With the help of a comparative mesocosm study, which is being carried out by a Master’s student from the Institute of Environmental Research at RWTH Aachen University together with Bayer AG employees, artificial ponds and flowing channels are being examined. A herbicide is used as a model substance. Direct effects on the periphyton and indirect effects on the various invertebrates are being examined. The Master’s thesis focuses on the invertebrates, whose colonisation density and species composition are monitored over time and compared both between the test systems and under exposure. In addition to live counts on site in two to three traps, one trap per sampling is also preserved and taxonomically determined in detail. The identification work will be technically accompanied by the research institute gaiac.