Abstract

Dugongs are fully aquatic marine mammals found in inshore coastal ecosystems. Until a decade ago, studies of dugong population biology were conducted through aerial survey and some telemetry, and health was examined through necropsy of recovered carcasses. In 2000, a mark-recapture tagging program commenced in southern Queensland to conduct the first hands-on investigation into diverse aspects of dugong biology including population dynamics, reproductive and life history analysis, and behavioural ecology. A combination of genetic and endocrine methods has been used to identify thousands of individuals along the southern Queensland coast and assess size, maturity, reproductive activity and body condition. Genetic methods have also been used to assess relatedness between individuals and to examine population level processes including trends, connectedness and movements. Since 2008, annual health assessments of live free-ranging dugongs (n = 120) have been conducted through capture and out-of-water sampling. Blood, urine, faeces and other clinically valuable samples have been analysed for haematology and blood biochemistry and reference intervals have been established. Endocrinology, microbiology, parasitology and toxicology have provided insight into baseline clinical health indices for healthy dugongs. Recently, these data have been used to assess health status of coastal dugongs before and after severe flooding events. In summer 2011, a massive discharge from coastal catchments caused extreme water turbidity and sedimentation over nearshore seagrass beds that constitute important dugong feeding areas. Health assessments of dugongs were conducted four months post-flood in Moreton Bay and also in Hervey Bay 300 km north, and in subsequent years, and these clinical results were compared to three years of pre-flood health data (50 dugongs). Indicators of physiological stress (including fecal and serum cortisol and glucocorticosteroids, blood enzymes), body condition (body weight, morphometrics), diet (stable isotopes), nutritional status (blood analytes, gut microbes), contaminant levels (heavy metals) and general health (blood analytes) were measured and the results are discussed here. Health assessment of dugongs provides vital information regarding the health of not only the sampled individuals, but of the population(s) and their aquatic ecosystem.

Acknowledgments

We thank The University of Queensland (UQ) Dugong Research Team and staff from Sea World Australia and Sydney Aquarium. Funding was provided by the Winifred Violet Scott Foundation, Australian Marine Mammal Centre and Sydney Aquarium Conservation Fund. Sea World Research and Rescue Foundation provided in-kind support for annual health assessments.

* Presenting author