Snow Algae Shade Most (Not All) Colored Snow

June 7, 2005

It may be the start of summer, but Ron Hoham and a few other scientists like him are thinking about snow, specifically colored snow.

Where others see an excuse to snicker about yellow snow, Hoham sees other shades—and one of the most extreme and overlooked life-forms on Earth.

Hoham is a biologist at Colgate University in Hamilton, New York. He is one of a handful of people in the world who study snow algae—microscopic organisms that thrive in the chilly, acidic, sun-blasted, and nutrient-poor confines of melting snow.

"The more I study them, the more I want to know about them, and the more I learn about them, the more fascinating I find them," Hoham said.

In addition to yellow snow, colored snow comes in greens, oranges, and reds. And though the source of yellow snow is always suspect, Hoham said the other colors are a sure sign of algae.

Why Study Snow Algae?

Bill Williams, a biologist at St. Mary's College of Maryland, said snow algae give biologists insight to the extreme conditions life on Earth has adapted to. This, in turn, provides clues to where to look for potential life on distant planets.

"To a plant biologist, that's the most interesting thing about snow algae," Williams said. "They manage to survive and even thrive in an environment that, for arcane reasons, is a really difficult environment to do photosynthesis in." (In photosynthesis, green plants use chlorophyll to convert sunlight into energy, mostly in the form of carbohydrates.)

The bright light, high ultraviolet radiation, and cool temperatures of the snowfields where many species of snow algae are found would destroy a houseplant, according to Williams.

But photosynthetic snow algae do thrive in these harsh habitats. In a 2003 study, published in the Proceedings of the National Academy of Sciences, Williams and colleagues showed that snow algae absorb, via photosynthesis, carbon dioxide at about one-tenth the rate of average plants.

The finding came as a surprise to many biologists, because previous studies had shown that snowfields generally emit carbon dioxide, not absorb it, Williams said.

"Whether [snow algae] can make a given patch of snow over an entire year a CO2 sink rather than a CO2 source is up for grabs," Williams said. He added that to enlist snow algae in the battle against global climate change, which may be fueled by CO2 emissions, would be futile.

Continued on Next Page >>


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