This project aims to increase the resilience of spotted turtle (Clemmys guttata) under anthropogenic and climate-induced stressors on Department of Defense (DoD) installations. The relative vulnerability of coastal and inland spotted turtle populations to hydrologic alterations, connectivity, and susceptibility will be evaluated using an interdisciplinary approach composed of laboratory, field, and model work. The spotted turtle is selected because it is currently under review for federal listing, and of the reptile and amphibian species under review, occurs on the most DoD installations (40 confirmed, ≥48 potential; DoD Partners in Amphibian and Reptile Conservation 2019; Petersen et al. 2017). Most research on the species has occurred in the Northeast U.S., with less information available for DoD sites in the Southeast and Mid-Atlantic. All populations are vulnerable under climate scenarios that reduce wetland hydroperiod. Coastal populations are additionally vulnerable to wetland loss and saltwater intrusion from sea level rise and overwash during major storm events (Willey et al. 2022; Agha et al. 2018, 2020). Thus, hydrology is considered the major climate-induced stressor because of its great impacts on turtle habitats and potential alterations to hydroperiod, water chemistry, and chemical transport. Spotted turtles are also exposed to landscape stressors such as distance to other suitable wetlands, road density, woody encroachment, and accessibility to potential poaching – a major threat to the species. Field work will focus on turtle movement, population surveys, quantifying stressors at occupied sites, collecting blood samples for measurement of chemical stressors and characterizing turtle health. Lab work will test the effects of salinity and temperature on physiological and immune responses in turtles. The omics-based assays will be conducted on a subset of biological samples collected from the field survey and controlled lab experiments. An individual based model (IBM) and Bayesian Network Relative Risk Model (BNRRM) supported by data will be used to explore how multiple stressors affect turtle populations and inform management for promoting their resilience on DoD installations. It is predicted that hydrological impacts on spotted turtle habitats will prove to be the primary factor influencing population resilience, with other stressors exerting less influence.

This project will involve a combination of field, laboratory and modeling work conducted over four years. Field work will occur at four DoD installations, one Department of Energy site, and one state park that borders a military installation. Field and laboratory work will quantify climate, landscape, and chemical stressors and evaluate the demographic (via population assessments), behavioral (via telemetry), and physiological (via biological and omics-based assays) effects on spotted turtles. Field and laboratory results will be used in two different modeling frameworks (IBM, BNRRM) to evaluate the effects of multiple stressors on this at-risk species.

This project will improve fundamental understanding of how multiple stressors interact to affect the resilience of spotted turtle populations. Although currently a candidate for federal listing under the Endangered Species Act, the species is widespread across DoD installations in the eastern U.S., affecting all service branches. Much of the research will occur in the Chesapeake Bay region, which is particularly vulnerable to climate stressors (e.g. sea level rise) and where DoD owns 1% of the land base and has 18 waterfront installations. The other portion of the work will occur in the southeastern U.S. where the species is very poorly known; the work would fill major data gaps for the region. In addition to providing baseline population data for monitoring future trends, the work would quantify stressors at each site and identify which stressors spotted turtles are most sensitive to, helping prioritize management actions and best management practices for the species.

References:

Agha, M., J.R. Ennen, D.S. Bower, A.J. Nowakowski, S.C. Sweat, and B.D. Todd. 2018. Salinity tolerances and use of saline environments by freshwater turtles: implications of sea level rise. Biological Reviews 93:1634-1648.

Agha, M., C.B. Yackulic, M.K. Riley, B. Peterson, and B.D. Todd. 2020. Brackish tidal marsh management and the ecology of a declining freshwater turtle. Environmental Management 66:644-653.

Department of Defense Partners in Amphibian and Reptile Conservation [DOD PARC]. 2019. Recommended Best Management Practices for the Spotted Turtle on Department of Defense Installations. Legacy Resource Management Program Report.

Petersen, C.E., R.E. Lovich, and S.A. Stallings. 2017. Amphibian and reptile biodiversity on United States Department of Defense Installations. A report to the Department of Defense Legacy Resource Management Program.

Willey, L.L., M.K. Parren, and M.T. Jones (eds). 2022. Status assessment and conservation plan for the spotted turtle in the eastern United State. Technical report to Virginia Department of Wildlife Resources and the U.S. Fish and Wildlife Service.