A SHORT-EXPOSURE, SUBLETHAL, SEDIMENT TOXICITY TEST USING THE MARINE BIVALVE MULINIA-LATERALIS - STATISTICAL DESIGN AND COMPARATIVE SENSITIVITY

Over the last 10 years a great deal of research effort has concentrate d on determining the effects of contaminated sediments on aquatic orga nisms. For marine systems, this effort has emphasized acute sediment t oxicity tests using amphipods, although a variety of other end points and species have been used. Another candidate species for marine, soli d-phase, sublethal sediment toxicity testing is the bivalve Mulinia la teralis. Useful attributes of this euryhaline bivalve include a wide g eographic distribution (along the North American Atlantic coast from P rince Edward Island to the Gulf of Mexico), easy lab culture, and amen ability to toxicity testing applications (end points are mortality and growth [milligrams per organism dry weight]). Detailed in this paper are organism selection and culture, establishment of statistical desig n, and an estimate of organism mortality and sublethal response variab ility. Results of Mulinia lateralis toxicity tests with 65 contaminate d sediments from eight sites are reported, as well as results of compa rative toxicity tests using two amphipod species, Ampelisca abdita and Eohaustorius estuarius. Analysis of statistical power indicates treat ment weight and survival responses that are 25% different from the sit e control responses can be detected with a probability of 95%. Results of comparative toxicity tests illustrate that although Mulinia latera lis and amphipod acute end points are relatively similar in sensitivit y, utilization of the Mulinia lateralis sublethal growth end point gre atly increases test sensitivity. This paper describes a new marine sed iment toxicity test that complements the existing suite of marine sedi ment toxicity assessment techniques.