The Role of Aquatic Refuges in the Wetland Complex of South Florida in Relation to Restoration

We defined fish and macro-invertebrate composition, movements, and ecology in surface and near-surface subterranean aquatic habitats. We also cooperated to define the habitat/topographic characteristics that make this region unique. Our objectives were to help define the seasonal movements of fishes in the region in relation to hydrology to provide data for modeling the interactions of hydrology, geology, and aquatic organisms.

The primary goal was to define the interactions of the aquatic-animal community with the geologic structure and hydrologic conditions of the Rocky Glades. This project addressed questions that have arisen from past work there. How do composition, size-structure, and recruitment of aquatic animals change during the flooding period? Are the dispersal patterns of animals related to water flow? Are the animals dispersing from the main sloughs to recolonize the Rocky Glades, or is the Rocky Glades a source of animal colonists for the sloughs? Do roadways act as barriers to movement? The objectives of this study segment were:

1. Collect baseline ecological data on the epigean aquatic communities in the karst landscape of the Rocky Glades.

2. Quantify the direction and degree of dispersal by fishes and invertebrates during the wet season.

3. Document the seasonal changes in species composition, size structure, and reproductive patterns of animals on the wetland surface.

4. Survey the topography of representative areas of the Rocky Glades, particularly around the sampling sites, to provide depth-distribution data for the simulation model of the region.

5. Develop a visual survey method for sampling fish communities in open, rugged terrain to follow community dynamics in the Rocky Glades in the wet season.

6. Identify the extent of near-surface voids.

The Atlantic Coastal Ridge is another area affected by urbanization and changing hydrologic management. Aquatic habitats, such as the transverse glades that cut through the Ridge, have been replaced by canals and will not be restored. Ground-water habitats and animal communities may have been less affected. As in karst areas elsewhere, deeper geological formations (>5 m) beneath the Rocky Glades and the Atlantic Coastal Ridge have voids of various dimensions known to house truly subterranean aquatic species (Radice and Loftus 1995, Bruno et al., 2001). These include the Miami Cave Crayfish (Procambarus milleri), known only from a few wells in southern Florida (Hobbs 1971). The composition, distribution, and abundance of other hypogean animals are poorly known. Ground-water withdrawal and saltwater intrusion (Leach et al. 1972), limestone mining, and pollution may threaten these communities before they have been fully catalogued.

The second goal of this project was to identify the composition, distribution by depth and space, and ecological relations of this subterranean fauna. The objectives of the second study element included:

1. Develop effective traps to capture invertebrates and possibly fishes from subterranean habitats.

2. Inventory hypogean communities and relate the composition and distribution to environmental factors.

3. Collect life-history data for the Miami cave crayfish from a large captive population.