Project: A Synthesis of Sediment Production, Transport, and Accumulation in Florida Bay

Web Sites: http://www.sfrestore.org/documents/ifp99/index.html, http://sofia.usgs.gov/, http://coastal.er.usgs.gov/flbay.

Location: Central Everglades (including Florida Bay)

Principal Investigator: Robert B. Halley, Geologist USGS 600 4th St. S. St. Petersburg, FL 33701
727-803-8747 x3020, 727-803-2032 (FAX), rhalley@usgs.gov

Project Personnel:

Other Supporting Organizations: USGS, SFWMD, ENP, NOAA

Associated Projects: Buttonwood Embankment, (Holmes); Remote Sensing of Florida Bay, (Stumpf); Bathymetry of Florida Bay, (Hansen); Geochemical Monitoring of Florida Bay, (Yates); Geochemistry of Wetland Sediments from South Florida, (Orem); Mudbank Seagrass Die-off, (Carlson)

Overview & Status: Project elements include the following processes: 1) modern rates of carbonate sediment production from radiocarbon measurements and geochemical measurements, mineralogical and chemical composition processes of erosion and deposition, resuspension and transport), recent deposition and the geography , geometry and biogeochemistry of net accumulation . Carbonate productivity in the Bay can be calculated using three methods. 1. accumulated sediments and dating to determine rates of sediment production Standing crop and turnover rate to determine short-term productivity and geochemical methods to determine short-term productivity and carbonate precipitation. Large discrepancies exist between the long-term and short-term productivity measures.. This geochemical validation and proposed sediment budget will indicate whether there has been a long-term change in the productivity of the Bay or if current processes can account for the differences inapparent sediment production and accumulation.

Needs & Products: Future ecosystem-scale changes in Florida Bay depend on changes in circulation that are, in part, a function of water depth. Water depth, in turn, changes in response to sea-level rise and changes in bathymetry. Several future sea-level rise scenarios have been published. This project defines the processes and rates of bathymetric change that, together with a sea-level rise prediction, allow water depths to be predicted and circulation changes to be modeled.

Products include several journal articles and USGS Open File reports as follows: Florida Bay salinity maps, surface and bottom salinity: the South Florida environment: Bottom types of Florida Bay: Sedimentary and biological environments, depth to Pleistocene bedrock, and Holocene sediment and reefthickness, Key Largo, South Florida; Geology and hydrogeology of the Florida; First-order time-averaged fluxes of 137Cs, 239+240Pu and Pb fluxes to 210Pb-dated sediments of Florida: Reconstructing the history of eastern and central Florida Bay using mollusk-shell isotope records: Sedimentary dynamics of Florida Bay Mud Banks on adecadal time scale.

Abstracts of Presentations at Meetings include: Stable carbon and oxygen isotopes in selected mollusks from Florida Bay: a paleoenvironmental perspective: Analyzing the isotopic composition of coral and mollusk skeletons to relate past salinity and nutrient levels in Florida Bay, Florida Bay mudbanks: relatively new piles of mostly old sediments: The dual roles of Florida Bay mudbanks in restoration: Seagrass facies and phases recorded in the sediments of Florida Bay: Florida Bay bottom-type map: West Everglades winter freshets during the current wet period and seasonal phase shifts in salinity cycles across Florida Bay: Increased salinity of Florida Bay and saltwater intrusion of the Biscayne aquifer during the early 20th century: simultaneous consequences of falling water tables along the margins of the Everglades: Providing a framework for assessment and restoration of the Everglades ecosystem: an example of the use of paleoecologic and geochemical data in Florida Bay: Sea-level rise and the future of Florida Bay in the next century.

Documents in preparation for FY2000 include: Finding the very recent past in Florida Bay: Identifying bomb radiocarbon in carbonate sediments: Sea-level rise and the future of Florida bay in the next century.

Application to Everglades Restoration: