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PREDICTING BENTHIC STRESS IN RELATION TO SEDIMENT CONTAMINATION FROM INTEGRATED ASSESSMENTS ALONG THE U.S. ATLANTIC AND GULF OF MEXICO COASTS
Citation:
Hyland, J. L., R. F. Van Dolah, J F. Paul, J K. Summers, W. L. Balthis, AND V D. Engle. PREDICTING BENTHIC STRESS IN RELATION TO SEDIMENT CONTAMINATION FROM INTEGRATED ASSESSMENTS ALONG THE U.S. ATLANTIC AND GULF OF MEXICO COASTS. Presented at SETAC 20th Annual Meeting, Philadelphia, PA, November 14-18, 1999.
Description:
Matching data on sediment contaminants and macroinfauna from 1,349 samples collected in estuaries along the U.S. Atlantic and Gulf of Mexico coasts were used to estimate risks of bioeffects from multiple-contaminant exposure. Sediment contamination was expressed as the mean ratio of individual contaminant concentrations relative to corresponding Effects Range-Median (ERM) or Probable Effects Level (PEL) values. Benthic condition was assessed using biotic indices specific for each region. Cumulative frequencies of stations with degraded vs. non-degraded assemblages were plotted against ascending values of the mean ERM and PEL quotients. Tenth-, 50th- and 90th-percentile points from degraded-station plots were used to separate contaminant levels into four ranges associated with either a low, moderate, high, or very high probability of impacts. Based on this approach, risks of benthic impacts would be low at mean ERM quotients u 0.022, 0.020, or 0.013 and at mean PEL quotients u 0.040, 0.035, or, 0.021 for mid-Atlantic, southeastern, and Gulf of Mexico estuaries, respectively. Only 7-30% of samples in these lower ranges had unhealthy benthic assemblages. Higher probabilities would be expected at contaminant levels above the 50th-percentile thresholds: mean ERM quotients > 0.098, 0.058, or 0.035 and mean PEL quotients > 0.179, 0.096, or 0.061. About 58-87% of samples in these ranges had unhealthy benthic assemblages. The incidence of impacts was highest at contaminant levels above the 90th-percentile thresholds (73-100% of samples). These bioeffect thresholds are well below those derived from laboratory acute-toxicity tests with amphipods.