1. The Fish Physiology Research Group, Department of Biological Sciences, Brunel University, Uxbridge, Middlesex, UB8 3PH, U.K., CEFAS Fisheries Laboratory, Remembrance Avenue, Burnham-on-Crouch, Essex, CM0 8HA, U.K., National Centre for Ecotoxicology and Hazardous Substances, U.K. Environment Agency, Wallingford, U.K., and Environmental and Molecular Fish Biology Research Group, The Hatherly Laboratories, School of Biological Sciences, Exeter University, Exeter, EX4 4PS