Abstract

For many reptile species, exposure to UVB radiation is essential to proper calcium metabolism.^1-4 We assessed the effect of UVB radiation on 25-hydroxyvitamin D, ionized calcium (iCa), and parathyroid hormone (PTH) levels of green sea turtles (Chelonia mydas). Animals were either kept outdoors with access to direct sunlight or indoors under artificial light without UVB spectrum. Eighteen juveniles (9 indoor, 9 outdoor) and 8 adults (4 indoor, 4 outdoor) were included in the study. All animals were fed identical diets including whole fish and vegetables. Mean values for 25-hydroxyvitamin D and iCa for the outdoor juveniles were 34.3 nmol/L and 0.98 mmol/L, respectively, and for indoor juveniles values were 7.11 nmol/L and 0.99 mmol/L, respectively. Mean values for 25-hydroxyvitamin D and iCa for the outdoor adults were 73.25 nmol/L and 1.175 mmol/L, respectively, and for indoor adults values were 14.0 nmol/L and 0.965 mmol/L, respectively. Two-way ANOVA analysis indicated UVB exposure (p < 0.0001) and age (p = 0.0004) had a significant effect on 25-hydroxyvitamin D with a significant interaction between the two variables (p = 0.0081). The interaction of variables had a significant effect on iCa (p = 0.0363). All PTH values in this study were near the minimum limits of detection, suggesting current PTH assays do not have sufficient cross-reactivity to offer valid results. Although no clinical signs of calcium deficiency or hyperparathyroidism were observed in the animals in the study, UVB exposure appears to be an important component of proper nutritional management of green sea turtles.

Acknowledgements

The authors would like to thank the Medical Laboratory Scientists at the SWC Animal Care Center, Jennifer Rego RVT, Jennifer Haselow RVT, Jessica Patterson and sea turtle animal care staff of SeaWorld California for their contributions to this study.

* Presenting author
⁺ Student presenter

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