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EUTROPHICATION OF COASTAL WATER BODIES: RELATIONSHIPS BETWEEN NUTRIENT LOADING AND ECOLOGICAL RESPONSE
Citation:
Latimer, J S., G Cicchetti, E H. Dettmann, R A. McKinney, S Rego, D J. Keith, AND R. R. Ahlgren. EUTROPHICATION OF COASTAL WATER BODIES: RELATIONSHIPS BETWEEN NUTRIENT LOADING AND ECOLOGICAL RESPONSE. Presented at International Symposium on Global Patterns of Nutrient Over-Enrichment in Coastal Waters, Washington, DC, October 11-13, 2000.
Description:
This newly initiated research will provide environmental managers with an empirical method to develop regional nutrient input limits for East Coast estuaries/coastal water bodies. The goal will be to reduce the current uncertainty associated with nutrient load-response relationships. The physical factors that affect tbe sensitivity of coastal systems to nutrient driven effects (e. g., algal biomass changes, hypoxia, and loss of submerged aquatic vegetation) will be investigated. We will initially examine estuaries, sub-estuaries, and embayments from systems distributed throughout the southern New England region. This approach will minimize latitudinal variation and ensure that the results are widely applicable. A combination of three indicators (chlorophyll-a, SA V index, and benthic condition. either individually or as a multidimensional index) may provide a valid and reasonable means to assess the system's response to nutrient over enrichment, and allow legitimate comparisons between systems. Time-averaged remotely sensed chlorophyll-a data will approximate water column biomass response to nitrogen loading. Seagrass coverage will integrate the shallow water benthic response, and sediment profile camera images will assess deep-water benthic condition. Within an estuarine system, all three variables provide good spa~al coverage, an extremely important criterion for this type of assessment. Once nutrient load-response relationships are successfully formulated for this region, we will expand this approach to other areas of the East Coast The expected research results will be delivered in stages; each successive tier will refine the scientific basis for management decisions. The first tier will be the development of a method to determine if a system has a eutrophication problem. This will be achieved from load-response models for the three response variables. These models, when validated, may have utility as regulatory tools to help set TMDL or TMAL limits. The models will also improve the scientific understanding of system response to nutrient pollution. possibly resulting in the identification of assimilative capacities and thresholds of response. The second tier will be to refine the models and reduce uncertainties in the initial relationships. This will more accurately determine the level of impairment due to nutrients. Eventually, state level managers may use the generated load-response relationships to determine acceptable loadings for different categories of designated use of coastal receiving waters.