Machines extracting minerals from the deep ocean cause significant damage to life on the seabed, new research shows. Scientists have conducted the largest study of its kind and documented the effects.
They found that the number of animals in the machines’ tracks dropped by 37% compared with untouched areas. Researchers discovered over 4,000 animals, 90% of which were new species, in a remote part of the Pacific Ocean.
Huge amounts of critical minerals for green technologies may lie in the deep ocean. Still, deep-sea mining in international waters remains controversial and is not allowed until its environmental impacts are fully understood.
Independent study commissioned by industry
Scientists from the Natural History Museum in London, the UK National Oceanography Centre, and the University of Gothenburg carried out the research. They worked at the request of the deep-sea mining company The Metals Company. The researchers emphasized that their work remained independent. The company could review the results before publication but could not alter them.
The team compared biodiversity two years before and two months after test mining, during which machines drove 80 kilometers across the seabed. They studied animals between 0.3 mm and 2 cm, including worms, sea spiders, snails, and clams.
In the tracks of the machines, the number of animals fell by 37%, and species diversity dropped by 32%.
“The machine removes the top five centimeters of sediment. Most animals live there. Remove the sediment, and you remove the animals,” said Eva Stewart, a PhD student at the Natural History Museum and the University of Southampton.
“Even if animals are not killed directly, pollution from mining could slowly kill less resilient species,” added Dr. Guadalupe Bribiesca-Contreras from the National Oceanography Centre. Some animals may have moved away, but whether they return remains uncertain.
In areas near the machine tracks where sediment clouds settled, animal abundance did not decrease. “We expected stronger impacts but saw only shifts in which species dominated,” said Dr. Adrian Glover from the Natural History Museum.
A spokesperson for The Metals Company described the results as encouraging. They said the data showed that biodiversity impacts are limited to directly mined areas and do not spread far.
Experts warn against large-scale mining
Other specialists expressed concern. “The study shows current technologies for deep-sea mining are too damaging for large-scale commercial operations,” said Dr. Patrick Schröder from the Environment and Society Centre at Chatham House. “These were only tests, yet the impacts were significant. Industrial-scale mining would cause even more damage.”
Deep-sea mining remains highly controversial. The latest research took place in the Clarion-Clipperton Zone, a 6 million-square-kilometer region of the Pacific Ocean. Experts estimate it contains more than 21 billion tons of polymetallic nodules rich in nickel, cobalt, and copper.
The world needs these minerals for renewable energy technologies. They are essential for solar panels, wind turbines, and electric vehicles. The International Energy Agency predicts demand for these minerals could at least double by 2040.
