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 Aquatic habitats, such as the transverse glades that cut through the Ridge, have been replaced by canals and will not be restored.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.
Klein, H.; Hampton, E. R.
Prepared in cooperation with the Central and Southern Florida Flood Control District, the Bureau of Geology Florida Department of Natural Resources, and other State, local, and Federal agencies
Johnson, R. A.; Anderson, G.
Loftus, W. F.
Loftus, W. F.; Perry, S. A.
The paper was presented at the U.S. Geological Survey Karst Interest Group meeting, St. Petersburg, FL, February 13-16, 2001
Bruno, M. C.; Cunningham, K. J.; Perry, S. A.; Trexler, J. C.
The paper was presented at the U.S. Geological Survey Karst Interest Group meeting, St. Petersburg, FL, February 13-16, 2001
Kobza, R. M.; Padilla, D.; Trexler, J. C.
Poster presented at the Greater Everglades Ecosystem Restoration (GEER) Conference, April, 2003
When the wetlands reflooded in June, we collected samples daily for the first two weeks, then reduced the frequency to twice weekly for the next two weeks, and finally made collections once a week until the marshes dried. All animals were identified, weighed, and measured in the lab, and the numbers of animals in each trap on a particular day was compared to the water flow and depth to assess directional movement. We processed samples of fishes and crayfish for stable-isotope analysis as they appeared on the surface to compare with isotope signatures after several weeks and several months aboveground. We also saved fishes for analysis of reproductive status to learn whether they are ready to spawn upon emergence onto the surface.
To complement data from the arrays, which are activity traps, we used visual sampling (Loftus et al. 1992; Frederick and Loftus 1993) to estimate fish composition and density on the surface of the Rocky Glades. We set up 24 survey plots, six at each array, that were scanned by binoculars each week in the wet season. Each 4-m2 plot was scanned for 2 minutes, and all individuals seen were counted, and identified to species and size-class.
We began to survey the micro-scale topography of representative areas of the Rocky Glades. The physical characteristics of the sampling sites are required in the simulation model. The surface extent and depth dimensions of solution holes and surrounding marsh surface are measured by standard surveying techniques. Those physical characteristics will be correlated with biological measures of species composition, survival, and density. We have begun to use ground-penetrating radar (GPR) to try to estimate belowground extent of deep solution holes.
To inventory the hypogean fauna beneath Rocky Glades and the Atlantic Coastal Ridge, we selected a series of existing wells along four east-west transect lines from Miami to Homestead in which to sample routinely. Borehole videography is helping us to select the best wells and depths for sampling. We are using a combination of pumping and filtering ground water from wells to collect copepod crustaceans (Bruno et. al., 2001, WRIR 01-4011). We tested several designs for traps to collect larger invertebrates and possibly fishes in wells. We also used GPR to locate areas of high porosity in which hypogean animals might be likely to occur. Drilling of new wells to access subterranean cavities began in February 2001, in which a combination of videography and trapping was used to capture and record animals for study. Any fishes or invertebrates collected were identified, and then sent to specialists for confirmation.
We used YSI-6000 continuous recorders to measure water-quality in ground water to characterize the environment of hypogean organisms. We collected parameters such as dissolved oxygen, pH and temperature at the surface, middle and bottom of the wells. We attempted to correlate the environmental variables with species distributions.
We collated data on the distribution of the Miami Cave Crayfish from wells, and trapped for it in existing and new wells. Because it is difficult to obtain enough wild-caught animals on which to base a life-history study, we gained access to a captive population at a local fish farm where we performed monthly assessments of the proportion of males, females, gravid females, and juveniles in the population, their size distributions, size at maturity, fecundity, egg size, and other important life-history parameters.
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