1. Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON N9B 3P4, Canada.
2. Department of Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada.
3. Daniel P. Haerther Center for Conservation and Research, John G. Shedd Aquarium, Chicago, IL 60605, USA; and Department of Wildlife, Fish & Conservation Biology, University of California Davis, Davis, CA 95616, USA.