1. *National Exposure Research Laboratory, US Environmental Protection Agency, 26 W. Martin Luther King Dr, Cincinnati, OH 45268, U.S.A.
2. †Department of Fisheries and Wildlife, Oregon State University, c/o US Environmental Protection Agency, 200 SW 35th Street, Corvallis, OR 97333, U.S.A.
3. ‡Biology Department, University of Toledo, Toledo, OH 43606, U.S.A.