Dead frogs killed from the amphibian chytrid fungus. Photo: Joel Sartore/NatGeo

In the early 1990s, researchers linked the mass die-offs of frogs around the world to a fungus they named Batrachochytrium dendrobatidis, or Bd for short. The fungus ravages frogs’ skin and makes it peel off–which for amphibians, their skin is critical to their survival. Now, as NatGeo recently reported, “a global team of 41 scientists has announced that the pathogen—which humans unwittingly spread around the world—has damaged global biodiversity more than any other disease ever recorded.” The fungus has led to the decline of at least 501 amphibian species over the past half-century, including 90 presumed extinctions.

There was lots of nuance in the new study which was published in Science Magazine and as the New York Times explained:

• The new study showed that some amphibians are at greater risk than others. The fungus thrives in cool, moist conditions. As a result, frogs that live in cloud forests on mountainsides have been hit particularly hard.
• Big frogs are at a greater risk, too, possibly because they don’t multiply as quickly as small ones.
• Certain factors once thought to account for the decimation of frog populations — like climate change and deforestation — are not the greatest threats, the scientists found
• Bd wiped out some species long before it was discovered. Only by going back to museum specimens were scientists able to estimate the toll.
• The decimation of frogs peaked in the 1980s, the researchers found, a decade before the discovery of Bd. Today, 39 percent of the species that suffered population declines in the past are still declining. Twelve percent are showing signs of recovery, possibly because natural selection is favoring resistant animals.

Why This Matters: Frogs and other amphibians affected by Bd are critical to the food webs and their home environments, if they’re wiped out then that could have serious consequences for other animals. In addition to being an indicator species and controlling insects, frogs also save human lives through medicine and we simply can’t afford to lose them. While scientists have found ways to eradicate Bd in some frog populations, at present, wild populations can’t be cured on a global scale. Public policy, namely restricting the trade of amphibians, can help slow the spread of the deadly fungus and give scientists time for further research and means to suppress its spread.