Beneath the ocean’s surface, along the floors of shallow coastal waters, exist gardens so lush you can see them from space.

These are seagrass meadows, congregations of aquatic flowering plants. They’re a lot like their terrestrial counterparts — except with sea turtles swooping through the stalks. Seagrass is a foundation species, meaning it acts as the anchor of an entire habitat for marine creatures like starfish, stingrays, and seahorses.¹

Seagrass is something of a foundation species for us, too. It is a key component of what, in 2019, we called the “Great Carbon Sink in the Sea.” Oceanic ecosystems — including seagrass meadows, seaweed, and many of the microorganisms that live in the ocean — capture billions of tons of carbon every year. And they do so far more effectively than most other ecosystems.² Seagrass is estimated to be about 35 times more efficient at absorbing and storing carbon than the rainforests of the world.³

Yet this valuable resource in the fight against climate change is also a victim of that very struggle. The International Union for Conservation and Nature estimates that seagrass populations are declining by 7 percent every year, making it the fastest disappearing habitat on Earth.⁴

As is often the case in the anthropocene, human activity is one of the main culprits. Industrial and agricultural pollution, the development of shipping channels and other coastal infrastructure, and fishing practices like trawling — not to mention warming waters and intensifying storms — are among the greatest threats to seagrasses.⁵

But human beings have also played an important role in bringing seagrass back from the brink of extinction in recent years. In seaforestation efforts around the world, we see an example of what it means to act as a beneficial participant in the global, interspecies community of the planet.

Rewilding the Ocean Floor

Rewilding is an environmental conservation strategy that goes beyond harm reduction. Instead, rewilding seeks to restore damaged ecosystems to their formerly robust states by creating the right conditions for interrupted natural processes to flourish once again.⁶ Sometimes, that means tearing down a dam so that a river can flow freely. Other times, it means reintroducing keystone plant and animal species back into environments where they’ve been eliminated.

One form of rewilding has shown particular promise in recent years: seaforestation, the act of reintroducing seagrasses and seaweeds to ocean ecosystems.⁷ Since 1999, a team of researchers from the Virginia Institute of Marine Science and The Nature Conservancy has been carrying out what has been hailed as the “largest seaforestation effort to date.” With the help of a few hundred volunteers, they’ve dispersed more than 70 million eelgrass seeds into the waters of the Volgenau Virginia Coast Reserve, a 40,000-acre expanse of undeveloped coastal wilderness on Virginia’s Eastern Shore.⁸

Once plentiful in these waters, the eelgrass population was eradicated in the 1930s by a combination of disease and severe storms. Today, it’s making a comeback. Thanks to the team’s efforts, the Reserve is now home to a 9,000-acre eelgrass habitat, one of the largest such habitats along the entire Eastern Seaboard.⁹

The eelgrass itself deserves much of the credit: Once the first generation of seeds reached maturity, it kicked off a positive feedback loop that paved the way for more eelgrass to come. The new eelgrass meadows absorbed tidal energy, calming the turbulent waters; silt and sediment cleared up. More sunlight reached the ocean floor, allowing new eelgrass plants to grow more easily. All the eelgrass needed was a push from a few concerned scientists and citizens.¹⁰

Today, the seagrass meadows of the Volgenau Virginia Coast Reserve sequester 3,000 metric tons of carbon and 600 metric tons of nitrogen every year. They’ve also vastly improved water quality along the Eastern Shore, and as a result, fish and invertebrate populations are steadily increasing.¹¹

Green Gravel and Oyster Reefs

While the Virginia project is the largest, it’s not the only one of its kind. The Ocean Conservation Trust, an English nonprofit, is currently working to restore four hectares of seagrass beds in the Plymouth Sound National Marine Park.¹² Likewise, the organization SeaForester is partnering with governments in Portugal, Norway, and Australia to explore new seaforestation methods that could make rewilding a little easier. One method has serious potential: green gravel.¹³

The green gravel approach starts in the lab, where kelp seedlings are cultivated on small stones. Once the kelp reaches sufficient maturity, the rocks can be scattered from boats all across the ocean, where they’ll settle on the seafloor and, hopefully, blossom into robust kelp forests.¹⁴

“Replanting seaweed forests is costly, but the green gravel approach in its simplest sense – taking a rock with a spore growing on it and throwing it off the side of a boat – could dramatically alter the cost-benefit equation,” says Axel Bugge, cofounder of SeaForester.¹⁵ By perfecting the method, SeaForester and other researchers working on green gravel hope to finally create a simple, scalable means of seaforestation.

Nor is seaforestation the only kind of rewilding happening in the world’s waterways. In New York City, the Billion Oyster Project is restoring large colonies of oysters, called “oyster reefs,” to New York Harbor. Like seagrass meadows, oyster reefs provide a habitat for other aquatic life while cleaning up the surrounding waters. A single oyster can filter as much as 50 gallons of water per day.¹⁶

New York Harbor was once home to 220,000 acres’ worth of oyster reefs, but a combination of pollution, overharvesting, and development sent populations plummeting by the turn of the 20th century.¹⁷ Working with 10,000+ volunteers and more than 100 schools, the Billion Oyster Project creates man-made oyster reefs and raises oysters in nurseries across New York Harbor, with the goal of reaching one billion oysters in New York City’s waters by 2035.¹⁸

Seaforestation for Fun and Profit

Seaforestation isn’t just good for the planet — it’s also good for the economy. Increasing interest in seaweed as both a carbon sink and a source of sustainable food and biofuel has led to a boom in the seaweed industry, with seaweed production doubling since 2010.¹⁹ Now, companies in the space are seizing the opportunity to do right by the world.

Take, for example, the London-based Notpla, which is using seaweed to make a biodegradable, edible alternative to plastic. Meanwhile, seaweed farmers — like British Columbia’s Canadian Kelp Resources — advocate for Westerners to support sustainable agriculture by eating more seaweed. A single seaweed farm the size of Washington State would yield enough protein to feed the entire planet.²⁰ Contrast that with more typical modes of large-scale farming: To simply rear livestock, we use more than a quarter of the planet’s terrestrial surface for grazing and a third of all arable land to grow crops for livestock feed.²¹

The seaweed industry is also bringing jobs to economically disenfranchised areas. Companies like Cascadia Seaweed and the Nuu-chah-nulth Seafood Limited Partnership are partnering with First Nations communities in Canada, where unemployment is often higher than the national average, to establish training programs and employment opportunities.²²

“It’s not just about sustaining local economies — it’s about community,” Larry Johnson, president of the Nuu-chah-nulth Seafood Limited Partnership, told Time. “Seaweed farming is unique for First Nations communities because it helps us create economies of our own that align with our traditions. Our role has always been to connect with the land and repair it.”

The Waters of Life

Scientists have long theorized that life on Earth began in the depths of the ocean.²³ It’s little wonder that, billions of years later, the world’s waters continue to play a fundamental part in the persistence of that life.

Climate change presents an existential threat to nearly every being on this planet. But the story of seaforestation proves the worst outcome is far from inevitable. By changing our relationship to and placing our trust in the natural world — and creating the conditions in which it can thrive again — we can take major steps toward undoing the damage we’ve done.

And there’s another lesson for us here, too. As a single blade of eelgrass sways in the ocean current, cleansing the water and capturing carbon, it reminds us that even the most unassuming organisms have something to contribute to our vast shared ecosystem; they’re worth cherishing.

— The Keap Team