SREL Reprint #3407

Effects of selenium exposure on the hematology, innate immunity, and metabolic rate of yellow-bellied sliders (Trachemys scripta scripta)

David L. Haskins1,2, Matthew T. Hamilton1,2, Nicole I. Stacy3, John W. Finger Jr.1,4,
and Tracey D. Tuberville1

1Savannah River Ecology Laboratory, University of Georgia, Drawer E, Aiken, SC 29802, USA
2D.B. Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA
3Large Animal Clinical Sciences, College of Veterinary Medicine,
University of Florida, Gainesville, FL 32610, USA
4Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA

Abstract: Selenium (Se) is a naturally occurring essential element that can be toxic to vertebrates at high concentrations. Despite studies that have documented that wild reptile species can accumulate copious amounts of Se, little is known regarding specific toxicologic effects of Se. In this study, 70 juvenile yellow-bellied sliders (Trachemys scripta scripta) were exposed to one of three seleno-L-methionine (SetMet) treatments (control, n = 24; 15 mg/kg, n = 23; and 30 mg/kg, n = 23) via weekly oral gavage for 5 weeks. At the conclusion of the experiment, kidney, liver, muscle, and blood samples were collected for quantitative Se analysis. Turtles in the SeMet treatment groups accumulated significantly higher amounts of Se in all tissue types relative to controls (all p < 0.001). Turtles in the 30 mg/kg SeMet group also accumulated significantly higher amounts of Se compared to the 15 mg/kg group (all p < 0.001). Although toxicity thresholds for reptiles have not been established, Se concentrations in liver tissue from both SeMet treatment groups exceeded reported avian toxicity thresholds for liver tissue. Neither oxygen consumption nor innate bactericidal capacity were impacted by SeMet exposure. However, turtles in the 30 mg/kg SeMet group exhibited anemia, which has been reported in other vertebrates exposed to Se. Furthermore, juvenile T. s. scripta in the 30 mg/kg SeMet group experienced 17% mortality compared to 0% in the 15 mg/kg treatment and control groups. To our knowledge, this study is the first to report dose-dependent Se-associated anemia and mortality in a chelonian species.

Keywords: Reptile, Slider, Selenosis, Immune response, Selenomethionine

SREL Reprint #3407

Haskins, D. L., M. T. Hamilton, N. I. Stacy, J. W. Finger Jr., and T. D. Tuberville. 2017. Effects of selenium exposure on the hematology, innate immunity, and metabolic rate of yellow-bellied sliders (Trachemys scripta scripta). Ecotoxicology 26(8): 1134-1146.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).