Toxicity of Chemically Spiked Sediment to the Carpet Shell Clam Ruditapes decussatus Embryos and Larvae

The objective of this research was to assess the toxicity of sediment contaminated with cadmium, DDT, chlorpyrifos, and fluoranthene to embryos and larvae of the European clam Ruditapes decussatus, exposed to two sediment fractions, the whole sediment and elutriate. The percentages of abnormal D-shaped larvae and larval mortality have been investigated. The median effective concentration (EC50) values, reducing 50% of the percentage of D-shaped larvae, in whole sediments and elutriates were, respectively, 1.17mg/kg and 417.1gl(-1) (3.71M) for cadmium, 1.66mg/kg and 97.8gl(-1) (0.48M) for fluoranthene, 1.71mg/kg and 384.8gl(-1) (1.08M) for DDT, and 0.96mg/kg and 339.5gl(-1) (0.96M) for chlorpyrifos. The 96h-median lethal concentrations (LC50) reducing larval survival by 50% were 4.04mg/kg 654.3gl(-1) (5.82M) for cadmium, 17.41mg/kg 8666.6gl(-1) (42.84M) for fluoranthene, 3.93mg/kg and 457.4gl(-1) (1.29M) for DDT, and 2.53mg/kg and 308.06gl(-1) (0.87M) for chlorpyrifos. Based on EC50 and LC50 comparisons to toxicity data for other marine species, these findings suggest that the R. decussatus embryotoxicity and larvae mortality bioassay were among the most sensitive tools for sediment quality assessment.