Dredged Material Analysis Tools; Performance of Acute and Chronic Sediment Toxicity Methods

This report and research were supported by the U.S. Army Corps of Engineers New York District and U.S. Environmental Protection Agency Region 2. The work was conducted to provide insight into the potential advantages and disadvantages of using chronic sediment toxicity tests with relevant benthic macroinvertebrates as part of dredged material evaluations, as described in the Inland and Ocean Testing Manuals USEPAUSACE 1991, 1998. Nine sediments collected from the New York Harbor NYH were used to assess test methods in a preliminary evaluation at one test facility and an interlaboratory evaluation at three test facilities. The two acute test methods 10-day Ampelisca abdita and Americamysis bahia currently used in evaluations of NYH material were compared to available chronic protocols to gauge relative performance of the toxicity tests. Acute tests are typically short-term e.g., 10-day lethality assessments conducted over a small portion of the test organisms life cycle, while chronic tests are longer-term and assess sublethal measurement endpoints e.g., growth and reproduction in addition to lethality. The available chronic test methods used in this study were the 28-day test using the estuarine amphipod, Leptocheirus plumulosus, and 20-day and 28-day tests using the marine polychaete Neanthes arenaceodentata. Use of chronic tests is recommended or required by dredged material evaluation guidance and regulations, respectively. The sublethal endpoints measured in chronic tests may be more sensitive measures of toxicity and more predictive of longer-term population effects. Of the tests compared, the currently used acute 10-day Ampelisca abdita test and the available chronic 28-day L. plumulosus test were the most responsive i.e., sensitive to the tested NYH sediments. Response is defined as the amount an endpoint e.g., survival was reduced for test organisms in site sediments relative to that same endpoint in the control sediment.