Disease risk analysis in sea turtles: A baseline study to inform conservation efforts.

The impact of a range of different threats has resulted in the listing of six out of seven sea turtle species on the IUCN Red List of endangered species. Disease risk analysis (DRA) tools are designed to provide objective, repeatable and documented assessment of the disease risks for a population and measures to reduce these risks through management options. To the best of our knowledge, DRAs have not previously been published for sea turtles, although disease is reported to contribute to sea turtle population decline. Here, a comprehensive list of health hazards is provided for all seven species of sea turtles. The possible risk these hazards pose to the health of sea turtles were assessed and "One Health" aspects of interacting with sea turtles were also investigated. The risk assessment was undertaken in collaboration with more than 30 experts in the field including veterinarians, microbiologists, social scientists, epidemiologists and stakeholders, in the form of two international workshops and one local workshop. The general finding of the DRA was the distinct lack of knowledge regarding a link between the presence of pathogens and diseases manifestation in sea turtles. A higher rate of disease in immunocompromised individuals was repeatedly reported and a possible link between immunosuppression and environmental contaminants as a result of anthropogenic influences was suggested. Society based conservation initiatives and as a result the cultural and social aspect of interacting with sea turtles appeared to need more attention and research. A risk management workshop was carried out to acquire the insights of local policy makers about management options for the risks relevant to Queensland and the options were evaluated considering their feasibility and effectiveness. The sea turtle DRA presented here, is a structured guide for future risk assessments to be used in specific scenarios such as translocation and head-starting programs.

Impacts of plastic ingestion on post-hatchling loggerhead turtles off South Africa.

Twenty-four of 40 (60%) loggerhead turtle Caretta caretta post-hatchlings (carapace<9cm) that died within 2months of stranding on southern Cape beaches in April 2015 contained ingested anthropogenic debris. Plastic comprised of 99% of debris: 77% hard plastic fragments, 10% flexible packaging and 8% fibres; industrial pellets comprised only 3%, compared to ~70% in 1968-1973, when 12% of stranded post-hatchlings contained plastics. Turtles selected for white (38%) and blue (19%) items, but translucent items (23%) were under-represented compared to beach mesodebris. Ingested loads did not decrease up to 52days in captivity, indicating long retention times. Plastic killed 11 turtles by blocking their digestive tracts or bladders, and contributed to the deaths of five other turtles. Our results indicate that the amount and diversity of plastic ingested by post-hatchling loggerhead turtles off South Africa have increased over the last four decades, and now kill some turtles.