The beginnings of a new ecosystem is forming in Antarctica, with green algae blooming across the surface of melting snow, a study published in Nature Communications this week has reported. These blooms could spread further in the future as climate change causes more snow to melt, creating the slushy conditions needed for the algae to thrive. Already, in some areas, the algae is so dense that the bright green snow can be seen from space.
The research team, made up of biologists from the University of Cambridge and the British Antarctic Survey, used both satellite data and ground observations to detect and measure green snow algae on the Antarctic Peninsula. For the satellite data, images were taken between 2017 and 2019 using the European Space Agency's Sentinel 2 satellite. Meanwhile, ground observations were conducted by the team at Ryder Bay, Adelaide Island and Fildes Peninsula, King George Island.
The final product of their hard work was the first ever large-scale algae map of the Antarctic Peninsula, which can now be used as a baseline to assess the rate at which algal blooms are forming across the continent due to climate change. The current green algal blooms could prove to be a source of nutrition for other species and they are already forming relationships with with fungal spores and bacteria.
"It's a community. This could potentially form new habitats. It's the beginning of a new ecosystem," explained Dr Matthew Davey, one of the lead researchers and a plant physiologist and chemical ecologist at the Department of Plant Sciences, University of Cambridge.
The research team identified 1,679 separate blooms of green snow algae, covering an astounding area of 1.9 sq km. They estimated that these blooms absorb roughly 479 tonnes of carbon dioxide a year, which is equivalent to the emissions of around 875,000 average UK car journeys. However, this is a relatively small amount on the global scale and is unlikely to make a significant impact on our carbon footprint.
Plus, the warming climate could have a negative impact on the algae regardless of the amount of atmospheric carbon it absorbs. "If it warms up a bit, you get a lot more blooms. If it warms up a lot, the whole system could crash completely because there's no snow," Dr Davey told New Scientist.
There are two factors that currently determine where the algal blooms are located. The temperature needs to be warm enough to turn the snow to slush. The largest blooms are located on the areas of the peninsula and surrounding islands that are warming the fastest and have an average temperature of just over 0°C. Also, there must be a nutrient source for the algae, such as penguin guano. Over 60% of the blooms found during the study were within 5 km of a penguin colony.
As useful as the team's findings are, green snow algae can only give a limited view of the bigger picture regarding the carbon cycle in Antarctica. Future studies will include red and orange algae, both of which were too difficult to detect for this initial study, and will measure blooms across the whole of Antarctica. This will give a better understanding of the total amount of carbon held in Antarctic snow algae, which could prove to be an effective carbon sink in the future for reducing carbon dioxide in the atmosphere.
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