Scientist

Faculty of Biology
Aquatic Ecology
Universitätsstrasse 5
D-45141 Essen
Germany

svenja.pfeifer@uni-due.de

PhD thesis: Temporal and spatial effects of stressors, biotic interactions and dispersal on riverine benthic invertebrate community variability

The variability of benthic invertebrate communities in streams is guided by stressors, biotic interactions and dispersal from nearby sites; these drivers interact in a complex way. This project aims at disentangling the role of the individual drivers by analysing temporal (i.e. time series) and spatial variability (near-natural, restored and differently degraded sites) of benthic invertebrate communities in the Emscher/Boye catchment and the Kinzig catchment (see CRC 1439 - RESIST for details). We hypothesise that the interplay of stressors, biotic interactions and dispersal in forming benthic invertebrate communities varies predictably in space and time, depending on the maturity of the stream and the acting stressor.

The project will be based on the analyses of time series of up to 20 years in both catchments, which will be continued throughout the project’s lifespan. We will analyse time series on a community metric level to identify short- and long-term changes and will link these to abiotic variables using statistical models. We will generate ecological profiles for all benthic invertebrate species that have been found in the Kinzig and Emscher/Boye catchments covering habitat preferences / stressor tolerance, biotic interactions (i.e. competitors) and dispersal abilities. We will compare the environmental profiles of the sites with ecological profiles of the species to identify the niches that have already been occupied in the process of recovery (Emscher/Boye) or following fluctuations in environmental variables and along land use gradients (Emscher/Boye, Kinzig). Results of the time series analysis and the matching of sites’ and species’ profiles will be synthesised into an overall appraisal of the contribution of stressors, biotic interactions and dispersal to community variability in near-natural, degraded and restored sites.