THE DETECTION OF CHRONIC BIOLOGICAL EFFECTS IN THE MARINE INTERTIDAL BIVALVE CERASTODERMA-EDULE, IN MODEL ECOSYSTEM STUDIES WITH PULVERIZEDFUEL ASH - REPRODUCTION AND HISTOPATHOLOGY

The cockle Cerastoderma edule was exposed to sediments variously compr ised of pulverised fuel ash (PFA) for two consecutive periods of 3 and 9 months. Chronic effects of PFA on this filter feeding bivalve were studied by examining changes in cellular and tissue pathology with the aid of a screening procedure developed for analysing histopathologica l conditions. The mortality rate was high, up to 43% for the 100% PFA sediment and growth of the individual bivalves was low. The accumulati on of metals appeared to be low at 1-10 times background tissue levels . Signs of cellular stress were seen in the digestive gland after the first 3 months. However, after 9 months, this same organ was in fairly good condition. Reproduction was delayed due to slow oocyte maturatio n.