1. Department of Biochemistry & Microbiology, P.O. Box 3055 Stn CSC, University of Victoria, Victoria, B.C., Canada, V8W 3P6, Pacific Environmental Science Centre, Environment Canada, 2545 Dollarton Highway, North Vancouver, BC, Canada, V7H 1 V2, and School of Earth and Ocean Sciences, P.O. Box 3065 Stn CSC, University of Victoria, Victoria, BC, Canada, V8W 3V6