Inter-Research > MEPS > v621 > p209-219  

MEPS 621:209-219 (2019)  -  DOI: https://doi.org/10.3354/meps12963

Highly feminised sex-ratio estimations for the world’s third-largest nesting aggregation of loggerhead sea turtles

Claire E. Tanner1, Adolfo Marco2,3, Samir Martins2, Elena Abella-Perez2, Lucy A. Hawkes4,*

1University of Exeter, College of Life and Environmental Sciences, Penryn Campus, Cornwall TR10 9FE, UK
2BIOS.CV, Rua Milagro, Sal Rei, Boa Vista, Cape Verde
3Estacion Biologica de Donana, Consejo Superior de Investigaciones Científicas (CSIC), C Americo Vespuccio, 41092 Sevilla, Spain
4University of Exeter, College of Life and Environmental Sciences, Hatherley Laboratories, Streatham Campus, Exeter, Devon EX4 4PS, UK
*Corresponding author:

ABSTRACT: Despite being a fundamental life-history character, there is a paucity of population-wide, data-driven studies of primary sex ratios for any marine turtle species. The Republic of Cape Verde hosts the third-largest nesting population of loggerhead turtles Caretta caretta in the world (hosting up to 15% of global nesting by the species). Weighting for the spatial distribution of nests, we estimate that 84% of female hatchlings are currently likely produced across the population, with 85% of nests laid on Boa Vista, where incubation temperatures are coolest. In future climate change scenarios (by 2100), irrespective of beach, island or sand colour, sex ratios reach over 99% female, and 3 islands (Fogo, Sao Nicolau, Santiago) would cease to produce males, with >90% of nests incubating at lethally high temperatures. Given that most of the population cannot move to nest on cooler islands, we highlight that temporal refugia are amongst the primary means available to this population to adapt. Under a low-emissions scenario, without phenological adaptation, there would only be an estimated 0.14% males produced across the whole population, while under mid- and high-emissions scenarios, male production may cease on most islands.


KEY WORDS: Climate change · Sex ratio · Caretta caretta · Loggerhead turtle · Marine turtle · Cape Verde


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Cite this article as: Tanner CE, Marco A, Martins S, Abella-Perez E, Hawkes LA (2019) Highly feminised sex-ratio estimations for the world’s third-largest nesting aggregation of loggerhead sea turtles. Mar Ecol Prog Ser 621:209-219. https://doi.org/10.3354/meps12963

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