Abstract
Due to heavy historical exploitation and increases in other anthropogenic threats such as poaching, bycatch, pollution, habitat loss and climate change,the hawksbill sea turtle in the western Caribbean is critically endangered and slow to recover (Fuentes et al., 2013; Hamann et al., 2013; NMFS & USFWS, 1993; Spotila, 2004).In sea turtles, like other species of reptiles, sex is determined by temperatures during incubation (Miller, 1997). This phenomenon, called Temperature-dependent Sex Determination (TSD), creates female hatchlings at higher temperatures and male hatchlings at lower temperatures(Mrosovsky et al., 2009).Anthropogenic climate change disproportionally threatens the embryonic stage of development by creating female skewed hatchling sex ratios, reducing hatch success, and reducing emergence success(Godfrey et al., 1999; Howard et al., 2014; Laloë et al., 2014, 2016). One of the largest nesting hawksbill populations within US jurisdiction exists at Buck Island Reef National Monument, US Virgin Islands, and provides a unique opportunity to study thermal embryonic stress (Spotila, 2004). Hobo logger temperature data, female biometric data,and geographic nest data were collected during nightly beach patrols on Buck Island as part of the Buck Island Sea Turtle Research Program(BISTRP). Hatch success and emergence success was calculated from data collected at nest excavations after the termination of incubation. ANOVA and Linear Regression analyses were conducted to determine whether significant differences existed in incubation temperatures with nest location, habitat type, soil composition, hatch success, and emergence success as factors. Additionally, sigmoidal Temperature-Dependent Sex Determination (TSD)curves were used to predict hatchling sex ratios from incubation temperatures. Statistically significant findings suggest that as climate change progresses, hawksbill populations will become increasing female and populations may continue to decline due to decreased hatch success.Managers can use these findings to predict average incubation temperatures and hatch success on Buck Island.