[1] Mem Univ, Dept Phys & Phys Oceanog, St John, NF A1B 3X7, Canada
[2] Plymouth Marine Lab, Plymouth PL1 3DH, Devon, England
[3] Univ Sci & Technol Lille, Stn Marine, F-62930 Wimereux, France
[4] Pacific Biol Stn, Nanaimo, BC V9T 6N7, Canada
[5] Univ Wageningen & Res Ctr, Dept Environm Sci, Aquat Ecol & Water Qual Management Grp, NL-6700 DD Wageningen, Netherlands
[6] Univ N Carolina, Dept Marine Sci, Chapel Hill, NC 27599 USA