VARIATION AMONG POPULATIONS IN THE RESISTANCE OF MYTILUS-EDULIS EMBRYOS TO COPPER - ADAPTATION TO POLLUTION

The effects of copper on embryo development were found to differ betwe en populations of the mussel Mytilus edulis L. (Mollusca: Bivalvia). C oncentrations of copper which caused significantly increased rates of abnormality, and thus decreased yields of normal larvae, in population s from an unpolluted site (Menai Straits, Wales, UK) and to a lesser e xtent in an intermediately polluted site (Oosterschelde, The Netherlan ds) did not affect development of embryos from a polluted-site (Wester schelde, The Netherlands) population. Crosses indicated that tolerance was mostly maternally determined, but there is also evidence of a pat ernal, i.e. genetic, effect. An appreciable quantity of background, no n-treatment, embryo abnormality appeared to be sperm-mediated.