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Project Summary Sheet
Fiscal Year 2007 Project Summary Report
Project Title: Use of Amphibian Communities as Indicators of Restoration Success
Overview & Objective(s): Declines in amphibian populations have been documented by scientists worldwide from many regions and habitat types. No single cause for declines has been demonstrated, but stressors like acid precipitation, environmental contaminants, the introduction of exotic predators, disease agents, parasites, and the effects of ultraviolet radiation have all been suggested. Because of their susceptibility to these and other stressors, amphibians are important as indicators of ecosystem health. Amphibians are present in all habitats and under all hydrologic regimes in the Everglades. The species present and the occupancy rate of a given species differ greatly across those gradients. These differences are due to hydropattern, vegetation, and other environmental factors. The combination of species composition and proportion of each habitat occupied at a given time form unique communities defined by those environmental factors. Therefore, if these communities can be reliably defined and measured, Everglades restoration success can be evaluated, restoration targets can be established, and restoration alternatives can be compared. This study will develop methodologies for defining and measuring the membership and area occupancy of amphibian communities. Further, we will investigate the relationship of occupancy of amphibians with hydroperiod and other environmental factors. Finally, we will provide a method for measuring restoration success based on these communities. Our objectives include:
Status: We continue to use data previously collected from Everglades National Park and Big Cypress National Preserve to develop methods and models for defining amphibian communities using the Proportion Area Occupied (PAO) model and multivariate statistical techniques (see Fact Sheet 2004-3106). In Everglades National Park and adjacent Water Conservation Areas 3A and 3B, we completed fieldwork on a large scale study to determine the PAO by each amphibian species across habitats defined by hydropattern. The PAO method estimates the abundance of sites at which each species occurs based on the capture results of several visits to each site. This method takes into account that some species are more difficult to detect, given that they are present, than others. This sampling was conducted along a hydrologic gradient from very long hydroperiod sloughs to the extremely short hydroperiod rocky glades of eastern Everglades National Park. Our sampling included call count, visual encounter surveys, PVC refugia captures, and trapping in over 20 sites.
To date this project has accomplished portions of most of the overall objectives of the task. Amphibian data have been collected extensively from Big Cypress National Preserve. Some question remained about the geographic range of two species, barking treefrogs (Hyla gratiosa) and pinewoods treefrogs (Hyla femoralis) within the park. To better understand that issue, additional sampling has been conducted in the northern extent of Big Cypress to test hypotheses concerning the occupancy of these species. These hypotheses include habitat differences and pH of water.
Meetings have been held with US Fish and Wildlife Service staff at the headquarters for Panther and Ten Thousand Islands NWRs in Naples, FL to discuss sampling in those refuges. The proposals for special use permits have been submitted, and the special use permit was obtained for Ten Thousand Islands. Panther NWR is still pending. Sampling these areas will begin prior to the beginning of FY 2008. These data will be combined with data from Big Cypress NP and additional data collected by partners in the Conservancy of SW Florida (not-for-profit NGO) and used to refine the occupancy models.
Hydrology data was requested from the USGS and the PES-funded EDEN project. These data have been received and we are currently working on querying the database to obtain hydroperiod means for each sampling location. Once these data are organized, USGS biometrician colleagues will assist in creating a better model based on Bayes' theorem.
Recent & Planned Products:
In FY07, 2 peer-reviewed journal articles and 1 major technical report were published. We also gave several presentations at Local, National and International Conferences and 1 additional manuscript were submitted to peer-reviewed journals. We plan on submitting further manuscripts on the. We will present results of our study at national and international meetings during FY08. We will also provide results of model simulations on the web.
Specific Relevance to Information Needs Identified in DOI's Science Plan in Support of Ecosystem Restoration, Preservation, and Protection in South Florida (DOI's Everglades Science Plan): [See Plan on SOFIA's Web site: http://sofia.usgs.gov/publications/reports/doi-science-plan/]:
U.S. Department of the Interior, U.S. Geological Survey
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Last updated: 04 September, 2013 @ 02:08 PM(KP)