It's a fact. Even a blitherin, slitherin' whyzard can't make a decent potion without amphibians -- or amphib parts,
at any rate. But the potion-masters down at the Pollywogparts Amphibian
Academy are starting to worry about a lack of ingredients.
Courtesy W. Battaglin, U.S. Geological Survey.
Toads and salamanders, it seems, are disappearing from one habitat after another. "Amphibian populations fluctuate," says James Collins, an Arizona State University biology professor who heads a National Science Foundation project on host-pathogen biology and the global decline of amphibians, "but the decline is clear globally, starting in the 1960s."
Should we blame the disappearance on overharvesting by the adolescent wizards-in-training at Logdarts? Probably not. Larger forces from the dark side are at work.
We muggles (non-wizards) deserve a good slice of blame for turning huge swaths of the planet into farms, roads and cities. But why are amphibians disappearing from pristine mountain habitats? Is it ultraviolet radiation, disease, exotic species, toxic chemicals -- or some deadly brew concocted from these factors?
Certainly, diseases play a role in some declines: A fungus-like organism called the chytrid, for example, is blasting frogs.
Now we hear a virus is slaying salamanders in Canada and the Western United States.
One sick story
Collins says that ranavirus has also been found in die-offs in Saskatchewan, North Dakota, Colorado and Utah. The virus, he says, "shows a terrific amount of genetic similarity" in the various locations.
Flying the Virus 2000?
Another possible source of infection is cannibalism -- the tiger salamander eats its comrades. We can only say it serves them right.
Until pathogen movement is understood, the Arizona amphibian researchers are taking no chances. To block one route of infection, they use a bleaching ceremony to kill virus on clothing and equipment before visiting research sites.
Collins says that beyond preserving the 'manders, there are interesting lessons to be learned about disease ecology and pathogen-host relationships. Curiously, while chytrids seem to kill off frogs, the salamanders may be back at their old levels within a few months of a severe ranavirus attack.
And how does the virus work? Is it like measles and influenza, which sweep through populations, striking the susceptible? Or is it always present, but only infecting hosts when conditions are right?
Dearth of death data
Although disease is one factor, Collins suspects that global change also plays a role. Increased ultraviolet light caused by ozone destruction, for example, could harm the immune system, allowing normally benign viruses to run amok.
As amphibian researchers watch the disappearance of their favorite critters, they worry that this is a symptom of a larger ecological havoc. So for the sake of the amphibs, the wizards at Pigzits Academy, and even for us muggles -- it would be nice to know what's slaying them salamanders.
Salamanders are found in the best witches' brews. But what are witches?
|There are 1
2 3 4
5 pages in this feature.
Bibliography | Credits | Feedback | Search
©2001, University of Wisconsin, Board of Regents.