An international study led by The Australian National University (ANU) and involving ZSL’s Institute of Zoology has found that a fungal disease has caused dramatic population declines in at least 501 amphibian species, including 90 extinctions, over the past 50 years.
The disease, which eats away at the skin of amphibians, has completely wiped out some species, while causing more sporadic deaths among other species. Amphibians, which commonly live part of their life in water and the other part on land, mainly consist of frogs, toads and salamanders.
The deadly disease, chytridiomycosis, is present in more than 60 countries – the worst affected parts of the world are Australia, Central America and South America. The researchers found that chytridiomycosis is responsible for the greatest loss of biodiversity due to a disease.
The disease is caused by chytrid fungus, which likely originated in Asia where local amphibians appear to have resistance to the disease.
The unprecedented number of declines places chytrid fungus among the most damaging of invasive species worldwide, threatening similar numbers of species as rats and cats.
Lead researcher Dr Ben Scheele said highly virulent wildlife diseases, including chytridiomycosis, were contributing to the Earth’s sixth mass extinction.
“The disease we studied has caused mass amphibian extinctions worldwide. We’ve lost some really amazing species,” said Dr Scheele from the Fenner School of Environment and Society at ANU.
He said more than 40 frog species in Australia had declined due to this disease during the past 30 years, including seven species that had become extinct.
“Globalisation and wildlife trade are the main causes of this global pandemic and are enabling disease spread to continue,” he said.
“Humans are moving plants and animals around the world at an increasingly rapid rate, introducing pathogens into new areas.”
Professor Trenton Garner at the Institute of Zoology explained: “Despite recent studies that have illustrated how some species can, to some degree, recover from chytridiomycosis, this study shows clearly how the chytrid crisis is an ongoing issue. We still urgently need extensive efforts to develop the strategies to counteract the impact of this devastating threat to biodiversity.”
Dr Scheele continued to explain improved biosecurity and wildlife trade regulation were urgently needed to prevent any more extinctions around the world.
“We’ve got to do everything possible to stop future pandemics, by having better control over wildlife trade around the world.”
Dr Scheele said the team’s work identified that many impacted species were still at high risk of extinction over the next 10–20 years from chytridiomycosis due to ongoing declines.
“Knowing what species are at risk can help target future research to develop conservation actions to prevent extinctions.”
“It’s really hard to remove chytrid fungus from an ecosystem – if it is in an ecosystem, it’s pretty much there to stay unfortunately. This is partly because some species aren’t killed by the disease,” he said.
“On the one hand, it’s lucky that some species are resistant to chytrid fungus; but on the other hand, it means that these species carry the fungus and act as a reservoir for it so there’s a constant source of the fungus in the environment.
Co-researcher Dr Claire Foster, who is also from the Fenner School of Environment and Society, said the ANU-led study involved collaborations with 41 different amphibian and wildlife disease experts from around the world.
“These collaborators enabled us to get first-hand insight into what has been happening on the ground in those countries,” she said.
The study is published in Science.