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Project Summary Sheet

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

Fiscal Year 2002 Project Summary Sheet

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

Web Sites:

Location (Subregions & Counties): Greater Everglades

Funding (Source): USGS Place-Based Studies

Principal Investigator(s): 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:

Supporting Organizations: USGS/BRD, NPS, ACE, EPA

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). Snail kite abandonment of wetlands in dry down conditions have led to unsubstantiated conclusions that drying events (presumably of any timing and duration) devastate snail populations, thus forcing kites to leave. Researchers and natural resource managers have subsequently 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. We did find that dry down timing was critical for recruitment, in that applesnails cease egg cluster laying (oviposition) once water levels fall below approximately 10 cm. A substantial portion of our effort will focus on snail kite foraging habitat, which consists primarily of wet prairie and slough (the relative importance of these discrete habitats types to kites has not been documented). The proposed study, for the first time, will provide data linking snail abundance to hydrology and habitat structure using validated sampling methods

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.

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.

Study Milestones
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Familiarity           x x        
Design             x o o o  
Field Work               o o o  
Data Analysis               o o o  
Initial Reporting               o      
Quality Assurance                 o o  
Results Published                 o o  
Synthesis                   o  
Note: "x" indicates task completed during quarter, and "o" indicates task planned, but not completed

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