UK's toads menaced by fungal attack

'Severe decline' likely, scientists predict

Scientists have predicted that the UK's toad population will suffer extinction in some areas within 10 years due to a deadly infectious fungal disease introduced into Britain via North American bullfrogs.

While the original non-native vectors of Batrachochytrium dendrobatidis have now been exterminated, the disease has persisted, and has been detected in Kent, Reuters reports.

Researchers from Imperial College London and the Institute of Zoology formulated a mathematical model which pointed to its eventual spread with "devastating" consequences for the European common toad (Bufo bufo).

Just how apocalyptic the scenario is depends on how long the fungus can survive in water when not flourishing on amphibian skin. Scientists believe it could be "a very long time", and Mat Fisher of Imperial College elaborated: "We start to see dramatic effects if the chytrid [fungus] lives for longer than seven weeks outside the host.

"We strongly suspect that it can live for longer because of the devastating effect it has had elsewhere, and the new models show that this would be very bad news for toads in this country."

The disease has indeed already done for entire amphibian populations in Australia and Central and South America, and is now menacing European toads. Scientists have, perhaps inevitably, "linked its spread to global warming".

The bottom line is that if Batrachochytrium dendrobatidis can live outside the host for a year, this would provoke a "severe decline" in the overall UK toad population and its complete disappearance from some areas within a decade.

Whatever the eventual outcome, the common British frog (Rana temporaria) will be unaffected, since it's immune to the disease.

The reserachers' findings are published in the Proceedings of the Royal Society. ®

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