1. Smithsonian Environmental Research Center, PO Box 28, Edgewater, Maryland 21037, United States
2. Western Ecology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 2111 SE Marine Science Drive, Newport, Oregon 97365, United States
3. Statistics Consultant, 2000 Kings Landing Road, Huntingtown, Maryland 20639, United States
4. Maritime Environmental Resource Center, Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science, One Williams Street, Solomons, Maryland 20688, United States