USE OF ECOSYSTEM HISTORY DATA IN RESOURCE MANAGEMENT AND RESTORATION: A CASE STUDY FROM FLORIDA BAY, EVERGLADES NATIONAL PARK

The diverse ecosystems of Everglades National Park include approximately 850 mi² of Florida Bay, a shallow estuarine body of water. Like the terrestrial Everglades, Florida Bay is currently the subject of a massive ecosystem restoration effort due to critical issues in Florida Bay, including salinity, water quality, and the health of the seagrass beds. In order to restore ecosystems to their natural state, however, it is necessary that land management agencies understand natural ecosystem variability prior to 20^th century human disturbance.

Paleoecological and geochemical data from short cores collected in Florida Bay provide evidence for natural variability in salinity and seagrass density and abundance prior to significant human activity in the region. These data are contrasted to post-human alteration data in order to establish the component of change that can be attributed to human activity versus change due to natural cycles.

Molluscan paleoecology exemplifies the human-induced changes that have occurred in Florida Bay in the latter half of the 20^th century. Data from five cores show an increase in the mussel Brachidontes exustus, which is tolerant of poor water quality and a wide range of salinities. The same cores also show a dramatic decrease in molluscan diversity during the last forty years. These findings indicate a system under stress. Conversely, paleoevidence indicates that the well-publicized seagrass die-off of 1987-88 may have been part of a natural cycle. Current research includes efforts to extract monthly and seasonal salinity patterns from analyses of mollusc shell growth layers. These analyses will illustrate monthly, seasonal and annual changes in water chemistry prior to alteration of the natural flow, thus providing target data for the restoration efforts to restore historical seasonal flow into Florida Bay.