A fungal disease that threatens to wipe out many amphibians is thriving because of climate change, a study suggests.

Researchers studying amphibians at a national park in Spain show that rising temperatures are closely linked to outbreaks of the chytrid fungus.

Chytrid fungus is a major contributor to the decline of amphibian populations around the world, threatening many species with extinction.

Details are published in the journal Proceedings of the Royal Society B.

"We have found an association between increasing temperatures and amphibian disease in a mountain region in Spain," said Dr Matthew Fisher of Imperial College London.

"This is a global emerging amphibian pathogen which is one of the worst vertebrate infectious diseases found so far. It is causing a huge amount of extinction and disease within amphibian populations."

More than 100 species of amphibians are known to be affected by the chytrid fungus (Batrachochytrium dendrobatidis). Some are very susceptible and die quickly while others which are more resistant are carriers of the pathogen.

The disease is already credited with wiping out frogs and toads in large numbers in Australia and South America.

Climate link

Dr Fisher and his Spanish colleagues uncovered an association between the emergence of the disease and global warming while studying changes in the number of midwife toads in Spain's Penalara Natural Park between 1976 and 2002.

The chytrid fungus, or BD as it is sometimes called, infects the skins of amphibians such as frogs, toads, salamanders and newts and interferes with their ability to absorb water.

Dr Fisher said climate change could be worsening the impact of the disease in one of two ways.

Warming temperatures could be reducing the amphibians' ability to mount a successful immune response to the fungus. Amphibians are cold-blooded so their ability to respond to the pathogen could change along with the external temperature.

On the other hand, global warming could be increasing the fungus' ability to grow faster on the amphibian and cause more disease.

"This is a wake-up call that we are losing biodiversity fast," Dr Fisher said. "Climate change appears to be changing patterns of disease and previously resistant species are becoming highly infected - even, in a number of cases, becoming extinct."

The Global Amphibian Assessment has warned that a third of the world's amphibian species are in danger of extinction, many because of the chytrid fungus.