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Evolution and the volcano

 

Tom Iraci / U.S. Forest Service file
  Research ecologist Charlie Crisafulli holds a frog that was netted during amphibian sampling in March 2005. A small steam plume rises from Mount St. Helens behind him.


It's been 30 years since Mother Nature kicked off an experiment in creative destruction at Mount St. Helens, and today the volcano serves as a prime example of how life adapts to changing conditions.

The changes on the mountain are fascinating to biologists - and perhaps unexpectedly, creationists as well.

For example, consider the amphibians of the ponds: When the volcano blew on May 18, 1980, an avalanche of logs, rocks and other debris wiped out some lakes and reshaped others. Biologists thought amphibians such as salamanders, frogs and toads would be among the hardest-hit species.

"They're thought to be very sensitive to environmental change," Charlie Crisafulli, a U.S. Forest Service ecologist who has been studying St. Helens since shortly after the eruption, told a "Nova" documentary team.

Elsewhere in the world, amphibians are high on the list of species threatened with extinction, due to loss of habitat as well as a mysterious frog-killing fungus.

So biologists were "absolutely shocked" to find that most of the area's amphibian species had survived the blast, Crisafulli said. The eruption created an array of 150 ponds that actually encouraged the amphibians to widen their territory.

These weren't your father's amphibians: The reshaped terrain reshaped the animals as well. The pond habitat favored Northwestern salamanders that could keep their gills and live their whole lives as aquatic animals, as detailed in this Seattle Times report.

"The salamanders are a good example of what I would call hedging your bets," Mount St. Helens monument scientist Peter Frenzen told me today.

The eruption wiped out land-dwelling amphibians, but new colonists could take advantage of protected burrows that were built by gophers beneath the ash.

A big factor behind the amphibians' resurgence is the fact that they've been able to stay a leap ahead of the things that could bring them down - predators, pathogens and parasites, which Crisafulli calls the "three P's." Once St. Helens' ecosystem fills out more completely, biologists expect the amphibian population to be brought back into check.

That might suggest that amphibians do best in off-balance environments, thanks to their ability to switch between marine and land habitats. But it really depends on the situation: Scientists have long argued that amphibians are in the midst of an extinction crisis precisely because their habitats are out of balance, in part because of human-caused pollution.

Unexpected consequences are a big part of the Mount St. Helens story, and not just for amphibians: After the eruption, some biologists thought that the thousands of acres of downed trees would leave the area more vulnerable to wildfires and insect infestation. Those concerns encouraged extensive salvage logging in some areas of the blast zone - but not within the 110,000-acre Mount St. Helens National Volcanic Monument that created by Congress in 1982.

The result was that significantly different ecosystems were created inside and outside the monument's boundaries. Selling all that salvaged lumber brought economic benefits for the region's hard-hit logging industry, but leaving the lumber alone didn't bring about the environmental problems some had feared: The volcanic ash that coated the trees served as a fire retardant as well as an insecticide.

Reviving the creationism connection
... Speaking of unexpected consequences, Mount St. Helens has become something of a poster child for "creation geologists" - the folks who argue that Earth was created in accordance with the chronology they say the Bible lays out.

If the floods sparked by the 1980 eruption could cut new canyons through the surrounding countryside, couldn't a global flood have done the same for the Grand Canyon a few thousand years ago? If the lava dome that has built up inside St. Helens' crater can produce anomalous radioisotope results, doesn't that imply that radioactive dating techniques could be way off? Questions like this are raised at places such as the Mount St. Helens Creation Information Center, not far from the mountain itself.

My colleague at msnbc.com, Alex Johnson, wrote about the St. Helens creationism connection five years ago. The TalkOrigins Archive addressed questions about the canyons, the claims about lava dating and Mount St. Helens' "coal" formation even longer ago. Nevertheless, today's 30th anniversary has sparked a revival of the creationist claims.

Reviving reminiscences
... And speaking of revivals, the anniversary also sparks a revival of Mount St. Helens memories. Thirty years ago today, I was in the midst of the ashfall in eastern Washington state - and through the magic of the Internet you can read the newspaper I helped put together on May 18, 1980.

To mark the occasion, my former colleagues at The Spokesman-Review in Spokane have put together a special report, including a heaping helping of reminiscences. If you have memories you'd like to share, please add them as comments below.

As you read stories about the rebirth of Mount St. Helens' ecosystem, and the scientific mysteries posed by its seismic activity, try to keep the eruption's 57 victims in your memory as well. The best-known casualty was David Johnston, the volcanologist who radioed "Vancouver! Vancouver! This is it!" just as the volcano blew. His name now graces Johnston Ridge, the site of a volcano observatory and visitor center. Check out this memorial website for remembrances of all the victims.

Update for 7 p.m. ET: Peter Frenzen, the U.S. Forest Service's monument scientist for Mount St. Helens, says that the changes at the volcano illustrate how a huge disturbance in an ecosystem can open up opportunities for a different mix of organisms to gain a foothold.

"I don't think it's quite evolution," he told me. "Evolution takes a longer time to play out. This is more of an environmental shift and a shift in the habitat."

Such an environment favors organisms that can cope more easily with that kind of shift - a characteristic that ecologists call "amplitude." The salamanders that can keep their gills and go aquatic provide a good example of amplitude. So do Mount St. Helens' deer mice. "When seeds are around, they're eating seeds," Frenzen said. "When insects are around, they're eating insects."

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