Pesticides may be behind extinction of frog species

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Sydney, Jan 5 (UNI) Pesticides may have been responsible for extinction of eight frog species, scientists say.

Experts have previously attributed to a combination of climate change and a deadly fungus to the collapse of frog populations.

Griffith University's Jean-Marc Hero says chemicals may have wiped out frog species in Queensland.

Brisbane environmental consultant Glen Ingram, who has studied some of the eight Queensland frog species that have become extinct since the late 1970s, said: ''There is a growing view that pesticides have a role in the extinctions of these frogs.

''People had assumed it was a fungus, probably being spread by global warming. Now, we're not at all sure.'' Scientists have previously highlighted the extinctions of dozens of frog species worldwide as an indication of consequences of climage change arising from increased greenhouse emissions.

Many frogs have been killed by the chytrid fungus, which infects their skin, impairing their breathing and nervous sytems. However, the fungus can be harmless to frogs and some experts claim it has become deadly because of climate change. They suggest that increases in cloud cover, temperature or ultraviolet radiation have spread the fungus.

However, several recent studies in California implicated chemicals in frog population declines.

California has experienced similar collapses in frog populations to Australia.

Four pesticides and herbicides identified in the studies are used widely in Australia.

Californian biologist Gary Fellers, of the Western Ecological Research Centre, who has participated in some of the studies, said pesticides could be a more significant factor in frog declines that the chytrid fungus.

''The role of the fungus is not well understood in many areas, including some of the places where scientists have declared it to be the primary or only factor causing amphibian declines,'' Dr Fellers told The Weekend Australian.

''The fungus might not be the whole story,'' he added.

Queensland's wave of frog extinctions began in the late 1970s, at the same time as organochlorine chemicals such as DDT were being phased out.

The organochlorines were replaced by organophosphorus and other chemicals. The Californian studies have implicated three organophosphorus pesticides and the herbicide atrazine in frog population declines.

All four chemicals are used widely in Australia.


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