Abstract

Characterizing the health status and reproductive success of wild populations of sea turtles can be difficult; however, obtaining data to do this can provide important insight into the stability and long-term success of a population. This study examined the use of baseline corticosterone, hematological, and biochemistry data to assess the health status and reproductive success of a population of nesting loggerhead sea turtles (Caretta caretta) on Jekyll Island, Georgia. A total of 37 nesting loggerhead sea turtles were sampled for this study. Eleven (29.7%) turtles were sampled in 2013 and 26 (70.3%) were sampled in 2014. A majority of the turtles sampled successfully nested (29/37, 78.4%; false-crawls: 8/37, 21.6%). There was no significant correlation between baseline corticosterone concentrations and reproductive success in this population. Corticosterone concentrations were significantly higher (p = 0.03) in turtles with obvious signs of trauma compared with those with no signs of trauma. There was a significant positive correlation (r = 0.461, p = 0.02) between corticosterone concentrations and monocyte counts. There was a significant negative correlation between monocyte levels and hatch success (r = -0.464, p = 0.05) and a positive correlation between phosphorus and hatch success (r = 0.405, p = 0.05). Calcium levels were significantly different (p = 0.01) between animals that false crawled and those that nested, with nesting turtles having lower calcium concentrations than those that false crawled. Turtles that false crawled were significantly (p = 0.008) more likely to have elevated potassium concentrations than turtles that nested. The results of this study suggest that baseline corticosterone, hematologic, and biochemistry data can be used to characterize the health status and reproductive success of nesting loggerhead sea turtles. Overall, this population of loggerhead sea turtles appears to be healthy and capable of using physiologic mechanisms to regulate their stress response to ensure successful reproduction despite the physiological or environmental stressors that may be present.

Acknowledgements

The authors thank Abaxis Inc. (Union City, CA) for providing chemistry rotors and the Illinois Zoological and Aquatic Animal Residency Program for supporting this research. Additionally, the authors thank the rehabilitation and research staff at the Jekyll Island Authority's Georgia Sea Turtle Center as well as their dedicated volunteers and AmeriCorps members.

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