When we think of vast, majestic forests, all we can see are rainforests, boreal forests, or even the last primeval woods expanding across temperate zones such as the Białowieża forest, the last remaining part of the gigantic forested area stretching across the European Plain in prehistoric times.

Almost no one will consider another type of “forest” as big and diverse and as important for biodiversity as the ones mentioned: the seaweed and kelp extensions in shallow waters around fertile coastlines in the world’s oceans. Consider, for example, the seaweed forest extension of the Great Southern Reef in Western Australia, comprising 71,000 square kilometers under the ocean, a surface area bigger than Ireland.

Algae forests are rich in nutrients and provide shelter for microorganisms, fish, marine mammals, and birds. Such ecosystems look like forests underwater, thanks to the thousands of multicellular marine algae or macroalgae species.

Among the many mammals and birds thriving in kelp-rich areas, thanks to the opportunities for protection and feeding they find, are seals, sea lions, whales, sea otters, gulls, terns, snowy egrets, great blue herons, cormorants, and shore birds.

When the water gets warmer

Macroalgae forests are also affected by the higher water temperatures that cause the so-called phenomenon of “coral bleaching”: when water is too warm, corals release the tiny plant-like organisms living on their protuberances, a species of single-celled microalgae called zooxanthellae, hence turning completely white.

Kelp forests won’t react as dramatically to temperature increases, albeit some species known for their medicinal and edible properties, like kelp (large brown algae), will prosper only across coastal areas influenced by cold currents, such as the European North-Atlantic coast and as far south as the Galician fjord-like “rías” in Northwestern Iberian Peninsula (one of the “finis terrae” for the Romans, hence the name of cape Finisterre, a place near the coastal city of A Coruña where they built an impressive lighthouse, the Tower of Hercules, still standing), as well as Northern Portugal just South of the Miño/Minho river.

Besides their importance for biodiversity as a unique habitat for marine life along some of the most productive coastlines in the world, comparative research by marine biologists at the University of Western Australia discusses the overlooked potential of macroalgae forests as carbon dioxide sinks. The researchers looked at 180 previous studies to conclude our little understanding on how the health of such forests affects climate.

“Coastal vegetated ecosystems such as mangrove forests, seagrass meadows, and tidal marshes contribute disproportionally to burial and sequestration of organic carbon in the marine environment (Duarte et al., 2013; Macreadie et al., 2021). Conserving, managing, and restoring these so-called ‘blue carbon’ ecosystems is one of the most practical and cost-effective ways to contribute to climate change mitigation and adaptation (Griscom et al., 2017).”

Healthy, enjoyable, low-impact food

Like terrestrial plants, seaweed concentrations use sunlight and large amounts of carbon dioxide to create energy via photosynthesis, generating oxygen as a byproduct (at sea, micro and macroalgae use the carbon dioxide already absorbed by the seawater from the atmosphere, so a warmer environment rich in CO2 increases its water absorption, which in turn affects the equilibrium of macroalgae.

But the potentially excessive proliferation of some macroalgae species over others could be addressed beneficially for local populations across productive coastlines: harvesting kelp, plant-looking algae of the order Laminariales growing in shallow oceans with temperatures between 6 and 14 degrees Celsius (43-57 Fahrenheit).

Harvested by traditional peoples in temperate areas of the world, kelp constituted an important sustain for coastal Native Americans from the Pacific Northwest, which would use algae for pigments and food preparation. A 2007 study by Erlandson et al. associates the abundance of kelp forests with human migration around the Pacific Rim: the coastal route from Northeast Asia to the Americas may have been related to the rich ecosystems facilitated by macroalgae forests, an ideal habitat for abalone, limpets, mussels, and other seafood found in Stone Age archaeological sites in Africa and the Americas. According to the US’ National Ocean Service:

“In ideal conditions, kelp can grow up to 18 inches per day, and in stark contrast to the colorful and slow-growing corals, the giant kelp canopies tower above the ocean floor. Like trees in a forest, these giant algae provide food and shelter for many organisms. Also like a terrestrial forest, kelp forests experience seasonal changes. Storms and large weather events, like El Niño, can tear and dislodge the kelp, leaving a tattered winter forest to begin its growth again each spring.”

Across the Pacific Ocean, Japan used algae for food preparation (from nori precursors to sauces) and paper-making. Chinese, Japanese, and Korean traditional cuisines use common Pacific species of macroalgae, like kombu (also “dasima” and “haidai”). Jōmon Period‘s (Japanese Neolithic) settlements have abundant remains of kombu leftovers, confirming its ancient consumption, which went on to present-day hypermodern Japan.

Kombu is consumed in dried (dashi konbu), pickled (su konbu), dried shreds (oboro konbu), and fresh (sashimi). Konbu-cha, a tea made by infusing kombu in hot water, is the inspiration for the “kombucha” fermented drinks that have taken over specialty supermarkets in the West.

The first algae markets in Europe weren’t food

Some coastal rural areas of Japan with diets high in algae and seafood are among the highest life expectancy places in the world. Kombu is high in iodine (an essential component for healthy development), dietary fiber, and several enzymes that help the human gut process difficult-to-digest foods.

Algae didn’t enter the mainstream diet in Eurasia in historical times. However, it may have been a part of the staples of Bronze Age populations across the Westernmost part of Eurasia. Areas especially rich in kelp forests, such as around the Galician rías and on the Miño estuary, are rich in Celtic folklore; could Celtic tribes at the extreme of Europe have profited from the sea biodiversity in such areas to gather seafood and, perhaps, even algae?

Fast-forward and, in the 19th century, macroalgae became an important source of sodium carbonate (washing soda, also known as soda ash) to produce soap, detergent, glass, paper, and other compounds that need high-sodium inorganic compounds. Some algae collected in Spain contained up to 30% carbonate concentration, deeming them ideal for soda ash.

To the North of the Spanish rich waters for fishing and algae of the Galician Costa da Morte, in the Scottish Highlands, many families were forcibly evicted during the Highland Clearances (at the end of the 18th and during the first half of the 19th century), became kelp harvesters on “crofts,” small coastal lots in which they fished and burned algae to make soda ash for additional income.

Other chemical processes using common salt to produce sodium carbonate made algae harvesting for such processes less appealing, but the medical and culinary applications were, then and now, nearly endless.

Health properties of algae

Adding fermented seaweed to food (nori sheets, “dasima”) and drinks (kombucha) can be tasty and healthy too: some seaweeds, fresh or fermented, are associated with anti-inflammatory, anti-allergic, antitumor, antioxidant, or neuroprotective properties. More importantly, as oceans warm up, kelp markets could help compensate for some of the expected overgrowth.

In Europe, several areas gifted with macroalgae forests, from the Faroe Islands to Ireland, to Northern Portugal, are developing local harvesting industries of “sea lettuce” (another denomination of kelp). In the Faroe Islands, Ólavur Gregersen and his family have been experimenting with seaweed-inspired cuisine:

“The results range from seaweed butter to his new favorite: seaweed pesto.”

Gregersen says that his family makes sure to have a tablespoon per day of seaweed with some of their meals. It goes well with yogurt, salad, or meat, adding healthy protein and omega-3 fatty acids. Algae could be considered a “superfood,” even when such a label is being abused in food and nutraceutical labeling.

Ólavur Gregersen co-founded Ocean Rainforest, which has specialized in seaweed cultivation since 2010; his pioneering work now assists the EU through a research project he coordinates called SeaMark:

“The goal [of SeaMark] is to upscale circular ocean cultivation and land-based integrated multi-trophic aquaculture systems, as well as to develop novel processing methods like fermentation and biotransformation. This will result in a more resilient food system (…).”

Seaweed as a staple food

The project is trying to develop 12 commercially-viable products, from food ingredients and feed additives to health supplements and even biodegradable packaging materials. One algae showing a bigger potential is “sugar kelp,” Saccharina latissima, growing naturally along the coast of Northern Europe to Spain’s Galicia. It can be cultivated quickly. Sugar kelp is closely related to kombu, the Japanese staple food.

The EU is the first world region poised to help create an industry of seaweed production in Europe. The EU is currently one of the world’s biggest seaweed importers, prone to suffer price increases or heavy metal pollution from the main (and cheapest) importing source, China. Other net exporters of seaweed derivatives are South Korea, Chile, and Japan.

Andrew Dunne writes on Horizon (an EU research and development magazine) that the global market for seaweed was worth nearly 14 billion euros in 2021, and it’s projected to reach 22 billion in 2028, according to projections by the Dutch government (the Netherlands is already a farming and flower-industry powerhouse):

“The European market for seaweed could be worth €9 billion in 2030 with demand in Europe forecast to rise from 270 000 tones in 2019 to 8 million tones over the period, according to the EU. It says production growth in Europe could create around 85,000 jobs.”

Can a culinary tradition start from scratch?

The project to develop a European industry for edible algae, is actively looking for the best seaweed strains, from sugar kelp to Ulva, thanks to algal specialists like Ronan Sulpice at the University of Galway, Ireland. Sulpice is trying to make the incipient industry more resilient, less detached from the year-to-year variability at the seashore, through a project called ASPIRE:

“At present, how we cultivate seeds for seaweed in Europe is a bit like how we cultivated land crops 10 000 years ago – it’s very basic but it is developing.”

Some algae varieties like Palmaria palmata (dulse, or dillisk) are growing in demand, and a kilogram can sell for up to 250 euros. With better strains chosen for production, the new industry could turn the hobby of a few pioneers into a new type of farming capable of connecting modern-day coastal Europeans to their ancestors.

According to an executive document on seaweed by the Dutch CBI (Ministry of Foreign Affairs), Europe mostly focuses on producing brown seaweed (kelp) such as oarweed (Laminaria digitata); tangle (Laminaria hyperborean); and rockweed or knotted kelp (Ascophyllum nodosum).

A beginning

As for the most popular species from outside Europe for European consumers, they are consistent with the global reach of some Asian staple foods that have become known all over the world: kombu (Saccharina and Laminaria), nori (Pyropia yezoensis and Pyropia Tenera), and wakame (Undaria). According to the same document, the top exporting nations within the European bloc were Spain, Germany, Ireland, the Netherlands, and France:

“Imports from within Europe took up almost a third (74.3%) of the total imports in 2020 with 5,007 tones. Compared to imports in 2017, intra-European imports of seaweed were 57% lower in 2020. Overall imports of seaweed were impacted by the lockdown in 2020, as seaweed is mostly consumed in Asian restaurants.”

Within Europe, and including the UK, the main importers of seaweed were, in this order, the UK, France, Germany, Austria, Italy, and Spain. Deeply influenced by the strong traditional relations between Japanese and French culture, France has developed a strong seaweed culinary culture in its Atlantic regions:

“Due to its wide coastlines and strong fishing history, French consumers have been traditionally familiar with eating wild seaweed, which was also harvested in the Brittany region. Brittany’s chefs have also been incorporating dulse seaweed and nori in their seafood menus, for example.”

Despite the growing production, though, France still relies on imports to fulfill its needs, “particularly for dried seaweed and other value-added products.” According to the Dutch document, the growing interest in veganism and organic products in the biggest EU markets, such as Germany, will drive seaweed demand in the coming years.