1. Department of Experimental Limnology, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Alte Fischerhütte 2, 16775 Stechlin, Germany
2. EcoLab, Université de Toulouse, CNRS, INPT, UPS, 118 route de Narbonne, Bât. 4R1, 31062 Toulouse cedex 9, France
3. Université de Lorraine, CNRS, LIEC, 57000 Metz, France
4. Department of Ecology, Berlin Institute of Technology (TU Berlin), Ernst-Reuter-Platz 1, 10587 Berlin, Germany