BAKER, PJ*; COSTANZO, JP; HERLANDS, R; WOOD, RC; LEE JR., RE; Miami University; Miami University; The Richard Stockton State College; The Richard Stockton State College; Miami University: A tolerance for freezing promotes winter survival of hatchlings of the northern diamondback terrapin, Malaclemys terrapin

Field observations and laboratory experiments were conducted on hatchlings of the northern diamondback terrapin (Malaclemys terrapin), a species that may overwinter within its natal nest in northern parts of its range. Hatchlings from 6 of 21 nests overwintered terrestrially, yet despite sub-zero temperatures (to -4.4&degC) in the nest, winter mortality was low. Laboratory studies showed that cold-acclimated hatchlings had low rates of evaporative water loss (2.8 mg g^-1 d^-1) relative to other species, which may prevent excessive dehydration during hibernation. Hatchlings supercooled deeply (to -15.1&degC) but were highly susceptible to inoculative freezing by ice and ice nucleating agents, which occur in their nest environment. Therefore, freeze avoidance is not a viable cold hardiness strategy in these turtles. However, hatchlings survived the freezing of their tissues (-2.5&degC for at least 24 h), suggesting that these turtles may survive brief chilling episodes in the nest by tolerating freezing.