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Diagnosis of Potential Stressors Adversely Affecting Benthic Communities in New Bedford Harbor, MA (USA)
Citation:
HO, K. T., M. C. PELLETIER, D. E. CAMPBELL, R. M. BURGESS, R. L. JOHNSON, AND K. J. ROCHA. Diagnosis of Potential Stressors Adversely Affecting Benthic Communities in New Bedford Harbor, MA (USA). Integrated Environmental Assessment and Management. Allen Press, Inc., Lawrence, KS, 8(4):685-702, (2012).
Impact/Purpose:
Under the Clean Water Act, states must categorize all surface waters in 305(b) reports and place those waterbodies that are impaired or threatened on 303(d) lists. Before the allowable total maximum daily loads (TMDLs) can be determined for a 303(d) listed site, the cause(s) of the impairment or threat to the waterbody must be identified. We evaluated a number of diagnostic tools for their ability to identify stressors in New Bedford Harbor (NBH), Massachusetts (USA), using a modified version of USEPA’s Stressor Identification (SI) guidance. Using this approach, we determined that toxic chemicals continue to be active stressors in NBH; a moderate nutrient stress exists as well, but we were unable to link the nutrient stressor with a source. Excess sedimentation does not appear to be an active stressor in this harbor. We found that the following tools were useful in diagnosing active stressors: toxicity tests, toxicity identification and evaluation (TIE) methods, comparison of grain size normalized total organic carbon (TOC) ratios with reference sites, and comparison of SICDIN with reference sites. This approach allowed us to successfully evaluate stressors in NBH retrospectively. This research allows the Agency to more accurately identify stressors within a complex coastal marine environment.
Description:
Under the Clean Water Act, states must categorize all surface waters in 305(b) reports and place those waterbodies that are impaired or threatened on 303(d) lists. Before the allowable total maximum daily loads (TMDLs) can be determined for a 303(d) listed site, the cause(s) of the impairment or threat to the waterbody must be identified. We evaluated a number of diagnostic tools for their ability to identify stressors in New Bedford Harbor (NBH), Massachusetts (USA), using a modified version of USEPA’s Stressor Identification (SI) guidance. The modifications include evaluating the source early in the diagnostic process, and linking source, stressor, and effect to identify the pollutant likely causing the impairment. The research includes tools under development that may be used to evaluate stressors in waterbodies. In this study we linked chemical sources and toxic chemicals in the sediment with spatial concentration studies; we also linked toxic chemicals in the sediment with toxicity test results using toxicity identification and evaluation (TIE) studies. For nutrients, we used geographical information systems (GIS) maps to determine sources and spatially integrated concentrations of dissolved inorganic nitrogen (SICDIN) to link nutrient levels with nutrient stress. Using this approach, we determined that toxic chemicals continue to be active stressors in NBH; a moderate nutrient stress exists as well, but we were unable to link the nutrient stressor with a source. Excess sedimentation does not appear to be an active stressor in this harbor. We found that the following tools were useful in diagnosing active stressors: toxicity tests, toxicity identification and evaluation (TIE) methods, comparison of grain size normalized total organic carbon (TOC) ratios with reference sites, and comparison of SICDIN with reference sites. This approach allowed us to successfully evaluate stressors in NBH retrospectively.