Controlling Sand Temperatures for Sea Turtles in the Choco Region of Colombia
The sex of a sea turtle is determined by the temperature at which the egg is incubated, with higher temperatures producing more females. A recent study in Australia documented a population of green sea turtles that was almost entirely female (Jensen et al. 2017), due to warming sand temperatures.
This pilot project, funded by WWF’s Wildlife Adaptation Innovation Fund, will test various methods to control the sand temperature of sea turtle nests to control their ambient temperature, and thus produce a more even sex ratio in the hatchlings.
Different levels of shade will be located above nests, and some nests will have a water irrigation system installed. Both these interventions will produce different levels of cooling. The project will be piloted with 35 nests in total: 5 without shade, 5 irrigated with water twice a day, and three groups of 5 with shade levels varying from 25 – 90%. 10 extra nests will serve as a control group. Thermocouples will be placed in the center of the egg mass of every treated and untreated nest. Three temperature readings (07:00, 13.00 and 19:00) will be taken daily. The results of these interventions will allow practitioners to suggest which treatment is more appropriate in order to mitigate changes in sex ratio due to high sand temperatures. These methods could then be continued by local communities in future nesting seasons. Testing is expected to be complete by February 2019.