1. Norwegian Institute for Water Research (NIVA); Biodiversity in Marine Environments Section; Gaustadalléen 21 Oslo NO-0349 Norway
2. Department of Biosciences; University of Oslo; PO Box 1066 Blindern Oslo NO-0316 Norway
3. Department of Environmental; Social and Spatial Change (ENSPAC); Roskilde University; Universitetsvej 1, PO Box 260 Roskilde DK-4000 Denmark