Potential male leatherback hatchlings exhibit higher fitness which might balance sea turtle sex ratios in the face of climate change
Sea turtles are vertebrates with temperature-dependent sex determination. Rising temperatures due to climate change cause female-biased sex ratios. We have assessed the influence of nest depth and shading conditions on nest temperatures and hatchling fitness of the leatherback sea turtle (Dermochelys coriacea). We relocated 48 leatherback clutches into a hatchery in 2013, 2014 and 2015, respectively. Of these, 24 clutches were placed under shade conditions and 24 were placed under unshaded (sun) conditions at three depths (50, 75, 90 cm). Fitness (as measured by greater carapace length, carapace width and hatchling weight) and locomotion performance (faster crawling and shorter righting responses) were better in leatherback hatchlings from the cooler, shaded nests than in those from the warmer, unshaded nests. In 2013, in clutches at a depth of 50 cm, hatching success was higher for the shaded clutches (79.68% ± 15.32%) than for the unshaded clutches (38.39% ± 34.35), while in clutches at deeper depths unshaded clutches had higher hatching success (35.58% ± 24.01%) than shaded clutches (60.62% ± 12.21%). Our results show that shaded conditions produced hatchlings with a higher fitness and a higher likelihood of being male. Therefore, our results can be used to provide conservation policies with a tool to decrease the current female-skewed sex ratio production caused by rising temperatures at most nesting rookeries around the world.
KeywordsClimate change Conservation Endangered species Global warming Incubation period Marine turtles Reproductive output
We thank John Denham and Director Carlos Fernandez for the management of PNR and their involvement in conservation projects. We also thank all coordinators, assistants and volunteers who worked at PNR over the years for their full dedication to the experiments. We thank Dr. Manuel Spinola for support in the analysis of data. The work was also supported by an international mobility grants for prestigious researchers by AIUP and by CEIMAR International Campus of Excellence of the Sea. Research permits were obtained from the Ministry of Environment and Energy (MINAE) of Costa Rica (R-SINAC-ACLAC-PIME- 009-2013).
MLR and AM conceived and designed the experiments. MLR performed the experiments and analyzed the data. MLR wrote the manuscript and AM and NE revised the manuscript.
- Chevalier J, Godfrey MH, Girondot M (1999) Significant difference of temperature-dependent sex determination between French Guiana (Atlantic) and playa Grande (Costa-Rica, Pacific) leatherbacks (Dermochelys coriacea). Ann Sci Nat Zool Biol Anim 20:147–152. https://doi.org/10.1016/S0003-4339(00)88882-6 CrossRefGoogle Scholar
- Girondot M, Monsinjon J, Guillon J-M (2018) Delimitation of the embryonic thermosensitive period for sex determination using an embryo growth model reveals a potential bias for sex ratio prediction in turtles. J Therm Biol 73:32–42. https://doi.org/10.1016/j.jtherbio.2018.02.006 CrossRefGoogle Scholar
- Glen F, Broderick AC, Godley BJ, Hays GC (2003) Incubation environment affects the phenotype of naturally incubated green turtle hatchlings. J Mar Biol Assoc UK 83(5):1183–1186Google Scholar
- Hewavisenthi S, Parmenter CJ (2001) Influence of incubation environment on the development of the Flatback turtle (Natator depressus). Copeia 2001:668–682. https://doi.org/10.1643/0045-8511
- Houghton JDR, Myers AE, Lloyd C, King RS, Isaacs C, Hays GC (2007) Protracted rainfall decreases temperature within leatherback turtle (Dermochelys coriacea) clutches in Grenada, West Indies: ecological implications for a species displaying temperature dependent sex determination. J Exp Mar Biol Ecol 345:71–77. https://doi.org/10.1016/j.jembe.2007.02.001 CrossRefGoogle Scholar
- International Panel on Climate Change (IPCC) (2013) Climate Change 2013. The physical science basis (Stocker TF, Qin D, Plattner GK et al., eds). Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change Cambridge University Press, CambridgeGoogle Scholar
- Jourdan J, Fuentes MMPB (2015) Effectiveness of strategies at reducing sand temperature to mitigate potential impacts from changes in environmental temperature on sea turtle reproductive output. Mitig Adapt Strateg Glob Chang 20:121–133. https://doi.org/10.1007/s11027-013-9482-y CrossRefGoogle Scholar
- Kraemer JE, Bell R (1980) Rain-induced mortality of eggs and hatchlings of Loggerhead Sea turtles (Caretta caretta) on the Georgia coast. Herpetologica 36:72–77 http://www.jstor.org/stable/3891858
- Matsuzawa Y, Sato K, Sakamoto W, Bjorndal KA (2002) Seasonal fluctuations in sand temperature: effects on the incubation period and mortality of loggerhead sea turtle (Caretta caretta) pre-emergent hat- chlings in Minabe. Mar Biol 140:639–646. https://doi.org/10.1007/s00227-001-0724-2 CrossRefGoogle Scholar
- Maulany RI, Booth DT, Baxter GS (2012) The effect of incubation temperature on hatchling quality in the olive ridley turtle, Lepidochelys olivacea, from alas Purwo National Park, East Java, Indonesia: implications for hatchery management. Mar Biol 159:2651–2661. https://doi.org/10.1007/s00227-012-2022-6 CrossRefGoogle Scholar
- McGehee MA (1990) Effects of moisture on eggs and hatchlings of loggerhead sea turtles (Caretta caretta). Herpetologica 46:251–258 http://www.jstor.org/stable/3892967
- Miller JD (1999) Determining clutch size and hatching success. In: Eckert KL, Bjorndal KA, Abreu-Grobois FA, Donnelly M (eds) Research and management techniques for the conservation of sea turtles. IUCN/SSC Marine Turtle Specialist Group Publication, Washington DC, pp 124–129Google Scholar
- R Core Team (2017) R: A Language and Environment for Statistical Computing. https://www.R-project.org/
- Rivas ML, Marco A (2016) The effect of dune vegetation on leatherback hatchling's sea-finding ability. Mar Biol 163(1). https://doi.org/10.1007/s00227-015-2796-4
- Steyermark AC, Spotila JR (2001) Body temperature and maternal identity affect snapping turtle (Chelydra serpentina) righting response. Copeia 4:1050–1057. https://doi.org/10.1643/0045-8511
- Yntema C, Mrosovsky N (1980) Sexual differentiation in hatchling loggerheads (Caretta caretta) incubated at different controlled temperatures. Herpetologica 36:33–36 http://www.jstor.org/stable/3891850