Determination of the sex ratio of immature Hawksbill turtles (Eretmochelys imbricata) by detecting testosterone with the ELISA test
Keywords:
Eretmochelys imbricata, sex ratio, testosterone, ELISA, feeding areas, Jiquilisco bayAbstract
The determination of the sex ratio of sea turtles in forage habitats is of great interest for their conservation. These individuals lack secondary sexual characteristics, making sexing difficult; therefore, the use of techniques such as enzyme-linked immunosorbent assay (ELISA) for the measurement of testosterone is important for wildlife research. The study was carried out in Jiquilisco Bay, Usulután, El Salvador, between the months of August 2017 and February 2018.77 blood samples were collected from juvenile Hawksbill turtles (Eretmochelys imbricata) from which blood plasma was collected. The samples were sent to the endocrinology laboratory of the Southwest Fisheries Science Center (SWFSC) of the National Oceanic and Atmospheric Administration (NOAA) in La Jolla, California, United States, to perform the ELISA test. The results demonstrate a 5.8:1 hawksbill sex ratio (female/male). The testosterone concentration values of immature females had a variation of 7.7-77.20 pg/ml. While the immature males presented a variation between 660.30-3083.20 pg/ml. Regarding the correlation between testosterone concentration and carapace length, a probability of p=0.783 was obtained in females and a probability of p=0.0847 in males, so there is no significant relationship; for the variables testosterone concentration and weight, a probability p=0.741 was obtained in females and a probability of p=0.7382 in males, so there is no significant relationship. Concluding that the use of morphometric parameters is not reliable for the sexing of immature individuals and the use of the testosterone ELISA technique is a safe and reliable option for sex determination in immature sea turtles
References
Al Hasbi AA, Alkindi AY, Mahmoud IY, Owens DW, Khan T, Al Abri A. 2006. Plasma hormone levels in the green turtles CheloniamydasDuring peak period of nesting at Ras Al-Hadd Oman. Journal of endocrinology. Volumen 191. 9-14pp.
Allen CD, Robbins MN, Eguchi T, Owens DW, Meylan AB, Meylan PA, et al. 2015. First Assessment of the Sex Ratio for an East Pacific Green Sea Turtle Foraging Aggregation: Validation and Application of a Testosterone ELISA. PLoS ONE 10(10).
Blanvillain G, Owens DW, Kuchling G. 2011. Hormones and reproductive cycles in turtles. Hormones and Reproduction of Vertebrates, Volume 3-Reptiles. Elsevier Inc. 277–303 pp.
Campbell, C.L. 2014. Estado de Conservación de la Tortuga Carey en las Regiones del Gran Caribe, Atlántico Occidental y Pacífico Oriental. Secretaría Pro Tempore CIT, Virginia USA. 76p
Chacon Chaverri D. 2004. Tortugas Carey del Caribe; biología, distribución y estado de conservación. Programa de conservación de las tortugas marinas de América Latina y el Caribe del Fondo mundial para la Naturaleza (WWF). Publicación No. 1
Chaloupka k, Musick P, Snover P. 2012 Status of the hawksbill turtle (Eretmochelysimbricata) in the Caribbean region. ChelonianConservBiol 3: 177−184
Eckert KL, Bjorndal KA, Abreu-Grobois F, Donnelly M (Editors). 1999. Research and Management Techniques for the Conservation ofSea Turtles. IUCN/SSC Marine Turtle Specialist Group Publication No. 4.
Lande R. 1988. Genetics and demography in biological conservation. Science New York. Volumen 241 (4872). 1455-1460pp
Leon YM, Diez CE. 1999. Population structure of Hawksbill turtles on a foraging ground in the Dominican Republic. Chelonian conservation and biology. Volumen 3 (2). 230-236 pp.
Liles MJ., Jandres, MV., Lopez, WA., Mariona, GI., Hasbun, CR., &Seminoff JA. 2011. Hawksbill turtles (Eretmochelys imbricata) in El Salvador: Nesting distribution and mortality at the largest remaining nesting aggregation in the Eastern Pacific Ocean. Endang. Species Res. 14, 23-30. (doi: 10.3354/esr 00338)
Liles MJ, Peterson JM, Linconln YS, Seminoff JA, Gaos AR, Peterson TR. 2014. Connecting international priorities with human wellbeing in lowincome regions: lessons from hawksbill turtle conservation in El Salvador. Local Environment: The international journal of justice and sustainability. Volumen 20. 1383- 1404pp.
Liles, M. J., M. J. Peterson, J. A. Seminoff, E. Altamirano, A. V. Henríquez, A. R. Gaos, V. Gadea, P. Torres, J. Urteaga, B. P. Wallace, and T. R. Peterson. 2015. One size does not fit all: importance of adjusting conservation practices for endangered hawksbill turtles to address local nesting habitat needs in the eastern Pacific Ocean. Biological Conservation 184:405–413.
Liles, M. J., T. R. Peterson, J. A. Seminoff, A. R. Gaos, E. Altamirano, A. V. Henríquez, V. Gadea, J. Urteaga, B. P. Wallace, and M. J. Peterson. 2019. Potential limitations of behavioral plasticity and the role of egg relocation in climate change mitigation for a thermally sensitive endangered species. EcoEvol. 2019; 9: 1603-1622. https://doi. org/10.1002/ece3.4774
Marcovaldi MA, Santos JB, Santos A, Soares LS, Lopez GG, Godfrey MH, Mendilaharsu M, Fuentes MP. 2014. Spatio-temporal variation in the incubation duration and sex ratio of hawksbill hatchlings: implication for future management. Journal of thermalbiologyElsevier. Volumen 44. 70-77pp
MARN (Ministerio de Medio Ambiente y Recursos Naturales). 2013a. Propuesta del plan de manejo actualizado para el periodo 2012–2017 del Área de Conservación Bahía de Jiquilisco. MARN, San Salvador, El Salvador.
MARN (Ministerio de Medio Ambiente y Recursos Naturales). 2013b. Resultados de las actividades para la conservación de las tortugas marinas en El Salvador en 2012. San Salvador: MARN.
Wibbels T. 2003. Critical approaches to sex determination in sea turtles. In: Lutz PL, Musick JA, Wyneken J, editors. The Biology of Sea Turtles Volume II. CRC Press; 103–134pp.
Wyneken, J. 2004. La anatomía de las Tortugas marinas. U.S. Department of commerce. NOAA TechnicalMemorandum NMFS-SEFSC-470, 84- 85pp.
Downloads
Published
Issue
Section
License
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
