Cold Hardiness and Desiccation Resistance in Hatchling Turtles

COSTANZO, J.P.*; LITZGUS, J.D.; IVERSON, J.B.; LEE, R.E.: Cold Hardiness and Desiccation Resistance in Hatchling Turtles

North American turtles hatch in late summer and spend their first winter either on land or under water. Adaptations for terrestrial overwintering of hatchlings in northern regions, where winter thermal and hydric regimes are harsh, have not been systematically investigated in many species. We measured intrinsic supercooling capacity, resistance to inoculative freezing, and desiccation resistance in terrestrial and aquatic hibernators indigenous to northern (Terrapene ornata, Chrysemys picta bellii, Kinosternon flavescens, Chelydra serpentina) and southern (C. p. dorsalis, Trachemys scripta, Sternotherus odoratus, S. carinatus) locales. Supercooling capacity and inoculation resistance tended to be higher in the terrestrial hibernators, especially C. p. bellii, and terrestrial hibernators better resisted evaporative water loss. Most species tolerated the loss of a modest amount of body water, although some S. carinatus died during desiccation experiments. With the possible exception of T. ornata, turtles did not regain lost body water from wet soil and immersion in free water was required for rehydration; therefore, desiccation resistance is an important adaptation to terrestrial hibernation. Resistances to inoculative freezing and desiccation were directly correlated, perhaps because they are governed by the same morphological attributes.

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