TASMANIA’S wildlife is under siege from a number of fronts — habitat loss, ongoing persecution, climate change, invasive species AND new and emerging diseases.

In recent years, readers of Tasmanian Times know this perhaps better than readers of the mainstream media. The interdependence of these threat factors suggests to me at least that Tasmania’s wildlife has probably now pased a threshold, a critical tipping point.

Unbalanced ecologies are appearing around the world as significantly disturbed environments lose their biodiversity — both in terms of overall species abundance and range of habitats they occupy. This is the very real state of our planet’s environment. The sudden emergence of new diseases in wildlife is really a harbinger of our current ecological ‘dis-ease’.

Another wildlife disease to add to Tasmania’s list of the new & emerging diseases is Platypus Ulcer Disease.

In the autumn of 1982 a man was walking his dog along the edge of the Elizabeth River in the Midlands town of Campbell Town. The dog grabbed a weak platypus with a large skin ulcer on its back and in the next few months another three very moribund (close to death) platypus and another very disabled and thin platypus with large skin ulcers were reported at Campbell Town. Over the next ten years following a spate of reports from fishers and members of the public, additional cases of ulcerated platypus were received from the South Esk River at Perth (5 animals), Meander River at Deloraine (2 animals), and at Westbury (1 animal) and Brumbys Creek at Cressy (1 animal). 

All these platypus, living in Tasmanian rivers, had disabling skin ulcers on the back, tail, head or legs. Surprisingly ‘the cause’ of these ulcers seemed to be the invasion of a particular fungus, Mucor amphibiorum; an organism first identified in frogs in the late 1970s. Attempts to understand the disease more fully and its impact on platypus populations led to useful research by Joanne Connolly and Niall Stewart.

As with investigations on the Devil Facial Tumour, high-density platypus populations were ‘hotspot’ locations for this disease and subsequent work suggested possible ‘spread’. Whether that spread pattern was real or purely based on increased awareness & reporting is unclear. A number of tributaries of the South Esk catchment were added to the distribution. These included the Liffey River flowing into the Meander. Some ulcerated platypus turned up in high altitude locations in the South Esk catchment (headwaters of the Meander River above Meander; and a number of natural lakes Woods Lake (740 m), Arthurs Lake (951m) and Gunns Lake (~990m), all draining into the Lake River, a central highlands tributary of the Macquarie/South Esk catchment.

In addition ulcerated platypus (several animals) were also observed on the Supply River, a small easterly flowing catchment that drains into the Tamar estuary, at Glengarry and another location north of Exeter. The North Esk catchment began to receive more attention in 1995/96 when reports of ulcerated platypus in the upper valley near Upper Blessington were received. A veterinarian who had been a frequent trout fisher in the area reported several animals with ulcers. About this time another confirmed sighting of an ulcerated platypus was reported from a tributary to the northwardly draining Pipers River near Karoola (Hogans Brook).

A new pathogen had entered Tasmania

The late Barry Munday and his student Niall Stewart conducted additional research on mucormycosis and their research brought forth the hypothesis that this new fungus was a new pathogen that had entered and established in Tasmania’s freshwater ecologies.

By 1997 it was apparent that platypus ulcer disease occurred extensively in the South and North Esk catchments in virtually all the main tributaries and indications of movement into headwater streams or lakes in at least three major tributaries (Macquarie, Lake and Meander Rivers). Sightings of ulcerated platypus were obtained from two separate river systems draining to the central north coast of Tasmania — the Mersey River below Lake Parangana and the Emu River (below Ridgley).

Platypus ulcer disease distribution as of December 2005.The green areas indicate catchments with numerous platypuses with confirmed mucormycosis. Red dots indicate locations where platypus with skin ulcers have been reported.

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More recent reports of ulcerated platypus in the Inglis/Flowerdale Rivers and the upper headwaters of the Pieman River are of concern. They are somewhat removed geographically from easterly catchments where mucormycosis is known (Emu River and Mersey catchments). This finding may merely reflect a lack of reporting on the status of platypus in the intervening catchments. Equally it could suggest that the transfer of this aquatic pathogen is occurring by other means than just platypus movements.

The uncorroborated reports of ulcerated platypus in Bradys Lake (651m) and Dee Lagoon (656m) are of interest in that both these Central Plateau lakes are headwaters leading into the Derwent River catchment. Both are recreational trout fisheries. These sightings also need urgent corroboration by field assessment and/or laboratory confirmation.

Reports of ulcerated platypus at the Salmon Ponds hatchery and at a commercial trout hatchery at Springfield in NE Tasmania suggest the role of fish as carriers and possible spreaders of this disease needs to be investigated.

How you can help

You can help by reporting your experiences with platypus through the “Are your platypus healthy?” project run by the Central North Field Naturalists,

Platypus_alert_page_2.pdf

Platypus_alert_page_1.pdf

All Tasmanian can get involved — recreational boaties, fishers, bushwalkers, ecotourism operators, landowners with land for wildlife etc.

Since its detection over 20 years ago, the body of evidence suggests that this is another new wildlife disease for Tasmania. Barry Munday came to the conclusion that M. amphibiorum was introduced to Tasmania with our platypus appearing to have a unique sensitivity to developing chronic skin ulcers caused by this fungus whereas the disease is not seen in mainland platypus. The role of the bio-accumulated organochlorines in Tasmania’s platypus — especially the immunogenic and hormone-disrupting synthetic PCBs — needs further investigation.

Another fungal disease, this time of frogs — chytridiomycosis — was also recently found to be widespread in Tasmania. This disease is wiping out frogs across the globe. That’s right, it is responsible for species extinctions; at least five in Australia so far.

While the World seems totally obsessed with a War on Terror, the insidious invasion and spread of ‘Bioterror’ is accelerating.

On this shrinking Planet, even Tasmania and its inhabitants have nowhere to run to and nowhere to hide any more. Welcome to this brave new world!

David Obendorf and Joanne Connolly

Since its detection over 20 years ago, the body of evidence suggests that this is another new wildlife disease for Tasmania. Barry Munday came to the conclusion that M. amphibiorum was introduced to Tasmania with our platypus appearing to have a unique sensitivity to developing chronic skin ulcers caused by this fungus whereas the disease is not seen in mainland platypus. The role of the bio-accumulated organochlorines in Tasmania’s platypus — especially the immunogenic and hormone-disrupting synthetic PCBs — needs further investigation.

While the World seems totally obsessed with a War on Terror, the insidious invasion and spread of ‘Bioterror’ is accelerating.