(ORDO NEWS) — Plants play a significant role in the planet’s carbon cycle through their ability to capture carbon dioxide from the atmosphere and store it in their bodies. And brown algae went further: they store carbon… in mucus.
Brown algae are distributed throughout the planet, and are mainly found at a depth of 40–100 meters.
In the process of photosynthesis, they absorb carbon dioxide from the surrounding water, and they do it quite efficiently: according to scientists, all brown algae on the planet absorb up to 550 million tons of carbon dioxide per year.
By comparison, Germany‘s greenhouse emissions are around 740 million tons annually.
Algae need carbon dioxide to grow, but they release about a third of the carbon they take in back into the seawater in the form of carbohydrate compounds.
Depending on what these compounds are, they are either quickly absorbed by other living organisms, or accumulate in the form of mucus (the algae themselves need it to protect themselves from drying out and being eaten by animals).
Having studied the composition of the mucus of one of the types of brown algae, pulverulent fucus, scientists from the Institute of Marine Microbiology of the Max Planck Society (Germany) found that more than half of it is fucoidan.
The molecule of this polysaccharide is so complex that few living organisms, in principle, are able to break it down.
So slime can hold carbon in its composition for a very long time, preventing it from returning to the atmosphere.
Curiously, such huge carbon losses do not particularly affect the growth of brown algae: the remaining two-thirds of the absorbed amount is enough for them to live, and since fucoidan does not contain any valuable trace elements (for example, nitrogen), the algae can “afford” itself to be wasteful and secrete large amounts of mucus.
The worldwide distribution and unprecedented efficiency in absorbing carbon dioxide make brown algae a promising tool to combat global warming.
Perhaps the immoderate carbon “appetites” of fucus and its brethren will ultimately help humanity reduce the amount of carbon in the atmosphere.
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