Evaporative Water Loss Rates of Four Species of Aquatic Turtles from the Coastal Plain of the Southeastern United States

Many isolated wetlands in the southeastern United States are naturally ephemeral, productive habitats that can support a high diversity of aquatic reptiles. As wetlands begin to dry, reptile species exhibit different behavioral responses including overland dispersal and terrestrial aestivation. Regardless of strategy, one of the greatest risks to individual survival is desiccation. We measured evaporative water loss rates (EWL; % body mass lost per hour) and total % body mass lost over 24 h in four species of semiaquatic turtles that frequent isolated wetlands in the southeastern United States: Chicken Turtles (Deirochelys reticularia), Eastern Mud Turtles (Kinosternon subrubrum), Common Musk Turtles (Sternotherus odoratus), and Yellow-Bellied Sliders (Trachemys scripta scripta). Mean percent body mass lost over 24 h ranged from 4.44-10.26% among individuals, was negatively correlated with body mass and varied among species, with higher EWL rates occurring in species with reduced shell robustness (the amount of the body covered by the shell). Mean EWL rates were highest in S. odoratus, lowest in K. subrubrum, and intermediate in D. reticularia and T. scripta. The EWL rates corresponded to species' natural history traits and behavioral adaptations to drought. Species with higher EWL rates could be more vulnerable to increased drought duration and frequency resulting from either climate change or anthropogenic modification of wetland hydrology, and easily measured traits such as shell robustness and body mass may be useful in predicting EWL rates and desiccation risk for particular age classes and other species of turtles.