Climate change and warming temperatures are a threat to sea turtles due to temperature effects on sex ratios and hatch success. A study published in 2016, for example, highlighted the risks of extremely warm incubation temperatures found on nesting beaches on St Eustatius, an island in the Caribbean. “By recording sand temperatures we were able to estimate the sex ratios of hatchling sea turtles born on the island,” comments Dr Nicole Esteban, a lead author of the 2016 study. “Our results showed that the primary sex ratio – the ratio of females-to-males found within a turtle nest – was highly skewed towards females. The concern is that in the future there will not be enough males to sustain the population and turtles will disappear from the island.”
Fortunately, conservation strategies can be put in place to lower sand temperatures. For example, it is possible to simply shade nests to cool them. However, the effects of such mitigation strategies have not been empirically quantified before. So in a new study published this week in Scientific Reports, Dr Esteban and her colleagues examined the effect different shading strategies had on sand temperatures. Three different shading treatments were trialed and all three options were effective at reducing sand temperatures. In addition, sand temperatures were found to differ between nesting beaches on the island. The study’s results showed that using shading strategies in combination with nest relocations from the warmer beach to the cooler beach could help decrease incubation temperatures by almost 2.5 °C. In terms of sex ratios, 2.5 °C could be the difference between a nest that is >97% female and one that is only >60% female.
Jessica Berkel, a co-author of the new study and a marine park manager of St Eustatius National Parks (STENAPA), says there are already plans to relocate turtle clutches from the warmer beach to the cooler beach on St Eustatius. This should help guarantee there are still enough male turtles born in the years to come. “The good news is that relocating and shading turtle nests is cheap and effective. This is a low-tech conservation strategy that can be implemented at field sites across the world that experience high incubation temperatures,” she comments. “Results of this new study are cause for optimism for sea turtle conservation world-wide.”
“Optimism for mitigation of climate warming impacts for sea turtles through nest shading and relocation” was published by Scientific Reports (2018). Authors: Nicole Esteban, Jacques-Olivier Laloë, Fionne S.P.L. Kiggen, Selma M. Ubels, Leontine E. Becking, Erik H. Meesters, Jessica Berkel, Graeme C. Hays and Marjolijn J.A. Christianen.