Abstract
Hatching success of sea turtle eggs can be reduced by a variety of biotic and abiotic factors. This study of the nesting ecology of leatherback (Dermochelys coriacea) and green (Chelonia mydas) sea turtles, investigated how several environmental factors and beach characteristics on Bioko Island, Equatorial Guinea influence sea turtle reproductive success. Average hatching success was 40.4% for green turtles and 41.73% for leatherback turtles. For leatherback turtles, clutch elevation relative to the high tide line (HTL) was found to be the most influential factor in determining hatching success, highlighting the sensitivity of this species to sea-level rise (SLR). Multiple linear regression analysis demonstrated that nest distance to vegetation, temperature, sand grain size, location on the beach, and sand conductivity also played significant roles in leatherback clutch hatching success. For leatherback clutches, 33% percent of nests were affected by inundation and 17% by predation. An optimum clutch elevation range for leatherback turtles was identified, where a distinct increase in hatching success was observed between − 0.286 and − 0.0528 m above the HTL. For green sea turtles, 64% of experimental nests were affected by predation, confounding conclusions about the roles of environmental characteristics in green turtle hatching success. We propose further investigation into influential characteristics in green turtle nests and confirmation of the observed optimum elevation range on Bioko Island and other nesting grounds. Identified sensitivities of each species to SLR and beach characteristics will be used to encourage the government of Equatorial Guinea to consider the vulnerability of their resident turtle populations when planning for future coastal development.
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Availability of data and materials
The datasets generated during and analysed during the current study are available from the corresponding author upon reasonable request.
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The code generated during the current study is available from the corresponding author upon reasonable request.
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Acknowledgements
We would like to thank the government of Equatorial Guinea, Universidad Nacional de Guinea Ecuatorial, Instituto Nacional de Desarrollo Forestal y Gestión del Sistema de Áreas Protegidas (INDEFOR-AP), Gertrudis Ribado Mene, The Leatherback Trust, our national and international field assistants (Francisco Ekang Mba Abaga, Juan Jose Edu Abeso Ada, Kenny Ambrose, Ruth Bower-Sword, Brian Dennis, Emily Mettler, Pergentino Ela Nsogo Oye, Adam Quade, Jonah Reenders, Lindsey Rush and Alexis Weaver), and lab assistants (Ian Silver-Gorges and Quintin Bergman) for their help and support. HESS Equatorial Guinea, Inc. (grant #208369) and Purdue University Fort Wayne Schrey Distinguished Professorship provided funding for this project. This work was conducted under appropriate permits form Universidad Nacional de Guinea Ecuatorial (permit #289/2016).
Funding
HESS Equatorial Guinea, Inc. (Grant: #208369) and Purdue University Fort Wayne Schrey professorship (Grant: F.900001149.03.001) provided funding for this project.
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Conceptualization: CAV, SH, FVP; methodology: CAV, EMS, PL, SH, FVP; formal analysis and investigation: CAV, EMS, PL; writing—original draft preparation: CAV; writing—review and editing: EMS, PL, SH, FVP; funding acquisition: SH, FVP; resources: SH, FVP; supervision: EMS, SH, FVP.
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Veelenturf, C.A., Sinclair, E.M., Leopold, P. et al. The effects of nest location and beach environment on hatching success for leatherback (Dermochelys coriacea) and green (Chelonia mydas) sea turtles on Bioko Island, Equatorial Guinea. Mar Biol 169, 56 (2022). https://doi.org/10.1007/s00227-022-04049-4
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DOI: https://doi.org/10.1007/s00227-022-04049-4