Pink snow causes water problems in the west

This article was originally featured on News from the Highlands.

Jim Elser searched the snowfields on the lower slopes of Clements Mountain in Glacier National Park, Montana. While tourists photographed towering cliffs nearby and searched for wildlife, Elser, an ecologist at the University of Montana and director of the Flathead Lake Biological Station, focused on just one thing: finding snow algae.

Elser and his research team trudged past blooming purple asters and yellow arnica wildflowers, gaining altitude until they reached a ridge above a small pool. The chirping of groundhogs replaced the sound of idling car engines in the Logan Pass parking lot, which was teeming with August visitors. A soft hum came from the bulky rectangular device strapped to the back of his colleague Joe Giersch, an aquatic entomologist at the University of Montana; The device, a light meter, warmed up in preparation for the scientists’ data collection.

Then, from about 100 meters away, the three scientists noticed a faint blush on the slushy snow in front of them. They race towards it.

Blush ribbons of seaweed ran 400 square feet across the sunny slope – Chlamydomonas nivalis, a red-pigmented green alga found in high alpine and polar regions around the world. Algae’s striking appearance on snow has earned it nicknames ranging from the delicious-sounding – watermelon snow – to the ominous – glacier blood. Scientists believe this alga could play an important role in melting glaciers and snowfields.

Sparkling fresh white snow is the most naturally reflective surface on earth. As algal blooms spread, they darken the snow, which then absorbs more heat and melts faster. This can create a feedback loop: as temperatures rise and more snow melts, snow algae, which need nutrients, light and liquid water, thrive and spread. The algal bloom is changing its own habitat and in doing so appears to be changing the surrounding habitat. A little over half of all runoff in the west comes from snowmelt, but the extent to which snow algae contribute to melting is not currently included in standard snowmelt models. These scientists hope their work can help us better understand the role it plays in climate change.

“It is an ephemeral flower on an ephemeral substrate.”

This summer, explorers from across the country traversed the mountains of Washington, Oregon, Wyoming, Utah and Montana in search of patchy snow. They collected samples and tested the reflectivity of patches of snow algae. Sometimes they stumbled over a spot too late and found only puddles of blood-red water where patches of snow and seaweed had already melted. The search for intact snow to sample became a race against the summer heat and algae growth. “It’s an ephemeral bloom on an ephemeral substrate,” Elser said. “The seasonal snow goes, and whether or not those patches have snow algae is also unpredictable.”

THE LATE SUMMER SUN slapped us on the neck while examining a piece of snow algae. A third member of Elser’s field team, Pablo Almela Gomez, a postdoctoral researcher at the University of Minnesota, held a long wooden pole. At the end of the pole, the spectroradiometer, a small black tube, dangled over a patch of snow. “This is the most beautiful patch of algae we’ve seen in a long time,” Giersch remarked. Only a few pine needles and small pebbles dotted the red spots.

The scientists used the device to record the snow’s albedo, a measure of how much downward sunlight is reflected back up. Red snow means lower albedo, which means more absorbed sunlight and faster snowmelt. Other factors also affect albedo, including dirt, dust, and ash from wildfires. Sand from the Gobi Desert can blow as far as the Pacific Northwest, while dust from the shrinking Great Salt Lake sometimes blankets the Wasatch Mountains. The team also measured the snow’s pigment concentration with a second spectroradiometer to find out how much of the red color spectrum, most likely from the snow algae, was present.

A bighorn sheep oversaw from a jagged cliff high above us as the team went through the rest of their routine: measuring the snow’s water content, collecting bags of snow samples, and extracting a snow core that revealed two layers of algal blooms, including a distinct band of rusty a few centimeters below the surface.

“The ice is melting, but your drink will still be nice and cold by the time the last piece of ice is gone. Then it’s like, ‘What happened? My drink is warm.” ”

Later that day, at a lab at the University of Montana’s Flathead Lake Biological Station, Elser and Almela Gomez would use the samples to test which inputs support snow algae growth. They melt the snow, mix it together and add nutrients like nitrogen and phosphorus. Then, after five to 10 days under grow lights in a cold incubator, they measure the chlorophyll levels to see how much the algae has grown.

The two types of nutrients come from different places. Previous work suggests the phosphorus is found in rocks that have been crushed by glacial movement, while nitrogen from chemical fertilizers and manure is injected into agricultural areas. The researchers suspect that both types of nutrients promote algae growth, but are particularly interested in nitrogen. They believe algal blooms may be particularly common in the Intermountain Rockies due to wind patterns, and they hope to learn more about the dynamics involved.

The team’s work is part of the small but growing field of snow algae research. The scientists hope to find out what makes snow algae thrive and where they are most likely to live. The Living Snow Project, a citizen science initiative started by researchers at Western Washington University, asked skiers, climbers, and hikers to help collect samples of pink snow. Scientists have also agreed on surging algal blooms in the French Alps.

Learning what influences snow algae growth is an important step in understanding a changing water supply. More algae potentially means more melt, and knowing where algae might be accelerating snowmelt is especially important in the drought-prone western US. Gradual snowmelt is good; It creates a more predictable water supply downstream for reservoirs and fills streams with the cold water that fisheries and other aquatic life depend on during the hot summer months. However, the rapid snowmelt brings with it a host of other problems.

Elser compared the role of snow to ice in a cocktail. “The ice is melting, but your drink will still be nice and cold by the time the last piece of ice is gone,” he said. “Then it’s like, ‘What happened? My drink is warm.’” When snow algae accelerate snowmelt, or melt all snow quickly, streams can become warmer than usual and have less water throughout the summer. “It’s a pretty big deal,” said Scott Hotaling, a member of the snow algae research team and an assistant professor at Utah State University who studies changing mountain ecosystems. “We’re talking about the entire West being in a drought, and if there’s another factor continuing the earlier meltdown, that’s important.”

WATER MANAGER and snowpack surveyors agree that faster melting is a problem, but they don’t necessarily agree on the role played by snow algae. Previous studies suggest this may matter: a 2021 article in the journal nature communication found that algal blooms were responsible for up to 13% of surface melting on Greenland’s ice sheet, while a study in Alaska suggests that snow algae account for 17% of all melting on a large ice sheet, a 21% increase. “A lot of studies have been done on these large ice sheets where there are flat surfaces,” said project member Trinity Hamilton, a geomicrobiologist at the University of Minnesota. But of course mountains are not flat. And researchers don’t yet understand how variations in topography and slope might affect where snow algae grow. Hamilton and her team’s future findings could pinpoint these missing pieces of the puzzle.

“It’s really no more of a concern than dirty or dirty snow, which can (also) accelerate melting.

“Truly knowing how much water is coming out of snowpack and when that is going to be critical for anyone who needs to know about water supplies, whether it’s agricultural producers or flooding,” said Erin Whorton, one Water supply specialist with the Natural Resource Conservation Service’s Idaho Snow Survey. “Snowpack is incredibly important to the way we work in the West.”

Once the effects of snow algae are better understood, Whorton believes they should be included in models that predict snowmelt timing. But not everyone agrees. Is the existence of snow algae in the high mountains a major threat, a nuisance, or something in between? “There are so many variables in snowmelt that you really just have to stick to the basics of climate variability,” said Scott Pattee, water supply specialist with the NRCS Washington Snow Survey. “It’s really no more worrisome than dirty or trashy snow, which can (also) speed up the melt.”

After the day of fieldwork at Glacier, the men packed up their gear and began sliding and sliding down the snowfield. The Garden Wall unfolded like a postcard in the distance. The snow we had just walked on now ran in rivulets and spilled onto the rocks below. We picked our way through muddy trails and descended at a small waterfall powered by an underground spring and snowmelt. Some of the melt, however small, was caused by the live pink bloom we visited earlier that day. Time will tell if it will further dry out the already parched West. “The algae are just trying to survive,” Almela Gomez said. “You are not to blame for anything.”

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