Manganese nodules: “We are on the eve of the largest deep-sea mining operations”

Whet out in the Pacific, 2,000 kilometers off the coast of Mexico, 4,000 meters below sea level, lies a region that makes the hearts of many people beat faster – albeit for very different reasons: the Clarion Clipperton Zone (CCZ), an area twice the size of India. Some regard it as an almost untouched natural paradise in which such fascinating creatures as deep-sea octopuses and ghost octopuses, carnivorous sponges and brittle stars cavort. The others see it as a hoard for raw materials from the deep sea.

The so-called manganese nodules lie on the ground. Black fist-sized rocks scattered over thousands of square kilometers. They contain nickel, cobalt and copper, and thus the raw materials for batteries in electric cars, wind turbines and solar systems. The metal contents of the nodules are twice as high as in deposits on land; that makes them particularly popular. So far they have not been raised, but that could change soon – with possibly devastating consequences for life in the depths. Researchers from the Natural History Museum in London are now making it clear in the specialist journal Current Biology what is at stake as a result of the mining.

The team led by marine ecologist Muriel Rabon has published a CCZ checklist in which they have compiled all species that have so far been registered on research expeditions in the Pacific region: 5578 different plants and animals, fungi and bacteria. 92 percent of them are considered completely new to science, more than 99 percent occur exclusively there because of the extreme living conditions. You will find most shrimp there, crayfish and other arthropods, but also echinoderms like sea urchins and sponges. For their analysis, the researchers evaluated more than 100,000 entries in seven different databases. They estimate that up to 8,000 unknown species are still slumbering undiscovered in the depths.

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“We find new species in every single sample from the sea floor,” reports Rabon. For them, the diversity of the sponges living there is “overwhelming”. Some resembled a classic bath sponge, others a vase, others a tiny chandelier. So far, however, it is completely unclear how all these species are connected to their environment – and what would happen if they disappeared. Because that could soon become a reality.

On July 9, a deadline will expire by which the International Deep-Sea Bed Authority had committed itself to drawing up binding regulations for industrial mining on the sea bed. According to this, countries are allowed to submit applications to commercially mine raw materials in the deep sea, even without clear rules. One of the first applicants could be the small Pacific state of Nauru, which is backed by the Canadian company The Metals Company (TMC). In autumn 2022, the group carried out the first industrial tests with its collectors. The tracked vehicles, larger than a Leopard 2 tank, suck up the nodules along with the seabed and pump them up onto a ship; the sediments are washed back into the sea. There are currently 17 exploration licenses in the zone, and Germany also holds one. TMC itself calls the nodules a “battery in a rock,” the “cleanest path to electric vehicles.”

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Studies show, however, that this route is not that “clean”. Experts warn that deep-sea mining would cause enormous environmental damage; including Matthias Haeckel, biogeochemist at the Helmholtz Center for Ocean Research in Kiel. He explains: “Much larger areas would be destroyed than on land, and regeneration would take much longer.” The reason: Everything runs very slowly at depths of thousands of meters. Only one percent of the organic substances produced by the photosynthesis of the algae in the light-flooded zone in the top 200 meters reach the bottom. It would therefore take several hundred to thousands of years for new life to grow back.

“You can’t just breed the organisms,” says Haeckel. You would have to get them from the depths to land, but on the way up their cells would burst because the pressure difference was too great. From investigations into mining attempts that took place 20 to 40 years ago, he reports: “It still looks as if you drove through it just yesterday.” Experiments with artificial nodules, on the other hand, have shown that the earliest ten years after mining first new microbial biofilms could form. “But they are far from being an ecosystem,” says Haeckel. If there is no life at the bottom, this could in turn affect the entire sea. The nutrients for the water column above were gone, as were the larvae for the fish.

The London ecologists are also concerned: “We are on the eve of the largest deep-sea mining operations that may be permitted.” Only then, they make it clear, could the damage be kept within limits.

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