Effects of incubation temperature on hatchling performance and phenotype in loggerhead sea turtle Caretta caretta

Abstract

Under natural conditions sea turtle eggs are subjected to a changing thermal environment, but little is known about the effect of these temperature fluctuations during incubation on the performance and phenotype of hatchlings. The aim of this study was to determine how incubation temperature pattern (increasing or stable) and incubation temperature regime (low or high) affect incubation and hatching duration, hatching and emergence success, hatchling phenotype (carapace length and weight) and self-righting interval at hatching. Loggerhead sea turtle Caretta caretta (Linnaeus, 1758) clutches were collected at different beaches on the Cape Verde archipelago and divided among incubators with different temperature regimes and patterns. Minimum straight carapace length and weight of all individuals were measured at hatching. In addition, the hatching duration and the time interval required for each hatchling to self-right were recorded. Results showed that incubation temperature regimes influenced all studied parameters more than the increasing temperature pattern. Low incubation temperature regimes, both in the increasing and stable pattern, increased the incubation time, produced bigger hatchlings and caused a slower righting response compared to the high temperature regimes. An optimal range of incubation temperatures was determined by assessing the most favorable values for hatchlings, although some differences were found in the higher temperatures of this optimal range between different rookeries. This means that turtle incubation in the laboratory should, as far as possible, follow the natural incubation temperature fluctuation of the studied rookery.