Influence of Sunlight on Vitamin D and Health Status in Green (Chelonia mydas) Sea Turtles with Fibropapillomatosis.

Green sea turtles (Chelonia mydas) are an endangered species, which as juveniles are prone to the debilitating disease green turtle fibropapillomatosis (FP). Previous work has shown an association between reduced immune function and FP. As vitamin D has been linked to immune function in numerous animals, the aim of this study was to compare vitamin D levels in green sea turtles with and without evident FP and determine if exposure to sunlight would influence vitamin D levels and other health parameters. Various health markers, including vitamin D, in turtles with and without evident tumors being treated at a rehabilitation facility in southeast Florida were compared to apparently healthy wild-caught juvenile green turtles. Turtles receiving treatment were housed in tanks exposed to higher or lower levels of sunlight for up to 6 months. Upon intake, tumored individuals had lower plasma vitamin D and ionized calcium levels and higher parathyroid hormone levels when compared to both wild-caught and rehabilitation turtles without evident tumors. Individuals exposed to greater sunlight showed greater increases in plasma vitamin D and a more successful recovery. The results suggest that increasing sun exposure in rehabilitation facilities may enhance health and recovery in green turtles with FP.