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CONTAMINANT THRESHOLDS FOR PREDICTING ADVERSE IMPACTS IN BENTHIC COMMUNITIES ALONG THE U.S. ATLANTIC AND GULF OF MEXICO COASTS
Citation:
Summers, J K., V D. Engle, J. L. Hyland, W. L. Balthis, E. R. Long, J F. Paul, AND R. F. Van Dolah. CONTAMINANT THRESHOLDS FOR PREDICTING ADVERSE IMPACTS IN BENTHIC COMMUNITIES ALONG THE U.S. ATLANTIC AND GULF OF MEXICO COASTS. Presented at EMAP 2001 Symposium, Pensacola, FL, April 24-27, 2001.
Description:
EMAP 2001 Symposium, April 24-27, 2001, Pensacola, FL
Matching data on sediment contaminants and macroinfauna from 1,349 samples collected as part of EMAP in estuaries along the U.S. Atlantic and Gulf of Mexico coasts were used to define thresholds for evaluating risks of benthic community-level impacts in relation to multiple-contaminant exposure. Sediment contamination was expressed as the mean ratio of individual contaminant concentrations relative to corresponding sediment
quality guidelines (SQGs), including Effects Range-Median (ERM) and Probable Effects Level (PEL) values. Benthic condition was assessed using multi-metric biotic indices developed for each region. Cumulative frequencies of stations with an impaired benthic assemblage were plotted against ascending values of the mean ERM and PEL quotients. Based on the observed relationships, contaminant levels were divided into four ranges corresponding to either a low, moderate, high, or very high incidence of impaired benthic condition.
Results showed that condition of the ambient benthic community provides a reliable and sensitive indicator for evaluating the biological significance of sediment-associated stressors. Upper thresholds, marking the beginning of the contaminant range associated with the highest incidence of benthic impacts (73-100% of samples, depending on the region and type of SQG), were well below those linked to high risks of sediment toxicity as determined by laboratory survival tests conducted with single species. Measures of the condition of the ambient benthic community reflect the sensitivities of multiple component species and life stages to persistent exposures under actual field conditions. Similar results were obtained with preliminary data from the west coast (Puget Sound).