1. Department of Ecology, University of Kaiserslautern, Kaiserslautern, Germany
2. Department of Biodiversity, University of Duisburg-Essen, Essen, Germany
3. Centre for Water and Environmental Research (ZWU), University of Duisburg-Essen, Essen, Germany
4. Department of Eukaryotic Microbiology, University of Duisburg-Essen, Essen, Germany