Manning platypus populations catastrophically affected by drought and bushfires

There were many observations of dead and dying platypus in the Manning River system during a recent survey, said MidCoast Council ecologist Mat Bell. Photo courtesy Aussie Ark
There were many observations of dead and dying platypus in the Manning River system during a recent survey, said MidCoast Council ecologist Mat Bell. Photo courtesy Aussie Ark

With recent news in the national media disclosing platypus may be at risk of extinction and calls for an urgent risk assessment for the species, the situation for platypus in the Mid Coast catchment is as critical here as elsewhere in Australia.

Local researchers strongly suspect the recent effects of drought and fire have had a catastrophic effect on local platypus populations.

Prior to the drought surveys showed the Manning catchment to be a stronghold for platypus, with populations being widespread in distribution and abundance. Frequent sightings also occurred in other rivers such as the Wallamba River.

Thanks to the ongoing severe drought and recent bushfires, the situation has changed drastically.

"With local rivers and creeks drying up and reduced to isolated shallow pools of generally poor water quality, platypus were forced to forage in these shallow, stagnant pools. Burrows became isolated from pools and platypus had to disperse to the remaining refuge pools," MidCoast Council ecologist Mathew Bell said.

Because platypus can only feed in water the declining water quality means a reduction in the food source for the species.

It also means platypus are more exposed to a high risk of predation from foxes and other animals.

Photo: copyright Klaus/Flickr

Photo: copyright Klaus/Flickr

Bushfires have exacerbated the situation with erosion, and sediments and ash washing into the river system, further degrading the quality of the water.

"While the recent rainfall has been a welcome relief to many of our waterways, by restoring a degree of flow and topping up and connecting pools, the initial rain does come at a cost - high sediment and nutrient loads, leading to loss of water quality and smothering of clean gravel and pebble substrates in waterways with sediment, which reduces the prey of platypus and their ability to find food," Mat said.

"There have even been reports of platypus killed and injured in the Upper Hunter when flash floods created torrents of water laden with sediment and debris which physically impacted the weak and stressed platypus in the refuge pools."

Human land use practices are also to blame for degradation of platypus habitat.

"There were many observations of cattle and other stock accessing the last of the rivers' refuge pools in which the remaining platypus were relying on. This uncontrolled stock access further affected platypus habitat by trampling, manure and further sedimation," Mat said.

On recent surveys of the Manning River system conducted jointly by the Department of Planning, Industry and the Environment (DPIE) and Barrington Tops-based conservation organisation Aussie Ark, there were many observations of dead and dying platypus.

"Also, the remains of several platypus were observed outside the den of a fox near the river, which highlights the predation risk," Mat said.

However, as platypus is nocturnal and a notoriously shy creature, it is difficult to observe and monitor. Mat says the observations on dead and dying platypus are consistent with observations of serious fish kills in local creeks and rivers.

Fish kill in the mid Manning. Photo: Dr Karen Bettink/MidCoast Council

Fish kill in the mid Manning. Photo: Dr Karen Bettink/MidCoast Council

"It's reasonable to assume that in the short to medium term there have been significant long-term negative impacts," Mat said.

"The long-term outlook for platypus is uncertain and we lack data and knowledge on the ability of platypus populations to recover from an event of this magnitude.

"The reduced remaining populations continue to face threats associated with the effects of a changing climate, over-extraction of water, impacts of stock in waterways and riparian zones, habitat loss and fox predation.

"Expert scientists will need to undertake targeted research, and government agencies and the community will need to work together to restore and protect habitat and give the populations the best chance of recovering," he said.

MidCoast Council ecologists are working alongside DPIE, Hunter Local Land Services and Aussie Ark to monitor the condition of the catchment's waterways for water quality, fish kills, platypus and Manning River helmeted turtles, with a particular focus on Bobin and Dingo creeks and the the Manning and Barnard rivers.

MidCoast Council has applied for a funding grant from the Australian Research Council to collaborate with the University of NSW to "investigate and describe local platypus populations and devise management actions to protect and enhance platypus habitat across the council area".

Photo copyright Maria Grist/Flikr

Photo copyright Maria Grist/Flikr

Not just platypus

MidCoast Council ecologists are not just concerned about platypus and the Manning River turtle. Actions are also being taken to help other fire and drought affected wildlife.

Monitoring of koalas and other wildlife is taking place in fire-affected council reserves with observations including remote cameras and detection dogs. Water stations have also been established for native wildlife in the reserves.

What you can do to help platypus

If you come across any stressed, injured or dead platypus, please report the sighting to MidCoast Council immediately.

Landholders are encouraged to protect waterways and riparian zones (river and creek banks) from stock, and undertake fox control measures.