In the form of fucoidan, brown algae could remove up to 0.55 gigatonnes of carbon dioxide from the atmosphere annually – Zoo House News
Brown algae are true miracle plants when it comes to absorbing carbon dioxide from the air. They even outperform the forests on land and thus play a crucial role in the atmosphere and our climate. But what happens to the carbon dioxide after the algae have absorbed it? Researchers at the Max Planck Institute for Marine Microbiology now report in the Proceedings of the National Academy of Sciences (PNAS) that the brown alga can remove large amounts of carbon dioxide from the global cycle in the long term and thus counteract global warming.
Fucoidan: Brown algae slime is not a favorite dish
Algae absorb carbon dioxide from the atmosphere and use the carbon to grow. They release up to a third of the carbon they absorb back into the seawater, for example in the form of sugary excretions. Depending on the structure of these excretions, they are quickly utilized by other organisms or sink towards the seabed.
“The excretions of brown algae are very complex and therefore incredibly difficult to measure,” says first author Hagen Buck-Wiese from the Max Planck Institute for Marine Microbiology in Bremen. “However, we managed to develop a method to analyze them in detail.” Using this method, the researchers examined a large number of different substances. The so-called fucoidan turned out to be particularly exciting. “Fucoidan made up about half of the excretions of the brown algae we studied, the so-called bladderwrack,” says Buck-Wiese. Fucoidan is an unruly molecule. “The fucoidan is so complex that it is very difficult for other organisms to use it. Nobody seems to like it.” As a result, the carbon from the fucoidan doesn’t return to the atmosphere quickly. “This makes the brown algae particularly good helpers in removing carbon dioxide from the atmosphere in the long term – for hundreds to thousands of years.”
Brown algae could bind almost all of Germany’s carbon dioxide emissions
Brown algae are remarkably productive. It is estimated that they absorb about 1 gigatonne (one billion tons) of carbon from the air per year. Using the results of the present study, this would mean that up to 0.15 gigatons of carbon, equivalent to 0.55 gigatons of carbon dioxide, are sequestered by brown algae annually in the long term. For comparison: According to the Federal Environment Agency, Germany’s annual greenhouse gas emissions currently amount to around 0.74 gigatons of carbon dioxide, estimate for 2020.
“And even better: The fucoidan does not contain any nutrients such as nitrogen,” explains Buck-Wiese. Thus, the growth of the brown algae is not affected by the carbon losses.
Other types and locations
For the current study, Buck-Wiese and his colleagues from the MARUM MPG bridging group Marine Glycobiology, which is based both at the Bremen Max Planck Institute and at the MARUM – Center for Marine and Environmental Sciences at the University of Bremen, conducted their experiments through the Tvärminne Zoological Station in southern Finland. “Next, we want to look at other brown algae species and other locations,” says Buck-Wiese. “The great potential of brown algae for climate protection must be further researched and used.”
Materials provided by the Max Planck Institute for Marine Microbiology. Note: Content can be edited for style and length.