1. Department of Aquatic Ecology; EAWAG; Swiss Federal Institute of Aquatic Science and Technology; Ueberlandstrasse 133 8600 Dübendorf Switzerland
2. Institute of Integrative Biology; ETH-Zurich; 8092 Zurich Switzerland
3. Department of Clinical Research; University of Bern and Swiss Institute of Bioinformatics; 3010 Bern Switzerland