If primitive forms of life ever existed on Mars, they might have looked like the denizens in Thomas Vogelmann's lab freezer.
No moldy cottage cheese here. Instead, the University of Wyoming botanist has collected samples of snow that glisten with the color of fresh watermelon. The snow gets its tint from colonies of snow algae that thrive under the harsh alpine conditions of the nearby Snowy Range Mountains, just west of Laramie.
Long the subject of scientific curiosity, these tiny one-celled organisms are coming under increasing scrutiny, researchers say, not only for hints they might give about the prospects for life on other planets, such as early Mars.
Snow algae also may play an important role in regulating atmospheric carbon dioxide. And some strains, such as those found in the permanent snowpack in the Rockies and Sierra Nevadas, exhibit traits that could be used to improve crops' resistance to cold or excessive amounts of sunlight.
"The more we think about them, the more remarkable these organisms become," says Dr. Vogelmann, who along with colleague William Smith, recently received a National Science Foundation grant of nearly $250,000 to study snow algae, which tints snow in green, red, and orange.
Of particular interest to the Wyoming team is Chlamydomonas nivalis, a species found in the Snowy Range Mountains.
At elevations from 11,000 to 12,000 feet, the permanent snow pack can reach depths of 10 feet or more. At that altitude, plants from more-temperate climates would wither under the intense sunlight and nighttime temperatures that hover at freezing. Ultraviolet levels run some 30 percent higher at 10,000 feet than at sea level. That would overload most plants' photochemical "factories" even at room temperature, let alone at 0 degrees C.
"Yet, somehow these algae manage to do photosynthesis. They thrive," Vogelmann says. "What are these algae doing that higher plants cannot do?"
By analyzing the amount of light within the snowpack and the algae's approach to photosynthesis in the lab, he says he hopes to answer that question.
Vogelmann suggests that enzymes involved in converting carbon dioxide to the sugars the algae and plants need may be different. If the differences and their genetic roots can be identified, and the genes spliced into other plants, crops such as spring wheat could enjoy a longer growing season, he adds.
The algae's color depends on their strain and stage of growth. Despite geographical differences in populations, one spot can host a remarkable diversity of algae. In the Pacific Northwest, "I can take you up a mountain and you'll see red snow at 3,500 feet containing algae that are found only in a few places around the world," says Ron Hoham, a biology professor at Colgate University in Hamilton, N.Y. "You'll see green snow in the forest at 4,500 feet - a different strain that can't tolerate open exposure. You'll see yet another type in the red snow at 6,500 feet."
The algae start out green. After the spring thaw, spores left by the previous crop lie on the ground, to be covered by the next winter's snows. When melting occurs, the spores release green cells whose tails help propel them toward the light. They stop near the top of the snow, where they remain until they reach their dormant stage, about two or three weeks later.
Another role algae may play is as environmental "scrubbers," researchers say. Dr. Hoham points out that researchers studying Quebec's "nitrogen budget" could not account for 40 percent of the nitrogen. "They didn't know where it was going," he says. Then researchers found that the snow algae were feasting on it, often reducing the nitrogen levels in snow they inhabit to near zero. "That's nitrogen that's not going into streams and rivers," he says.
Decrease CO2 buildup
In addition, snow algae may play an important role in putting a brake on the buildup of atmospheric carbon dioxide. Dr. Smith says that currently, computer models designed to simulate the Earth's CO2 budget show levels of the gas rising more quickly than they actually are. Plants, he says, represent an obvious, though insufficiently quantified "sink" trapping CO2. That role, he says, likely extends to snow algae.
During the winter, snow covers vast stretches of the Northern hemisphere. There, he says, it insulates microbes that continue to break down organic material in the soil, giving off carbon dioxide.
"We know that carbon-dioxide concentrations beneath snow can be three to four times higher than in the ambient air," he says. One of the key questions centers on where snow algae get the bulk of their CO2 - from the atmosphere or from beneath the snow.
His research focuses on snow algae's role as sinks for CO2. When it comes to sequestering CO2, he says, "this group of algae could be the most important algae in the terrestrial ecosystem, especially in temperate latitudes."