mario Brauns