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Project Summary Sheet

U.S. Geological Survey, Greater Everglades Priority Ecosystems Science (GE PES) Initiative

Fiscal Year 2006 Study Summary Report

Study Title: Historical Changes in Salinity, Water Quality and Vegetation in Biscayne Bay
Study Start Date:3/15/02   Study End Date: 9/30/06
Web Sites:;
Location (Subregions, Counties, Park or Refuge): Biscayne National Park, Miami-Dade County, Monroe County
Funding Source: USGS Greater Everglades Priority Ecosystems Science (PES) Initiative; South Florida Water Management District (Previous FY - not in FY05 or FY06)
Principal Investigator(s): G. Lynn Wingard
Study Personnel: (For FY06) Thomas Cronin; Chuck Holmes; William Orem; Debra Willard; L. Wingard; M. Marot; J. Murray; US Geological Survey. C. Budet, R. Ortiz, Contractors.
Supporting Organizations: South Florida Water Management District; Biscayne National Park, Southern Estuaries Sub-Team of RECOVER.
Associated / Linked Studies: Paleosalinity as a Key for Success Criteria in South Florida Restoration; Ecosystem History of the Southwest Coast-Shark River Slough Outflow Area; Monitoring Sub-Aquatic Vegetation through Remote Sensing: A pilot study in Florida Bay; and Synthesis of South Florida Ecosystem History Research. Also, DOI Landscape Initiative with Biscayne National Park (USGS Lead: Sonya Jones) and Venture Capital Fund Project Transitioning from a freshwater to a saltwater environment: the introduction of a non-native gastropod Melanoides tuberculatus into Biscayne National Park.

Overview & Objective(s): The objectives of this project were to examine in broad context the historical changes in the Biscayne Bay ecosystem at selected sites on a decadal-centennial scale, and to correlate these changes with natural events and anthropogenic alterations in the South Florida region. Specific emphasis was placed on historical changes to 1) amount, timing, and sources of freshwater influx and the resulting effects on salinity and water quality; 2) shoreline and sub-aquatic vegetation; and 3) the relationship between sea-level change, onshore vegetation, and salinity. In addition, historical seasonal salinity patterns were derived from biochemical analyses of ostracodes, foraminifers, and corals. Land management agencies (principally SFWMD, ACOE and Biscayne NP) are using the data derived from this project to establish performance criteria for restoring natural flow, and to understand the consequences of altered flow. These data also can be used to forecast potential problems as upstream changes in water delivery are made during restoration.

Status: SFWMD contract was completed in FY04, so in FY05 and FY06 we have focused our efforts on conducting additional analyses on samples to refine age models and preliminary interpretations of cores by filling in data gaps. Part of refining the age model includes developing a carbon correction factor for Biscayne. This task proved more difficult than anticipated and has involved collaborative work with Florida International University and Beta Analytical Laboratories. A report is currently being prepared detailing the Age Models developed from this effort. All faunal and floral data and all modern site data for Biscayne were proofed to original data and released in an Access database format in Spring 2006 at Summary reports on Biscayne cores were delayed while the age models were developed and database verified for release. These reports are currently being prepared and will be completed in FY07. Preliminary summaries of the syntheses of Biscayne Bay work were presented at the GEER conference in June 2006 and we are continuing to work with the RECOVER Southern Estuaries Team in establishing restoration targets for the Biscayne Bay ecosystem. This collaborative effort will continue in FY07 and will be incorporated into the Synthesis Project.

Recent Products:

Cronin, T. M. and Walker, H. A., 2006, Restoring Coastal Ecosystems and Abrupt Climate Change: An Editorial Essay: Climatic Change.

Cronin, T.M., Wingard, L. B., Dwyer, G. S., Swart, P. K., Willard, D. A., and Walker, H., 2006, Climate Variability, Sea-level Rise, and Coastal Ecosystem Restoration: Greater Everglades Ecosystem Restoration Conference, June 2006.

Orem, W., 2006, Historical Changes in Carbon, Nitrogen, and Phosphorus in Sediments from Biscayne Bay and Florida Bay: Greater Everglades Ecosystem Restoration Conference, June 2006.

Wingard, G.L., 2005, Application of Paleoecological Methods to Coastal Resource Management: An Example from Biscayne National Park, George Wright Forum, v. 22, n. 3, pp. 13-21.

Wingard, G.L., and project members, 2006, Ecosystem History Access Database, available at

Oral presentations have been given to the Southern Estuaries Sub-Team of the RECOVER Regional Evaluation Team (6-2005, 9-2006) and to Fish & Wildlife, South Florida Water Management District and ACOE personnel (8-2006).

Planned Products: Note: the first two planned products also are linked to the Synthesis Project.

Open File Report: Age Models for Selected Cores in Biscayne Bay and Florida Bay - Authors: Holmes, Wingard, Willard, Marot and Hudley. [Status: in preparation - expected release Fall 06]

Journal Article, potentially to be submitted to Estuaries - Historical distribution of environments in Biscayne Bay and Florida Bay - Authors: Wingard and Hudley. [Status: in review by Fall 06-Winter 07]

Journal Article - Late Holocene Environmental History of Biscayne Bay - Authors: Cronin, Wingard, Swart, Dwyer, Albietz [Status: in review by Fall 06-Winter 07]

Specific Relevance to Information Needs Identified in DOI's Science Plan in Support of Ecosystem Restoration, Preservation, and Protection in South Florida (DOI's Everglades Science Plan): [See Plan on SOFIA's Web site:]:

One of the primary DOI activities discussed in the DOI Science Plan is to "ensure that hydrologic performance targets accurately reflect the natural predrainage hydrology and ecology" (DOI Science Plan, p. 14). The primary goal of the Ecosystem History of Biscayne Bay study has been to determine the predrainage hydrology and ecology of the Bay and surrounding wetlands. Data from this project are being used by the Southern Estuaries Sub-Team (SET) of the Regional Evaluation Team (RET) of RECOVER to set performance measures (PMs) for Biscayne Bay. This team includes clients from DOI-NPS, DOI-F&WS, NOAA, ACOE, and SFWMD.

Additionally, this study supports the Biscayne Bay Coastal Wetlands Project and the Additional Water for Everglades National Park and Biscayne Bay Feasibility Study, and it provides information relevant to the Combined Structural and Operational Plan (CSOP) and Landscape Modeling Projects. This study supports these projects by 1) conducting research to understand the predrainage hydrology, including the amount, timing and seasonality of freshwater delivered to the bay historically; 2) examining the historical environmental conditions, including the linkage between hydrology (water quality and quantity), ecology, and habitats; 3) providing the modelers with data on historic conditions in order to set targets and performance measures that reflect natural hydrologic patterns; and 4) providing long-term historical data on trends and cycles within the biological component of the ecosystem that can be forecasted to predict the effects of implementation of hydrologic restoration on the ecology of coastal communities. Specifically, this study supports the Biscayne Bay Coastal Wetlands Project by addressing the questions "How much freshwater, and in what seasonal patterns, was delivered historically to Biscayne Bay?" (DOI Plan, p. 63), "What are the links between hydrology and ecology in the Biscayne Bay coastal wetlands?" (p. 64), and "What are the key indicators of natural ecological response . . ." and "what are the baseline conditions of the indicators?" (p. 66). The data generated by this project are particularly valuable because they provide 100 to 500 years worth of data on changes to the system. This study supports the Additional Water for Everglades National Park and Biscayne Bay Feasibility Study by addressing the questions "What were the physical and ecological conditions in . . . Biscayne Bay prior to drainage and modification . . ." (DOI Plan p. 63), "What are the hydrologic targets needed to mimic historic flows . . . ? (p. 63).

Key Findings:

  1. The salinity of Biscayne Bay has been steadily increasing over time in all nine cores examined. Although the timing and onset of increased salinity varies at the different core sites, there are no exceptions to this trend.
  2. Sites in both central and southern Biscayne Bay show indications of increasing marine influence at the sites. These trends could be a result of rising sea level, of changes to the natural flow of fresh water or both, but the timing of changes at some of the near-shore sites suggests both factors are involved.
  3. In near shore areas, distinct, but site specific, changes in freshwater influx over time have occurred, and our data suggest that some sites we assumed had historic point-source inflow of fresh water did not, even prior to human alteration of the natural environment. Wetlands sites in very close proximity to each other have historically been affected by localized hydrologic regimes.
  4. Implications for managers: 1) Biscayne Bay appears to be evolving toward a more marine environment and sea-level rise should be factored into the planning process; 2) generalized performance measures and targets for the near-shore and wetlands areas may not reflect the natural variability seen at these sites; and 3) mid-Bay sites are very different from near-shore sites and have been for hundreds of years, therefore restoration targets should not seek uniformity in benthic environments.

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