Pools and Fluxes of Nutrients in Florida Bay Sediments

Extensive and persistent phytoplankton blooms have plagued Florida Bay every fall and winter since 1992, reducing water-column light penetrations and causing continued seagrass mortality. Our previous research has shown that Florida Bay sediment nutrients might play a major role in initiating and supporting Florida Bay phytoplankton blooms. Because sediment quality is as important as water quality in controlling phytoplankton blooms and promoting seagrass regrowth in Florida Bay, any restoration efforts in Florida Bay will require information on the amounts and flux rates of nutrients supporting these persistent blooms. This project will determine the linkage between sediment nutrients and Florida Bay phytoplankton blooms.

We have measured spatial and seasonal variation in Florida Bay sediment nutrient pools and fluxes. Spatial variation in total sediment porosity, grain size, and carbon, nitrogen, phosphorous, and silica concentrations, as well as dissolved and solid-phase forms of nitrogen and phosphorous and microalgal abundance, were measured at 24 sites across Florida Bay in July and August 1997 and again in January and February 1998.

Sediment-water nutrient fluxes were measured quarterly at four sites in Florida Bay using four large acrylic chambers in situ.