BBC Future
In Depth

The race to stop a global killer

  • Trouble for toads
    A Europe-wide project called RACE is trying to stop a deadly fungus threatening the lives of many amphibians, including the midwife toad (Copyright: Science Photo Library)
  • Mass killer
    The fungal disease called Batrachochytrium dendrobatidis, or Bd, is already responsible for the mass death of over 350 amphibian species worldwide. (Copyright: Dirk Schmeller)
  • Wipeout fear
    If Bd continues unchecked, many fear it will push many species of amphibians across the globe to the brink of extinction. (Copyright: Dirk Schmeller)
  • Disease monitor
    The Europe-wide RACE project is collecting frogs, toads and newts, and checking them to see how the disease is spreading. (Copyright: Dirk Schmeller)
  • Weighing up odds
    The RACE project’s monitoring efforts are a crucial part of understanding the spread of Bd and how to control it. (Copyright: Dirk Schmeller)

HIDE CAPTION

A deadly fungus sweeping the world is behind the mass death of hundreds of amphibian species. Researchers in Europe have teamed up to work out how to stop it – can they succeed?

Scientific endeavour isn’t always as glamorous as crashing atoms into each other deep underground in Switzerland, or sending rovers to roam the surface of Mars looking for clues to life. For Dirk Schmeller, a researcher at the CNRS research centre in Moulis, southern France, there are more fundamental problems to deal with – like how to get a stubborn ass to shift.

Donkeys and mules may not be the most hi-tech option for lugging large volumes of water down a Pyrenees mountain, but it’s the most effective… until you get an uncooperative animal, of course. “We can thank Gaston and Justin, but we aren’t thanking Emile,” says biologist Adeline Loyau, Schmeller’s co-worker and wife, while discussing who to include in the acknowledgements section when writing up their research. Gaston, Justin and Emile were the donkeys Loyau and Schmeller hired to carry lake-water samples down from the mountain last summer. Her displeasure with Emile stems from a stressful day she spent unsuccessfully trying to get the beast to budge, in turn condemning Loyau to a backbreaking hike to and from a lake with up to 30 kilos (66 pounds) of water.

The donkeys have a key role in trying and save some of the world’s most vulnerable amphibians from their plight. Schmeller, Loyau and their colleagues are part of a Europe-wide project, RACE (Risk Assessment of Chytridiomycosis to European Amphibian Biodiversity), investigating – and trying to halt the spread of – a fungal disease that threatens to devastate amphibian populations across the globe.

The disease is already responsible for the mass death of over 350 amphibian species, pushing many to the brink of extinction. “If a single pathogen were causing the death, decline and extinction of 30% of mammal species (including humans), the entire world would be paying attention,” wrote the evolutionary biologists Valerie McKenzie and Anna Peterson from the University of Colorado last month. “This is what has been happening to the world's amphibians.”

Jaime Bosch first encountered the amphibian threat in Europe just over a decade ago. He was studying communication between midwife toads (Alytes obstreticans) in a lake in the Peñalara national park outside Madrid, when his worst nightmare began to appear before his eyes. The toads were beginning to die off in huge numbers, a once thriving lake became a graveyard for countless floating bodies. By 1999, Bosch and his colleagues at the Museo Nacional de Ciencias Naturales in Madrid reported that no living animals were found in 86% of the toad’s usual mating ponds in Central Spain.

But this wasn’t just happening in Spain. Thousands of dead amphibians were found floating in waters in North and Central America, and Australia. What was causing this mass slaughter seemed to have little regard for borders or which species it infected. In 1999, scientists finally tracked down the culprit and gave the disease a name: Batrachochytrium dendrobatidis, or Bd.

“Lakes of death”

Since then, a handful of scientists have got together to track its spread throughout Europe. Fungal epidemiologist Matthew Fisher, now at Imperial College, London, recalls how he first got involved in Europe’s Bd fight in 2002. He had just returned to the UK from studying the evolution of killer fungi at the University of Berkeley, California, when he read Bosch’s work on this mysterious new disease. Fisher got in touch, little suspecting the gruesome nature of what he was about to encounter.

“Jaime started FedEx-ing me these boxes of rotting frogs,” Fisher explains. As well as stinking out a lab, rotten bodies aren’t very useful for studying the genetic roots of the disease. Fisher needed a live sample of the fungus, but even Bd has its limits, and is easily killed by the bacteria in rotting flesh. “You have to get it from a frog that is either close to death, or recently dead,” he says.

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