Details of Award
NERC Reference : NE/L009501/1
Adaptation and resilience of marine turtles to climate change
Training Grant Award
- Lead Supervisor:
- Professor A Broderick, University of Exeter, Biosciences
- Grant held at:
- University of Exeter, Biosciences
- Science Area:
- Marine
- Terrestrial
- Overall Classification:
- Marine
- ENRIs:
- Environmental Risks and Hazards
- Global Change
- Natural Resource Management
- Science Topics:
- None
- Abstract:
- The student will work with Ascension Island Government Conservation Department (CASE partner) to investigate the predicted impacts of climate change on the globally important green turtle (Chelonia mydas) population of Ascension Island, the potential for adaptation and the development of management strategies. This research addresses a key biodiversity policy need identified by the CASE partner in the Green Turtle Species Action Plan (GTSAP) to: Take measures to monitor and mitigate the potentially deleterious effects of climate change, and will have significant impacts on the management of the UK's largest marine turtle aggregation. The impact of climate change on marine turtles is predicted to be most profound at nesting beaches, where sea level rise will result in habitat loss, and rising temperatures will affect incubation conditions, impacting offspring survival and sex (sex of marine turtles is determined by temperature with hotter temperatures producing more females). The UK Overseas Territory of Ascension Island hosts the second largest green turtle nesting population in the Atlantic, which is potentially vulnerable to climate change as its remote location provides little opportunity for range shifts. The island is also unusual in having beaches of different sand type and colour, which create highly variable incubation temperatures for clutches over small spatial scales, making it a unique setting to study population-level responses to climate change. Previous work has found that offspring sex ratios at Ascension Island are female biased, with temperatures on some beaches approaching the maximum thermal tolerance of embryos. Currently, however, we do not know how the population will fare under different climate change scenarios. Recent experimental work suggests that turtles nesting on some beaches are locally adapted to stressful thermal environments, for example eggs laid on hot beaches have a higher success at hotter incubation temperatures than those from cooler beaches. The student will artificially incubate eggs across a range of temperatures to establish the sex determining temperatures for Ascension Island green turtles. Eggs will be sampled from beaches with different incubation temperatures to examine variation in sex determining temperatures between females. This has not been not previously studied at any location world-wide. The distribution of green turtle clutches across the island will be mapped (position, elevation and depth), and incubation temperatures of a sample of clutches from each beach recorded using temperature dataloggers placed amongst the eggs at laying.The relationship between clutch temperature, hatch success and sand temperature of beaches (from remotely sensed datasets) will be established and used to estimate contemporary offspring sex ratios at Ascension Island. Models of future temperature and sea level rise will be used to predict how offspring production and the availability of nesting habitat will change at Ascension. These models will provide detailed predictions for changes in marine turtle productivity and nesting beach morphology under different climate change scenarios, providing a vital management tool for defining conservation priorities locally, feeding into global efforts to predict the likely impacts of climate change. Building on previous work, the student will further explore the possibility of local adaptation in embryonic thermal tolerances by conducting a series of experiments. Clutches laid on hot and cool beaches will be switched to compare clutch survival and offspring phenotype under foreign thermal regimes relative to control clutches translocated within their beaches of origin. This approach will help to quantify any buffering to climate change that might be afforded by thermally tolerant sub-populations. These experiments will also help to inform the efficacy of clutch relocation which is one of the likely mitigation methods.
- NERC Reference:
- NE/L009501/1
- Grant Stage:
- Completed
- Scheme:
- DTG - directed
- Grant Status:
- Closed
- Programme:
- Industrial CASE
This training grant award has a total value of £83,515
FDAB - Financial Details (Award breakdown by headings)
| Total - Fees | Total - Student Stipend | Total - RTSG |
|---|---|---|
| £16,226 | £56,292 | £11,000 |
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