Research from St. Eustatius suggests that new, and relatively simple, conservation methods can help reduce some of the negative effects of climate change on sea turtle populations:
In the article published by Scientific Reports, a range of experiments were conducted between 2012 and 2017 in St Eustatius Marine Park in the Dutch Caribbean by Swansea University and Wageningen University & Research in association with St Eustatius National Parks, Groningen University and Deakin University in Australia. Lead scientist Dr Nicole Esteban from Swansea University says that turtles do not have sex chromosomes. It is the incubation temperature in sand surrounding a clutch of eggs that determines the sex of a turtle hatchling, which is known as Temperature-Dependent Sex Determination.
Eggs incubating at cooler temperatures (generally lower than 29°C) produce male turtles and eggs incubating at warmer temperatures produce females. This has led to concerns that, in the context of climate change, warming air temperatures may lead to female-biased sea turtle populations.
The research team developed a series of trial experiments to test the effect of various shading treatments that were easily available (white sand, white sheet, palm leaves). The sand temperatures below the shaded areas were recorded using small temperature loggers buried at turtle nesting depths on Zeelandia and Oranjebaai beaches in St Eustatius. The data were combined with long-term beach temperature data to estimate the effect of shading and relocation between the beaches on hatchling sex ratios.
In the study, a conservation mitigation matrix is presented that summarize evidence that artificial shading and nest relocation can be effective, low-cost, low-technology conservation strategies to mitigate impacts of climate warming for sea turtles.
Of the three shading treatments tested, palm leaves (easily found in nature!) were found to be the most effective. The full article Optimism for mitigation of climate warming impacts for sea turtles through nest shading and relocation is open-access and available online.
[Image: Silke Baron]