FUNGAL DISEASE
Deadly Frog Fungal Disease Is Spreading
Science Daily — 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.
Researchers swab a small frog (litoria wilcoxii). (Credit: Kerry
Kriger)
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.
Note: This story has been adapted from a news release issued by
Griffith University.
