COMPARISON OF MARINE SEDIMENT TOXICITY TEST PROTOCOLS FOR THE AMPHIPOD RHEPOXYNIUS-ABRONIUS AND THE POLYCHAETE WORM NEREIS (NEANTHES) ARENACEODENTATA

The 10-d amphipod survival toxicity test protocol using Rhepoxynius ab ronius was compared to the 20-d polychaete worm growth and survival pr otocol using Nereis (Neanthes) arenaceodentata. Of the 341 sediment sa mples collected in California and tested over a 2-year period, 78% sig nificantly inhibited R. abronius survival, whereas 2 and 26% significa ntly inhibited N. arenaceodentata survival and biomass, respectively. Statistical power associated with each protocol endpoint was determine d,by calculating the minimum significant difference (MSD) for each tes t protocol for this data set. The 90th percentile MSDs for R. abronius survival and N. arenaceodentata survival and biomass were 16, 36, and 56%, respectively. Survival of R. abronius was significantly negative ly correlated with a number of toxicants including metals, pesticides, polycyclic aromatic hydrocarbons, and polychlorinated biphenyls. No s ignificant correlations were determined between N. arenaceodentata sur vival or biomass and contaminants measured. Amphipod survival was also negatively correlated with sediment total organic carbon and grain si ze, but when samples with a high percent fine grain size (>90% fines) were eliminated from consideration, the overall conclusions of the stu dy were not altered. The 10-d amphipod survival protocol using R. abro nius was a more sensitive indicator of toxicity, but the results indic ate that this was due to greater statistical power rather than greater sensitivity of the test organisms or endpoints.