1. Department of Watershed Sciences; Western Center for Monitoring and Assessment of Freshwater Ecosystems; Ecology Center; Utah State University; 5210 Old Main Hill Logan UT USA
2. Thule Institute; University of Oulu; PO Box 7300 FIN-90014 Oulu Finland
3. Finnish Environment Institute; Freshwater Centre; University of Oulu; PO Box 413 FIN-90014 Oulu Finland
4. Department of Biology; University of Oulu; PO Box 3000 FIN-90014 Oulu Finland