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Australian frog species, already threatened by habitat destruction and disease, are under additional pressure due to changing rainfall and rising temperatures due to climate change.
Some of Australia's leading frog experts are concerned about the possibility of serious impacts, with some fearing that climate change will cause some species to disappear before being documented by science.
Many Australian frogs are nowhere else in the world, but the continent is also on the brink of climate impacts related to extreme heat, drought and rising temperatures.
Frogs are known to be at high risk of climate change because they are ectotherms, animals whose body temperature is regulated by their environment.
Global populations of frogs and other amphibians have already been devastated by the chytrid fungus, a disease that appeared in the 1980s and 1990s. Now, climate change could also wreak havoc.
Professor Michael Mahoney, of Newcastle University, has been studying amphibians for three decades. "It's the cumulative impact," he says. "Yes, there are frogs that have been significantly reduced because of the fungus. If they now face the added insult of the impacts of climate change, this just makes it all harder. "
How many shelters are there?
To make matters worse, Australia's 2016 national plan to reduce the effects of the fungus speculated that climate change and rising temperatures could also increase the vulnerability of amphibians to the disease.
Mahoney says that all frogs have a different "critical thermal maximum", a temperature above which they die, so they must find places to hide and stay cool and wet.
"The problem is then, how many shelters are there? Available effective habitat is becoming smaller and smaller. Can frogs keep up with current climate change? We do not really know the answer to this question. "
Mahoney says some Australian frog species live in high altitude rainforests and cool temperate zones with a thermal maximum of 29 ° C. "All that is above that, and they are dying," he says. "In the last four or five years, four or five days have exceeded 32 ° C. [in those areas]. "
Climate change will have a slower impact than the outbreak of fungi: "It will be a much more regular decline process. It gives us more time to look at adaptation, but it's also scary because people become complacent. "
Jodi Rowley, frog expert and biologist at the Australian Museum and at the University of New South Wales, says there are about 240 known frog species in Australia. However, it is estimated that about 20% of all likely frog species in Australia have not been named and described in scientific journals.
She said that in Southeast Asia, "deforestation occurs faster than we can discover species in the forest" and the same problem could affect frogs in Australia.
Professor Ross Alford of James Cook University said, "It is theoretically possible that the same phenomenon is happening because of climate change, even in Australia. We also do not know how the fungus will change and interact with climate change. Because frogs are so influenced by temperature and humidity – like the fungus – in hot, dry years, they huddle together and spread diseases between them. "
Laura Brannelly, conservation biologist at the University of Melbourne, is studying how frogs are coping with climate change and diseases. "For frogs in particular, climate change is a real threat because they depend a lot on the availability of water. In addition, water patterns are changing in Australia, particularly in areas like the Australian Alps, "she said.
For example, says Brannelly, the habitat of the endangered Alpine Tree Frog was affected by drought and reduced snowfall. "If there is no snow, it disrupts their reproductive cycle. I suspect that there will be a lot of decline [in alpine regions] and climate change is a contributing factor.
"One or two consecutive bad years of extreme drought could result in the complete disappearance of a small population, which is of great concern to endangered species."
Tabitha Rudin, of the University of Western Australia, is studying the presence of a rampant frog prevalent in the south-west of the country, an area that has reported a drop of about 19% in winter precipitation since then. the 1970s, and further declines planned.
"Such drying conditions are a growing challenge for many amphibians, particularly for terrestrial breeding species, as they lay their eggs on land rather than on water and depend on constant rainfall during development. embryos. "
To integrate
Creeping frogs are able to live in places with very different average annual rainfall, which means that even within the species, some could be better adapted to drier climates than others.
Solve the problem?
Rudin is investigating whether a technique known as "assisted gene flow" could be used to help this species, and perhaps many others, by breeding to encourage tolerance to drier conditions.
She has already produced hybrid offspring in the laboratory with greater tolerance to drying conditions. "We now have to check whether this positive effect is sustained over several generations," she says. Rowley says that one of the major problems for frogs is that there is relatively little data on their whereabouts. It is therefore difficult to track changes caused by climate change or disease.
To solve this problem, she co-founded FrogID, a citizen science project that attempts to locate frog sites by encouraging users to record their calls.
"People want to know what's going on there with frogs and they notice changes, but the data just is not there," she says. "We have a lot of anecdotal stories from people who say they no longer hear them."
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