Riches of the seabed: exploiting a remote ecosystem


Today, billions of tons of these nodules cover large swathes of the ocean floor, several kilometers below the surface.

A field of nodules in the Clarion-Clipperton area.GEOMAR

One of the largest areas is the Clarion-Clipperton area, which covers 1.7 million miles of the Pacific seabed and contains extensive nodule fields.

Territorial waters,

200 nautical miles

from the shore

Territorial waters,

200 nautical miles

from the shore

Territorial waters,

200 nautical miles

from the shore

Source: International Seabed Authority

Life among the nodules

Polymetallic nodules are an anchor for a fragile, slow-growing ecosystem that includes species found nowhere else on Earth.

For creatures that cannot swim easily, nodes are islands on which to settle and build a life. The muddy seabed is too soft to be a home for them.

Glass sponges are the most common sponges in the Clarion-Clipperton area. They can live for thousands of years and provide important habitats for other creatures. They are living archives, recording the ancient climate of the deep sea in their skeletons, like tree rings.

Several glass sponges grow on top of each other, including a brown vase-shaped sponge from the genus Oopsacas and a white sponge from the family Euplectellidae.GEOMAR

Other species float and swim above the nodule fields.

An unidentified species of jellyfish.GEOMAR

This waving squid – which is a worm, not a squid – hovers above the nodules, settling only to feed.

A squid uses its tentacle-like appendages to collect marine snow, organic particles falling from the top layer of the ocean.Craig Smith, DeepCCZ project

Carnivorous sponges attached to nodules catch small crustaceans which scurry nearby.

Two carnivorous sponges. On the left, a species of the genus Cladorhiza. On the right, a ping-pong tree sponge of the genus Chondrocladia, which uses hooks to capture its prey.Craig Smith, DeepCCZ project

Some creatures even live in the crevices of nodules, like this pearly worm.

Photograph of a polychaete worm living in a nodular crevice.

A worm has buried itself in a nodule.AG Glover, H. Wiklund, TG Dahlgren, MJ Brasier

Many of the species discovered so far in the Clarion-Clipperton area are found only on the nodules themselves. If the nodules disappear, they will also disappear.

Photograph of a polychaete worm.

The polychaete worm Neanthes goodayi, new to science, lives among the nodules.AG Glover, H. Wiklund, TG Dahlgren, MJ Brasier

Harvest nodules

Mining companies describe the nodules as a “battery in rock” because they contain the metals essential to a clean energy economy that relies on batteries and electric vehicles.

The Clarion-Clipperton area is in international waters and is overseen by the International Seabed Authority. Large areas have been set aside for mining by different countries, but commercial exploitation has not yet started.

Two species of deep-sea holothurians, one sitting and one swimming.GEOMAR

The actual mining operation is simple: dredge or vacuum nodules from muddy sediment. But removing the nodules destroys everything living on them.

Scientists take a sample of the Antipatharia black coral.GEOMAR

Mining the seabed also raises grainy plumes that can travel up to five miles. These sediment clouds can bury nodule fields, smother the filters of sponges and anemones living outside the mining area, and obscure the bioluminescence that squid and fish use to hunt and mate.

A cloud of fine sediment rising from the seabed, caused by a remotely operated vehicle. A mining head – several times bigger and faster – could create a bigger cloud. (Engineers are looking for ways to limit the size of the plumes.)Craig Smith, DeepCCZ project

Without nodules, many of these species will not be able to relocate to disturbed seabeds. And with very little natural water movement, these deep dredge scars can linger for decades.

A Dumbo octopus floats above a gouge in the seabed.GEOMAR

After eight months, the edges and grooves of a Belgian dredge scar are still sharp.

The Belgian part of the Clarion-Clipperton zone.ROV Team Kiel 6000, GEOMAR

After 37 years, a French dredge scar is softened but still bare.

The French section of the Clarion-Clipperton zone.GEOMAR

Divide the seabed

The Clarion-Clipperton zone is currently divided into 16 exploration zones controlled by different countries, including zones reserved for some of the world’s least developed countries. Other exploration areas have been designated in the Atlantic Ocean and the Western Pacific.

Researchers descend a vehicle to study the seabed.GEOMAR

The metals found in the nodules can be mined from the ground, but some of these mines are riddled with human rights abuses. Land-based mining also has a heavy environmental cost: forest clearing, air contamination, water pollution and threat to biodiversity.

Deep-sea mining of the world’s largest habitat – and the little-known species that inhabit it – could begin in earnest as early as 2024.


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