Publishing Marine and Freshwater Research CSIRO Publishing PO Box 1139 (150 Oxford St) Collingwood, Vic. 3066, Australia Telephone: +61 3 9662 7618 Fax: +61 3 9662 7611 Email: mfr@publish.csiro.au Published by CSIRO Publishing for CSIRO and the Australian Academy of Science www.publish.csiro.au/journals/mfr All enquiries and manuscripts should be directed to: Volume 52, 2001 © CSIRO 2001 A journal for the publication of original contributions in physical oceanography, marine chemistry, marine and estuarine biology and limnology Marine Freshwater Research