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Developing an Index of Benthic Condition for the Acadian Biogeographic Province

Stephen S. Hale and Sandra J. Benyi

Atlantic Ecology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 27 Tarzwell Drive, Narrgansett, RI 02882

The National Coastal Assessment has sampled benthic assemblages each summer since 2000 in coastal areas of the U.S. Acadian Biogeographic Province (tip of Cape Cod to Canadian border). We are developing a multimetric index to be used as an indicator of benthic condition. During the first two years, states (ME, NH, MA) sampled benthic assemblages at 182 stations with a 0.01-m2 Young-modified Van Veen grab and sieved the samples through a 0.5-mm mesh. We used stepwise and canonical discriminant analysis with several candidate metrics of benthic condition to develop a discriminant score that could distinguish between sites with low benthic environmental quality (BEQ, based on levels of sediment chemical contaminants, sediment toxicity, and dissolved oxygen level of the bottom water) and sites with high BEQ. We developed a discriminant function, using measures of diversity and community structure, that successfully classified 85% of the stations. Our next step will be to validate the index with independent data sets. The benthic index will provide environmental managers an indicator they can use to make both spatial comparisons and year-to-year comparisons of benthic community condition.

Keywords: benthic assemblages, benthic index, ecological indicators, Gulf of Maine, Acadian Biogeographic Province

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