Pink snow spells trouble for water in the West

This article originally appeared on High Country News.

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

Elser and his research team cut through blooming purple asters and yellow arnica wildflowers, gaining altitude until they crested a ridge above a small basin. Groundhog chirps replaced the sound of car engines idling in the Logan Pass parking lot, which was packed 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 tool, was warming up in preparation for the scientists’ data collection.

Then, about 100 meters away, the three scientists noticed a slight blush in the muddy snow ahead. They made a beeline for him.

Ribbons of red algae ran 400 square feet across the sunny hillside. Chlamydomonas nivalis, a red-pigmented green alga found in polar and alpine regions around the world. The striking appearance of the algae in the snow has earned it nicknames ranging from the delicious watermelon snow sound to the ominous glacier blood. Scientists believe that this algae could play an important role in the melting of glaciers and snowfields.

Fresh white snow is the most naturally reflective surface on Earth. When the algae bloom, they darken the snow, which then absorbs more heat and melts more quickly. This can create a feedback loop: As temperatures rise and more snow melts, snow algae, which needs nutrients, light and liquid water, flourish and spread. The algal bloom alters its own habitat and appears to alter the surrounding habitat in the process. Slightly more than half of the total runoff in the West comes from snowmelt, but the extent to which snow algae contributes to melting is not currently included in standard snowmelt models. These scientists hope their work can help us better understand the role it plays as the climate changes.

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

This summer, researchers from across the country scoured the mountains of Washington, Oregon, Wyoming, Utah and Montana in search of spotted snow. They collected samples and tested the reflectivity of the snow algae patches. Sometimes they stumbled upon a site 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. “Seasonal snow is going away, and whether or not those patches have snow algae is also unpredictable.”

THE LATE SUMMER SUN bumping our necks as we surveyed a patch of snow algae. A third member of Elser’s field team, Pablo Almela Gómez, 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 best patch of algae we’ve seen in a long time,” Giersch said. Only a few pine needles and small pebbles dotted the red spots.

The scientists used the device to record the albedo of the snow, a measure of the fraction of sunlight that is reflected downward. Red snow means lower albedo, which means more absorbed sunlight and faster melting. Other factors also influence the albedo, such as dirt, dust, and ash from forest fires. 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 pigment concentration of the snow with a second spectroradiometer to determine how much of the red color spectrum, most likely from snow algae, was present.

A bighorn sheep surveyed from a jagged cliff high above us as the team worked through the rest of their routine: measuring the water content of the snow, collecting snow core bags, and taking snow samples that revealed two layers of blooms. of algae, including a distinct rusty band a few inches below the surface.

“The ice is melting, but your drink is still nice and cold until the last bit of ice is gone. So it’s like, ‘What happened? My drink is hot. ”

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 will melt the snow, mix it up, and add nutrients like nitrogen and phosphorous. Then, after five to 10 days under grow lights in a cold incubator, they’ll measure chlorophyll levels to see how much the algae grew.

The two types of nutrients come from different places. Previous work suggests that phosphorus is found in rocks ground up by moving glaciers, while nitrogen is extracted from chemical fertilizers and manure in agricultural areas. The researchers suspect that both types of nutrients encourage algae growth, but they are particularly interested in nitrogen. They believe that algal blooms might be especially common in the Rocky Mountains between mountains 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. Scientists hope to find out what allows snow algae to thrive and where they are most likely to live. The Living Snow Project, a citizen science initiative created by researchers at Western Washington University, asked skiers, climbers and hikers to help collect samples of pink snow. Scientists have also converged on the increase in algae 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 could accelerate melt is especially crucial for the drought-prone western US. Gradual thaw is good; it creates a more predictable downstream water supply for reservoirs and infuses streams with the cool water that fisheries and other aquatic life depend on during the hot summer months. However, the rapid melting of snow brings a host of other problems.

Elser compared the role of snow to that of ice in a cocktail. “The ice is melting, but your drink is still nice and cold until the last bit of ice is gone,” she said. “So it’s like, ‘What happened? My drink is hot.’” If snow algae speed up snow melt or melt it quickly, streams may end up hotter than normal and have less water as the summer progresses. “It’s a big problem,” 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 talked about the entire West being in a drought, and if there’s going to be another factor that perpetuates the previous melt, that’s important.”

WATER MANAGERS And snowpack surveyors agree that faster melting is a problem, but they don’t necessarily agree about the role played by snow algae. Previous studies suggest it could be significant: a 2021 article in the journal nature communications found that algal blooms were responsible for up to 13% of the surface melt that occurs on the Greenland ice sheet, while a study in Alaska suggests that snow algae account for 17% of total melt in a large ice field, an increase of 21%. “A lot of studies have been done on these large ice sheets, where there are flat surfaces,” said Trinity Hamilton, a project member and a geomicrobiologist at the University of Minnesota. But the mountains, of course, are not flat. And researchers still don’t understand how variations in topography and slope might shape where snow algae grows. Future findings by Hamilton and her team could locate these missing pieces of the puzzle.

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

“Really knowing how much water is coming from snowpack and when it’s going to be critical for anyone who needs to know about water supply, whether they’re agricultural growers or for flood control,” said Erin Whorton, water supply specialist. water with the Natural Resources Conservation Service’s Idaho Snow Survey. “Snowpack is incredibly important to the way we operate 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 liminal existence of high-mountain snow algae a major threat, a pesky nuisance, or something in between? “There are so many variables in snowmelt that one really needs 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 of a concern than dirty snow or trash, which (also) can speed up melting.”

After the day of fieldwork at Glacier, the men packed up their gear and began slipping and sliding across the snowfield. The rock face of the Garden Wall unfolded like a postcard in the distance. The snow we had just walked over was now running in rivulets, emptying into the rocks below. We made our way through muddy patches of the trail and descended past a small waterfall, fueled by an underground spring and melting snow. A part of the melt, however small, was caused by the hot pink flower we had visited earlier that day. Time will tell if the already parched West will dry out even more. “The algae are just trying to survive,” said Almela Gómez. “They are not guilty of anything.”

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