1. Institute of Marine Research; Nye Flødevigveien 20 4817 His Norway
2. Department of Natural Sciences; University of Agder; P.O. Box 422 4604 Kristiansand Norway
3. Department of Biosciences; Centre for Ecological and Evolutionary Syntheses (CEES); University of Oslo; P.O. Box 1066 Blindern 0316 Oslo Norway