Florida Keys National Marine Sanctuary Water Quality

The Florida Keys are an archipelago, which extend in a NE to SW direction from Miami to Key West and out to the Dry Tortugas. In 1990, President Bush signed into law the Florida Keys National Sanctuary and Protection Act (HR5909) which designated a boundary encompassing >2,800 square nautical miles of islands, coastal waters, and coral reef tract as the Florida Keys National Marine Sanctuary (FKNMS). The Comprehensive Management Plan required the FKNMS to have a Water Quality Protection Plan (WQPP) thereafter developed by EPA and the State of Florida (EPA 1995). The original agreement for the water quality monitoring component of the WQPP was subsequently awarded to the Southeast Environmental Research Program at Florida International University.
Quarterly field sampling program began in March 1995. Field parameters measured at each of 112 station (surface and bottom at most sites) include salinity (practical salinity scale), temperature (°C), dissolved oxygen (mg L-1), turbidity (NTU), photosynthetically active radiation (PAR), and light attenuation (Kd, m-1). Water quality variables (all reported in mg L-1) include the dissolved nutrients NOx (EPA353.4), nitrite (EPA353.4), ammonium (EPA350.1), and soluble reactive phosphorus (EPA365.1). Total unfiltered concentrations include those of nitrogen (ASTM D7156), organic carbon (NU-062-1.8), phosphorus (EPA365.1), silicate (EPA366.0) and chlorophyll a (SM10200H; μg L-1).
Spatial biogeochemical characterization of the FKMNS waters using Factor Analysis and Hierarchical Clustering rendered seven biogeochemically distinct water bodies whose spatial distribution is closely linked to geomorphology, circulation, benthic community pattern, and human impact. Water type segments are, Lower, Middle and Upper Keys, Offshore, Marquesas, Back Country, Back Shelf. This segmentation has been adopted with minor changes by federal and state environmental agencies to derive numeric nutrient criteria.