Science

Deadly fungus responsible for mass amphibian extinction

By George Blake

A recent report has found a deadly fungus that affects amphibians is responsible for the largest ever documented loss of nature due to a single disease.

The disease, chytridiomycosis, is caused by a fungus that attacks the skin of amphibians, interfering with their ability to regulate levels of water and electrolytes, which can eventually lead to heart failure. The fungus was first identified as a threat in the 1990s, but this is the first time its impacts have been examined on a global scale.

Chytridiomycosis is present in over 60 countries, with South and Central America and tropical Australia the worst affected. Between 1965 and 2015, 501 species (6.5% of known species) have been pushed towards extinction and 90 species are presumed or confirmed to be extinct.

“It’s a staggering thing to consider,” Jonathan Kolby, a herpetologist at James Cook University in Australia, tells The Washington Post. “We’ve never before had a single disease that had the power to make multiple species extinct, on multiple continents, all at the same time.”

Dr Ben Scheele of the Australia National University said, “Highly virulent wildlife disease, including chytridiomycosis, is contributing to the Earth’s sixth mass extinction”. According to experts, the fungus, along with habitat loss and climate change is “one more nail in the coffin for the state of amphibians globally.”

The impact these declines will have upon ecosystems are currently unclear. Frogs, for example, consume algae as tadpoles helping keep algal blooms at bay, devour mosquitos that spread disease, and provide food for birds and other animals. The omittance of frogs in this chain could be dire.

The fungus is thought to have originated in East Asia, which is the only region to remain unaffected by the fungus. The modern-day strain is thought to have diverged from its most recent ancestor in the early 20th century, coinciding with the onset of the commercial trade in amphibians.

Scientists state that globalisation and anthropogenic trade (especially the live wildlife trade) has broken down dispersal barriers, facilitating the spread of diseases that threaten Earth’s biodiversity. There are also fears about possible future outbreaks in currently unaffected areas, particularly Madagascar and Papua New Guinea, which are home to many endemic species.

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