The Effect of Air Temperature on the Incubation Period and Hatching Success of In Situ Loggerhead Sea Turtle (Caretta caretta) Clutches in Broward County, Florida

The survival rates of pre-emergent sea turtle hatchlings are critically dependent upon temperature. This study aimed to determine if changes in air temperature can explain some of the variability in hatching success observed over a 12 year period for loggerhead sea turtle (Caretta caretta) nests in Broward County. Air temperature data for the hatching seasons of 1999 to 2010 were obtained from the NOAA National Climatic Data Center’s Fort Lauderdale beach station. The loggerhead sea turtle hatching data collected by the Broward County Sea Turtle Conservation Program from the same time period was examined to assess the potential effects of air temperature on the hatching success and the incubation duration. Mean yearly incubation times were analyzed for trends and compared to mean nesting season temperatures. The relationships between the incubation durations and mean seasonal and intra-seasonal air temperature fluctuations as well as the relationship between hatching success and air temperature was tested for significance. The hatching success was also compared to the incubation times in order to establish if shorter incubation durations, were related to lower hatching success rates. There have been large fluctuations in the average daily hatching success rates ranging from 10 to 100% over the twelve years examined in this study in Broward County. Significant decreases in incubation durations were apparent during times of increasing average air temperatures. In five of the twelve seasons there was also a significant relationship between the hatching success rates and the average air temperature, in which lower hatching success rates were evident during times of higher average air temperatures. There was a significant correlation between the incubation durations and the hatching success rates in six of the seasons as well, suggesting that lower hatching success rates are related to shorter incubation times. The pattern in average yearly hatching success rates were significantly related to the average monthly air temperatures in July suggesting that lower hatching success rates during the month of July were a result of higher temperatures during this time of the hatching season. A better understanding of the effects that air temperature has on loggerhead sea turtle clutches in Broward County can provide future insights for the fluctuating survival rates of sea turtle clutches and if the changes are natural or the result of conservation efforts