1. Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, 0349 Oslo, Norway
2. Department
of Ecology and Genetics/Limnology, Uppsala University, Norbyvägen
18D, 752 36 Uppsala, Sweden
3. Department
of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Lennart Hjälms väg 9, 750 07 Uppsala, Sweden
4. Finnish Environment Institute, P.O. Box 140, 00251 Helsinki, Finland
5. Section
for Aquatic Biology and Toxicology, Department of Biosciences, University of Oslo, 0316 Oslo, Norway
6. Department
of Forest Ecology and Management, Swedish University of Agricultural Sciences, 901 83 Umeå, Sweden