SREL Reprint #2982




Remarkable Amphibian Biomass and Abundance in an Isolated Wetland: Implications for Wetland Conservation

J. Whitfield Gibbons1,2, Christopher T. Winne1,2, David E. Scott1, John D. Willson1,2, Xavier Glaudas3, Kimberly M. Andrews1,2, Brian D. Todd1,2, Luke A. Fedewa4, Lucas Wilkinson1, Ria N. Tsaliagos5, Steven J. Harper1,2, Judith L. Greene1, Tracey D. Tuberville1,2, Brian S. Metts1,2, Michael E. Dorcas6, John P. Nestor1, Cameron A. Young1,2, Tom Akre1, Robert N. Reed7, Kurt A. Buhlmann1, Jason Norman1, Dean A. Croshaw1,8, Cris Hagen1, and Betsie B. Rothermel1

1Savannah River Ecology Laboratory, University of Georgia, Drawer E, Aiken, SC 29802, USA
2Institute of Ecology, University of Georgia, Athens, GA 30608, USA
3University of Nevada, Las Vegas, 4505 Maryland Parkway, Las Vegas, NV 89154–4004, USA
4Partners in Amphibian and Reptile Conservation, 2221 West Greenway Road, Phoenix, AZ 85023, USA
5Wayland Baptist University, 5530 E. Northern Lights Boulevard, Suite 24, Anchorage, AK 99504, USA
6Department of Biology, Davidson College, Davidson, NC 28035–7118, USA
7Department of Biology, Southern Utah University, Cedar City, UT 84720, USA
8Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148–0001, USA

Abstract: Despite the continuing loss of wetland habitats and associated declines in amphibian populations, attempts to translate wetland losses into measurable losses to ecosystems have been lacking. We estimated the potential productivity from the amphibian community that would be compromised by the loss of a single isolated wetland that has been protected from most industrial, agricultural, and urban impacts for the past 54 years. We used a continuous drift fence at Ellenton Bay, a 10-ha freshwater wetland on the Savannah River Site, near Aiken, South Carolina (U.S.A.), to sample all amphibians for 1 year following a prolonged drought. Despite intensive agricultural use of the land surrounding Ellenton Bay prior to 1951, we documented 24 species and remarkably high numbers and biomass of juvenile amphibians (>360,000 individuals; >1,400 kg) produced during one breeding season. Anurans (17 species) were more abundant than salamanders (7 species), comprising 96.4% of individual captures. Most (95.9%) of the amphibian biomass came from 232095 individuals of a single species of anuran (southern leopard frog [Rana sphenocephala]). Our results revealed the resilience of an amphibian community to natural stressors and historical habitat alteration and the potential magnitude of biomass and energy transfer from isolated wetlands to surrounding terrestrial habitat. We attributed the postdrought success of amphibians to a combination of adult longevity (often >5years), a reduction in predator abundance, and an abundance of larval food resources. Likewise, the increaseof forest cover around Ellenton Bay from <20% in 1951 to >60% in 2001 probably contributed to the longterm persistence of amphibians at this site. Our findings provide an optimistic counterpoint to the issue of the global decline of biological diversity by demonstrating that conservation efforts can mitigate historical habitatdegradation.

Keywords: amphibian decline, biodiversity, drought, land use, wetland recovery

SREL Reprint #2982

Gibbons, J. W., C. T. Winne, D. E. Scott, J. D. Willson, X. Glaudas, K. M. Andrews, B. D. Todd, L. A. Fedewa, L. Wilkinson, R. N. Tsaliagos, S. J. Harper, J. L. Greene, T. D. Tuberville, B. S. Metts, M. E. Dorcas, J. P. Nestor, C. A. Young, T. Akre, R. N. Reed, K. A. Buhlmann, J. Norman, D. A. Croshaw, C. Hagen, and B. B. Rothermel. 2006. Remarkable Amphibian Biomass and Abundance in an Isolated Wetland: Implications for Wetland Conservation. Conservation Biology 20(5):1457-1465.

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