Snow Algae Shade Most (Not All) Colored Snow

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According to Hoham, the Colgate biologist, snow algae also serve as bioindicators. Such organisms can change in number, structure, or function and thus point to changes in the integrity or quality of the environment.

In particular, Hoham said snow algae's adaptability to acidity makes them good indicators for acid rain, while their resistance to ultraviolet light can flag depletion of the ozone layer, which boosts ultraviolet radiation.

But Hoham said he is mostly content with trying to figure out why and how snow algae exist at all. Even though they may not have direct relevance to humans, understanding how snow algae survive advances understanding of life in general.

Besides, conducting field studies of snow algae, Hoham added, is an ideal way to pass the workday: Snow algae are primarily found thriving in pockets of snow that linger in high alpine environments well into the summer. "I've seen some neat, beautiful areas as a result of studying these," he said.

Extreme Life Cycle

Hoham's work is beginning to unravel the mysteries of snow algae. Like all life-forms, snow algae need liquid water to thrive. As such, their most active times of the year come in the late spring and early summer, when the temperature rises sufficiently to melt winter's snow.

When the first snowmelt trickles through the snowpack to reach rock and soil below—where snow algae pass the winter in a dormant stage—the algae "wake up," germinate, and squirm up through the ice crystals toward the sunlight. This colors the snow, Hoham said.

The algae are all green algae at heart. The green comes from chlorophyll, which allows the microscopic plants to get energy from the sun. The red and orange colors of some snow algal species come from secondary pigments that screen out ultraviolet light, which can be damaging in open, high alpine snowfields.

Once a snowfield is all but melted and the snow's nutrients have been nearly depleted, the algae shift to a reproductive stage. In this they create hardy cells that will lie dormant on the ground until the next spring, when the cycle begins anew.

In his Colgate University lab, Hoham and his undergraduate students are conducting experiments with a few species of Chloromonas (a type of snow alga) to try and define the optimal conditions for their growth.

The researchers have found that the species, which are found in upstate New York, are optimally suited to their environment, with the exception of one parameter: day length.

"They'd do a lot better at growing and reproducing if they had more day length, which is interesting," Hoham said. "If I were reproducing, I'd want some darkness." It seems the biologist also has a sense of humor when it comes to discussing colored snow.

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