Ecological Modelling 251 (2013) 150–157 Contents lists available at SciVerse ScienceDirect Ecological Modelling jo u r n al hom ep age : www.elsevier.com/locate/ecolmodel Using a microclimate model to evaluate impacts of climate change on sea turtles M.M.P.B. Fuentes a,∗ , W.P. Porter b a Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD, 4811, Australia b Department of Zoology, 250 N. Mills Street, University of Wisconsin-Madison, Madison, WI 53706, USA a r t i c l e i n f o Article history: Received 20 May 2012 Received in revised form 9 December 2012 Accepted 11 December 2012 Available online 4 February 2013 Keywords: Temperature-dependent sex determination Climate change Global warming Microclimate Correlative model Sea turtles a b s t r a c t Sea turtles are thought to be particularly vulnerable to climate change as projected increases in tempera- ture 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 devel- opment 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 physi- ology 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 TM 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 vali- dation 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. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Global climate change is a major issue in ecosystem and wildlife management throughout the world (Fuentes et al., 2012). It has already produced significant and measurable impacts on almost all ecosystems, taxa and ecological processes and its impacts are expected to increase rapidly (Hughes, 2000; Peterson et al., 2002; Walther et al., 2002; Parmesan and Yohe, 2003). To respond ∗ Corresponding author. Tel.: +61 07 4781 5270; fax: +61 07 4781 6722. E-mail addresses: mariana.fuentes@jcu.edu.au (M.M.P.B. Fuentes), wpporter@wisc.edu (W.P. Porter). effectively to predicted climatic changes it is important to under- stand how changes will affect biodiversity (Margules and Pressey, 2000; Kearney and Porter, 2009; Mokany and Ferrier, 2011). This need has stimulated the development of various models to assess and project future impacts from climate change (Botkin et al., 2007; Trivedi et al., 2008). This is particularly true for animals that are thought to be especially vulnerable to climate change. An exam- ple is oviparous reptiles, such as sea turtles that have life history, physiology and behavioral traits that are extremely influenced by environmental temperature. Sea turtles have temperature- dependent sex determination (TDS) – wherein the sex of their hatchlings is determined by the incubation temperature during embryonic development (Janzen and Paukstis, 1991; Mrosovsky 0304-3800/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.ecolmodel.2012.12.020