1. Faculty of Biology, Department of Aquatic Ecology, University of Duisburg-Essen, Essen, Germany
2. Department of Environmental Sciences, Institute for Water and Wetland Research, Radboud University Nijmegen, Nijmegen, The Netherlands
3. National Institute for Public Health and the Environment, Bilthoven, The Netherlands
4. Institute of Environmental Sciences, Leiden University, Leiden, The Netherlands