A test protocol is described to measure sublethal sediment toxicity using the juvenile life stage of the polychaete, Neanthes. The sublethal endpoints include total biomass and average individual biomass relative to controls following a 20-day exposure period. The Neanthes bioassay has distinct advantages over other available sediment toxicity tests including year-round availability of laboratory-cultured test organisms, use of a relatively simple test protocol, and easily measured sublethal endpoints.
Tests conducted in 1988 with sediments collected from three contaminated sites and one relatively uncontaminated site in Puget Sound, Washington, indicate that the biomass endpoints are responsive to changes in sediment quality. A comparison of the test results for the Neanthes bioassay to those obtained with the amphipod Rhepoxynius abronius 10-day acute toxicity test and seven other sediment bioassays commonly used in testing Puget Sound sediments indicates that the Neanthes bioassay is moderately sensitive relative to available sediment bioassays.