Comparison of the acute toxicity of various contaminants to Ampelisca verrilli versus A. abdita in aqueous and sediment exposure tests

The infaunal amphipod Ampelisca verrilli is commonly found in estuarine and marine environments along much of the Atlantic coast and part of the Gulf of Mexico. This species is often much more abundant than A. abdita in southeastern estuaries, particularly when water temperatures are high, and it survives well in a variety of sediment types. Static aqueous (24 and 96 hr) and sediment (10 d) bioassays were conducted using both species to compare their relative sensitivity to various contaminants. Results of the 24 and 96 hr aqueous tests indicated that A. verrilli is less sensitive to SDS than A. abdita, but both species showed comparable sensitivity when exposed to Cd. Results from 10-d sediment assays of samples collected at 19 sites throughout SC during 1994 showed significant mortality at 50% of the sites which had elevated (> ERL) levels of two or more contaminants. In contrast, no significant mortality was noted when these sediments were tested with A. abdita. Results obtained from additional sediment assays using both species and sediments spiked with different concentrations of Cd will also be presented.