The diamondback terrapin (Malaclemys terrapin) occurs exclusively in tidally-influenced coastal habitats along the East and Gulf coasts of North America. It is the only species of turtle endemic to temperate estuarine ecosystems; as such, it represents an intermediate form between freshwater turtles and fully marine turtles. We study the physiological mechanisms and behavioral adjustments that play a role in maintenance of water and salt balance in terrapins, and the energetic cost of osmoregulation in this species. We also investigate seasonal changes in metabolism and behavior of terrapins, and consider the implications of overwintering strategies for maintenance of osmotic homeostasis.
Diamondback terrapin conservation
Diamondback terrapin populations have decreased throughout their range, and this reptile is currently listed as a “Species of Concern” in North Carolina. Factors contributing to population decline are habitat loss, road and boat mortality, nest predation, and mortality due to incidental bycatch in fishing gear. We are engaged in long-term surveys to assess relative abundance and distribution of diamondback terrapins in waters utilized by commercial and recreational crab fisheries in the marshes of southeastern North Carolina. We are also using radiotelemetry and micro-dataloggers to assess home range, diving and basking patterns, seasonal movements, and habitat utilization.
Fisheries interactions with sea turtles
Incidental capture of endangered sea turtles in fishing gear is a cause of concern for fisheries managers, fishers, and environmentalists alike. Sea turtles may sustain serious injuries while entangled or hooked in fishing gear and may drown if they are not discovered and released in time. The behavioral and physiological consequences for sea turtles released alive from fishing gear may be substantial, but little research has been directed at assessing the health status of sea turtles following a fisheries encounter. When combined with post-release behavior data, measurements of biochemical and hormonal variables indicative of exhaustive exercise, disruption of respiratory and metabolic processes, cellular and tissue damage, and induction of a stress response may prove to be a useful tool in evaluating survivability of sea turtles released from fishing gear.
Thermal biology of leatherback turtles
The leatherback turtle (Dermochelys coriacea) is the largest extant species of sea turtle and has the widest geographic range of any reptile, with migratory routes that take them from nesting beaches in the tropics to foraging grounds at temperate and sub-polar latitudes. Leatherback turtles maintain relatively stable internal body temperatures (25-29C) that are several degrees higher than ambient water temperatures while freely swimming in both tropical and temperate seas. We use remote monitoring technology to study the contributions of behavioral and physiological adjustments to thermoregulation in this unique turtle.