Antarctica’s peculiar green snow is spreading, according to researchers who have created the first large-scale map of microscopic algae growing on the chilly, southernmost continent. As the climate warms, snow algae is becoming a more and more important terrestrial carbon sink.
“This is a significant advance in our understanding of land-based life on Antarctica, and how it might change in the coming years as the climate warms,” study leader Matt Davey, faculty member of the University of Cambridge’s Department of Plant Sciences, said. “Snow algae are a key component of the continent’s ability to capture carbon dioxide from the atmosphere through photosynthesis.”
The study’s researchers, from University of Cambridge and the British Antarctic Survey, explained the lay of the Antarctic land. “In the limited terrestrial ecosystems of Antarctica, all photosynthetic organisms will make a significant contribution to the ecology of their habitat,” the scientists wrote in their paper, which is published in Nature Communications. With only about 0.18% of Antarctica’s continental area ice-free, there’s very little exposed ground for traditional vegetation. Thus, evolution got creative and developed snow algae.
Expeditions in the 1950s and 1960s first described the green and red patches on and below the snow surface. Since then, researchers have learned that Antarctica’s diverse algal species are important for nutrient and carbon cycling. “Considering that a single snow algal bloom can cover hundreds of square meters, snow algae are potentially one of the region’s most significant photosynthetic primary producers, as well as influencing nutrient provision to downstream terrestrial and marine ecosystems,” the researchers wrote.
Researchers combined their own measurements on the ground with satellite images taken between 2017 and 2019 to map the algae. They found that algae grows in “warmer” areas along the Antarctica coastlines and west coast islands, where temperatures in the continent’s summer months rise just a hair over 0 degrees Celsius. Marine birds and mammals also influence the algal distribution, as their excrement is a natural fertilizer. More than 60% of algal blooms were within 5 kilometers of penguin colonies.
Lead author Andrew Gray explained, “As Antarctica warms, we predict the overall mass of snow algae will increase, as the spread to higher ground will significantly outweigh the loss of small island patches of algae.”
Images via Gray, A., Krolikowski, M., Fretwell, P. et al. / Nature Communications (Creative Commons Attribution 4.0 International License)