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Project Summary Sheet

U.S. Geological Survey, Greater Everglades Science Initiative (Place-Based Studies)

Fiscal Year 2003 Project Summary Report

Project Title: Paleosalinity as a Key for Success Criteria in South Florida Restoration

Project Start Date: 10/01/2000 Project End Date: 9/30/05

Web Sites: http://sofia.usgs.gov/flaecohist/

Location (Subregions, Counties, Park or Refuge): Everglades National Park, Monroe County

Funding Source: USGS's Greater Everglades Science Initiative (PBS)

Principal Investigator(s): G. Lynn Wingard

Project Personnel: Thomas Cronin; Chuck Holmes; James Murray; Robert Stamm; Joseph Murray, Carlos Budet, Jessica Albeitz, Marci Marot; US Geological Survey. Gary Dwyer, Duke University.

Supporting Organizations: South Florida Water Management District; Everglades National Park

Associated / Linked Projects: Historical Changes in Salinity, Water Quality and Vegetation in Biscayne Bay; Ecosystem History of the Southwest Coast-Shark River Slough Outflow Area; Monitoring Sub-Aquatic Vegetation through Remote Sensing: A pilot study in Florida Bay.

Overview & Objective(s): There are three primary objectives to this project. 1) Test and develop a methodology for extracting water chemistry data from selected calcareous marine/estuarine shelled animals. 2) Develop an understanding of the biology of the selected organisms so that the water chemistry data extracted from their shells can be put into temporal context. 3) Apply this technique to shells found in sediment cores that span the last 100-300 years of South Florida history in order to determine the seasonal variation in salinity and water sources prior to significant human alteration of the environment. These data will provide resource managers with the necessary information to establish targets and performance measures as restoration of more natural timing and delivery of water proceeds.

Status: Progress has been made on several methods of deriving salinity data from sediment cores. First, experimental work on molluscan shell chemistry and growth is in progress. Successful growth of Chione shells under known water conditions has been achieved both in the lab and the field; these shells are currently being analyzed and water chemistry will be analyzed as soon as an affordable lab can be found. Additional molluscan experiments have been started in FY03 using Sr as a marker introduced into the water periodically and testing growth and salinity tolerances of other common mollusks found within the cores in south Florida. Second, calibration of ostracode Mg/Ca ratios to instrumental salinity (Robblee, unpublished data) readings has been completed for core data from Russell Bank core; results showed that ostracode Mg/Ca can accurately predict salinity to within 1-4ppt. Mg/Ca ostracode data and molluscan assemblage analyses have been completed on core from Rankin Basin. Third, a statistical method of deriving a single salinity value from molluscan percent abundance assemblage data has been developed and compared to instrumental readings; this method tracks the trends in change. With additional experimental data on molluscan salinity tolerances this statistical method may provide accurate salinity estimates.

Recent & Planned Products: Two abstracts presented at GEER/Florida Bay Science Conference as a poster and a talk. A summary chapter on the Ecosystem History of Florida Bay, with the emphasis on Paleosalinity was generated for the Florida Bay PMC synthesis documented presented to the PMC at GEER. This summary will be published either as part of the whole PMC document, or independently. An OFR or journal article on the Rankin core will be written by Fall of FY03.

Relevance to Greater Everglades Restoration Information Needs: "Getting the water right" is one of the primary restoration goals identified by the South Florida Restoration Task Force. The Comprehensive Everglades Restoration Plan (CERP) Florida Bay Florida Keys Feasibility Study Project (FBFKFS) has specifically identified the importance of understanding freshwater flow into Florida Bay and the changes incurred due to alterations in flow. The USGS Science Plan for south Florida has identified five primary science objectives (SO) to address the needs of restoration and this project meets 3 of those objectives for Florida Bay: SO2, determine the historical setting of the greater Everglades ecosystem; SO3, establish baselines and variations for restoration targets; SO5, predict ecosystem response to anthropogenic and natural change. This project fulfills these objectives by providing information on natural patterns of change in salinity, water quality, vegetation, and benthic fauna in Florida Bay and the nearby wetlands over the last 100-500 years. Data on historical patterns of change over centennial and decadal time scales allows CERP project managers to set realistic restoration targets that take natural patterns of change into consideration, and provides predictive capabilities on how the system will respond to future changes.

Key Findings:

  • Synthesis of data from all paleoecology research done in Florida Bay to date has demonstrated that rainfall is the predominant driver of salinity variation in the Bay.
  • Comparison of Mg/Ca trace element record from sediment core ostracodes to instrumental salinity record from Florida Bay over the last 50 years has demonstrated that Mg/Ca accurately reflects salinity to within 1-4 ppt.
  • Significant freshwater influx occurred in the area of Rankin Basin prior to 1900 based on analyses of core.



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