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Seaweed, a promising avenue for the preservation of the planet


Feeding humans and animals, replacing plastic, serving as medicine while limiting global warming… Seaweed would offer an immense field of innovation to help the planet. Decryption.

From February 9 to 11, the city of Brest, in Brittany, will host the first international summit dedicated to the preservation of the oceans, called One Ocean Summit. Twenty Heads of State will meet there alongside environmental NGOs and scientists. On the program: take stock of the situation of maritime areas, seek concrete solutions to protect them but also think about how to better exploit them.

Philippe Potin, marine biologist and research director at the CNRS, and Vincent Doumeizel, ocean advisor to the United Nations Global Compact, will be there to present a solution. “We have to bet on seaweed!”, they exclaim in concert, contacted by France 24. “Often, when we talk about seaweed, we have this negative image of green or brown clusters washed up on the beaches in Brittany or in the West Indies. It’s a shame”, deplores Philippe Potin. “When they are found on the beaches, it is because they have been torn from their base because of pollution or industrial activities. They are not the problem, they are a consequence.”

“The reality is that these plants play an essential role for our planet”, insists the researcher. Algae are to maritime spaces what forests are to land surfaces. “They too are the lungs of the planet. Thanks to their photosynthesis, they absorb CO2 and release oxygen,” explains the scientist, who specializes in the issue at the Roscoff biological station in Brittany. “Alone, they are responsible for half of the oxygen renewal on Earth. They do a great service to the climate.”

“They are also essential to life in the ocean because they make it possible to create special habitats for thousands of species of fish or shellfish”, insists the scientist. “By ricochet effect, it is partly thanks to them that we can have a great diversity of fishing on the coasts.”

In total, some 10,000 species of algae visible to the naked eye are scattered all over the planet – from kelps on the coasts of Brittany to kelps in Tasmania, via wakames in Japan.


“The least exploited resource in the world”

In addition to their role for the climate and biodiversity, these plants could be used in a large number of sectors ranging from food to industry, including medicine. “Today, it is one of the least well-exploited resources on the planet”, insists Vincent Doumeizel, author of the book “The Algae Revolution” (Equateurs edition).

“Our planet is made up of 70% water and yet our seas and oceans only serve 3% of our food. It’s absurd”, he continues. It is this observation that prompted this former employee of the agri-food sector to take an interest in aquatic plants. “We know that one of the great challenges of this century is that we have reached our terrestrial limits when it comes to our food systems. We are short of land, our intensive agriculture is particularly harmful to the planet… It is clearly time to think about new uses.”

However, seaweed seems to have everything from a magic ingredient. Already consumed daily in Asia, they are acclaimed by dieticians: packed with protein, vitamins and fibre, they contain only a few lipids. According to a study conducted by the University of Wageningen, in the Netherlands, devoting 2% of the oceans to culture, with the ecosystems linked to it – their fish and shellfish – could thus make it possible to cover the protein needs of all the planet.

Not to mention that it’s not just humans they can feed. “We can use it as food for animals, especially cattle. This would improve their immune system”, assures Vincent Doumeizel. In agriculture, France already has several villages, mainly in Brittany, using them as fertilizer for their plantations.

In the medical field too, algae are beginning to appear, especially in antifungal or anti-inflammatory creams. Fucale is thus known to relieve heartburn. Another example: recently, a patent was filed for a cream and a gel based on Skeletonema marinoi to fight against acne.

As far as industrial uses are concerned, Europe has around ten companies which have launched into the production of biodegradable packaging from algae, to replace plastic. “Others are thinking about using them to make clothes. In the Netherlands, a start-up has looked into hygienic protection from algae”, lists the specialist.

“It is finally in the field of energy that they prove difficult to exploit”, nuance Philippe Potin. “We had considered for a time to make it an agrofuel but the quantities needed are far too large.”

Asia pioneering, the rest of the world lagging behind

“In reality, all this is nothing new. Seaweed has been eaten for hundreds of years. Prehistoric men ate it, as well as indigenous populations all over the world”, explains Vincent Doumeizel. “The practice simply disappeared almost everywhere in Greco-Roman times, except in Asia.”

Today, Asia, a pioneer in seaweed farming, that is to say the cultivation of seaweed in artificial ponds, accounts for 99% of world production. In 2015, China was far ahead, with 13 million tonnes collected, followed by Indonesia with 9 million tonnes.

Seaweed fields off Fujian province, China, in December 2019. © Hector Retamal, AFP

In Europe, France and Norway dominate a still very limited production. Unlike Asia, seaweed farming is still in its infancy there. According to the European Commission’s 2021 Blue Economy Report, only 32% of algae in Europe comes from it. The remaining 68% comes from a so-called wild harvest, that is to say the uprooting of these plants directly in their natural environment. “We are really at the hunter-gatherer stage!”, Vincent Doumeizel quips.

The global market, however, is expanding. According to the Food and Agriculture Organization of the United Nations (FAO), production tripled between 2000 and 2018. It is “the fastest growing food production sector globally”, notes the institution.

Finding a balance between exploitation and protection

Today, Philippe Potin and Vincent Doumeizel are calling for seaweed farming to be accelerated. “In addition to the economic potential, it is all the more crucial since a lot of algae are now massively disappearing due to the warming of the oceans linked to climate change”, explains Philippe Potin, citing the example of the coast of California where a kelp forest has shrunk by 80% in recent years. “Developing seaweed farming will restore ecosystems.”

“But obviously, it has to be done in a very reasoned and careful way,” he continues. “There is no question of further damaging our oceans by doing anything to grow algae at all costs.” In Asia, seaweed farming shows certain limits. Like traditional intensive agriculture, it is regularly singled out because it often takes precedence over other activities linked to the sea. The use of fertilizers to speed up production is also frequent. “And these are often monocultures which in fact crush other species”, deplores Philippe Potin.

In Europe, there is also a major difficulty: “Of the thousands of existing species of algae, we are only able today to cultivate a dozen, and especially Asian species”, explains the biologist. . “We therefore need to step up research work on our European species. We want to avoid importing exotic algae that would disrupt ecosystems.”

Philippe Potin and Vincent Doumeizel thus took the lead of the Safe Seaweed Coalition. This new organization is managed by the United Nations, the CNRS and the Lloyd’s Register Foundation. Their ambition: to bring together industrialists, scientists and producers to structure this exploitation and set up legislation on an international scale.

At the One Ocean Summit, Vincent Doumeizel must also meet with Barbara Pompili, the Minister for Ecological Transition. “France has enormous potential. We have an algal zone in Brittany that is unique in the world. The government must be aware of this.”

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