A Probabilistic Survey of Sediment Toxicity in West Coast Estuaries: Results from the National Coastal Assessment 1999-2000

Janet O. Lamberson, Walter G. Nelson, and Henry Lee II

U.S. Environmental Protection Agency (USEPA), ORD, WED, Pacific Coastal Ecology Branch, Newport, OR

The toxicity of estuarine sediments to benthic organisms was measured with 10-day static whole sediment toxicity tests measuring survival with the amphipods Ampelisca abdita, Eohaustorius estuarius and Hyalella azteca. Sediment porewater toxicity tests using egg fertilization and embryo developmental success were conducted with the sea urchins Arbacia punctulata and Strongylocentrotus purpuratus by the US Geological Survey Biomonitoring of Environmental Status and Trends Program (USGS-BEST). Sediment porewater was extracted from test sediments, adjusted if necessary to standard salinity, and run at three concentrations: 100%, 50% and 25% of salinity adjusted porewater. Toxicity was tested using endpoints of egg fertilization success, and % normal embryo development to the pluteus stage
at each porewater concentration.

Sediment toxicity ranged from low to high in California small estuaries and San Francisco Bay sediments, low to moderate in Washington small estuaries and Puget Sound sediments, and low to moderately low in Oregon small estuary and Columbia River sediments. Results show some (17%) incidence of sediment toxicity to the amphipod Ampelisca abdita, but some sites may be false positives or false negatives. Differences in sensitivity between the amphipod species A. abdita and E. estuarius to San Francisco Bay sediments were apparent. There was inconsistent toxicity of sediments among species (amphipods compared with sea urchins) in whole sediment and porewater toxicity tests.

Keywords: sediment, toxicity, amphipods, sea urchins, West Coast estuaries