Mangrove diamondback terrapin

Malaclemys terrapin rhizophorarum

Overall vulnerability:

Very High
lower vulnerability
higher vulnerability

Conservation status:

Species of Greatest Conservation Need

General Information

One of several subspecies of the diamondback terrapin, the mangrove diamondback terrapin is endemic to the Lower Keys in Florida. This species gets its name from the striking diamond-shaped pattern on its shell. The diamondback terrapin is a popular animal, making appearances in sports, popular culture and as a delicacy on many dining menus throughout its history with humans. Diamondback terrapins are uniquely able to thrive in varying levels of salinity and are strong swimmers with equally strong jaws for crushing shelled prey items. Females often trek far inland to nest in patches of coastal vegetation. Females can store sperm from more than one male, at times resulting in clutches with multiple fathers. Like many turtles, diamondback terrapins have temperature-dependent sex determination.

Habitat Requirements

Diamondback terrapins have multiple adaptations that allow them to survive in both freshwater and fully saline water, however adult terrapins have a strong preference for brackish coastal habitats. Mangrove diamond back terrapins occur in mangrove and open beach habitat in the Lower Florida Keys.


Climate Impacts

The mangrove diamondback terrapin is extremely vulnerable to sea level rise within its Lower Keys habitat, with over 95% of habitat inundated at only 1 meter of sea level rise. The natural barrier of island isolation as well as human development and incompatible land use will prevent mangrove diamondback terrapins from moving with shifting habitat. Although the terrapin is naturally tolerant of varying salinity levels, it is not likely to adapt to a completely inundated habitat. Like many reptiles, diamondback terrapins have temperature-dependent sex determine and embryos become female when incubation temperature rises above 82 degrees Fahrenheit. Substantially warmer temperatures over time could lead to imbalanced sex ratios in the species. Additionally, since the mangrove diamondback terrapin is a subspecies, natural or assisted migration to areas where other diamondback terrapins occur would likely result in genetic swamping of this distinct Lower Keys population.

More information about general climate impacts to species in Florida.

Vulnerability Assessment(s)

The overall vulnerability level was based on the following assessment(s):

  • Standardized Index of Vulnerability and Value Assessment

    Vulnerability: Extremely vulnerable

    The primary factors contributing to vulnerability of the mangrove diamondback terrapin are sea level rise, the presence of barriers, habitat fragmentation, runoff and storm surge, and synergies with development.

Adaptation Strategies

  • Conservation and restoration of existing coastal habitat is critical to increase habitat and species health and resilience at the onset of intensifying climate change.
  • If nesting habitat becomes degraded or sex ratios are impacted by rising temperatures, artificially created or altered nesting habitat to maintain nesting success and optimal sex ratios is a possible adaptation strategy. For example, shade structures could be added to nesting sites to improve the likelihood of achieving balanced sex ratios.
  • If barriers to natural migration are too great as sea level rise accelerates, assisted migration to an isolated area where interbreeding with other diamondback terrapins or development of a captive breeding program may be considered for this species.

More information about adaptation strategies.

Additional Resources