Salamander threatened

Ultraviolet radiation and a harmful fungus may pose a threat to a rare form of the long-toed salamander living in the Three Creek watershed south of Sisters, according to Oregon State University scientists.

While studying Three Creek's amphibian populations, OSU Zoologist Andy Blaustein recently discovered a unique form of the long-toed salamander which may be a distinct, endemic species.

"This (salamander) grows a very different type of skull and jaw structure under certain conditions and we don't know why," Blaustein said.

According to Dede Olson, research ecologist with the U.S. Forest Service, the larval form of these salamanders grows an abnormally large head and long teeth, resembling fangs.

"In the lab, the larvae lost the fangs and their heads shrunk," said Olson. She said that Three Creek is "the first site where they've documented cannibalism in these salamander larvae."

"(To) eat salamanders of the same species is relatively unique," Blaustein said. "Only a couple of salamander species in the world do this."

In fact, less than five or six of the 4,500 global amphibian species exhibit cannibalism, he said.

The cause of this strange adaptation is yet unknown.

"We are testing to see whether or not it has to do with ephemeral ponds - ones that can dry up (seasonally)," Blaustein said, "and we are looking at food type."

"The sites where (they) occur are barren of vegetation," Olson added. "There is nothing else to eat, so we think that's why they become cannibalistic."

"We definitely think it is (a unique species) because the same species is found in the (Willamette) valley and we don't see cannibalistic morphology in the valley," Blaustein said.

While the jury is still out on the species designation, eminent threats cloud the future of this rare salamander and other amphibian species in the region.

Blaustein first published a report in 1994 documenting the impact of ultraviolet radiation on amphibian egg mortality in the Three Creek watershed.

He has observed that long-toed salamander larvae born from eggs exposed to sunlight were deformed and soon died. Blaustein discovered that when he shielded the eggs from sunlight, the larvae survived.

"This was the first case showing that ambient UV radiation kills amphibian eggs in nature," he said.

Increased mortality incidence over time caused Blaustein to implicate the progressive destruction of the earth's protective ozone layer, which allows more ultraviolet radiation to reach the surface, especially at higher elevations.

But the salamanders are not the only victims of the sun's lethal radiation.

"Cascade frogs in the Three Creek region have abnormal retinas," Blaustein said. "The frogs bask in the sun and their retinas are destroyed by UV light."

Both the Cascades frog and the western toad are highly susceptible to ocular UV damage, most commonly at high altitude, he explained.

Blaustein adds that the "implications to humans are there - UV (radiation) causes cataracts as well as skin cancer."

The impact of UV on the amphibians' immune system compounds the damage to their eyes, potentially making them even more at risk from a fungus known as Saprolegnia.

According to Blaustein, Saprolegnia is "a well-known problem in fish hatcheries.

"Saprolegnia will kill eggs, larvae and adults of frogs and toads," Blaustein said. "They are hit by the fungus coming in on stocked fish. (Fisheries managers) release them with that stuff all over their bodies. The fungus gets transmitted to the amphibians and kills them."

Rich Holt, senior fish pathologist for the Oregon Department of Fish and Wildlife, begs caution when blaming the hatcheries for the plight of Three Creek's amphibians.

"This is a naturally occurring pathogen," Holt explained. "It doesn't just spontaneously generate."

"We see some Saprolegnia in both wild fish and hatchery fish, but not recently in hatcheries in Central Oregon," he said. "We do our best to minimize levels of pathogen in the hatcheries, (but) I would expect there might be some Saprolegnia in high mountain lakes that didn't have fish naturally occurring."

Three Creek and Little Three Creek lakes both fit that description.

Olson has observed an increase in egg mortality due to fungal infection over the last several years.

"From 1982-1986, I saw no egg mortality," she said. "These were (also) high water years."

Higher lake and pond levels keep the eggs covered, preventing them from drying out.

"Since 1990 (the fungus)has appeared in several lakes," she said.

Blaustein contends that the amphibians' weakened immune systems makes them more susceptible to fungus.

"Both together kill the animals more effectively," he said.

Olson cautiously supports Blaustein's UV/fungus connection theory, saying it is "the most parsimonious explanation, but the immunology hasn't been done to demonstrate that."

"Saprolegnia is found throughout the Central Oregon Cascades, and it may be native," Olson added. "People haven't really studied (it) that long. What we do know is that the fungus can be prevalent in fish hatcheries.

"Most of these lakes don't have natural fish populations," Olson said. "They were once covered by glaciers, then the glaciers receded and left isolated lakes behind. They are (stocking) only for recreation."

"Little Three Creek Lake is helicopter-stocked." Olson added. "That's one way the fungus can get there."

When asked if the Three Creek hatchery fish were infecting amphibians, ODF&W's Holt said, "I would like to see the data that shows that.

"Certainly we'd be concerned if it turned out that the hatchery (was) the source," he said. "But that's a policy decision and you'd have to check with Portland (ODF&W HQ).

Holt suggested that the fungus may naturally occur on crayfish or any available dead tissue, or even on amphibians themselves.