A Red Tide Of Glacier Blood Threatens BC Watersheds

Algae that turns snow dark red is linked to faster melting of the glaciers that feed BC rivers in drought.

watermelon snow on a hiking trail in Alaska
Recent studies indicate that the pink-hued snow — often referred to as watermelon snow — characterized by the presence of Chlamydomonas nivalis algae thriving in cold water, melts faster compared to clean snow. Photo credit: Dene Miles on Dreamstime

Most of us on BC’s coast know about red tides that turn seafood toxic, water red, and close areas to seafood harvesting.

Did you know that there’s another kind of algae that turns things red in BC–and also affects our food security? 

Algae blooms can turn snow and ice dark red–a natural condition known as “glacier blood” or “watermelon snow.” Researchers are now in a race against global warming to study these organisms before they vanish along with BC’s shrinking glaciers.

On Alaska’s Harding Icefield, these algae blooms contribute to approximately one-sixth of the snowmelt, according to a study published on September 18 in Nature Geoscience. This discovery implies that future climate simulations should consider the impact of these algae, a factor currently overlooked in predictions about glacial melt. Photo credit: Bryant Olsen on Flickr

In a ‘Catch 22,’ blooms of watermelon snow speed up the melting of the snowpack that the algae need to survive. Because dark snow absorbs more sunlight and heat, snowpack melts faster, which allows even more algae to grow in “a feedback loop of accelerated melting.” explains a paper in Science News

Much more than algae is at risk. During droughts, BC watersheds are replenished by melt from snowpack and ice built up during winter months. But warmer temperatures are depleting these stores, creating a shortage for everything from drinking water to farming, hydropower to salmon spawning, and entire ecosystems.

Chlamydomonas nivalis and Chlamydomonas reinhardtii are two kinds of  algae which bloom on snow when the temperature and nutrients in snow are just right, and some blooms are dramatic enough to be visible from space, 

A team led by BC scientist Lynne Quarmby at Simon Fraser University used satellite images of watermelon snow to show where algae blooms, snowpack melts faster than would otherwise occur. 

Snow algae researcher Lynne Quarmby is the senior author of a study that mapped the distribution of snow algae on mountains in Alberta, British Columbia, and Canada’s north, along with Alaska, Idaho, Montana and Washington State. Photo credit: Simon Fraser University on Flickr

“Losing the algae is just an indicator that we’re losing snowpack and glaciers, and these will impact our lives and the lives of lots of other organisms.”

Lynne Quarmby, scientist at Simon Fraser University

Quarmby’s team studied thousands of satellite images from 2019 to 2022, then visited eight sites in southern BC to test the algae. Their paper in Science Advances reported increased meltwater at all sites of major algae blooms.

The findings serve as a warning about our changing climate, Quarmby told CBC News. “Losing the algae is just an indicator that we’re losing snowpack and glaciers, and these will impact our lives and the lives of lots of other organisms.”

The tiny organisms that create watermelon snow have a global impact: Quarmby’s website notes that the seasonal cycles of freezing and melting snowpack provide water for one-sixth of Earth’s population, and faster glacial shrinking will affect entire ecosystems and regional climates.

Written by The Skeena

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