Affiliation: | (1) School of Biological Sciences, University of Portsmouth, King Henry Building, King Henry Ist Street, Portsmouth, UK;(2) The River Laboratory, Institute of Freshwater Ecology, East Stoke, Wareham, Dorset, UK;(3) Present address: Institute for Environment and Health, University of Leicester, Lancaster Road, P.O. Box 138, LEI 9HN Leicester, UK |