Dead, shrivelled frogs are unexpectedly turning up across eastern Australia. We need your help to find out why


Green Tree Frog
Jodi Rowley, Author provided

Jodi Rowley, Australian Museum and Karrie Rose, University of SydneyOver the past few weeks, we’ve received a flurry of emails from concerned people who’ve seen sick and dead frogs across eastern Victoria, New South Wales and Queensland.

One person wrote:

About a month ago, I noticed the Green Tree Frogs living around our home showing signs of lethargy & ill health. I was devastated to find about 7 of them dead.

Another wrote:

We previously had a very healthy population of green tree frogs and a couple of months ago I noticed a frog that had turned brown. I then noticed more of them and have found numerous dead frogs around our property.

And another said she’d seen so many dead frogs on her daily runs she had to “seriously wonder how many more are there”.

So what’s going on? The short answer is: we don’t really know. How many frogs have died and why is a mystery, and we’re relying on people across Australia to help us solve it.

Why are frogs important?

Frogs are an integral part of healthy Australian ecosystems. While they are usually small and unseen, they’re an important thread in the food web, and a kind of environmental glue that keeps ecosystems functioning. Healthy frog populations are usually a good indication of a healthy environment.

The stony creek frog is one of the species hit by this mysterious outbreak.
Jodi Rowley, Author provided

They eat vast amounts of invertebrates, including pest species, and they’re a fundamental food source for a wide variety of other wildlife, including birds, mammals and reptiles. Tadpoles fill our creeks and dams, helping keep algae and mosquito larvae under control while they too become food for fish and other wildlife.

But many of Australia’s frog populations are imperilled from multiple, compounding threats, such as habitat loss and modification, climate change, invasive plants, animals and diseases.

Although we’re fortunate to have at least 242 native frog species in Australia, 35 are considered threatened with extinction. At least four are considered extinct: the southern and northern gastric-brooding frogs (Rheobatrachus silus and Rheobatrachus vitellinus), the sharp-snouted day frog (Taudactylus acutirostris) and the southern day frog (Taudactylus diurnus).

A truly unusual outbreak

In most circumstances, it’s rare to see a dead frog. Most frogs are secretive in nature and, when they die, they decompose rapidly. So the growing reports of dead and dying frogs from across eastern Australia over the last few months are surprising, to say the least.

While the first cold snap of each year can be accompanied by a few localised frog deaths, this outbreak has affected more animals over a greater range than previously encountered.

This is truly an unusual amphibian mass mortality event.

In this outbreak, frogs appear to be either darker or lighter than normal, slow, out in the daytime (they’re usually nocturnal), and are thin. Some frogs have red bellies, red feet, and excessive sloughed skin.

A browned, shrivelled green tree frog
A browned, shrivelled green tree frog (Litoria caerulea)
Suzanne Mcgovern, Author provided

The iconic green tree frog (Litoria caeulea) seems hardest hit in this event, with the often apple-green and plump frogs turning brown and shrivelled.

This frog is widespread and generally rather common. In fact, it’s the ninth most commonly recorded frog in the national citizen science project, FrogID. But it has disappeared from parts of its former range.

Other species reported as being among the sick and dying include Peron’s tree frog (Litoria peronii), the Stony Creek frog (Litoria lesueuri), and green stream frog (Litoria phyllochroa). These are all relatively common and widespread species, which is likely why they have been found in and around our gardens.

We simply don’t know the true impacts of this event on Australia’s frog species, particularly those that are rare, cryptic or living in remote places. Well over 100 species of frog live within the geographic range of this outbreak. Dozens of these are considered threatened, including the booroolong Frog (Litoria booroolongensis) and the giant barred frog (Mixophyes iteratus).

The giant barred frog is a threatened species that lives in the geographic range of this outbreak.
Jodi Rowley, Author provided

So what might be going on?

Amphibians are susceptible to environmental toxins and a wide range of parasitic, bacterial, viral and fungal pathogens. Frogs globally have been battling it out with a pandemic of their own for decades — a potentially deadly fungus often called amphibian chytrid fungus.

This fungus attacks the skin, which frogs use to breathe, drink, and control electrolytes important for the heart to function. It’s also responsible for causing population declines in more than 500 amphibian species around the world, and 50 extinctions.

For example, in Australia the bright yellow and black southern corroboree frog (Pseudophryne corroboree) is just hanging on in the wild, thanks only to intensive management and captive breeding.

The teeny tiny southern corroborree frogs have been hit hard by the chytrid fungus.
Jodi Rowley, Author provided

Curiously, some other frog species appear more tolerant to the amphibian chytrid fungus than others. Many now common frogs seem able to live with the fungus, such as the near-ubiquitous Australian common eastern froglet (Crinia signifera).

But if frogs have had this fungus affecting them for decades, why are we seeing so many dead frogs now?




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


Well, disease is the outcome of a battle between a pathogen (in this case a fungus), a host (in this case the frog) and the environment. The fungus doesn’t do well in warm, dry conditions. So during summer, frogs are more likely to have the upper hand.

In winter, the tables turn. As the frog’s immune system slows, the fungus may be able to take hold.

Of course, the amphibian chytrid fungus is just one possible culprit. Other less well-known diseases affect frogs.

The near-ubiquitous Austrlaian common eastern froglet is one species that seems able to live with the devastating chytrid fungus.
Jodi Rowley, Author provided

To date, the Australian Registry of Wildlife Health has confirmed the presence of the amphibian chytrid fungus in a very small number of sick frogs they’ve examined from the recent outbreak. However, other diseases — such as ranavirus, myxosporean parasites and trypanosome parasites — have also been responsible for native frog mass mortality events in Australia.

It’s also possible a novel or exotic pathogen could be behind this. So the Australian Registry of Wildlife Health is working with the Australian Museum, government biosecurity and environment agencies as part of the investigation.

Here’s how you can help

While we suspect a combination of the amphibian chytrid fungus and the chilly temperatures, we simply don’t know what factors may be contributing to the outbreak.

Why green tree frogs are dying en masse is still a mystery.
Sophie Hendry, Author provided

We also aren’t sure how widespread it is, what impact it will have on our frog populations, or how long it will last.

While the temperatures stay low, we suspect our frogs will continue to succumb. If we don’t investigate quickly, we will lose the opportunity to achieve a diagnosis and understand what has transpired.

We need your help to solve this mystery.

Please send any reports of sick or dead frogs (and if possible, photos) to us, via the national citizen science project FrogID, or email calls@frogid.net.au.




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The Conversation


Jodi Rowley, Curator, Amphibian & Reptile Conservation Biology, UNSW, Australian Museum and Karrie Rose, Australian Registry of Wildlife Health – Taronga Conservation Society Australia, University of Sydney

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

Australian farmers are adapting well to climate change, but there’s work ahead


PETER LORIMER/AAP

Neal Hughes, Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES)Australian farmers have proven their resilience, rebounding from drought and withstanding a global pandemic to produce record-breaking output in 2020-21.

But while the pain of drought is fading from view for some, the challenge of a changing climate continues to loom large.

Farmers have endured a poor run of conditions over the last 20 years, including a reduction in average rainfall (particularly in southern Australia during the winter cropping season) and general increases in temperature.

While these trends relate to climate change, uncertainty remains over how they will develop, particularly over how much rain or drought farmers will face.

Research published today by the Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES) examines the effects of past and potential future changes in climate, and sets out how productivity gains to date have been helping farmers adapt to the drier and hotter conditions.

Conditions have been tough

The research examines the effect on farms of climate conditions over the past 20 years, compared to the preceding 50 years.

Holding other factors constant (including commodity prices and technology) ABARES estimates the post-2000 shift in conditions reduced farm profits by an average of 23%, or around A$29,000 per farm per year.




Read more:
Climate change since 2000 has cut farm profits 22%


As with past research, these effects have been strongest among cropping farmers in south-eastern and southern-western Australia, with impacts of over 50% observed in some of the most severely affected areas.


Effect of 2001 to 2020 climate conditions on average farm profit

Simulated broadacre farm profit with current (2015–16 to 2018–19) farms and commodity prices and recent (2000–01 to 2019–20) climate conditions. Interpolated farm-level percentage changes relative to 1949–50 to 1999–2000 climate.
ABARES farmpredict model (Hughes, Lu et al. 2021)

Farmers have been adapting

While these changes in conditions have been dramatic, farmers’ adaptation has been equally impressive.

After controlling for climate, farm productivity (the output from a given amount of land and other inputs) has climbed around 28% since 1989, with a much larger 68% gain in the cropping sector.

These gains have offset the adverse climate conditions and along with increases in commodity prices have allowed farmers to maintain and even increase average production and profit levels over the last decade.

While productivity growth in agriculture is nothing new, the recent gains have been especially focused on adapting to drier and hotter conditions.

Within the cropping sector, for example, a range of new technologies and practices have emerged to better utilise soil moisture to cope with lower rainfall.

As a result, Australian farmers have produced remarkable harvests making use of limited rain, particularly in Western Australia.

Adaptation has also involved movement of traditional Australian cropping zones, increasing cropping in higher rainfall coastal areas, and reducing cropping in marginal in-land areas.

Climate change could make conditions tougher

While climate models generally project a hotter and drier future, a wide range of outcomes are possible, particularly for rainfall.

Climate projections suggest that nationally farmers could experience reductions in average winter season rainfall of 3% to 30% by 2050 (compared to 1950-2000).

The study simulates the effect of future climate change scenarios with current farm technology and no further productivity gains.

As such, these scenarios are not a prediction, but an indication of which regions and sectors might be under the greatest pressure to adapt.

For example, under most scenarios cropping farmers in Western Australia will face more pressure than those in eastern Australia.

Livestock farms will also face more pressure under high emissions scenarios as they are especially impacted by higher temperatures.

Generally, inland low-rainfall farming areas are expected to face greater challenges than regions closer to the coast.


Simulated change in farm profits relative to historical (1950 to 2000) climate

Change in simulated average farm profit for broadacre farms, assuming current commodity prices (2015–16 to 2018–19), and current farm technology (no adaptation), relative to historical climate conditions (1949–50 to 1999–2000). Bars show minimum, maximum and average across the GCMs for each scenario.
Source: ABARES farmpredict model (Hughes, Lu et al. 2021)

There is more work ahead

Recent experience shows that productivity growth can help offset the impact of a changing climate.

However, there remains uncertainty over how far technology can push farm efficiency beyond current levels.

Further, even if technology can offset climate impacts, other exporting nations could still become more competitive relative to Australia, if they are less affected by climate change or can adapt faster.

Here, investment in research and development remains crucial, including efforts to improve the productivity and reduce the carbon footprint of existing crop and livestock systems, along with research into more transformational responses to help diversify farm incomes.

Farmland can be repurposed.
Mick Tsikas

This could include for example, carbon and biodiversity farming, plantation forestry and the use of land to produce renewable energy.

Carbon and biodiversity farming schemes are the subject of ongoing research and policy trials, and already we have seen farmers generate significant revenue from carbon farming.

Uncertainty over the future climate, especially rainfall, remains a key constraint on adaptation. Efforts to refine and better communicate climate information through initiatives such as Climate Services for Agriculture could help farmers and governments make more informed decisions.

While the future is still highly uncertain, the challenge of adapting to climate change is here and now.

Significant resources have been committed in this area, including the Australian government’s Future Drought Fund.

We need to make the most of these investments to prepare for whatever the future holds.The Conversation

Neal Hughes, Senior Economist, Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES)

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