The Diamondback Terrapin
This week we have a post from UNCW professor, Dr. Amanda Southwood Williard.
Sea turtles are not the only reptiles that live in salty habitats. Saltwater crocodiles, marine iguanas and sea snakes make coastal waters their home. There are also several species of semi-aquatic turtles that utilize estuarine or brackish water habitats. Of these, the diamondback terrapin (Malaclemys terrapin) is, perhaps, the most charming.
Diamondback terrapin in the salt marsh.
Diamondback terrapins inhabit salt marshes, coves and tidal creeks along the Eastern and Gulf coasts of the United States from Cape Cod, Massachusetts in the north to Corpus Christi, Texas in the south. Terrapins are most likely to be seen during their active season, which extends from March through October. During this time, they forage on small species of crabs and snails in shallow, flooded marshes at high tide and retreat to deeper waters or bury in the mud of the intertidal zone during low tide. When the weather becomes cooler in the late fall, terrapins bury themselves in the marsh mud and become dormant for the winter.
A diamondback terrapin burrowed in the mud.
Long-term monitoring of terrapin populations suggest terrapin numbers are declining in certain parts of their range. Factors such as habitat loss, road and boat mortality, nest predation and mortality due to fisheries interactions are thought to contribute to population declines. In North Carolina, terrapins are currently listed as a “Species of Concern”, however, a recent report by the Wildlife Resource Commission’s Scientific Council on Amphibians and Reptiles recommends re-classifying this species as “Threatened.” Additional monitoring is necessary to establish the terrapin’s conservation status and identify the primary threats facing this species in coastal North Carolina. Of concern is the potential for incidental capture and mortality of terrapins in the economically-important nearshore blue crab fishery. Terrapins captured in submerged crab pots cannot reach the surface to breath and drown if they are not removed from the pots in a timely manner.
A crab pot fitted with bycatch reduction devices.
Researchers at the University of North Carolina Wilmington have been collaborating with local fishermen, fisheries managers and conservation agencies to better understand diamondback terrapin biology and the most effective ways to protect this species in our region. Population surveys and studies of terrapin habitat utilization may provide guidance for fisheries managers seeking ways to modify fishing practices so incidental capture of terrapins is reduced. Additionally, studies designed to investigate terrapin and crab catch rates in crab pots equipped with bycatch reduction devices (BRDs) provide data critical for assessing the feasibility of this management approach for the coastal blue crab fishery in North Carolina.
If you are interested in diamondback terrapin conservation and biology, the following website provides information, photos, and other resources to help you learn more about this charismatic species: http://www.dtwg.org/
Thanks to Dr. Willard for sharing information on her work. Next time you visit the Aquarium you can see our diamondback terrapins in the Buzzard Bay exhibit: right across from our sea turtle hatchlings. This week Turtle A is 9.4 centimeters long and weighs 148.7 grams. Turtle B is 10.2 centimeters long and weighs 205.4 grams. Not sure what to do with this weight and length? Learn more in our Hatchling to Yearling lesson plan. Have you ever seen a diamondback terrapin before? Share your story in the comments below!
