PARENT SESSION
Poster Session 4: Marine Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Nutrient Mass Flux through Long Key Channel, Florida Bay.

Gibson, Patrick^*,1, Boyer, Joseph¹, Smith, Ned², ¹ Southeast Environmental Research Center, Miami, FL, USA² Harbor Branch Oceanographic Institution, Ft. Pierce, FL, USA

ABSTRACT- Florida Bay water quality has been an issue of much concern and research over the past 20 years. In this time, the bay has experienced massive ecological disturbances that include seagrass die off, persistent algal blooms, decline in fisheries, and a near 100% mortality of sponges that have been linked to water quality issues. Florida Bay estuary occupies the midpoint of a hydrological continuum connecting Lake Okeechobee and the Everglades to the north and the Florida Keys National Marine Sanctuary and reef tract in the Atlantic to the south and east. The reef tract has shown high rates of live coral loss in the last 20 years and some have hypothesized that eutrophication by outwelling of nutrients from Florida Bay is to blame. The nutrient dynamics in this hydroscape will be greatly affected by the Comprehensive Everglades Restoration Plan (CERP), an eight billion dollar effort to restore freshwater volume and flow to the everglades ecosystem. Nutrient budgets for the Florida Bay have been developed and models have been produced but these are largely unbalanced. The two published budgets are in disagreement about the flux of nutrients through the Keys passes and in fact vary by an order of magnitude and in opposite directions. This is largely due to applying coarse scale (monthly at best) nutrient measurements to different hydrological models operating on different scales. This study directly measured exchange of nutrients and water through Long Key Channel on a half-tidal time scale (6 hour or finer) in order to quantify mass flux between Florida Bay and the Atlantic. Preliminary results indicate that there is annual net export of N and P from Florida Bay; however this flux is flow driven as the flow-weighted mean concentrations of TN and TP are equivalent for inflows and outflows. Although rigorous analyses need to be completed it appears unlikely that water flowing from Florida Bay is capable of increasing nutrient concentrations of the Florida Keys National Marine Sanctuary waters.

Key words: florida bay, florida keys, nutrient flux, outwelling