Surving the Epidemic –
The Australian Rescue Mission
Teresa Nirta

So named for their arresting black and yellow patterns – like those Australian Aborigines adorned during traditional Corroborees – the illusive Corroboree Frogs are no bigger than a human fingernail, making them difficult to spot in the wild. Unfortunately, because of declining numbers, they soon mightn’t be seen at all.

The chytrid fungus Batrachochytrium dendrobatidis is devastating frog populations worldwide. Scientists researching biodiversity hot spots in the Americas suspect two thirds of their 110 species of Harlequin Frogs are extinct because of this fungus. In Australia scientists suspect the fungus may have already wiped out as many as five native frog species.

In a race against the clock scientists have begun to trial antifungal drugs and diagnostic tests, but for Australia’s endangered Corroboree Frogs a breeding program may be the only immediate solution.

David Hunter and Rod Pietsch, Threatened Species Officers with the NSW Department of Environment and Conservation, believe the Common Eastern Froglet might be compounding the grim situation. “We believe the froglet has a natural resistance to the fungus and is acting as a host for the disease, contaminating any Corroboree Frog it comes in contact with.”

Buying time

The fight to beat the fungus and save the species begins with the scientists screening Corroborees for chytrid fungus. “We find the frogs in the field and swab their hands, feet and belly,” David explained. The samples are placed in an iced esky and sent to the Animal Health Research Laboratory at the CSIRO in Melbourne where the swabs undergo genetic PCR screening. “This process allows us to see how prevalent the fungus is in the wild,” Rod told PAWS.

The next stage involves collecting Corroboree Frog eggs from the wild and placing them in modified shipping containers for hatching and raising. Once the eggs hatched and the tadpoles have metamorphosed, scientists raise the frogs for three years. “The first three years of life is when the frogs are most at risk of contracting chytridiomycosis or dying of natural causes,” Rod explained. “By protecting them during these years of high mortality and injecting them back into the wild, we hope to boost numbers and increase their survival chance”.

In 2001, the Foundation directed funds from its Endangered Species Appeal towards the long-term breeding programme at the Amphibian Research Centre in Victoria and the Taronga Zoo in Sydney. Recently, the Foundation's Young Committee also raised money to fund the programme. Our volunteer Fiona McCuaig, who chairs the committee, met the frogs and Environment Minister Bob Debus at the opening of the new Taronga Zoo captive rearing compound

This captive rearing concept is already successful in giving part of the wild population’s offspring a head-start in the fight against the epidemic. Getting two Corroborees to mate and breed in captivity however still proves difficult.

“Unfortunately we’re not having much success at actually breeding Corroborees, which is common when breeding different frog species,” David told Paws. To assist reproduction scientists will provide larger natural enclosures and administer artificial hormones, used successfully with other endangered frog species.

“Once our captive reared frogs are of age we’ll send them back into their natural habitat. We’ll also keep some for breeding, assuming we can work out how to breed them. And I’m confident we will,” David asserted.

Ultimately the future of Corroboree Frogs largely depends on their capacity to acquire resistance to chytrid. This could be a long process, however, and will require successful breeding and reintroduction to prevent extinction in the short term. Some Queensland frog species have already developed natural resistance and hopefully this will happen for the Corroboree too, so we can continue to see the black and gold stripes of this tiny frog in its natural Australian habitat.

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