frog fungus (Credit Photo: Douglas Woodhams )
International researchers may have discovered a way in which to help frogs battle against a fungus that is sweeping across the world. The chytrid fungus has had a devastating impact on frog populations around the world for the last 30 years. Initially confined to Australia and South America the fungus is now global and found almost everywhere that researchers look for it.
Two potential treatments for frog disease.
The scientists from Europe, Australia and the US have just released a report in Frontiers in Zoology which looked at ways in which the fungus could be dealt with. Two methods were examined :
- use of fungicides – which were effective in the lab but there are concern over the ability to use the method in the wild setting. There would be no way to prevent reinfection of the fungus once the frog had been treated.
- use of bacteria – the scientist discovered that some of the bacteria that live naturally on the skin of frogs can prevent infection of the fungus.
Using bacteria that live naturally on the skin of frogs would be a much more effective way of tackling the Batrachochytrium dendrobatidis (Bd) fungus that is devastating frog populations across the world. Especially if the bacteria does not just treat and cure the infection but can also prevent reinfection.
“The approach works in the lab,” explains Benedikt Schmidt, a conservation biologist from the University of Zurich. ”Now we need to test how the method can be used for frogs living in the wild.
“Treating individuals in a zoo, for example, is a piece of cake, fighting the fungus out in nature, however, is a different kettle of fish altogether.”
Chytrid fugus affecting frogs across the world.
Since the discovery that the chytrid fungus was the cause of the disease (chytridiomycosis) in 1998 researchers have been tracking the path of the disease and trying to discover ways in which to halt it’s progress. Studies of museum samples show that the earliest known infected frog was a specimen from Africa dating from 1938.
From Africa the fungus has spread so that it is now found on every continent that frogs inhabit. The fungus arrived in Europe through the frogs that lived in the mountains of Spain. During a study of ponds in Switzerland almost a half of all ponds surveyed had evidence of the fungus.
While major frog deaths have not yet occurred in the UK the fungus is known to be widespread – albeit at a low level – in frog habitats across the country. It was initially discovered in Kent in 2004 and another outbreak in Cumbria in 2006. This led to a national investigation as to the prevelence of Bd in the UK.
Once the disease becomes established in a population it can have a major impact on numbers. For species that are close to extinction it can be the final straw in their survival. Bd was thought to be a defining influence in the extinction of the sharp-snouted day frog (Taudactylus acutirostris).
Skin bacteria could offer real hope for frogs.
If it is possible to introduce fungus fighting bacteria into the habitats of frogs and amphibians at risk then it offers a real option to help the third of amphibian species that are currently at risk of extinction. It certainly offers a more viable option than trying to treat individual frogs of their infections. It’s all down to if the researchers can move their studies from the lab into the real world.
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