May 4, 2007 The deadly chytrid fungus is making devastating in-roads into Australia's vulnerable frog populations, with a Griffith University study revealing the disease-causing fungus is now established in frog populations throughout Eastern Australia.
Griffith researcher Kerry Kriger has just completed a PhD study within the Endangered Frog Research Group in Griffith University's Centre for Innovative Conservation Strategies, focusing on the geography of the disease across the region from the mountains to the coast between Cairns and southern NSW.
Kerry said that chytridiomycosis – the disease caused by the fungus – was likely absent from Queensland until 1978. It is now prevalent in moist, temperate areas around Australia, and around the world. Scientists theorize the rapid spread has been driven by international trade in amphibians as well as environmental factors. "Chytrid has spread so quickly that frogs often have no chance to evolve resistance to it," Kerry said.
"It's highly infectious, so when it arrives in an area most frogs are likely to contract it. It attacks the keratin in the frogs' skin, and may also produce a toxin that poisons the frog. The disease can have an 80 per cent mortality rate, and is already believed to be responsible for 6-8 species extinctions in eastern Australia. "Overseas dozens of species have disappeared due to the disease."
Kerry said research was underway around Australia to understand and control the disease, both through fungicidal treatment of infected tadpoles and frogs, and large scale preventative measures such as limiting the import and transport of amphibians between areas and countries. Unfortunately, the fungus does not threaten cane toad populations.
Project supervisor and Research Centre Director Associate Professor Jean-Marc Hero said at least one-third of the world's 6,060 amphibian species are threatened with extinction.
"Frogs are recognised as an important bio-indicator, acting as an early warning system for environmental problems. While habitat loss is the greatest threat to coastal frogs, this new disease has had devastating effects in the frog populations in the hinterland regions," he said.
"Additional pressures including habitat loss, air and water-borne pollutants such as herbicides and even climate change could weaken frogs' immune systems, and make them more prone to fungal infections," Associate Professor Hero said.
Members of the public can help reduce the spread of this fungal pathogen by not handling frogs and not re-locating frogs or tadpoles from one place to another.
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