COMPARISONS BETWEEN SEDIMENT BIOASSAYS AND ALTERATIONS OF BENTHIC MACROINVERTEBRATE ASSEMBLAGES AT A MARINE SUPERFUND SITE - COMMENCEMENT BAY, WASHINGTON

Laboratory sediment bioassays and alterations of benthic macroinvertebrate assemblages were evaluated at 43 stations in Commencement Bay, Washington, and at 4 stations in Carr Inlet, Washington (a reference embayment). Three bioassays were evaluated: the amphipod mortality test using Rhepoxynius abronius, the oyster larvae abnormality test using Crassostrea gigas and the Microtox® test using Photobacterium phosphoreum. Alterations of benthic assemblages were determined using numerical classification analysis. Bioassay responses and alterations of benthic assemblages were closely related to chemical contamination, suggesting that most biological effects resulted from chemical toxicity. Although all three bioassays were reasonably successful in predicting the presence or absence of moderately to severely altered benthic assemblages, considerable differences were found in the ability of the tests to identify only the altered assemblages. The Microtox bioassay successfully identified the highest percentage of altered benthic assemblages. By contrast, the oyster larvae abnormality bioassay falsely predicted the lowest percentage of altered assemblages. Tiered application of results of both the Microtox and oyster larvae tests improved the accuracy with which altered assemblages were identified. Copyright © 1990 SETAC