Aquatic Sciences Meeting, Albuquerque 2001

PC19 Benthic Processes and Ecology

Date: Thursday, February 15, 2001

Location: Southwest Hall

Johnson, R, L, USEPA, Narragansett, USA, johnson.roxannel@epa.gov

Perez, K, T, USEPA, Narragansett, USA, perez.kenneth@epa.gov

Davey, E, W, USEPA, Narragansett, USA, davey.earl@epa/gov

Cardin, J, A, USEPA, Narragansett, USA, cardin.john@epa.gov

Rocha, K, J, USEPA, Narragansett, USA, rocha.kenneth@epa.gov

Dettmann, E, H, USEPA, Narragansett, USA, dettmann.edward@epa.gov

DISCRIMINATION OF NATURAL AND NON-POINT SOURCE (DIN) EFFECTS FROM ANTHROPOGENIC EFFECTS AS REFLECTED IN BENTHIC STATE IN THREE NEW ENGLAND ESTUARIES

In order to protect estuarine resources, managers must be able to discern the effects of natural conditions and non-point source inputs, and separate these combined effects from anthropogenic point source effects. Our approach was to evaluate benthic community assemblages, riverine nitrogen inputs, salinity, flushing times, and sediment chemistry in three small southern New England estuaries. One estuary has multiple anthropogenic point source inputs; the other two estuaries have no point source inputs. Each estuary has unique conditions of nutrient inputs, flushing times, and salinity. The benthic communities were compared using diversity and similarity indices. We tested for differences between estuaries using parametric statistics on nitrogen inputs, mean salinity, flushing times, species richness, and Shannon indices. Permutation tests were used on the similarity indices. The similarity indices showed the greatest difference between the impacted site (lowest nitrogen input) and the site with intermediate nitrogen input. This unexpected ranking suggested that the higher nitrogen load effects on the benthic system at the site with no point source impacts are over-ridden by the anthropogenic effects on benthos of the impacted site.

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Aquatic Sciences Meeting, Albuquerque 2001

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