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U.S. Department of the Interior
U.S. Geological Survey

Ecosystem History of Biscayne Bay and the Southeast Coast

Overview | Biscayne Bay Ecosystem | Project Goals | Ecosystem Studies | Collaborators and Results |


map showing Biscayne Bay region, seagrass, hardbottom and barren bottom communities

The U.S. Geological Survey is participating in a multi-institutional effort to assess, monitor, and restore the ecosystem of South Florida. Federal, State and local agencies are collaborating to establish a firm scientific basis for land management and water policy issues. Historical changes in South Florida related to rapid population growth in the early to middle 1900's have led to significant alteration of the natural hydrocycles and water quality of Florida and Biscayne Bays. These changes have affected the salinity and nutrient supply and introduced toxic components into Biscayne Bay. The Biscayne Bay ecosystem shows increasing signs of distress: declines in fisheries, increased pollution, and dramatic changes in nearshore vegetation. Northern and central Biscayne Bay are strongly affected by the urban development associated with the growth of Miami. Southern Biscayne Bay is influenced by drainage from the Everglades, which has been altered by canals and agricultural activities. Restoration and preservation of Biscayne Bay and Biscayne National Park are dependent on a comprehensive understanding of the linkages between the hydrologic system and the bay ecosystem, and of natural versus human-induced variability of the ecosystem.

Biscayne Bay Ecosystem

The ecosystem of Biscayne Bay includes the marginal freshwater and saltwater wetlands, intertidal communities, and marine communities. The health of each of these communities can be linked to their interaction with the hydrologic regime of South Florida. Major factors that may affect these communities are:

The health of the Biscayne Bay ecosystem requires that a critical balance be maintained among the ecosystem communities. Significant changes in one will ultimately affect the others. Changes in the wetland communities (including vegetation) can alter surface water flow regimes and bird and fish behavior. Alteration of seagrass distribution will affect mollusk, foraminifer, and ostracode distributions, among others. Our ability to interpret historical changes, as well as monitor future conditions, in the bay and surrounding area will allow us to improve or maintain the sensitive balance in freshwater quantity and quality necessary for the ecosystem components to continue to exist.

Project Goals

In order for the restoration of Biscayne Bay to begin, it is necessary to have a comprehensive understanding of the evolution of the present ecosystem. The goals of this project are as follows:

Ecosystem Studies

Modern biotic distribution and environmental data are gathered from surficial sediment and water samples collected throughout Biscayne Bay. The sediments are described and analyzed for animals (mollusks, foraminifera, ostracods) and plants (diatoms, pollen, and dinoflagellate cysts). Data from the water samples include temperature, salinity, dissolved oxygen, clarity, nutrients, and bacteria. These data are statistically compared to determine environmental conditions important to the distributions of the organisms.

The historical record is interpreted from the examination of biotic components from sediment cores collected on mudbanks within the bay. The interpretation of these biotic data, based on their modern distributions, allows us to reconstruct the ecosystem history of the bay. Dating of the core sediments is vital to our understanding of cause and effect relationships between changing environments and the ecosystem. Dating is accomplished by using several radiometric techniques that include Lead-210 and Cesium-137.

Collaborators and Results

The U.S. Geological Survey, through collaboration with the National Park Service, South Florida Water Management District, and Metropolitan Dade County Environmental Resources Management, will gain a more comprehensive understanding of the evolution of the Biscayne Bay ecosystem and its components. This understanding will allow us to determine the impact of increasing human population and activities on the ecosystem and allow planners to make well founded decisions regarding restoration and land use policies for the future.

The ecosystem history of Biscayne Bay and the Southeast Coast of Florida Project anticipates the following products:
  • A distribution map of the major biotic, sedimentologic, and hydrologic components analyzed.
  • Maps describing the changes in the ecosystem through time.
  • A digital database describing the modern distribution of plants and animals in the bay.
  • A synthesis document on the ecosystem history and evolution of Biscayne Bay.
The project has the following schedule:
  • Collect seasonal surficial sediments as assess core site localities.
  • Collect short cores.
  • Write a report on modern biotic distributions.
  • Prepare time series analyses of ecosystem change.
  • Compilation of historical ecosystem data into synoptic maps and electronic data.

By Scott Ishman

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For more information contact:

Scott Ishman
Geology Department
Mail Code 4324
Southern Illinois University
Carbondale, Ill 62901
Telephone: (618) 453-7377
E-mail: sishman@geo.siu.edu

Related information:

SOFIA Project: Ecosystem History of Biscayne Bay and the Southeast Coast

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