Algae Blooms Turn Antarctica’s Ice Green

Scientists predict that the organisms’ presence will increase as global temperatures increase

Most people imagine Antarctica as an icy, stark-white tundra. But visit during warmer months and one might be surprised by a splash of color.

“The snow is multi-coloured in places, with a palette of reds, oranges and greens — it’s quite an amazing sight,” says Matt Davey, an ecologist at the University of Cambridge.

Brightly colored blooms of microscopic grow on the surface of Antarctic ice and give it those extraordinary hues. Over the last two years, Davey led a team to study and map the striking green algae blooms that dot the Antarctic Peninsula, the part of the continent that juts up near South America.

The team identified 1,679 green blooms using images from the European Space Agency’s Sentinel 2 satellite and measurements made on the ground, per a Cambridge statement. The researchers from the University of Cambridge and British Antarctic Survey published their findings in Nature Communications last week.

As Martyn Herman reports for Reuters, the presence of algae in Antarctica has been recorded for some time—even famed British explorer Ernest Shackleton noticed it during his pioneering polar expeditions in the early 20^th century. However, an effort to map algae blooms on this scale is unprecedented, Reuters reports.

“Our work was really the first large-scale survey of snow algae for Antarctica,” Andrew Gray, lead author on the study and researcher at the University of Cambridge, tells Michael Marshall reports at New Scientist.

The distribution of the blooms is also strongly influenced by nearby bird and mammal populations. Over 60 percent of the blooms were near a penguin colony because the bird’s guano is excellent fertilizer, according to the statement.

Researchers also found that the algae blooms grow best in slushy snow, meaning they appear more frequently in warmer temperatures. Now that the scientists have measured the baseline amount of algal blooms, they aim to measure whether the blooms increase in size or frequency as global temperatures increase in the future, Davey tells Reuters.

The authors predict that, as Antarctica warms and its ice melts, the green algae blooms will lose some of their icy habitat on the fringes of the continent but gain new habitats of slushier snow further inland, leading to a net increase in blooms.

The blooms are at their largest during the summer months, when they cumulatively cover up to 1.9 square kilometers, per the BBC. “Even though the numbers are relatively small on a global scale, in Antarctica where you have such a small amount of plant life, that amount of biomass is highly significant,” Davey tells the AFP.

As Lily Katzman reported for Smithsonian magazine in February, scientists recently recorded red-pigmented algae blooms on the Antarctic Peninsula. Davey’s team didn’t measure red or orange blooms in this study, but are planning to study them in the future, per Reuters.

“A lot of people think Antarctica is just snow and penguins,” Davey tells AFP. “In fact, when you look around the fringe there is a lot of plant life.”

“There are probably many different species of algae, all with quite different niches. Some will live right at the top of the snow surface, others quite a bit deeper—and their numbers will change depending on the temperature,” Alison Smith, a biologist at Cambridge and author on the study, tells the BBC.

"But we don't know yet whether their numbers will increase or decrease. And if you don't monitor the situation, you'll never know,” Smith says.