Prof. Dr. Weitere ist Leiter der Abteilung Fließgewässerökologie am Helmholtz-Zentrum für Umweltforschung – UFZ in Magdeburg
Abstract:
Food webs represent the flow of matter and energy in communities. Within aquatic ecosystems, food webs regulate water quality by mediating processes such as the mineralization of organic matter and thus the self-purification or the utilization of algae (=> eutrophication) and bacteria (=> pathogens). Such internal processes within water bodies are of high interest for the management of surface waters besides the regulation of inflow of pollutants from external sources. However, their control and thus the opportunity for manipulation by management is often unknown. The presentation introduces food webs as target for the assessment and management of running water ecosystems and addresses food web related processes in running waters which regulates water quality parameters. One part of the presentation focuses on large rivers, where planktonic processes play an important role for the biological flux of matter. Here, excessive production of planktonic algae is a major water quality problem in many rives which can efficiently be reduces by benthic macroinvertebrates. We show that the activity of benthic invertebrates is controlled by the habitat quality and demonstrate consequences for different scenarios of biocontrol of eutrophication. A second part of the presentation focuses on streams and small rivers with low importance of planktonic processes and dominance of benthic (biofilm-related) processes. Biofilms show a large variability in food quality. The presentation demonstrates how the food quality is regulated and shows consequences for the control of biofilms by food web processes.

After the seminar (ca. 16:00 h), everybody is welcome to join us for drinks and munchies in the „coffee corner on the second floor“.