GROWTH AND SURVIVAL OF CRYOPRESERVED OYSTER AND CLAM LARVAE ALONG A POLLUTION GRADIENT IN THE GERMAN BIGHT

The effects of contaminants along a well-defined North Sea pollution gradient were assessed during the Bremerhaven Workshop using cryopreserved veliger larvae of the Pacific oyster Crassostrea gigas and the Manila clam Tapes philippinarum. The results demonstrate that larval survival steadily improves as the transect moves offshore towards the Dogger Bank, with higher mortalities occurring in the surface microlayer and sediment elutriate samples than in the subsurface bulk waters. Clam larvae were more sensitive to contaminants and natural food availability than the younger oyster larvae. The results from survival and growth data also discriminate between 2 dominant local water masses traversed by the transect.