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Project Summary Sheet

U.S. Geological Survey, Greater Everglades Science Program: Place-Based Studies Initiative

Fiscal Year 2003 Project Summary Report

Project: The Influence of Hydrology and Associated Habitat Structure on Spatial and Temporal Patterns of Applesnail Abundance and Recruitment

Project Start Date: 2001 Project End Date: 01/31/2005

Web Sites: ATLSS.ORG

Location: The Greater Everglades ecosystem

Funding Source: Critical Ecosystems Studies Initiative

Principal Investigator: Dr. Phil Darby, Department of Biology, University of West Florida, 11000 University Parkway, Pensacola, FL 32514,, PH: (850) 474-2647 Co-P.I.s: Dr. George Stewart, University of West Florida, Pensacola, FL. Dr. Rob Bennetts, USGS/BRD, Gainesville, Fl

Project Personnel: Donald L. DeAngelis, Phone: 305-284-1690 e-mail:

Other Supporting Organizations: USGS/BRD, NPS

Associated Projects: Component of ATLSS Program

Overview & Status: As the exclusive food of the endangered snail kite and prey to a variety of other wetland fauna, applesnails are generally recognized as a critical resource warranting monitoring in the context of the Greater Everglades ecosystem restoration (Science Subgroup 1996, USFWS 1999). Researchers and natural resource managers have recommended nearly continuous inundation of wetlands deemed critical habitat to kites. We have found, however, that adult applesnails aestivate in dry down conditions for 2 to 3 months in duration with 84% to 63% survival, respectively. Our preliminary results indicate consistently higher snail densities in the prairie habitat relative to the Nymphaea-dominated slough. A similar trend was found for crayfish. Habitat effect on freshwater prawn density varied among sites, but no overall habitat effect was indicated. Our data appear to support the hypothesis that snail abundance in prairie exceeds that in slough habitats. We are also testing the hypothesis that snail abundance differs between prairie versus slough habitats, as well as the selection of these habitats by foraging kites. Qualitative assessment of our data thus far suggests that within the wet prairie communities, there may be specific associations among snails and some plant species. Such associations will be a primary focus of our study over the next two years, and we expect to refine our hypothesis regarding apple snail-plant community- snail kite interactions accordingly.

Needs & Products: The overall goal of the proposed project is to provide information to help predict the impact of changes in hydrology (and associated vegetation) to applesnail abundance following WCA-3A decompartmentalization. The specific objectives for the proposed project are as follows: (1) estimate applesnail abundance in wet prairie habitats (relatively short hydroperiod) relative to slough habitats (relatively long hydroperiod) with potential linkages to snail kite foraging habitat selection; (2) estimate snail abundance in sites with foraging snail kites, and incorporate data from the study into a larger coordinated effort to link snail kite habitat use and snail availability; and (3) document baseline seasonal applesnail egg production (not yet available in wetlands south of Lake Okeechobee) and assess the potential impacts of drying events on annual snail egg production. Given the inextricable link between hydrology, vegetation and apple snails, our research effort will support the development of ecologically significant performance measures that respond to the Greater Everglades restoration activity.

Application to Everglades Restoration: The applesnail is an important performance measure in CERP because it is the exclusive prey of the snail kite, and information on apple snail production and spatial distribution under different water management is essential for CERP evaluations.

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