The diamondback terrapin (Malaclemys terrapin), North America’s only estuarine turtle species, inhabits brackish waters of coastal salt marshes. In physical appearance, terrapins are one of the most variable turtle species in the United States. All individuals have light-colored concentric rings on their carapace, but the color of their shell can range from light gray to black. Even within populations, there can be light and dark individuals with colors ranging from orange and yellow to greenish backgrounds. As a sexually dimorphic species, female terrapins grow to be larger than males and have much bigger heads. Diamondback terrapins have been known to prey on periwinkle snails, an invasive mollusc to the Atlantic coast. Terrapins therefore play an important role in the ecosystem by preventing periwinkle snails from overgrazing healthy marsh grasslands and turning them into barren mudflats.

 

Terrapins are characterized by a slow rate of development to reproductive maturity, small clutch sizes, and relatively long lifespans. Such attributes predispose populations to reduced viability when experiencing disproportionate mortality of a specific sex or age class. In turn, populations of such long-lived organisms are extremely vulnerable to anthropogenic impacts. The status of terrapin populations across their range (New England to the Gulf of Mexico) is either unknown or declining. Terrapins, as with the vast majority of turtle species worldwide, have been negatively impacted by anthropogenic disturbance in the form of habitat fragmentation, development, commercial and recreational harvest, and road mortality. Along Georgia's developed barrier islands and marsh-bordered mainland, adult female diamondback terrapins are heavily at-risk to road mortality during the nesting season. Roadways along marsh habitats are often elevated and attract nesting females in their search for high, dry ground in which to lay their eggs. In certain areas, such as on Jekyll Island, hundreds of turtles have been documented crossing the road in a single nesting season (May-July). Additionally, crab harvesting in Georgia presents an anthropogenic threat to terrapin populations. While adult females are usually too large to fit inside crab pots, juvenile and male terrapins can become entrapped in them. As the crab pots are submerged and infrequently checked, terrapins inside usually drown. Turtle excluder devices can be installed on crab pots to prevent terrapins from entering, however they are not required by law. As a result of this threat and the others facing Georgia's diamondback terrapins, they are listed in the state as a "Species of Concern." 

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Given the state's designation of terrapins, our lab has an interest in researching this charismatic turtle. Utilizing novel techniques and technologies, we study terrapin spatial ecology, movements, and habitat use. Much of this information is lacking for the species, as it is difficult to conduct this type of research in the salt marsh ecosystem. Furthermore, our lab participates in general population surveys and mark-recapture efforts to monitor the overall status of terrapins in the region.