Although in the field of ecotoxicology, the determination of toxicity of, for example, pesticides in our environment, often happens through standardized lab experiments of high quality, the results of this kind of experiments cannot be translated into natural systems. This is because many different factors that are present in nature can directly or indirectly influence the toxicity of pesticides. BioMon partners CML and Naturalis collaborate in this research in which the isolated effects of pesticides and nutrients on fresh water ecosystems is tested. We look at communities that cover a large part of the freshwater food web, such as macroinvertebrates, algae and bacteria. DNA techniques are used and calibrated using traditional morphological techniques to determine life communities.