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GLOBE AND MAIL (Toronto, Ontario) 13 July 06 Frogs spreading fatal fungus, scientists say Invading bullfrogs carry infection that wipes out other amphibians (Matthew Kwong)
Vancouver: The microscopic menace that has been killing off large populations of amphibians in Australia, Europe and Central America is now being spread by invading bullfrogs in British Columbia, scientists have found.
A study from the University of Victoria warns of an impending fungal infection carried by giant, bullfrogs that have invaded the Fraser Valley and south Vancouver Island.
Scientists have blamed the fungus, Batrachochytrium dendrobatidis , for staggeringly rapid declines in endangered species populations around the world ever since it was discovered in 1998.
Now the University of Victoria research paper, published in this month's Biology Letters, has identified the fungus in B.C. The report finds that the alien American bullfrog -- originally brought over in the 1930s for the province's frog-farming industry -- has infected native species such as the rough-skinned newt and the northern leopard frog.
"The problem with the disease is that when these declines happen, within four to six months, 80 per cent of these [native] frogs disappear," said study co-author Purnima Govindarajulu.
"We're trying to be proactive. Can we stop the kind of catastrophic declines here that have been happening across the world?" Although the fungus-carrying American bullfrogs are not affected themselves, spores are shed in the water and can bind to the epidermis of other amphibians. Once infected, the sick amphibian's skin reddens and sheds unusual amounts before the animal dies.
"How exactly [the fungus] causes death we don't know, but all the fluid balance is done through the sensitive skin," Dr. Govindarajulu said, adding that B.C. now holds the "global responsibility" of saving the world's last healthy population of western toads from the pathogen.
"[The western toad] has been declared globally endangered as a red-listed species, but because we have quite a big population in B.C., we're starting to worry about them." The fungus already wiped out the midwife toad species in France, but efforts to contain an outbreak by eradicating the infectious bullfrogs proved useless there, said University of Victoria biologist Brad Anholt.
Hungry, intruding American bullfrogs -- the largest species of North American frog -- have been an ecological concern in southern Vancouver Island for years.
University of Victoria researchers worried in 2001 that the reptilian giants were eating their way to the top of the food chain and would soon supplant native species. (American bullfrogs can grow to 600 grams and eat insects, snakes, salamanders, rodents, other frogs and even birds.) But compounded with the discovery that the generalist predators also transmit a lethal fungus, bullfrogs are now proving to be an even larger problem than before.
"Originally we thought it might just be bullfrogs eating [native species], but now it might be bullfrogs eating plus carrying a disease," said Dr. Anholt.
While bullfrogs are native in Ontario, Quebec, New Brunswick and Nova Scotia, they're only invasive in B.C. The fungus has also never been detected in any other Canadian province.
But if B.C. wants to protect its unique and endangered amphibians, humans need to realize the everyday impact they can have on aquatic ecosystems, Dr. Anholt said.
"We hope people will be more well aware of moving tadpoles in buckets.
"It's great to have kids be interested in biology, but bullfrogs can get spread about and take the fungus with them." Humans are the primary way by which bullfrogs migrate. Other factors such as converting ponds to permanent ponds, introducing fish to fishless ponds and cutting down trees near native frog habitats only make it easier for the predatory bullfrogs to thrive.
"Our thinking is, are there ways to change habitat so [native species] can co-exist with bullfrogs," Dr. Govindarajulu asked.
Scientists believe the original fungus strain came from African clawed frogs shipped for pregnancy tests in the 1940s. After years of cross-contamination, the American bullfrog likely picked up the disease.
Frogs spreading fatal fungus

TIMES COLONIST (Victoria, British Columbia) 14 June 06 Invasive bullfrog spreads fatal disease: Humans to blame as native species face added threat, UVic scientists find (Sandra McCulloch)
Non-native American bullfrogs not only eat everything in sight, but some carry a microscopic fungus that can kill our native frogs and other amphibians such as salamanders, a University of Victoria biologist said Tuesday.
What makes things worse is that people are largely to blame for the spread of the disease-carrying bullfrogs.
"If left unchecked, we don't know what can happen," said Dr. Purnima Govindarajulu. She and UVic biologist Dr. Brad Anholt wrote a paper on the subject published in the international journal Biology Letters, on Tuesday.
In Panama, Europe and Australia, the disease has wiped out 50 per cent of species in four to six months, she said, and the remaining species' populations dropped by 80 per cent.
"As far as we know, we haven't seen that on southern Vancouver Island -- what we would like to do is not see it ever," Govindarajulu said. "We'd like to get enough information to figure out how we can stop it from happening."
American bullfrogs, measuring up to 20 centimetres long, are benign carriers of the disease, with the fungus living in the animal's skin, said Govindarajulu. The bullfrogs are unaffected but the fungus is deadly to native species.
Govindarajulu's research shows it is mainly humans who are moving the bullfrogs around. "People put them in a bucket and move them in a car -- and they're all the way up to Courtenay now."
She doesn't want to cause a panic but Govindarajulu warns that people need to stop moving bullfrogs especially now that its known their threat to the environment is even more serious.
"Because it's an emerging problem, we need to work really quickly," said Govindarajulu. "We've applied for funding and we've also set up collaboration with provincial and federal biologists. It would be really good to be really pro-active."
American bullfrogs are vegetarians in their tadpole stage but become carnivorous as they mature into frogs. They eat garter turtles, snakes, birds, and one on the Sunshine Coast is rumoured to have eaten a small cat.
Vancouver Island is home to the red-legged frog, which is "blue listed," meaning its numbers may be declining. Pacific tree frog numbers are healthy and they're not at risk from this fungus. The Western toad also lives here in good numbers, but is threatened in many other places around the world.
Meanwhile, Victoria biologist Stan Orchard is running into funding problems with his ongoing bullfrog-eradication program.
He has been zapping the invading bullfrogs with electroshocks and has killed hundreds of the amphibians over the last few years with funding by the Capital Regional District water department. This year he's focusing on Florence and Langford lakes.
News that the bullfrogs might carry a deadly fungal infection "reinforces the rationale for eradicating, and we're getting on with it now," said Orchard on Tuesday. The problem is, WorkSafe B.C. insists anyone using electricity to shock bullfrogs must be trained and training costs money.
"The intensive eradication program is really just getting underway. The last hurdle was to get the money," said Orchard. His website is at www.bullfrogcontrol.com

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