How Seaweed Shapes Our Past and Future

What do we make of the weediness of seaweeds?

This is Non-Native Species, a column by Jessica J. Lee on plants, people, and their intertwined migration stories.

The cliffs carried the wind down, blasting the Margate shore on which we stood. The North Sea, gray and flat, pooled around my boots, and the dog—seeing waves for the first time—skipped away from the rising surf. There wasn’t any clear ground for us to stand on: The beach was blanketed in weeds spent by the winter tide. The smell of rot and salt had accumulated as I watched the waves lump new seaweeds onto the Kent coast—one of Britain’s richest for seaweeds.

No one was coming to the beach that day. It was only just April and cold. Britain was still held tight by travel restrictions, and we couldn’t leave the land we stood on. But the wrack and algae and brown kelp still moved—thriving amid the chalk reef of the shoreline. I lifted a frond of kelp with the toe of my boot, letting its length twine around me, and imagined its journey to shore. For seaweeds move wherever the sea—or we—might take them.

Algae, as a term, is a broad brushstroke: It gestures toward the difficult, unclassified things that live in the otherworld of water. Taking in some fifty thousand species in freshwater and salt, they span taxonomic kingdoms—from bacteria to the not-quite-plant, single- and multi-cellular—and depending on where you live, these classifications themselves can shift. Much of this is down to size. But seaweeds like kelp and wrack—the macroalgae of the world—capture our attention more readily.

Some twelve thousand species of seaweed have been recorded, and it is likely you’ll be familiar with some of them. They are the algae we eat: dulse, wakame, kombu. Or like bladder wrack, a source of iodine in medicines. Porphyra algae is processed to become the nori used in sushi or to make Welsh laverbread. They are a staple for nearly every coastal community. But move inland and seaweeds take on another connotation entirely, not as staple food, but as fertilizer and farm fodder.

They pervade even our land-bound lives: If you brushed your teeth today, your toothpaste may have contained seaweed as a gelling agent. Seaweed products are in everything from paper to pharmaceuticals to fuels. And in this shape-shifting space, they come to mean so much to humans: sustenance, familiarity, otherness, and futurity.

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As a child, I was no lover of seaweeds. They were weeds after all, with the unwanted tendency to drift out of place. No matter that in my Taiwanese mother’s language they were sea vegetables (海菜 | hǎicài), a term more resonant of sustenance. They were the things of another world that brushed at my legs as I swam, that evoked a rising terror.

And in this shape-shifting space, they come to mean so much to humans: sustenance, familiarity, otherness, and futurity. 

I was a fearful child, and the same fear of seaweed I had while swimming carried over onto land. At the dinner table, I pushed away stray pieces of it, picked it out of stir-frys, and turned up my nose at nori. I couldn’t bring myself to eat the tofu-and-seaweed salads my sister loved or my mother’s sparerib soups strewn with kelp. For a long time, seaweed felt to me too redolent of the sea.

My Welsh grandparents and father spoke of laverbread: a seaweed puree made of boiled Porphyra algae. I couldn’t understand wanting to eat it; the squidge between my teeth and that murky fug of sea turned my stomach. My mother, I knew, wanted me to love these foods. But I was picky—more than picky—and more accustomed to the crunch of North American snacks than the bounce and bite my family sought.

But somewhere in growing up, my curiosity about algae shifted. I had long loved being in water, and it began to make little sense to be fearful of something that so often came from the place I loved. I lay in my bed often, imagining I was immersed in water, a pattern of shifting light dancing on my bedroom ceiling. I cannot entirely account for it, and perhaps it was a childish wish: I wanted, if such a thing were possible, to dwell entirely in a world dim-lit, filtered by a haze of plankton, in the bottom of a shallow sea. I was drawn by color—by the blue-green and olivine light of kelp—more than anything. I wanted to make seaweed a familiar thing—not some distant, othered thing—to know it as more than food, as more than fertilizer. I knew that how I imagined seaweed mattered.

In adulthood I turned, as I often do, to historic flora. In the late eighteenth century and through the nineteenth, as botany became an acceptable, polite pastime for women in Britain, algae—and seaweeds especially—became something of a fashion. Without showy, sexualized flowers, seaweeds were considered particularly suitable for women to study.

I marveled at the digital archive of Anna Atkins’s 1840s cyanotypes of seaweed, merging art and science in creating a historic record of seaweeds on the Kent shore. And Amelia Griffiths, a prolific nineteenth-century botanizer of the shore, for whom at least two species of algae are named; Margaret Gatty, who authored two volumes on the subject; and Isabella Gifford, author of The Marine Botanist. All were among the many in a “seaweed sorority” that made enormous contributions to our understandings of algae at a time when women’s contributions to science were often sidelined.

I read how, famously, in 1963, seaweed farmers on Japan’s western coast erected a memorial to a British phycologist, Kathleen Mary Drew-Baker, dubbed the “Mother of the Sea.” She had never set foot in Japan, but her studies of seaweed in Britain, published in Nature in 1949, solved a vital puzzle needed to revive the local nori industry: She was the first to document the life cycle of Porphyra, discovering that the spore stage of the seaweed relied upon the shells of bivalves. In Japan, the shells that normally littered the seabed had been decimated by mines during the war. It was this woman’s discovery that provided a pathway to thriving harvests again.

Reading all this, I wondered if the women who studied seaweeds felt something of kinship for their central—but visibly marginal—role in our world.

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What do we make of the weediness of seaweeds? Of that facet of their existence that eludes familiarity and containment? We write it into our stories, and we try, futilely perhaps, to ascribe it a rightful, delimited place in the world.

In Ruth Ozeki’s novel A Tale for the Time Being, the protagonist discovers a lunch box wrapped in a Ziploc bag off the coast of British Columbia, washed across the Pacific following the Japanese tsunami. It glints out at her from beneath a tangle of bull kelp, a talisman of past disaster and a literal embodiment of the migrations the sea makes possible.

Ozeki’s plot was rooted in reality. In 2012, fifteen months after the Tōhoku earthquake brought the sea to shore, a dock from Japan’s Aomori Prefecture washed up on an Oregon beach. The dock, according to the EPA, was “covered with organisms not native to North America, including sea stars, barnacles, mussels, amphipods, and algae.” Among the species recorded as having made the 5,000-mile journey was wakame kelp—the seaweed you may know from soups or salads.

We write it into our stories, and we try, futilely perhaps, to ascribe it a rightful, delimited place in the world.

Culinarily, Undaria pinnatifida is prized for its sweetness and texture. Being quite tender, it is well-suited to salads and soups, where it floats, diaphanous, unlike other kelps. Among invasion biologists, however, the species is classed as being among the world’s worst invasive species. Indigenous to the coasts of East Asia, wakame thrives in the sublittoral zone near the shore: in shallow waters, estuaries, and—as if to underscore the degree to which our fates are bound—on anthropogenic structures like docks.

And not simply due to the anomalies of floating docks, but thanks largely to the ship hulls and ballast waters of our cargo industries, wakame is now a species with a “global non-native range.” Read that again: It is everywhere, but still out of place.

Wakame now grows steadily along the coasts of Britain and Europe, Australasia, and the Americas. And while eradication programs have held little success, some are turning to other possibilities, like farming and harvesting the kelp. Most winter afternoons, I cook rice cake soup flecked with green strips of “invasive” wakame. Reading the packet, I learn that the seaweed I buy is hand-harvested off the Portuguese coast.

And this is where my hope to know seaweeds on their own terms—as something beyond our uses for it—dissolves. Because seaweeds remain bound to us and to our human stories. Because our movements around this globe cannot easily be undone. As we drive our desires across the world, the seaweeds are our passengers.

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Ultimately, as I learned as a child and in growing up, how we imagine seaweed matters. Off the coast of South Africa, in the patch of ocean recently made famous by a man and an octopus, campaigners are now working to cultivate an identity for a wild kelp forest in the hopes of conserving it. The Great African Seaforest, so-named by the network of storytellers, filmmakers, and scientists at the Sea Change Project, is a crucially biodiverse ecosystem.

Kelp forests cover nearly a quarter of the world’s coastlines, where they help to prevent coastal erosion and sequester enormous amounts of the carbon we are so readily releasing into the atmosphere. But giant kelp, Macrocystis pyrifera, thrives in water between fifty and sixty degrees Fahrenheit (ten to fifteen degrees Celsius), and the oceans can no longer be relied upon to stay in that range. As we warm the world, kelp forests are disappearing: In Australia and Tasmania, for example, just 5 percent of the once-vast forest remains. And we now know that seaweeds hold the records of such transformations fast: At the Ocean Memory Lab in California, century-old seaweed samples have been used to extract data on oceanic conditions of the past.

The efforts behind the Great African Seaforest tell us that seaweeds rely upon us, too, for the stories we tell about them. More than heritage, however, seaweeds and algae more generally have come to occupy an imagined future in our world. We are dreaming of seaweeds beyond the sea.

North American and European agriculture are poised to turn toward aquaculture—particularly of seaweeds. Distant from the quaint seaweed farms of yore, kelp and algae are becoming cogs in an industrially farmed future. Algae is grown in tanks and from enormous cultivation rigs laid on the seabed. A Singapore-based entrepreneur has built a vertical algae farm, where seaweed grows upward, far from the sea. Seaweeds could be used to sequester carbon on large scales and serve as fodder for potential biofuels. They have become bioplastics, and proteins from algae have been genetically manipulated into more-drought-tolerant tobacco crops. The language around seaweed farming often evokes sustainability—underscoring how deeply our thinking about it is bound up with the future.

From climate change and ecological collapse to carbon capture, seaweeds are repositories of our greatest fears and grandest ambitions for the future. They unpick scientific paradigms, politics, and nationalisms, all the things that ask for circumstances, species, and people to stay in place. Standing on the shore in Margate, it was hard to imagine all this could come from the kelp tangled around my boots. Still I walked the beach, dodging waves, knowing that seaweeds teach us about softening the hard borders of our human worlds.