Amanda N. Rice¹, J. Hardin Waddle¹, Valerie M. Johnson², Kenneth G. Rice³ and Frank J. Mazzotti^4
1University of Florida, Department of Wildlife Ecology and Conservation, Gainesville, FL
²University of Florida, Department of Wildlife Ecology and Conservation, Big Cypress National Preserve, Ochopee, FL
³U.S. Geological Survey, Florida Integrated Science Center, Fort Lauderdale, FL
⁴University of Florida, Institute of Food and Agricultural Sciences, Fort Lauderdale Research and Education Center (IFAC/FLREC), Fort Lauderdale, FL

Declines in amphibian populations have been scientifically documented worldwide in many regions and habitat types. No single cause for these declines has been found, but stressors such as water diversion, acid precipitation, environmental contaminants, exotic predators, disease, parasites, and ultraviolet radiation have all been suggested as potential factors. Because of their susceptibility to these and other stressors, abundance in many aquatic systems, and role in transferring energy from aquatic to terrestrial habitats, amphibians are important indicators of ecosystem health. Through system-wide monitoring, Everglades amphibian communities can act as sentinels of overall ecosystem health as well as indicators of restoration success.

We show that hydropattern can shape amphibian communities in the Everglades. Amphibians are present in all habitats and across the entire hydrologic gradient in the Everglades. However, species occurrence and occupancy rates (that is, the proportion of a given habitat in which a species is found) differ greatly across this gradient. Although little historic information is available concerning amphibian populations in the Everglades, we can observe differences in community structure across the current hydrologic gradient and infer historic conditions using hydrologic modeling tools such as the Natural Systems Model. For example, we can describe the past or future of a community with a restored, longer hydroperiod in Water Conservation Area 3B by observing the present community of similar hydroperiod, vegetation, elevation, etc. in Water Conservation Area 3A. Observed changes in community structure due to the hydropattern gradient include both changes in species composition (from toad to aquatic salamander dominated communities) and occupancy rates (10% to 90% by a species). The combined use of species presence and occupancy rates across the Everglades amphibian community is a powerful tool for assessing restoration effects as a single model applies to the entire Everglades system.

Current observations of community structure and descriptions of historic and restored conditions can be used to establish restoration targets for (and monitoring restoration effects on) amphibian communities in the Everglades. Monitoring of species presence and occupancy on a 3 to 5-year basis should be sufficient to detect changes such as colonization or local extinction of species in the amphibian community due to restoration.

Contact Information: Kenneth G. Rice, U.S. Geological Survey, Florida Integrated Science Center, 3205 College Ave., Ft. Lauderdale, Florida, 33314, Phone: 954-577-6305, Fax: 954-475-4125, Email: ken_g_rice@usgs.gov

(This abstract is from the 2006 Greater Everglades Ecosystem Restoration Conference.)

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