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DISCRIMINATION OF NATURAL AND NON-POINT SOURCE EFFECTS FROM ANTHROGENIC EFFECTS AS REFLECTED IN BENTHIC STATE IN THREE ESTUARIES IN NEW ENGLAND
Johnson, R L., K T. Perez, E W. Davey, J A. Cardin, AND K J. Rocha. DISCRIMINATION OF NATURAL AND NON-POINT SOURCE EFFECTS FROM ANTHROGENIC EFFECTS AS REFLECTED IN BENTHIC STATE IN THREE ESTUARIES IN NEW ENGLAND. Presented at American Society of Limnology and Oceanography, Albuquerque, NM, February 12, 2001.
In order to protect estuarine resources, managers must be able to discern the effects of natural conditions and non-point source effects, and separate them from multiple anthropogenic point source effects. Our approach was to evaluate benthic community assemblages, riverine nitrogen inputs, salinity, flushing times, and sediment chemistry in three small estuaries in southern New England. One estuary is a superfund site; the other two estuaries had no point source inputs. Each estuary has unique conditions of nutrient inputs, flushing times, and salinity. The benthic communities were compared using a diversity index and a similarity index. We tested for differences between estuaries using parametric statistics on nitrogen inputs, mean salinity, flushing times, species richness, Shannon indices. Additionally, a permutation test was used on the similarity indices. The similarity index showed the greatest difference between the superfund site (site with the lowest nitrogen input) and the site with intermediate nitrogen input. This unexpected ranking suggested that the higher nitrogen load effects on the benthic system in the non-superfund site are over-ridden by the anthropogenic effects on benthos of the superfund site.