Staines, Melissa, Versace, Hayley, Laloe, Jacques-Oliver, Madden-Hof, Christine, Smith, Caitlin, Haskin, Elouise, Lawrence, Anissa, Tibbets, Ian, Booth, David, Pilcher, Nicolas, and Hays, Graeme (2024) Prevalence of male-producing nesting sites for endangered sea turtles in the asia-pacific region and globally. In: Proceedings of the 42nd Annual Symposium on Sea Turtle Biology and Conservation. p. 246. From: 42nd Annual Symposium on Sea Turtle Biology and Conservation, 24-29 March 2024, Pattaya, Thailand.

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Abstract

Projection models are being increasingly used to manage threatened taxa by estimating their responses to climate change. Sea turtles are particularly susceptible to climate change as they have temperaturedependent sex determination and so increased sand temperatures could result in the ‘feminisation’ of hatchling sex ratios. Additionally, the implications of temperature data logger accuracy and precision are rarely considered prior to their application in many ecological studies. We assessed the accuracy and precision of three commonly used temperature data loggers (Hobo®, iButton® and TinyTag®) for ecological studies. Through water bath laboratory studies, we found that the accuracy was highest in TinyTags (±0.23°C) and lowest in HOBOs and iButtons (±0.43°C and ±0.49°C respectively). Our results suggest that these temperature loggers can provide reliable descriptions of sand temperature if they are not over-interpreted. We then wanted to consider the risk of climate-induced feminisation for nesting sites within the Asia-Pacific region, as there has been a significant gap in our knowledge of the sand temperatures and hatchling sex ratios for this important region. We modelled the likely long-term trends in sand temperatures and hatchling sex ratios at a nesting site for endangered green turtles (Chelonia mydas) and critically endangered hawksbill turtles (Eretmochelys imbricata) in eastern Papua New Guinea (PNG). A total of 1078 days of sand temperature data were collected from 28 logger deployments at nest depth between 2018 and 2022 on two islands within the Conflict Island Group, PNG. Long-term trends in sand temperature were generated from a model using air temperature as an environmental proxy. The influence of rainfall and seasonal variation on sand temperature was also investigated. Between 1960 and 2019, we estimated that sand temperature increased by ~0.6°C and the average hatchling sex ratio was relatively balanced (46.2% female, SD = 10.7). Additionally, the sex ratio models were unlikely to be influenced by changing rainfall patterns, as our analyses indicated that there were no trends in historical rainfall anomalies and projections indicated no further changes to rainfall until 2100. A relatively balanced sex ratio such as this is starkly different to the extremely female-skewed hatchling sex ratio (>99% female) reported for another Coral Sea nesting site, Raine Island (~850 km west). This PNG nesting site may be rare in the global context, as it is less threatened by climate-induced feminisation. Although there is no current need for ‘cooling’ interventions, the mean projected sex ratios for 2020–2100 were estimated to be 76%–87% female, so future interventions (such as irrigation) may be required to increase male production. This research is part of the ‘Turtle Cooling’ Project and is a broader collaboration with many independent monitoring groups across seven different countries. These relationships have facilitated our ability to fill a substantial knowledge gap on the likely hatchling sex ratios for these important turtle rookeries in the Asia Pacific. Through this research, we hope to expand on existing hatchling sex ratios datasets for global sea turtle populations and highlight the variables that drive cool sand temperatures at male-producing sites.

Item ID:	93627
Item Type:	Conference Item (Abstract / Summary)
Date Deposited:	27 Aug 2026 03:15
FoR Codes:	41 ENVIRONMENTAL SCIENCES > 4101 Climate change impacts and adaptation > 410102 Ecological impacts of climate change and ecological adaptation @ 50% 31 BIOLOGICAL SCIENCES > 3103 Ecology > 310305 Marine and estuarine ecology (incl. marine ichthyology) @ 50%
SEO Codes:	18 ENVIRONMENTAL MANAGEMENT > 1805 Marine systems and management > 180599 Marine systems and management not elsewhere classified @ 50% 19 ENVIRONMENTAL POLICY, CLIMATE CHANGE AND NATURAL HAZARDS > 1905 Understanding climate change > 190507 Global effects of climate change (excl. Australia, New Zealand, Antarctica and the South Pacific) (excl. social impacts) @ 50%
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