U.S. Department of the Interior
U.S. Geological Survey
Fact Sheet FS-171-95
Biscayne Bay Ecosystem |
Project Goals |
Ecosystem Studies |
Collaborators and Results
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 alteration and control of freshwater flow entering
Biscayne Bay.
- Urbanization of Dade County, thereby increasing storm runoff
and pollutants into Biscayne Bay.
- Natural and artificial changes to vegetation associated with
fires and urbanization.
- Natural disasters, including hurricanes, and prolonged wet
or dry seasons.
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:
- Assess the modern distribution of the plants and animals
(biota) of the Biscayne Bay ecosystem with respect to present
environmental conditions.
- Interpret the historical record of environmental change
within Biscayne Bay by using biotic indicators.
- Determine agents (natural and (or) human-induced) that may be
responsible for changes in the ecosystem of Biscayne Bay.
- Make recommendations concerning approaches for Biscayne Bay
restoration and monitoring.
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.
A Paleoenvironmental Record from Manatee Bay, Barnes Sound, Florida
For More Information, Please Contact:
Scott Ishman
U.S. Geological Survey
926A National Center
Reston, VA 20192
Telephone: (703) 648-5316
E-mail: sishman@usgs.gov
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