SEA TURTLES
Quantifying the impacts of sea level rise and climate warming on Ascension Island’s iconic green turtles
Green turtles are perhaps Ascension Island’s most iconic wildlife visitor.
The island is home to the second-largest nesting aggregation of green turtles in the Atlantic, which migrate each year from foraging grounds located along the continental shelf of South America to lay their eggs on Ascension’s sandy beaches.
Sea turtles have long been ambassadors for exploring the conservation implications of climate change, and the two-pronged nature of the threat they face is well understood: not only is the sex and survival of sea turtle hatchlings highly sensitive to temperatures experienced during development; their coastal nesting sites are also vulnerable to inundation and erosion through sea-level rise and increased storminess. These impacts are likely to be particularly severe for populations nesting on isolated islands like Ascension where there are limited opportunities to adapt through range shifts. To date, however, there are have been no specific projections of how the Ascension green turtle population will be affected by the combination of sea-level rise and rising air temperatures.
As part of the CRACAB project, scientists at the University of Exeter are combining local climate forecasts with 3D aerial imagery of nesting beaches and temperature-response curves for hatchling sex and survival to predict the long-term outlook for the Ascension’s green turtles under a range of emission scenarios. The team will also be exploring a range of possible mitigation options, including sympathetic coastal land use planning and assessing the feasibility of artificial nest shading.
Keep checking the blog for update on how this work package progresses.
The stats
23,700
Annual number of green turtle nests at Ascension Island (Weber et al. 2013)
29°C
Temperature above which green turtle sex ratios become female-dominated
2.5 mm/year
Current rate of sea level rise at Ascension Island (*1993 – 2001; Woodworth et al. 2012)