Effects of hatchery shading and nest depth on the development and quality of Chelonia mydas hatchlings: implications for hatchery management in Peninsular, MalaysiaJason van de Merwe A B D , Kamarruddin Ibrahim A C and Joan Whittier A D
A School of Biomedical Sciences, Department of Anatomy and Developmental Biology, University of Queensland, St Lucia, Qld 4072, Australia.
B Current address: School of Environmental and Applied Sciences & Centre for Aquatic Processes and Pollution, Griffith University, Gold Coast, Qld 4214, Australia.
C Current address: Turtle and Marine Ecosystem Center (TUMEC), Rantau Abang, 23050 Dungun, Terengganu, Malaysia.
D Corresponding author. Email: firstname.lastname@example.org
Australian Journal of Zoology 53(3) 205-211 https://doi.org/10.1071/ZO03052
Submitted: 14 October 2003 Accepted: 13 April 2005 Published: 16 June 2005
One of the decisions made by hatchery managers around the world is what degree of shading and nest depth are required to maximise the production of high-quality hatchlings at optimal sex ratios. The primary objectives of this study were to determine the effects of (1) hatchery shading and nest depth on nest temperatures and emergence lag, and (2) nest temperatures and nest depth on hatchling sex ratio and quality. In 2001, 26 Chelonia mydas clutches from Ma’Daerah beach, Terengganu, Malaysia, were relocated alternatively at depths of 50 cm and 75 cm into a 70%-shaded and a 100%-shaded hatchery. Data loggers were placed into the centre of each relocated clutch to record the temperature every hour over the course of incubation. When the hatchlings emerged, a sample of the clutch was run, measured and weighed and a separate sample was examined histologically for sex characteristics. Nest temperatures ranged between 28°C and 30°C and generally showed increases over the second half of incubation due to metabolic heating of the clutch. There was no significant correlation found between nest temperature and any of the hatchling parameters measured. Hatchlings from 75-cm-deep nests had a longer emergence lag (46.4 (±10.2) h) than hatchlings from 50-cm-deep nests. Hatch and emergence success were similar to those of natural populations and hatchling sex ratios were male dominant, with an average of 72% males. There was a poor correlation between mean middle-third incubation temperatures and sex ratio. Hatchlings from 75-cm-deep nests had similar running speeds but lower condition index than their conspecifics from 50-cm-deep nests.
We acknowledge the Earthwatch Institute and the University of Queensland for project support and Mark Hamann, Chloe Schauble, Kendra Coufal, staff from the Department of Fisheries, Malaysia and Earthwatch volunteers for field support. Kamarruddin Ibrahim was supported by a Malaysian Commonwealth Ph.D. Scholarship during this study. Incidentals to J. Whittier and J. van de Merwe were supplied by a University of Queensland Research Grant, with extra support throughout the project from the Rio Tinto Earthwatch Fellowship Scheme and the Shell Global Partnership Scheme. All research was conducted under Department of Fisheries, Malaysia permits and under an Animal Experimental Ethics Approval Certificate from the Animal Welfare Office at the University of Queensland (ANAT/565a/90/PHD).
Ackerman, R. A. (1981). Growth and gas exchange of embryonic sea turtles (Chelonia, Caretta). Copeia 1981, 757–765.
Ackerman, R. A. , Seagrave, R. C. , Dmi’el, R. , and Ar, R. (1985). Water and heat exchange between parchment-shelled reptile eggs and their surroundings. Copeia 1985, 703–711.
Blanck, C. E. , and Sawyer, R. H. (1981). Hatchery practices in relation to early embryo of the loggerhead sea turtle, Caretta caretta (Linn.). Journal of Experimental Marine Biology and Ecology 49, 163–177.
| CrossRef |
Bolger, T. , and Connolly, P. L. (1989). The selection of suitable indices for the measurement and analysis of fish condition. Journal of Fish Biology 34, 171–182.
Booth, D. T. , and Astill, K. (2001a). Incubation temperature, energy expenditure and hatchling size in the green turtle (Chelonia mydas), a species with temperature-sensitive sex determination. Australian Journal of Zoology 49, 389–396.
| CrossRef |
Booth, D. T. , and Astill, K. (2001b). Temperature variation within and between nests of the green sea turtle, Chelonia mydas (Chelonia: Cheloniidae) on Heron Island, Great Barrier Reef. Australian Journal of Zoology 49, 71–84.
| CrossRef |
Broderick, A. C. , Godley, B. J. , Reece, S. , and Downie, J. R. (2000). Incubation periods and sex ratios of green turtles: highly female biased hatchling production in the eastern Mediterranean. Marine Ecology Progress Series 202, 273–281.
Broderick, A. C. , Godley, B. J. , and Hays, G. C. (2001). Metabolic heating and the prediction of sex ratios for green turtles (Chelonia mydas). Physiological and Biochemical Zoology 74, 161–170.
| CrossRef | PubMed |
Bustard, R. (1970). Temperature and water tolerances of incubating sea turtle eggs. British Journal of Herpetology 1970, 196–198.
Bustard, R. , and Greenham, P. (1968). Physical and chemical factors affecting hatching in the green sea turtle, Chelonia mydas (L.). Ecology 49, 269–276.
Christens, E. (1990). Nest emergence lag in loggerhead sea turtles. Journal of Herpetology 24, 400–402.
Ewert, M. A. , Jackson, D. R. , and Nelson, C. G. (1994). Patterns of temperature-dependent sex determination in turtles. Journal of Experimental Zoology 270, 3–15.
| CrossRef |
Georges, A. , Limpus, C. J. , and Stoutjesdijk, R. (1994). Hatchling sex in the marine turtle Caretta caretta is determined by proportion of development at a temperature, not daily duration of exposure. Journal of Experimental Zoology 270, 432–444.
| CrossRef |
Godfrey, M. H. , and Mrosovsky, N. (1997). Estimating the time between hatching of sea turtles and their emergence from the nest. Chelonian Conservation and Biology 2, 581–585.
Godfrey, M. H. , Barreto, R. , and Mrosovsky, N. (1996). Estimating past and present sex ratios of sea turtles in Suriname. Canadian Journal of Zoology 74, 267–277.
Godfrey, M. H. , Barreto, R. , and Mrosovsky, N. (1997). Metabolically-generated heat of developing eggs and its potential effect on sex ratio of sea turtle hatchlings. Journal of Herpetology 31, 616–619.
Harry, J. L. , and Limpus, C. J. (1989). Low-temperature protection of marine turtle eggs during long distance relocation. Australian Wildlife Research 16, 317–320.
Limpus, C. J. , Baker, V. , and Miller, J. D. (1979). Movement induced mortality of loggerhead eggs. Herpetologica 35, 335–338.
Maloney, J. E. , Darian-Smith, C. , Takahashi, Y. , and Limpus, C. J. (1990). The environment for development of the embryonic loggerhead turtle (Caretta caretta) in Queensland. Copeia 1990, 378–387.
McGehee, M. A. (1990). Effects of moisture on eggs and hatchlings of loggerhead sea turtles (Caretta caretta). Herpetologica 46, 251–258.
Mortimer, J. A. (1990). The influence of beach sand characteristics on the nesting behaviour and clutch survival of green turtles (Chelonia mydas). Copeia 1990, 802–817.
Mrosovsky, N. (1994). Sex ratios of sea turtles. Journal of Experimental Zoology 270, 16–27.
| CrossRef |
Mrosovsky, N. , and Yntema, C. L. (1980). Temperature dependence of sexual differentiation in sea turtles: implications for conservation practices. Biological Conservation 18, 271–280.
| CrossRef |
Pilcher, N. J. , and Enderby, S. (2001). Effects of prolonged retention in hatcheries on green turtle (Chelonia mydas) hatchling swimming speed and survival. Journal of Herpetology 35, 633–638.
Spotila, J. R. , Standora, E. A. , Morreale, S. J. , and Ruiz, G. J. (1987). Temperature dependent sex determination in the green turtle (Chelonia mydas): effects on the sex ratio on a natural nesting beach. Herpetologica 41, 74–81.
Wibbels, T. , Balazs, G. H. , Owens, D. W. , and Amoss, M. S. (1993). Sex ratio of immature green turtles inhabiting the Hawaiian archipelago. Journal of Herpetology 27, 327–329.