Project: Community Dynamics along a Salinity/Habitat Gradient in Florida Bay

Web Site:

Location: Central Everglades, including Florida Bay; Monroe County

Principal Investigator: Michael B. Robblee, Mike_Robblee@usgs.gov, 305.348.1269

Project Personnel: Ed Matheson, eddie.matheson@dep.state.fl.us, 727.896.8626x2223; Gordon Thayer, gordon.thayer@noaa.gov, 252.728.8747; Lawrence Rozas, lawrence.rozas@noaa.gov, 409.766.3532

Other Supporting Organizations: NOAA/National Marine Fisheries Service; Florida Department of Environmental Protection/Florida Marine Research Institute

Associated Projects: NOAA Pink Shrimp (Joan Browder and Maria Criales), Johnson Key Basin shrimp project (Michael Robblee)

Overview & Status: This is Year 2 of a three year project to evaluate fish and invertebrate community structure in seagrasses in relation to salinity in Florida Bay. The goal was to compare the communities present in relation to seagrass and salinity. Project objectives included documenting fish and shrimp community structure: at the end of the dry season (annual high salinity) and wet season (annual low salinity); along the local depth/macro habitat gradients (bank, basin and near key); in relation to seagrass micro-habitat (seagrass blade density, blade length, biomass, etc.); and in years when the bay functioned as a positive estuary and as a negative estuary. Field collections have been completed. Unfortunately extremes (positive, negative estuary) of salinity conditions were not encountered during the two years and 4 seasonal collections. Sample processing is on schedule. The Oracle database planned for this project is running and needs to be tested. An initial publication describing methods and our first year results is in preparation.. Florida Bay is a marine lagoon located downstream of the Florida Everglades. Salinity patterns influence biological activities greatly. Direct freshwater flow into Florida Bay occurs through Taylor Slough or the C-111 Canal into northeastern Florida Bay. Shark River Slough, the principal freshwater flow way of Everglades National Park, empties into Whitewater Bay and the mangrove estuaries of the Park’s southwest coast. Freshwater from Shark River Slough enters Florida Bay from the west after mixing with near shore waters of the Gulf of Mexico. Salinity conditions in Florida Bay vary with rainfall in south Florida both seasonally and inter-annually. During extremely wet periods in south Florida estuarine conditions may extend over most of Florida Bay. Thus, among years, Florida Bay ranges between a positive and negative estuary, during very wet and very dry years, respectively. Storing and diverting water for water supply and flood control have modified the quantity, timing and distribution of fresh water flows entering Florida Bay. This thought to have contributed to a general marinification of the bay over the last century and to have increased the frequency and intensity of hypersaline events. Upstream channelization has increased the speed with which floodwaters enter the bay and the rapidity with which subsequent salinity changes occur, especially in northeastern Florida Bay.

Needs & Products: This project is generally on schedule. The greatest need would be for an extremely wet or dry year to occur in south Florida and for the bay to exhibit positive or negative estuarine conditions. It would then be appropriate to continue field collections in order to capture fish and invertebrate community responses across the bay representative of these conditions. Absent extreme salinity conditions this project has documented the seasonal distribution of fish and invertebrates in relation to macro and microhabitat conditions across Florida Bay for two generally average years. This data set strongly complements the long-term data set being developed for Johnson Key Basin. Publications are planned which will thoroughly discuss these data in relation to salinity and seagrass habitat.

Application to Everglades Restoration: Understanding the relationship between salinity and secondary productivity (abundance, community structure, recruitment, etc.) in Florida Bay is a critical science need in order for management to make decisions on restoration of Florida Bay.