1. Postdoctoral Fellow, Dept. of Marine Technology, Norwegian Univ. of Science and Technology, NO-7491 Trondheim, Norway (corresponding author).
2. Associate Professor, Institute of Geography and Geology, Univ. of Copenhagen, DK-1350 Copenhagen, Denmark.
3. Research Professor, Dept. of Marine Technology, Norwegian Univ. of Science and Technology, NO-7491 Trondheim, Norway.
4. Professor, Dept. of Marine Technology, Norwegian Univ. of Science and Technology, NO-7491 Trondheim, Norway.