Deep-sea mining operations have been found to cause significant damage to seabed life, according to scientists conducting the largest study of its kind.
Researchers found that the number of animals in the paths of mining vehicles was reduced by 37% compared to undisturbed areas.
The study, conducted in a remote area of the Pacific Ocean, identified over 4,000 animals on the seafloor, with 90% being new species.
The deep ocean holds vast reserves of critical minerals essential for green technologies, but deep-sea mining in international waters remains controversial and is currently restricted pending further research into its environmental impact.
The research was carried out by scientists from the Natural History Museum in London, the UK National Oceanography Centre, and the University of Gothenburg, at the request of deep-sea mining company The Metals Company.
The scientists affirmed that their work was independent, and while the company had access to the results before publication, they were not permitted to alter them.
The team compared biodiversity levels two years before and two months after a test mining operation, which involved driving machines across 80km of seafloor.
Their analysis focused on animals ranging from 0.3mm to 2cm in size, including worms, sea spiders, snails, and clams.
The study revealed a 37% decrease in the number of animals and a 32% reduction in species diversity within the vehicle tracks.
“The machine removes about the top five centimetres of sediment. That’s where most of the animals live. So obviously, if you’re removing the sediment, you’re removing the animals in it too,” lead author Eva Stewart, PhD student at the Natural History Museum and the University of Southampton, told BBC News.
“Even if they are not killed by the machine, pollution from the mining operations could slowly kill some less resilient species,” said Dr Guadalupe Bribiesca-Contreras from the National Oceanography Centre.
While some animals may have relocated, Dr. Bribiesca-Contreras added, “whether or not they come back after disturbance is a different question”.
However, in areas adjacent to the vehicle tracks where sediment plumes settled, no decrease in animal abundance was observed.
“We were expecting possibly a bit more impact, but [we didn’t] see much, just a shift in which species were dominant over others,” Dr Adrian Glover, research scientist at the Natural History Museum, told BBC News.
“We’re encouraged by these data,” a spokesperson for The Metals Company told BBC News.
“After years of activist alarm that our impacts would spread thousands of kilometers beyond the mine site, the data show that any biodiversity impacts are limited to the directly mined area,” they added.
However, some experts believe the findings may not be positive for mining companies.
“I think the study shows that current technologies for harvesting are too damaging to permit large-scale commercial exploration,” Dr Patrick Schröder, senior research fellow at the Environment and Society Centre at think tank Chatham House, told BBC News.
“These were only tests and the impact was significant. If they did that at large scale, it would be even more damaging,” he added.
Deep-sea mining is a contentious issue, centered around a fundamental dilemma.
The recent research was conducted in the Clarion-Clipperton Zone, a 6 million sq km area of the Pacific Ocean estimated to contain over 21 billion tonnes of polymetallic nodules rich in nickel, cobalt, and copper.
These critical minerals are essential for renewable energy technologies needed to combat climate change, serving as key components in solar panels, wind turbines, and electric vehicles.
The International Energy Agency projects that demand for these minerals could at least double by 2040.
While these minerals must be sourced, many scientists and environmental groups are deeply concerned about the potential for irreversible damage from deep-sea mining.
Concerns are rising that the unique biodiversity of the largely unexplored deep ocean could be jeopardized before it is fully understood.
Oceans play a crucial role in regulating the planet’s climate and are already significantly threatened by rising temperatures.
The International Seabed Authority (ISA), which oversees activities in international waters, has not yet authorized commercial mining but has issued 31 exploration licenses.
To date, 37 countries, including the UK and France, support a temporary ban on deep-sea mining.
This week, Norway postponed mining plans in its waters, including the Arctic.
However, in April, former US President Donald Trump advocated for the expedited approval of domestic and international projects to secure mineral supplies for weapons production.
If the ISA concludes that current mining methods are excessively destructive, companies may seek to develop less disruptive techniques for extracting nodules from the seafloor.
The research is published in the scientific journal Nature Ecology and Evolution.
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