Conservation and the invisible hitchhikers

How does the largely unexplored world of biodiversity living within us all affect wildlife management?

An examination of parasites living in threatened brush-tailed rock-wallabies has revealed both marsupial-specific and more cosmopolitan parasite species. The presence of parasites more usually associated with humans and our animal associates (livestock, rats etc) in wild rock-wallabies is concerning as it indicates that new parasites are transferring into wildlife. However, the mechanism and significance of this transfer remains uncertain.

Australian Museum Research Institute PhD student Elke Vermeulen has been exploring the poorly known biodiversity of parasites found within brush-tailed rock-wallabies (Petrogale penicillata). Parasites are interesting because most animal species play host to a unique parasite community which represents a large but poorly characterised component of biodiversity. However, in a rapidly globalizingworld, parasites and diseases are increasingly able to jump between species to pose a significant risk to wildlife. This so called ‘spill-over’ is most commonly seen when parasites typically found in humans and associated species (domestics and commensals) are transferred into wildlife populations.

One potential pathway for this spill-over is through the management of threatened species, especially where captive breeding is used to produce individuals for release into the wild. In captivity, animals frequently have increased contact with people and pests such as rats, as well as sometimes livestock and pets. This unusual close proximity provides the opportunity for parasites and diseases to move between species and then to be transferred into the wild when captive bred individuals are released. The potential for these pathogens to impact the health of individuals both in captivity and the wild is therefore significant and may impact the success of conservation programs.

To investigate how the movement of rock-wallabies between captivity and the wild was impacting their parasite faunas, we targeted the presence of two well known but potentially problematic protozoan parasites (Giardia and Cryptosporidium) in 318 scats (droppings) collected in captive, wild and reintroduced populations of the threatened brush-tailed rock-wallaby. DNA screening revealed, in both wild and captive rock-wallabies, the presence of marsupial-specific protozoans (as expected), but also those more typically associated with humans. This indicates that these potentially pathogenic organisms have already found their way into wildlife populations.

Since the impact and sources of these pathogens currently remains uncertain additional research is required before we can fully understand the diversity, dynamics and epidemiology of these and other parasites in Australian wildlife.

Dr Mark Eldridge
Principal Research Scientist, Australian Museum Research Institute

More information:

• Vermeulen, E.T., Ashworth, D.L., Eldridge, M.D.B. and Power M.L. (2015). Diversity of Cryptosporidium in brush-tailed rock-wallabies (Petrogale penicillata) managed within a species recovery programme. International Journal for Parasitology: Parasites and Wildlife 4: 190-196.
• Vermeulen, E.T., Ashworth, D.L., Eldridge, M.D.B. and Power M.L. (2015). Investigation into potential transmission sources of Giardia duodenalis in a threatened marsupial (Petrogale penicillata). Infection, Genetics and Evolution 33: 277-280.

Acknowledgements:

• Elke Vermeulen is a PhD student in the School of Biological Sciences, Macquarie University and the Australian Museum Research Institute. She is co-supervised by Dr Michelle Power, Macquarie University and Dr Mark Eldridge, Australian Museum Research Institute.
• This research was funded by ARC Linkage grant LP110200569 to Macquarie University, NSW Office of Environment and Heritage and the Australian Museum.