Author: Patrick J. Baker

Publisher:

Published: 2008

Total Pages: 75

ISBN-13:

Three research projects were conducted to further our understanding of the physiological adaptations that promote survival of terrestrially-hibernating hatchling turtles. Unit I, Cold Hardiness of Hatchlings of the Diamondback Terrapin examines the functional basis for cold hardiness in hatchlings of the diamondback terrapin, Malaclemys terrapin, a species that may hibernate terrestrially in the northern portion of its range. Hatchlings subjected to experimental freezing survived exposure to temperatures as low as -3.0°C, suggesting that freeze tolerance may account for the high winter survival observed in natural nests. Freeze tolerance in hatchling M. terrapin is promoted by high susceptibility to inoculation, which is known to promote slow freezing allowing cells time to adapt to the attendant physical and osmotic stresses. Unit II, Oxidative Stress and Antioxidant Capacity of a Terrestrially-hibernating Hatchling Turtle examines the role of endogenous antioxidants in preventing oxidative damage following periods of supercooling and freezing in hatchling Chrysemys picta. The results of this study suggest that hatchling C. picta have a well-developed antioxidant defense system that minimizes oxidative damage during hibernation. Unit III, Asynchrony in the Timing of Emergence from the Nest by Hatchlings of Freshwater Turtles describes the timing of emergence from the nest by hatchling turtles. Average date of fall emergence from the nest did not vary among species; however, a species-specific pattern of emergence in spring was observed. Chrysemys picta emerged in late March and early April and, on average, these hatchlings left their nests two weeks earlier than G. geographica and four weeks earlier than T. scripta. Hatchlings of C. picta overwintered in nests that were shallow relative to the other terrestrially-hibernating species, and minimum nest temperatures were significantly lower in winter. Although hatchlings of C. picta are smaller than those of G. geographica and T. scripta, they can gain a survival and/or growth advantage by emerging earlier. The fitness benefits of early emergence may lead to the improvement of cold-hardiness adaptations in northern populations of turtles.