1. WSL Swiss Federal Inst. for Forest, Snow and Landscape Research; Zürcherstrasse 111 CH-8903 Birmensdorf Switzerland
2. Eawag: Swiss Federal Inst. of Aquatic Science and Technology; Überlandstrasse 133 CH-8600 Dübendorf Switzerland
3. Inst. of Evolutionary Biology and Environmental Studies, Univ. of Zurich; Winterthurerstrasse 190 CH-8057 Zürich Switzerland