Abstract
At least 150 free-range green turtles (Chelonia mydas) died in Moreton Bay, Queensland, and northern New South Wales, Australia from September to December 2014.
The outbreak appeared to begin in September 2014 when it was noticed that there was an unusual number of strandings of large green turtles (curved carapace length > 70 cm) in and around the northern region of Moreton Bay, Queensland and northern New South Wales. It was unusual to see large numbers of strandings of this particular size of green turtles. Usually the size of animals presented to rehabilitation centres in this region is around 40-cm curved carapace length.
The outbreak occurred in the Moreton Bay area and extended up to the sunshine coast and Bribie Island. Affected animals were also found in northern New South Wales as far south as the Coffs coast. It should be noted that rainfall in this area from around May 2014 until the beginning of the outbreak was unusually low.
Animals were recovered by national parks staff and transported to various local rehabilitation centres. Animals presented either with lethargy or neurological signs such as head tilts or circling. Most animals were in good body condition, indicating a reasonably acute illness. Faecal samples were positive for coccidia oocysts. A number of animals were euthanased, and necropsies were carried out.
Histopathology confirmed the diagnosis of coccidiosis - Caryospora cheloniae. Histopathology of affected animals included severe necrotizing coccidial enterocolitis and subacute to chronic necro-granulomatous encephalomyelitis associated with coccidial schizonts.
The number of animals affected began to decline by December 2014. The total number of animals that died during the outbreak is estimated to be greater than 150. Most affected animals had a curved carapace length > 70 cm. Many of the animals were pre-pubescent females. Treatment at rehabilitation centres was generally unrewarding, especially if the animal was displaying neurological signs. Most of the animals that were presented to rehabilitation centres were either euthanased or died.
A previous outbreak of coccidiosis in the same region affecting green turtles in 1991 has been previously described in which over 70 animals died.1
Acknowledgements
The authors wish to thank Queensland National Parks and Wildlife staff and staff at Sea World, Australia who assisted with the care of these animals during rehabilitation.
* Presenting author
Literature Cited
1. Gordon AN, Kelly WR, Lester RJG. Epizootic mortality of free-living green turtles, Chelonia mydas, due to coccidiosis. Journal of Wildlife Diseases. 1993;29(3):490–494.