Beginning in the fall of 2014, a number of small juvenile green sea turtles (Chelonia mydas) with unusual symptoms stranded on the east coast of Florida from Nassau County through Monroe County. Affected individuals were generally 20–30 cm straight carapace length and in fair to good body condition. Many had neurological symptoms that ranged from incoordination of muscle groups to abnormal, exaggerated movements of the mandible. Blood work showed very few major abnormalities. Most of the individuals were hypoglycemic, while others were normoglycemic. Individuals that died were necropsied and histopath performed. Consistent histopathological findings included enteric coccidiosis with associated enteritis and mucosal hyperplasia. Several of the individuals also had spirorchiid trematode infections involving various systems, including the brain. Fecal analysis for parasites revealed large numbers of Caryospora sp. oocysts in many of the affected turtles. Samples from some of the cases were analyzed for algal toxins. A number of the affected turtles had very high concentrations of domoic acid in feces, stomach contents, intestinal contents, and kidneys. Another had concentrations of saxitoxin in its feces that were too high to quantify. About 50% of affected turtles stranded dead and another 50% of live stranded turtles died during rehabilitation. Thirty-five turtles recovered completely and were released, and a small number remain in rehabilitation. This event lasted through the summer of 2015. Findings from our investigation suggest that multiple factors contributed to these strandings, although concurrent health problems complicated some aspects of interpretation. Clinical infections by Caryospora sp. have been rarely detected in the United States in prior years and clinical evidence of domoic acid toxicosis has not been previously reported in sea turtles.
The authors wish to thank Lara Croft, Whitney Crowder, Michael Garner, Nicole Gottendenker, Craig Pelton, Melanie Stadler, Heather Walden, and Bette Zirkelbach for contributing to this study as well as the members of the Sea Turtle Stranding and Salvage Network for their help in rescuing the turtles.
* Presenting author