Volume transport and nutrient loading between Florida Bay and the Florida Keys National Marine Sanctuary through Long Key Channel

The purpose of this study was to directly quantify the transport of water and nutrients between Florida Bay and the Florida Keys National Marine Sanctuary. The study was located at Long Key Channel, the principal conduit for exchange between these two federally protected ecosystems. Measurements of volume and mass transport were taken using acoustic Doppler current meters along with concurrent collections of water for nutrient concentrations. These water samples were collected by an underwater autosampler engineered specifically for this project. Results indicate an annual net flux of 5500 metric tons of total nitrogen (TN) and 90 metric tons of total phosphorus (TP) from Florida Bay to the Atlantic through the Middle Keys tidal channels. These estimates are less than half of previously reported values and are minor compared to input of nutrients to the FKNMS from offshore tidal bores.