Fuentes, M.M.P.B., and Porter, W.P. (2013) Using a microclimate model to evaluate impacts of climate change on sea turtles. Ecological Modelling, 251. pp. 150-157.

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Abstract

Sea turtles are thought to be particularly vulnerable to climate change as projected increases in temperature may skew the sex ratio of their hatchlings, decrease hatchling success and thus threaten population persistence. Given the seriousness of the threat from climate change it is critical to understand the rate at which soil temperatures at sea turtles’ nesting grounds are likely to change. This has stimulated the development of correlative models to assess and project how projected increases in temperature may impact sea turtle's reproductive output. Correlative models correlate climatic variables to soil temperature and hatchling sex ratio. These models have been widely used due to their simplicity and the flexibility of their data requirement. However, outputs are restricted by the environmental conditions used for the model and thus does not allow exploration of daily variation in sand temperature. Further, the potential error inherent in this approach has not been determined.

Researchers working with other animals with temperature-dependent sex determination (TDS) have developed microclimate models to determine nest temperature and potential impacts from climate change. Microclimate models use the interaction between climate, soil, and topography with physiology and nesting behavior of animals to determine future production of hatchling sex ratios. Until now, microclimate models have never been applied to sea turtles and its correlation and consistency with correlative models has never been explored. To address this, we used the Niche Mapper™ microclimate model to project soil temperature at key sea turtle nesting grounds under various scenarios of global warming. Results from the microclimate model are compared to published projections from correlative models. The two approaches accurately and congruently model current soil temperature and project a feminization of the northern Great Barrier Reef green turtle population as climate change progresses. To provide guidance of when to use each approach we also reviewed the applicability and effectiveness of each model. The microclimate model provided a more robust picture of the incubating environment as it has the potential for projecting soil temperature for every hour of the day at various locations and depths within a nesting ground. This allows exploration of whether animals with TDS can counteract the impacts of global warming by changing nest depth and nesting distribution. With time and the validation of the microclimate model with short-term projections, the microclimate model can also be used to refine short-term adaptive management strategies as they can provide explicit recommendations on site-specific scales for translocation of eggs and alteration of the nesting environment.

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