1. Department of Biological Sciences, University of Windsor, Windsor, Ontario, N9B 3P4 Canada, School of Natural Resource and Environmental Management, Simon Fraser University, Burnaby, British Columbia, V5A 1S6 Canada, and Ecotoxicology Division, Great Lakes Laboratory for Fisheries and Aquatic Sciences, Department of Fisheries and Oceans, 867 Lakeshore Road, Burlington, Ontario, L7R 4A6 Canada