MP3 Chronic and Sublethal Sediment Toxicity
254 Portland Ballroom
1:20 PM - 4:40 PM, Monday
() Field Validation of Chronic Sublethal Dredged Material Laboratory Bioassays: A 3 Year Summary.
Moore, D.1, Diener, D.1, Hester, B. 1, Anghera, S.1, Farrar, D.2, Bridges, T.2, 1 MEC Analytical, Weston Solutions, Inc, Carlsbad, CA, USA2 USACE - ERDC, Vicksburg, MS, USA
ABSTRACT- Standard evaluation of dredged material includes measuring acute toxicity in benthic organisms over a ten day period in the laboratory, but chronic toxicity is not routinely evaluated. In response to the need for chronic toxicity tests to measure long-term effects, the USACE recently completed the development of two new chronic sublethal bioassays with the marine polychaete worm Neanthes arenaceodentata and the estuarine amphipod Leptocheirus plumulosus. In order to determine whether these tests accurately predict negative environmental impacts upon the benthic community, a field validation program has been implemented. These two tests have been used to evaluate different concentrations of a selected contaminated sediment and a clean reference sediment. These sediments were placed in test containers and deployed in the field at a selected test location. At specified intervals over a three year period, sediments in selected test containers were retrieved and analyzed for sediment chemistry, infaunal community composition/re-colonization and toxicity. Results of the chronic sublethal laboratory bioassays were compared to effects observed in situ to evaluate the ability of the proposed tests to predict impacts on benthic infauna in the environment. In addition, the chronic tests were compared to the more standard 10-day acute toxicity tests (with 3 other marine amphipod species) to evaluate whether acute or chronic sublethal tests provide a better prediction of observed benthic community responses. Results of prelminaryanalysis suggests that laboratory based tests provide overly conservative estimates of potential benthic community impacts. Results of both acute and chronic tests are detecting effects at lower treatment levels than can be detected using traditional measures of community response.
Key words: sediment, chronic, benthic, field