Meeting Abstract
Marine turtles have temperature dependent sex determination (TSD), by which lower nest temperatures produce more males. Nest temperature variation can be affected by environmental factors such as rainfall, shade, and sand type. We measured relationships among nest temperatures, rainfall, and hatchling sex ratios of green turtle (Chelonia mydas) at a nesting site in Boca Raton, Florida USA across the 2010-2013 nesting season. Rainfall events were synchronized with the temperature profiles of each nest sample. We analyzed nest temperature data to identify any signal that rainfall events altered nest temperatures. A subset of hatchlings was sexed laparoscopically to provide empirical measures of the sex ratio for the beach. Nest temperature profiles were synchronized with rainfall data from weather services to identify relationships with hatchling sex ratios. The majority of hatchlings in the samples were female suggesting that across the four seasons most nest temperatures were not sufficiently cool to produce males. However, in the early portion of the nesting season and in wet years, nest temperatures varied and significantly more males hatched. The study suggests that rainfall events can lower nest temperatures during incubation, but the embryonic sex response to rainfall may produce results not appreciated by temperature alone. Thus, predicting sex ratios under field conditions remains challenging.
