A deadly fungus threatens to wipe out 100 frog species – here’s how it can be stopped


Deborah Bower, University of New England and Simon Clulow, Macquarie University

What would the world be like without frogs? Earth is in its sixth mass extinction event and amphibians are among the hardest hit.

But in the island of New Guinea, home to 6% of the world’s frog species, there’s a rare opportunity to save them from the potential conservation disaster of a chytrid fungus outbreak.

The amphibian chytrid fungus is a microscopic, aquatic fungus that infects a protein in frog skin. It interferes with the balance of electrolytes and, in turn, effectively gives frogs a heart attack.




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If the amphibian chytrid fungus invades New Guinea, we estimate 100 species of frogs could decline or become extinct. This disease, which emerged in the 1980s, has already wiped out 90 species of frogs around the world.

The New Guinean horned land frog, Sphenophryne cornuta, with young. These frogs are under threat from a fungus that has wiped out 90 frog species around the world.
Stephen Richards

Collaborating with 30 international scientists, we developed a way to save New Guinea’s frog species from a mass extinction, one that’s predictable and preventable. We need urgent, unified, international action to prepare for the arrival of the deadly fungus, to slow its spread after it arrives and to limit its impact on the island.

It’s rare we can identify a conservation disaster before it occurs, but a long history of amphibian declines in Australia and South America has equipped us with the knowledge to protect areas where the amphibian chytrid fungus is yet to reach.

Why we should care about frogs

Like Australian frogs, New Guinea frogs may be particularly vulnerable to the chytrid fungus. These frogs share a close genetic relationship suggesting that, if exposed, New Guinea frogs may respond similarly to Australian ones, where around 16% of frog species are affected.

Impacted frogs include corroboree frogs, Australian lacelid frogs and green and golden bell frogs.




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Losing so many species can have many terrible impacts. Tadpoles and frogs are important because they help recycle nutrients and break down leaf litter. They are also prey for larger mammals and reptiles, and predators of insects, invertebrates and small vertebrates. They help keep insect plagues, such as those from flies and mosquitoes, in check.

Frogs are also an important source of human medical advancements – they were even used for a human pregnancy test until the 1950s.

A call to action to protect frogs

Frogs are one of the most threatened groups of species in the world – around 40% are threatened with extinction.

And species conservation is more expensive once the species are threatened. They can be more costly to collect and more precious to maintain, with a greater need for wider input from recovery groups to achieve rapid results.

In our study, we highlight the increased costs and requirements for establishing captive breeding for two species of closely related barred frog, one common and one threatened. We determined that waiting until a species is threatened dramatically increases the costs and effort required to establish a successful breeding program. The risks of it failing also increase.

Our research draws on lessons learned from other emerging diseases and approaches taken in other countries. By addressing the criteria of preparedness, prevention, detection, response and recovery, we detail a call for action to protect the frogs of New Guinea. It will require dedicated funding, a contingency plan for the likely, eventual arrival of the disease and a task force to oversee it.




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This task force would oversee active monitoring for disease and prepare an action plan to implement on the disease’s arrival. We have already begun to establish facilities that can handle captive breeding and gene banking for frogs in collaboration with PNG counterparts.

The need for amphibian conservation in New Guinea also presents an opportunity for investment and training of local scientists. More species unknown to science will be described and the secret habits of these unique frogs will be discovered before they are potentially lost.

Conservation in New Guinea is complicated

The island of New Guinea is governed by Papua New Guinea on the eastern side and Indonesia on the western side. So it will take a coordinated approach to reduce risks in both countries for successful biosecurity.

Historically, New Guinea has had little import or tourism. But as the country develops, it becomes more at risk of emerging diseases through increased trade and and entry of tourists from chytrid-infected regions, especially with little biosecurity at entry ports.

What’s more, many species there are unknown to science and few ecological studies have documented their habitat requirements. Unlike Australia, many of New Guinea’s frogs have adapted for life in the wet rainforest.

Rather than developing into tadpoles that live in water, more than 200 frog species in New Guinea hatch from their eggs as fully formed baby frogs. It’s difficult for us to predict how the amphibian chytrid fungus will affect these frogs because Australia has only a handful of these types of species.

We don’t know how to remove the amphibian chytrid fungus from large areas once it has invaded, so strict biosecurity and conservation contingency planning is needed to protect New Guinea’s frogs.




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For example, all incoming goods into New Guinea should be inspected for possible hitchhiker frogs that could carry chytrid. Camping or hiking equipment carried by tourists should also be closely inspected for attached mud, which could harbour the pathogen, as is the case in Australia.

International researchers have experience in emerging amphibian diseases. Papua New Guineans and Indonesians have traditional and ecological expertise. Together we have the opportunity to avert another mass decline of frogs. Without taking action, we could lose a hundred more species from the world and take another step towards mass extinction.The Conversation

Deborah Bower, Lecturer in Ecosystem Rehabilitation, University of New England and Simon Clulow, MQ Research Fellow, Macquarie University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Deadly frog fungus has wiped out 90 species and threatens hundreds more



File 20190328 139341 1bs2rtv.jpg?ixlib=rb 1.1
The Mossy Red-eyed Frog is among hundreds of species threatened with extinction at the hands of chytrid fungus.
Jonathan Kolby/Honduras Amphibian Rescue and Conservation Center

Benjamin Scheele, Australian National University and Claire Foster, Australian National University

It started off as an enigma. Biologists at field sites around the world reported that frogs had simply disappeared. Costa Rica, 1987: the golden toad, missing. Australia, 1979: the gastric brooding frog, gone. In Ecuador, Arthur’s stubfoot toad was last seen in 1988.

By 1990, cases of unexplained frog declines were piling up. These were not isolated incidents; it was a global pattern – one that we now know was due to chytridiomycosis, a fungal disease that was infecting and killing a huge range of frogs, toads and salamanders.

Our research, published today in Science, reveals the global number of amphibian species affected. At least 501 species have declined due to chytrid, and 90 of them are confirmed or believed extinct.




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When biologists first began to investigate the mysterious species disappearances, they were at a loss to explain them. In many cases, species declined rapidly in seemingly pristine habitat.

Species declines typically have obvious causes, such as habitat loss or introduced species like rats. But this was different.

The first big breakthrough came in 1998, when a team of Australian and international scientists led by Lee Berger discovered amphibian chytrid fungus. Their research showed that this unusual fungal pathogen was the cause of frog declines in the rainforests of Australia and Central America.

However, there were still many unknowns. Where did this pathogen come from? How does it kill frogs? And why were so many different species affected?

After years of painstaking research, biologists have filled in many pieces of the puzzle. In 2009, researchers discovered how chytrid fungus kills frogs. In 2018, the Korean peninsula was pinpointed as the likely origin of the most deadly lineage of chytrid fungus, and human dispersal of amphibians suggested as a likely source of the global spread of the pathogen.

Yet as the mystery was slowly but surely unravelled, a key question remained: how many amphibian species have been affected by chytrid fungus?

Early estimates suggested that about 200 species were affected. Our new study reveals the total is unfortunately much larger: 501 species have declined, and 90 confirmed or suspected to have been killed off altogether.

The toll taken by chytrid fungus on amphibians around the world. Each bar represents one species; colours reveal the extent of population declines.
Scheele et al. Science 2019

Devastating killer

These numbers put chytrid fungus in the worst league of invasive species worldwide, threatening similar numbers of species as rats and cats. The worst-hit areas have been in Australia and Central and South America, which have many different frog species, as well as ideal conditions for the growth of chytrid fungus.

Large species and those with small distributions and elevational ranges have been the mostly likely to experience severe declines or extinctions.

Together with 41 amphibian experts from around the world, we pieced together information on the timing of species declines using published records, survey data, and museum collections. We found that declines peaked globally in the 1980s, about 15 years before the disease was even discovered. This peak coincides with biologists’ anecdotal reports of unusual amphibian declines that occurred with increasing frequency in the late 1980s.

Encouragingly, some species have shown signs of natural recovery. Twelve per cent of the 501 species have begun to recover in some locations. But for the vast majority of species, population numbers are still far below what they once were.

Most of the afflicted species have not yet begun to bounce back, and many continue to decline. Rapid and substantial action from governments and conservation organisations is needed if we are to keep these species off the extinct list.




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Saving amphibians from a deadly fungus means acting without knowing all the answers


In Australia, chytrid fungus has caused the decline of 43 frog species. Of these, seven are now extinct and six are at high risk of extinction due to severe and ongoing declines. The conservation of these species is dependent on targeted management, such as the recovery program for the iconic corroboree frogs.

The southern corroboree frog: hopefully not a disappearing icon.
Corey Doughty

Importantly, there are still some areas of the world that chytrid has not yet reached, such as New Guinea. Stopping chytrid fungus spreading to these areas will require a dramatic reduction in the global trade of amphibians, as well as increased biosecurity measures.

The unprecedented deadliness of a single disease affecting an entire class of animals highlights the need for governments and international organisations to take the threat of wildlife disease seriously. Losing more amazing species like the golden toad and gastric brooding frog is a tragedy that we can avoid.The Conversation

Benjamin Scheele, Research Fellow in Ecology, Australian National University and Claire Foster, Research Fellow in Ecology and Conservation, Australian National University

This article is republished from The Conversation under a Creative Commons license. Read the original article.