Interplay between age class, sex and stress response in green turtles (Chelonia mydas)
Tim S. Jessop A B and Mark Hamann C DA Center for Reproduction of Endangered Species, Zoological Society of San Diego, CA 92112, USA.
B School of Biological Sciences, University of Wollongong, NSW 2522, Australia.
C School of Tropical Environmental Studies and Geography, James Cook University, Qld 4811, Australia.
D Corresponding author. Email: mark.hamann@jcu.edu.au
Australian Journal of Zoology 53(2) 131-136 https://doi.org/10.1071/ZO04061
Submitted: 2 August 2004 Accepted: 3 March 2005 Published: 6 April 2005
Abstract
We investigated plasma hormone profiles of corticosterone in green turtles (Chelonia mydas) in response to a capture stress protocol. Further, we examined whether age class and sex were covariates associated with variation in both basal corticosterone levels and the adrenocortical stress response of non-breeding green turtles. Green turtles responded to the capture stress protocol by significantly increasing plasma levels of corticosterone over an eight-hour period. Further, there was a significant effect of age class on the capacity for green turtles to produce corticosterone in response to a capture stressor, with juvenile green turtles having higher basal levels of corticosterone and producing significantly more corticosterone in response to capture stress than non-breeding adult turtles. In contrast there was no significant sex difference in the corticosterone stress response of green turtles irrespective of age class. In summary, green turtles exhibited an adrenocortical response to a capture stress protocol. This response was significantly associated with different age classes, perhaps suggesting that the response is increased in juvenile turtles to offset the reduced probability of survival consistent with this more vulnerable age class.
Acknowledgments
The work was carried out as part of a Queensland Parks and Wildlife Service (QPWS) turtle conservation project. Several volunteers or national park staff assisted in fieldwork. We are particularly grateful for the contributions of Dr Colin Limpus and Duncan Limpus of the QPWS for logistical and field support. We also thank Dr Joan Whittier at the University of Queensland for providing laboratory supplies and reagents necessary to conduct hormone assays. TSJ was supported by an Australian Postgraduate Award during fieldwork and then by a Millennium post-doctoral fellowship from the Zoological Society of San Diego during preparation of this manuscript. The research was covered by a University of Queensland Animal Ethics permit (ANAT/121/98/ARC).
Aguirre, A. A. , Balazs, G. H. , Spraker, T. R. , and Gross, T. S. (1995). Adrenal and hematological responses to stress in juvenile green turtles (Chelonia mydas) with and without fibropapillomas. Physiological Zoology 68, 831–854.
Gregory, L. F. , and Schmid, J. R. (2001). Stress response and sexing of wild Kemp’s Ridley sea turtles (Lepidochelys kempii) in the northeastern Gulf of Mexico. General and Comparative Endocrinology 124, 66–74.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Limpus, C. J. , Couper, P. J. , and Read, M. A. (1994). The green turtle, Chelonia mydas, in Queensland: population structure in a warm temperate feeding area. Memoirs of the Queensland Museum 35, 139–154.
Wingfield, J. C. , Maney, D. L. , Breuner, C. W. , Jacobs, J. D. , Lynn, S. , Ramenofsky, M. , and Richardson, R. D. (1998). Ecological bases of hormone–behavior interactions: the ‘emergency life history stage’. American Zoologist 38, 191–206.
