1. Department of Biology, University of North Georgia, Oakwood, GA 30566-3414, USA;
2. Great Lakes Institute for Environmental Research, University of Windsor, 2990 Riverside Drive West, Windsor, ON, N9B 3P4, Canada;
3. School of the Environment, Laurentian University, Sudbury, ON, P3E 2C6, Canada;
4. School of Ecology and Environmental Science, Yunnan University, Kunming, Yunnan, China