Slime for the climate, delivered by brown algae

Brown algae are true wonder plants when it comes to absorbing carbon dioxide from the air. They even outcompete forests on land in this, and thus play a decisive role for 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 algae can remove large amounts of carbon dioxide from the global cycle in the long term and thus can counteract global warming.

Fucoidan: Brown algae slime is not a favourite dish
Algae take up 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 either quickly used by other organisms or sink towards the seafloor.

"The excretions of brown algae are very complex and therefore incredibly complicated to measure," says first author Hagen Buck-Wiese from the Max Planck Institute for Marine Microbiology in Bremen. "However, we have managed to develop a method to analyse them in detail." With this method, the researchers scrutinised 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 species we studied, the so-called bladderwrack," says Buck-Wiese. Fucoidan is a recalcitrant molecule. "The fucoidan is so complex that it is very hard for other organisms to use it. No one seems to like it." As a result, the carbon from the fucoidan does not 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 gigaton (one billion tons) of carbon per year from the air. 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 each year in the long term.

For comparison: Germany's annual greenhouse gas emissions currently amount to about 0.74 gigatons of carbon dioxide, according to the Federal Environment Agency (Umweltbundesamt, estimation for 2020).

"And even better: The fucoidan does not contain any nutrients such as nitrogen," Buck-Wiese explains further. Thus, the growth of the brown algae is not affected by the carbon losses.

More species and sites
For the current study, Buck-Wiese and his colleagues from the MARUM MPG Bridge Group Marine Glycobiology, which is based at both the Bremen Max Planck Institute and MARUM - Centre for Marine and Environmental Sciences at the University of Bremen, conducted their experiments at the Tvarminne Zoological Station in southern Finland.

"Next we want to look into other brown algae species and other locations," says Buck-Wiese. "The great potential of brown algae for climate protection definitely needs to be further researched and utilised."

Research Report:Fucoid brown algae inject fucoidan carbon into the ocean

Related Links
Max Planck Institute for Marine Microbiology
Climate Science News - Modeling, Mitigation Adaptation

Tweet

Thanks for being there;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Monthly Supporter
$5+ Billed Monthly

paypal only

SpaceDaily Contributor
$5 Billed Once

credit card or paypal

2022 UK's hottest year on record: provisional Met Office figures
London (AFP) Dec 28, 2022
This year is set to be the UK's warmest on record, according to provisional figures released by the Met Office on Wednesday. It had the "highest annual average temperature across the UK, exceeding the previous record set in 2014 when the average was 9.88 degrees Celsius (49.78 degrees Fahrenheit)", the Met said in a statement. The figure for 2022 would be announced later. Since 1884, each of the ten years recording the highest annual temperature have occurred from 2002, according to the for ... read more