NCCOS Project Explorer (NPE)

Benthic and pelagic grazing of phytoplankton in Florida Bay(2010)

Project Description:
Modifications made to the Everglades as a result of the Comprehensive Everglades Restoration Plan (CERP) could have a significant impact on habitats and living resources within Florida Bay and the surrounding marine system as well as aesthetic, resource management, or economic impacts. The South Florida Program (SFP) is the primary NOAA contribution to addressing South Florida ecosystem restoration and CERP goals, and aims to develop a capability to understand and predict changing conditions in South Florida coastal areas by supporting an integrated suite of research and modeling activities investigating the downstream effects of Everglades restoration on the South Florida coastal system. CSCOR-sponsored research is characterizing present conditions and ecosystem processes towards a goal of gauging or predicting future impacts of CERP decisions on valuable marine resources and managing those resources from that perspective. This large investment of human resources and finances has resulted in a reasonable scientific understanding of the marine system and a clearer indication of potential changes in water quantity and quality in and into Florida Bay, the Florida Keys, Biscayne Bay and the SW Florida shelf resulting from proposed CERP scenarios. Research is focused on data collection/synthesis and system modeling and is being directed at the broader goals of the region-wide CERP restoration, particularly combining and meshing current Everglades, Biscayne Bay, Florida Keys, and surrounding waters hydrologic and water quality models into a single comprehensive regional ecosystem model. Without this research, calibration, and verification of the Regional hydrologic and water quality models and quantifying important physical and water quality parameters of the system would not be possible. Benthic & Pelagic Grazing of Phytoplankton in Florida Bay: Florida Bay is a critical habitat and nursery for a wide range of commercially and recreationally important fish and invertebrate species. Unfortunately, this estuarine ecosystem has experience an unprecedented series of ecological disturbances during the past decade, including decreased water clarity associated with frequent picocyanobacteria blooms (i.e., Synechococcus sp.). These recurrent algal blooms are a primary water quality concern ss high concentrations of algal biomass have been implicated in the loss of seagrasses, resource fisheries, sponges and spiny lobsters in this system. To date, the focus has focused almost exclusively on nutrients as the cause of algal blooms. However, preliminary data has led us to an alternative hypothesis: algal blooms are being promoted by a substantial reduction in the two primary algal mortality processes, benthic grazing by sponges and pelagic grazing by zooplankton. Although sponges were formerly the primary benthic grazer in Florida Bay, the recent loss of sponge biomass in this system has substantially decreased the grazing loss rates for algal cells.

Expected Outcome:
The CSCOR South Florida Program research and modeling outcomes support the development of alternative management strategies, and the prediction of changes in the ecosystem due to restoration scenarios proposed. Outcomes include: • Quantified the exchange of water and nutrients over the Southwest Florida shelf into Florida Bay as baseline data. • Quantified nitrogen transformations within key vegetation units across Taylor Slough. • Quantified the net exchange of N between Taylor Slough/River and Florida Bay along the longitudinal axis of the Mangrove Salinity Transition Zone. • Quantified spatial distribution of sediment parameters relevant to DOP cycling in Florida Bay, essential for the Florida Bay model for predicting the sediment/water exchange of DOP. • Characterized components of the DOM from the source waters of Taylor Slough and Shark Slough, and the bioavailability of individual components to to plankton communities. • Quantified the role of DOM in plankton dynamics of Florida Bay. • Quantified data on the status of the seagrasses within the FKNMS, the importance of seagrass primary production in the FKNMS, baseline conditions for the seagrass community health and determined relationships between water quality & benthic community status. • Identified trends in the distribution and status of the benthic soft bottom communities in Florida Bay. • Quantified grazing rates of the primary benthic (sponge) and pelagic (zooplankton) herbivores on phytoplankton communities in Florida Bay. The primary outcome of the Benthic & Pelagic Grazing of Phytoplankton in Florida Bay project is to determine the grazing rates of the primary benthic (sponge) and pelagic (zooplankton) herbivores on the various groups of phytoplankton within Florida Bay. Results will be directly usable for the water quality model under development by the South Florida Water Management District and will also be applicable to the development of alternative management strategies and the prediction of changes in the ecosystem due to restoration scenarios proposed.