Brown algae can remove up to 0.55 gigatonnes of carbon dioxide from the atmosphere each year
Brown algae take up large amounts of carbon dioxide from the air and release some of the carbon they contain into the environment in the form of slime. This slime is difficult for other marine organisms to break down, so carbon is removed from the atmosphere for a long time, as researchers at the Max Planck Institute for Marine Microbiology in Bremen now show. They reveal that an algal mucus called fucoidan is specifically responsible for this carbon removal, and they estimate that brown algae can remove up to 550 million tons of carbon dioxide from the atmosphere each year.
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Algae absorb carbon dioxide from the atmosphere and use that carbon to grow. They release up to one-third of the carbon they absorb into seawater, for example, as sugar waste. Depending on the structure of these excretions, they are either immediately used by other organisms or sink towards the sea floor. “The brown algae excreta are very complex, which makes them very complex to measure,” says Hagen Buck-Wiese, lead author at the Max Planck Institute for Marine Microbiology in Bremen. “But we have managed to develop a method to analyze them in detail.”
In this way, researchers have probed a number of different substances. So-called fucoidan turned out to be particularly exciting: “Fucoidan made up about half of the excrement of the brown alga species we investigated, the so-called bladderwrack,” Buck-Wiese says. . Fucoidan is a refractory molecule. “Fucoidan is so complex that it is very difficult for other organisms to utilize it. Nobody seems to like it.” “This makes brown algae particularly good helpers in removing carbon dioxide from the atmosphere over the long term, over hundreds to thousands of years.”
Brown algae could bind almost all of Germany’s carbon footprint
Brown algae are very productive. They are estimated to absorb about 1 gigatonne (1 billion tons) of carbon from the atmosphere annually. Using the results of current research, this means that up to 0.15 gigatonnes of carbon equivalent to 0.55 gigatonnes of carbon dioxide will be sequestered by brown algae each year in the long run. For reference, Germany’s annual greenhouse gas emissions currently amount to about 0.74 gigatonnes of carbon dioxide according to the Federal Environment Agency (Umweltbundesamt, 2020 est.). “Better yet, fucoidan does not contain nutrients such as nitrogen,” Buck-Wiese further explains. Therefore, brown algae growth is not affected by carbon loss.
In the current study, Buck-Wiese and his colleagues from the MARUM MPG Bridge Group Marine Glycobiology, which is based at both the Max Planck Institute Bremen and the MARUM – Center for Marine Environmental Sciences at the University of Bremen, and his colleagues at the Twarminne Zoo in Southern Finland. “Next we want to look at other brown algae species and other locations,” Buck-Wiese says. “The great potential of brown algae for climate protection needs to be further researched and exploited.”
Original: Climate-friendly slime from brown algae
Than: Max Planck Institute for Marine Microbiology | University of Bremen
