TOXICITY OF FRESH AND FREEZE-DRIED HYDROCARBON-POLLUTED SEDIMENTS TO CRASSOSTREA-GIGAS EMBRYOS

Sediments from a known hydrocarbon-polluted site were stored fresh and freeze-dried, and subsequently used in liquid and suspended phase bio assays with Crassostrea gigas (Thunberg) oyster embryos. Fresh sedimen ts did not affect embryogenesis while freeze-dried sediments stopped e mbryogenesis in the morula stage at 500 g I-1 and in the trocophore st age at 50 g I-1. At 5 g I-1, freeze-dried sediments were innocuous in the liquid phase bioassay (elutriate filtered through 0.45 mum) but ap peared to reduce embryogenesis success in the suspended phase bioassay . The need for further research into the effects of the storage condit ions and preservation methods of the sediment samples on the fate of t he associated pollutants is demonstrated.