Increased inputs of anthropogenic nutrients in a water body can trigger increased algal biomass and eutrophic conditions that impair aquatic life and other designated uses. Chlorophyll a concentration is a surrogate for phytoplankton biomass and other symptoms of eutrophication. Schaeffer et al. (2011) developed a reference condition approach for deriving numeric nutrient criteria for Florida coastal waters based on chlorophyll a data derived from ocean-color imagery taken by the Sea-viewing Wide Field of View Sensor (SeaWiFS) satellite.
The chlorophyll a reference database was created by aggregating data from 74 segments of the Florida coast that are known to be relatively unimpacted by anthropogenic nutrient inputs and support designated uses. The segments came from the Florida Panhandle, West Florida Shelf, and Atlantic Coast from the Georgia border to Biscayne Bay. Segments that had poor satellite imaging as the result of bottom reflectance, coastal seagrass coverage, or dissolved organic carbon coloring were excluded from the database. Satellite-derived chlorophyll a values were validated using field data collected by various agencies.
Annual geometric means of satellite-derived chlorophyll a concentrations were calculated for each of the 74 coastal segments for the years 1998–2009 (n=12). Then, proposed criteria values for each segment were calculated from the 90th percentile of the annual geometric means distribution.
In addition, the study also included an approach to enable transition of assessments from the SeaWiFS satellite to two newer satellite sensors: the Moderate Resolution Imaging Spectroradiometer Aqua (MODIS) and the Medium Resolution Imaging Spectroradiometer (MERIS) (Schaeffer et al. 2011).
Reference:
Schaeffer, B.A., G.A. Sinclair, J.C. Lehrter, M.C. Murrell, J.C. Kurtz, R.W. Gould, and D.F. Yates. 2011. An analysis of diffuse light attenuation in the northern Gulf of Mexico hypoxic zone using the SeaWiFS satellite data record. Remote Sensing of Environment 115(12):3748–3757.