Research Publications: UM-SG-RS-2020-02



Effects of constant and fluctuating incubation temperatures on hatching success and hatchling traits in the diamondback terrapin (Malaclemys terrapin) in the context of the warming climate




Rowe, CL; Liang, D; Woodland, RJ


Journal of Thermal Biology
88 : 1 - 9




As global temperatures continue to rise, so too will the nest temperatures of many species of turtles. Yet for most turtle species, including the estuarine diamondback terrapin (Malaclemys terrapin), there is limited information on embryonic sensitivity to elevated temperature. We incubated eggs of M. terrapin at three, mean temperatures (31, 34, 37 degrees C) under two thermal exposure regimes (constant or semi-naturally fluctuating temperature) and measured hatching success, developmental rate, and hatchling size. Hatching success was 100% at 31 degrees C and 67% at 34 degrees C, respectively; at 37 degrees C, all eggs failed early in the incubation period. These values were unaffected by exposure regime. The modeled LT50 (temperature that was lethal to 50% of the test population) was 34.0 degrees C in the constant and 34.2 degrees C in the fluctuating thermal regime, reflecting a steep decline in survival between 33 and 35 degrees C. Hatchlings having been incubated at a constant 34 degrees C hatched sooner than those incubated at 31 degrees C under either constant or fluctuating temperature. Hatchlings were smaller in straight carapace length (CL) and width after having been incubated at 34 degrees C compared to 31 degrees C. Larger (CL) hatchlings resulted from fluctuating temperature conditions relative to constant temperature conditions, regardless of mean temperature. Based upon recent temperatures in natural nests, the M. terrapin population studied here appears to possess resiliency to several degrees of elevated mean nest temperatures, beyond which, embryonic mortality will likely sharply increase. When considered within the mosaic of challenges that Maryland's M. terrapin face as the climate warms, including ongoing habitat losses due to sea level rise and impending thermal impacts on bioenergetics and offspring sex ratios, a future increase in embryonic mortality could be a critical factor for a population already experiencing ecological and physiological challenges due to climate change.

Maryland Sea Grant Topic(s):

'Related Research Project(s)' link to details about research projects funded by Maryland Sea Grant that led to this publication. These details may include other impacts and accomplishments resulting from the research.

'Maryland Sea Grant Topic(s)' links to related pages on the Maryland Sea Grant website.

The Blue Crab: Callinectes Sapidus

An essential resource for researchers, students, and managers.  Get your copy today!

pile of cooked crabs