The role of advection in transporting nutrients to the Florida reef tract

Near-bottom current meter and dissolved nutrient data are used to describe the advection of nutrients from theFlorida Keys to the reef tract, where elevated nutrient concentrations have been shown to adversely affect reefcorals. Results indicate a long-term across-shelf flow toward the reef tract that averaged 2 cm s⁻¹ during the 13-month study. Combining the average flow rate with a representative dissolved inorganic nitrogen (DIN)concentration of 2.71µM yields an average DIN transport rate of 55 µmole m⁻² s⁻¹ seaward past the study site.Low-frequency, non tidal across-shelf flow was toward the reef 80% of the time and a mean of 11 days was requiredto transport nutrients 8 km from the Keys to the reef tract (median = 4. 7 d). M₂ tidal currents transport nutrientsseaward 0.38 km during the average ebb. Spectral analysis indicates no cause-and-effect relationship betweenacross-shelf flow and the local wind field.