1. Radboud University Nijmegen, Institute for Water and Wetland Research, Department of Environmental Science, P.O. Box 9010, NL-6500 GL, Nijmegen, The Netherlands
2. Akvaplan-niva, High North Research Centre for Climate and the Environment, 9296, Tromsø, Norway
3. Statoil ASA, N-7005, Trondheim, Norway