Monitoring bio-available marine contaminants with mussels (Mytilus edulis L) in the Netherlands.

After discussing the usefulness of mussels (e.g. Mytilus edulis) for investigating contamination in the marine environment, four cases are presented: (1) A survey of Cu bioavailability in and around the Eastern Scheldt during one winter (1974-1975); (2) A surveillance with a six years interval (1974; 1980) of the bioavailability of Zn along the Dutch North Sea coast. (3) A monitoring programme over the period 1972-1980 showing the decrease in bioavailable Hg in the water column of the Ems-Dollard estuary after decreased emissions at Delfzijl. (4) Retrospective monitoring of two PCB's, as a background for the effectiveness of legal restrictions to PCB use. These four cases are considered a first step in understanding the effects of pollutants in marine ecosystems. In depth physiological, histological and biochemical studies could lay the basis for improved routine biological effect monitoring.