Effects of projected changes in tropical cyclone frequency on sea turtles

Abstract

Tropical cyclones are amongst the world’s most destructive natural hazards and can negatively affect sea turtles by disturbing their foraging and nesting habitats, increasing localised mortality of their eggs, and potentially skewing hatchling sex ratios towards females. Cyclonic frequency, intensity, distribution and seasonality are predicted to alter with climate change. This will influence both the effects of cyclones on the nesting grounds and reproductive output of sea turtles and the frequency with which these nesting grounds are hit by cyclones. However, only a few studies have investigated how future cyclonic activity will affect turtle populations. Studies conducted to date have concentrated on how projected intensification of cyclonic activity will affect sea turtles and have found that intensification of cyclones will reduce hatching success at sea turtle nesting grounds. No study to date has, however, considered or investigated how the predicted changes in cyclone frequency and distribution may affect sea turtle populations. Here, we used climate change models and turtle life history information to predict how projected changes in the frequency of cyclones will affect 4 sea turtle species: green turtle Chelonia mydas, flatback turtle Natator depresus, hawksbill turtle Eretmochelys imbricata and loggerhead turtle Caretta caretta, nesting on the eastern Australian (Queensland) coast. To account for known variability in model projections of cyclonic activity, we used 11 regional climate model simulations for an A2 greenhouse gas emission scenario for conditions predicted for 2055 and 2090. The model projections indicated a tendency towards a reduction in cyclonic activity at the studied nesting grounds in the future and, thus, a decrease in the effects on sea turtle nesting along the Queensland coast.