Frogs are considered a good indicator of the health of the Earth

[Guest guest]

Frog killer found after 6-year stakeout

'Noah's Ark' program aims to save species from extinction

By Schulder

CNN

http://edition.cnn.com/2006/TECH/science/02/21/frog.fungus/

Tuesday, February 21, 2006 Posted: 1539 GMT (2339 HKT)

Frogs are considered a good indicator of the health of the Earth.

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-- Lips, Southern Illinois University biologistYOUR E-MAIL

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ATLANTA, Georgia (CNN) -- You've got to respect frogs. The

amphibians have an astonishing variety of survival skills.

For example, gastric brooding frogs swallow their fertilized eggs to

protect them from predators. When the eggs hatch and the tadpoles

mature, the mother safely regurgitates her froglets.

Such adaptations have kept frogs around for millions of years, but a

recent checkup has scientists concerned. They fear a sudden mass

extinction of amphibians on a scale and pace not experienced since

the age of dinosaurs.

Nearly a third of the world's 6,000 species of frogs, toads and

salamanders are in danger of disappearing, according to the Global

Amphibian Assessment.

In the past 20 to 30 years, about 120 species of frogs are believed

to have become extinct, the assessment found.

Human destruction of habitat is one reason for the loss. But there

is a new enemy for which there may be no defense.

On the trail in Central America

In 1998, Lips, a young biologist from Southern Illinois

University, helped identify a fungus that seemed to be killing off

entire species of amphibians, including, possibly, the gastric

brooding frog mentioned above.

It's called the chytrid fungus, and how it kills is a mystery.

The best guess, according to Joe Mendelson, curator of herpetology

at Zoo Atlanta, is that it attacks keratin, a protein that

waterproofs the parts of a frog's skin most subject to wear and

tear. The loss of keratin, it's believed, might throw off the

critical water balance in a frog's body.

" That's just a guess, " Mendelson said, " but the best one we have

right now. "

For years, the fungus was one step ahead of Lips and her team of

biologists. They'd visit a forest where frogs were thriving, then

return a couple of years later to find most had disappeared -- and

with them the evidence of their fungal demise.

Lips' team set up a stakeout in a Panamanian rain forest called El

Cope. There had been previous die-offs, beginning in the Monteverde

Cloud Forest of Costa Rica, and it seemed the fungus was heading

southeast. The fungus hadn't yet arrived in El Cope, but Lips said

she suspected the rain forest would be its next stop.

Over six years, Lips and her team walked the forest, finding 64

thriving species of amphibians and no sign of the fungus, but one

day that all changed.

In September 2004, one of Lips' graduate students found a frog

sitting on a rock in the middle of the day -- unusual because that

type of frog was only active at night. The frog wasn't moving, and

it was behaving as if it had the flu. It became the first frog on

the group's stakeout to test positive for the fungus.

Soon after the first infected frog was found, dead frogs started

turning up every day, Lips said. But within four months, she

said, " We ran out of dead frogs to count. "

No more could be found. Lips and her team packed up their research

and headed home.

The results of their work have now been published in the Proceedings

of the National Academy of Sciences. The findings are important

because they establish how quick and devastating a killer this

fungus, which is spreading around the world, has become, Mendelson

said.

'Noah's Ark' solution

Frogs are considered a good indicator of the health of the Earth.

They breathe through permeable skin and live both on land and in

water. They likely would be the first type of species to suffer from

pollution.

They are also a critical link in the food chain. Lips and her

colleagues reported that in one Panamanian region that experienced a

massive frog die-off, the snakes that feed on frogs began starving

to death. Birds and mammals that eat the frogs there may also be in

decline, Lips said.

The question remains why, after such a long history of adaptation

and survival, are entire species succumbing to a fungus?

One explanation has troubling implications for humans, said Claude

Gascon, an ecologist with the group Conservation International.

The concern, Gascon said, is that between loss of habitat, toxins in

the environment and global warming, " the Earth has been so stressed

by mankind's footprint that, in the case of frogs, the chytrid

fungus was the tipping point that indicates a dangerous turn in the

overall health of the Earth's ability to sustain us all. "

Lips' research established the path of the fungus, which is moving

southeast through Central America. Her map should help scientists

anticipate where the fungus is heading next.

Her findings have triggered a mission to rescue frogs in the path of

the fungus, led by Zoo Atlanta's Mendelson and Ron Gagliardo of The

Atlanta Botanical Garden. The approach, reminiscent of Noah's Ark,

involves capturing enough males and females from each species, and

breeding them in captivity, to establish survival colonies.

The hope is this approach can buy enough time for scientists to

figure out how to protect frogs from the fungus and reintroduce them

safely into the wild, wherever in the world they are threatened.