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InvestigatesSeagrassTHE MOST IMPORTANT place on earth that virtually no one has ever heard of is called the Saya de Malha Bank.
Among the world’s largest seagrass fields and the planet’s most important carbon sinks, this high-seas patch of ocean covers an area the size of Switzerland. More than 320 km from land, the submerged bank is situated in the Indian Ocean between Mauritius and Seychelles.
It has been called the world’s largest invisible island as it is formed by a massive plateau, in some spots barely hidden under 9 metres of water, offering safe haven to an incomparable biodiversity of seagrass habitats for turtles and breeding grounds for sharks and humpback and blue whales.
Researchers say that the Bank is one of the least scientifically studied areas of the planet partly because of its remoteness.
The area’s unpredictable depths have also meant that, over the centuries, merchant ships and explorers tended to avoid these waters. It has long been the type of fantastical realm so uncharted that on the old maps, it would be designated “Here Be Monsters”.
More recently, though, the Bank has been traversed by a diverse cast of characters, including shark finners, bottom trawlers, seabed miners, stranded fishers, starving crews, wealthy yachters and libertarian seasteaders.
The tragedy, however, is that since the Saya de Malha Bank is mostly located in international waters, where few rules apply, its biodiversity is being systematically decimated by a huge fleet of industrial fishing ships that remain largely unchecked by government oversight.
The Bank remains unprotected by any major binding treaties largely due to an anemia of political will by national authorities and a profits-now costs-later outlook of fishing interests.
The question now: Who will safeguard this public treasure?
More than five hundred years ago, when Portuguese sailors came across a shallow-water bank on the high seas over 1,100 km east of the northern tip of Mauritius, they named it Saya de Malha, or “mesh skirt”, to describe the rolling waves of seagrass below the surface.
Seagrasses are frequently overlooked because they are rare, estimated to cover only a tenth of 1% of the ocean floor.
“They are the forgotten ecosystem,” says Ronald Jumeau, the Seychelles ambassador for climate change.
Nevertheless, seagrasses are far less protected than other offshore areas. Only 26% of recorded seagrass meadows fall within marine protected areas, compared with 40% of coral reefs and 43% of the world’s mangroves.
The Saya de Malha Bank is so existentially crucial to the planet because it is one of the world’s biggest seagrass meadows and thus carbon sinks. Much like trees on land, seagrass absorbs carbon dioxide from the atmosphere and stores it in its roots and soil.
But seagrass does it especially fast — at a rate 35 times that of tropical rainforest.
What makes the situation in the Saya de Malha Bank even more urgent is that it’s being systematically decimated by a multinational fleet of fishing ships that virtually no one tracks or polices.
Often described as the lungs of the ocean, seagrasses capture about a fifth of all its carbon and they are home to vast biodiversity. Seagrass also cleans polluted water and protects coastlines from erosion, according to a 2021 report by the University of California.
At a time when ocean acidification threatens the survival of the world’s coral reefs and the thousands of fish species that inhabit them, seagrasses reduce acidity by absorbing carbon through photosynthesis, and provide shelters, nurseries and feeding grounds for thousands of species, including endangered animals such as dugongs, sharks and seahorses.
But the Saya de Malha is under threat. More than 200 distant-water vessels — most of them from Sri Lanka and Taiwan — have parked in the deeper waters along the edge of the Bank.
Ocean conservationists say that efforts to conserve the Bank’s seagrass are not moving fast enough to make a difference. “It’s like walking north on a southbound train,” says Heidi Weiskel, Acting Head of Global Ocean Team for the International Union for Conservation of Nature (IUCN).
In May 2022, the United Nations General Assembly adopted a resolution to declare 1 March as World Seagrass Day. The resolution was sponsored by Sri Lanka.
Speaking at the assembly, the permanent representative of Sri Lanka to the UN, Ambassador Mohan Pieris, said seagrasses were “one of the most valuable marine ecosystems on earth”, highlighting, among other things, their outsized contribution to carbon sequestration.
But recognition is one thing; action is another. As the ambassador gave his speech in New York, dozens of ships from his country’s fishing fleet were 14,000 km away, busily scraping the biggest of those very ecosystems he was calling on the world to protect.
The Saya de Malha Bank has also emerged as an attractive target for the mining industry that argues that the ocean floor is an essential frontier for rare-earth metals needed in the batteries used in cell phones and laptops.
Vacuuming up the treasured nodules of rare-earths requires extraction by massive excavators. Typically 30 times the weight of regular bulldozers, these machines drive along the sea floor, suctioning up the rocks, crushing them, and sending a slurry of pulverised nodules and seabed sediments through a series of pipes to a vessel above.
After separating out the minerals, the mining ships then pipe back overboard the processed waters, sediment and mining “fines”, which are small particles of ground-up nodule ore.
Most of the Bank is too shallow to be a likely candidate for such mining, but cobalt deposits were found in the Mascarene Basin, an area that includes the Saya de Malha Bank, in 1987.
South Korea holds a contract from the International Seabed Authority, the international agency that regulates seabed mining, to explore hydrothermal vents on the Central Indian Ridge, about 400 km east of Saya de Malha, until 2029. India and Germany also hold exploration contracts for an area about 1,200 km southeast of the Saya de Malha Bank.
All of this activity could be disastrous for the Bank’s ecosystem, according to ocean researchers.
Mining and exploration activity will raise sediments from the ocean floor, reducing the seagrass’s access to the sunlight it depends on.
Sediment clouds from mining can travel hundreds or even thousands of kilometres, potentially disrupting the entire mid-water food web and affecting important species such as tuna.
The ocean floor itself is also slow to recover from mining activity.
In 2022, scientists found that tracks were still visible from a deep-seabed mining test that had been completed off the coast of Charleston in South Carolina, half a century ago, according to a report by the Post and Courier newspaper in the United States.
The areas between the tracks were devoid of fish and sponges. Research published in 2023 found that a year after test seabed mining disturbed the ocean floor in Japanese waters, the density of fish, crustaceans and jellyfish in nearby areas was cut in half.
Proponents of deep seabed mining stress a growing need for these resources. In 2020, the World Bank estimated that the global production of minerals like cobalt and lithium would have to be increased by over 450% by 2050 to meet the growing demand for clean energy technology.
However, critics of the industry say that due to the long transport distances and corrosive and unpredictable conditions at sea, the cost of mining nodules offshore will far outstrip the price of doing so on land.
Other critics contend that technology is changing so quickly that the batteries used in the near future will be different from those that are used now.
Better product design, recycling and reuse of metals already in circulation, urban mining and other “circular economy” initiatives can vastly reduce the need for new sources of metals, says Matthew Gianni, co-founder of the Deep Sea Conservation Coalition.
More recently, though, The Metals Company, the largest seabed mining stakeholder, has shifted away from arguing about batteries and instead claimed that the metals are needed for missiles and military purposes.
The Deep Sea Conservation Coalition, a group of nongovernmental organisations and policy institutes working to protect the deep sea, reports that over 30 countries have called for a moratorium or a precautionary pause on deep-seabed mining due to growing global opposition to this type of mining.
Still, government officials in Mauritius and Seychelles seem to be eager to take advantage of the financial opportunity that seabed mining appears to represent. In September 2024, the countries agreed to a deal to initiate oil exploration in and around the Saya de Malha Bank, a region they jointly manage.
In 2021, Greenpeace, a member of the conservation coalition, chose the Saya de Malha Bank as the location for the first ever underwater protest of deep-seabed mining.
As part of that protest, Shaama Sandooyea, a 24-year-old marine biologist from Mauritius, dove into the Bank’s shallow waters with a sign reading “Youth Strike for Climate”.
She had a simple point to make: The pursuit of minerals from the seafloor, without understanding the consequences, was not the route to a green transition. She said:
“Seagrasses have been underestimated for a long time now.”
This article, published by The Journal Investigates, is by Ian Urbina, Maya Martin, Joe Galvin, Susan Ryan and Austin Brush – Editors at The Outlaw Ocean Project.
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