Red Snow, Green Snow - snow algae

Science News, May 20, 2000 by Susan Milius

He and his students will also describe a reproductive pattern that Hoham had never seen before in this group of green algae. When mobile cells of what seems to be a new species of Chloromonas start to mate, most have oblong shapes. Some 8 hours later, the oblong cells have blimped out, so the combining cells are spherical.

After mating, the snow algae drift back to the ground with the dwindling snow. In this spartan world, swift depletion of nutrients such as nitrogen jolts the cells into growing their protective coats and assuming a holding mode before their habitat melts away. In this way, they stay safe until the next spring rush.

Where an uninitiated person might see just a big pile of slush, snow biologists recognize a teeming, speck-eat-dot world. As primary producers, the algae capture energy from the sun. Bacterial colonies develop around the algae. Rotifers and other higher-level predators then move in.

More complex beasts, such as Mesenchytraeus ice worms, also come to graze. "You'll know them if you see them," chuckles Hoham. The dark squiggles, an inch-plus long, even have segments like earthworms.

Collembola, or snow fleas, hop about this nearly invisible zoo. Tardigrades, or water bears, also are on the prowl but more at a lumber than a hop. These flyspeck-size hunters have a blob of a body with a tiny head mounted low in front. Proportionally big claws adorn their eight stubby legs, which have no joints. "You wonder how on Earth they hold together, with part of them going one way and part another," Hoham says.

With all these beings, fungi find plenty of material to decompose. They weave their strands through the snowfields.

A white expanse of snow is far from barren, Hoham says. "Basically, you've got everything in it you would find in a freshwater ecosystem," he explains.

But unlike idyllic rivers and streams, the snow ecosystem doesn't offer people a fresh-caught meal. Duval says that after he explains that he hasn't lost something in the snow, hikers often say, "I hear that watermelon snow can kill you."

Duval's never even tasted it. While he doesn't expect the algae to prove toxic, he fears the abundant bacteria. "I would advise people not to eat watermelon snow," he says. "You don't want to get diarrhea in an alpine environment."

He does acknowledge the skimpiness of experimental evidence on this last topic. His extensive algae files include just one study, by physicians in Reno, Nev., who fed six people concentrated snow algae. Only one person developed diarrhea, the doctors reported in 1997 in WILDERNESS AND ENVIRONMENTAL MEDICINE.

While Thomas doesn't recommend taking chances with bacteria either, he has tried a quick taste of colored snow. "It's nondescript, a little tangy, like watermelon," he says.

What hasn't killed snow algae has made them stronger, or at least, more interesting to biochemists and physiologists.

A series of papers in the late 1970s and 1980s by British scientists reported chemical tricks for withstanding extreme cold. They described what Hoham calls "most peculiar" fatty acids in the creatures' cell membranes. The compounds' carbon chains have an unusually high ratio of double bonds to single bonds. These ratios make the fatty acids more fluid at low temperatures, just as margarines with polyunsaturated oils stay squishier in the fridge than lard with its heavy load of saturated fat. Membrane flexibility should help algal cells continue to function at low temperatures.