Pink snow means problems for water in the west

This article was originally on Highland news.

Jim Elser scanned the snowfields clinging to the lower slopes of Clements Mountain in Montana’s Glacier National Park. While nearby tourists snapped photos of towering rock faces and looked for wildlife, Elser, an ecologist at the University of Montana and the director of the Flathead Lake Biological Station, focused on just one thing: finding snow algae.

Elser and his research team hiked past blooming purple asters and yellow arnica wildflowers, gaining elevation until they reached a ridge above a small basin. The chirping of marmots 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-measuring instrument, was warming up in preparation for the scientists’ data collection.

Then, about 100 yards away, the three scientists noticed a faint blush on the muddy snow ahead. They walked towards it.

Rouge-colored algae ribbons ran 400 square feet down the sunny slope – Chlamydomonas nivalis, a red-pigmented green alga found in high alpine and polar regions around the world. The algae’s striking appearance on snow has earned it nicknames ranging from the delicious-sounding – watermelon snow – to the ominous – glacial blood. Scientists believe that these algae may play an important role in the melting of glaciers and snowfields.

Sparkling fresh white snow is the most naturally reflective surface on Earth. When algal blooms emerge, 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, the snow algae — which need nutrients, light and liquid water — bloom and expand. The algal bloom changes its own habitat and appears to change the surrounding habitat in the process. Just over half of total 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’s a short-lived bloom on a short-lived substrate.”

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

THE LATE SUMMER SUN slapped our necks as we examined a patch 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 algae field we’ve seen in ages,” Giersch noted. Only a few pine needles and small stones freckle the red spots.

The scientists used the device to record the albedo of the snow, a measure of how much of the sunlight shining downwards is reflected back up. Red snow means lower albedo, which means more sunlight is absorbed and the snow melts faster. Other factors also affect albedo, including dirt, dust and ash from wildfires. Sand from the Gobi Desert can blow all the way to 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 watched from a jagged cliff high above as the team worked through the rest of their routine: measuring the snow’s water content, collecting bags of snow samples, and taking a snow core that revealed two layers of algal blooms, including a obvious rusty band a few inches below the surface.

“The ice melts, but your drink stays nice and cold until that last piece of ice is gone. Then it’s like, ‘What happened? My drink is warm.’ ”

Later that day, in a lab at the University of Montana’s Flathead Lake Biological Station, Elser and Almela Gomez would use the samples to test which inputs help snow algae grow. 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 grew.

The two types of nutrients come from different places. Previous work suggests the phosphorus is found in rocks ground up by glacial movement, while nitrogen is blown in from the chemical fertilizers and manure in agricultural areas. The researchers suspect that both types of nutrients stimulate algae growth, but they are particularly interested in nitrogen. They believe algal blooms are especially common in the Intermountain Rockies because of 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 allows snow algae to thrive and where they are likely to live. The Living Snow Project, a citizen science initiative by researchers at Western Washington University, asked skiers, climbers and hikers to collect pink snow samples. Scientists have also agreed on rising algal blooms in the French Alps.

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

Elser compared the role of snow to ice in a cocktail. “The ice is melting, but your drink is still nice and cold until that last piece of ice is gone,” he said. “Then it’s like, ‘What happened? My drink is warm.’” If snow algae melt the snow faster or melt all the snow quickly, streams can get warmer than normal and contain less water as the summer progresses. is 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 a will be another factor that perpetuates earlier melting, that’s important.”

WATER MANAGERS and snowpack experts agree that faster melting is a problem, but they don’t necessarily agree on the role snow algae play. Previous studies suggest it could be significant: a 2021 article in the journal Nature communication found that algal blooms were responsible for up to 13% of the surface melt of the Greenland ice sheet, while a study in Alaska suggests that snow algae are responsible for 17% of total melting on one large ice field, an increase of 21%. “There have been a lot of studies done on these big ice sheets, where you have 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 may shape where snow algae grow. The future findings of Hamilton and her team could find these missing pieces of the puzzle.

“It’s actually as concerning as dirty or dirty snow, which can (also) accelerate melting.

“Really knowing how much water is coming out of the snowpack and the timing of it will be critical for anyone who needs to know about water supply, whether it’s agricultural producers or for flood control,” said Erin Whorton, a water supply specialist with the Idaho Snow Survey of the Natural Resource Conservation Service. “Snowpack is incredibly important to the way we work in the West.”

Once the effects of snow algae are better understood, Whorton thinks they should be incorporated into models that predict the timing of snowmelt. But not everyone agrees. Is the liminal existence of high mountain snow algae a major threat, an annoying annoyance 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, a water supply specialist with the NRCS Washington Snow Survey. “It’s actually as concerning as dirty or dirty snow, which can (also) accelerate melting.”

After a day of fieldwork in Glacier, the men packed up and began slipping and sliding down the snowfield again. The Garden Wall rock face unfolded like a postcard in the distance. The snow we had just walked over now flowed into streams and spilled onto the rocks below. We made our way through muddy stretches of trail and descended past a small waterfall, powered by an underground spring and melting snow. Some of the melt, however small, was caused by the live pink flower we had 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. “They are not guilty of anything.”

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