Machines mining minerals in the deep ocean have been found to cause significant damage to life on the seabed, scientists carrying out the largest study of its kind say.
They found that the number of animals found in the tracks of the vehicles was reduced by 37% compared to untouched areas.
The researchers found more than 4,000 animals, 90% of which were new species, living on the seafloor in a remote area of the Pacific Ocean.
Vast amounts of critical minerals needed for green technologies could be locked in the deep ocean, but deep-sea mining in international waters is very controversial and currently not permitted until more is known about the environmental impacts.
The research by scientists at the Natural History Museum in London, the UK National Oceanography Centre and the University of Gothenburg was conducted at the request of deep-sea mining company The Metals Company. The scientists said their work was independent, and the company was able to view the results before publication but was not allowed to alter them.
The team compared biodiversity two years before and two months after the test mining that drove machines for 80km on the seafloor. They looked specifically at animals 0.3mm – 2cm in size, such as worms, sea spiders, snails, and clams. In the tracks of the vehicle, the number of animals fell by 37% and the diversity of species by 32%.
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.
Although some animals may move away, it is uncertain if they will return after disturbances. The study found that in areas near the vehicle tracks, where clouds of sediment landed, the abundance of animals did not decrease, presenting a complex picture of the ecological impact.
Dr. Adrian Glover, a research scientist at the Natural History Museum, suggested that while they expected more significant impacts, the data showed mostly shifts in species dominance rather than overall reductions in animal numbers.
The spokesperson for The Metals Company expressed encouragement by the findings, stating that concerns over biodiversity impacts had been mostly unfounded. Conversely, some experts argue that the current mining methods are too destructive for large-scale commercial exploration.
Deep-sea mining is controversial, particularly in the Clarion-Clipperton Zone, a vast area of the Pacific Ocean thought to contain significant reserves of nickel, cobalt, and copper-rich minerals. The necessity for these materials to support renewable energy technologies puts additional pressure on decision-making surrounding oceanic mining.
The International Seabed Authority has yet to approve commercial mining, although exploration licenses have been granted. Meanwhile, some nations advocate for a temporary ban on mining, amid fears of ecological degradation before fully understanding marine biodiversity.
In conclusion, while deep-sea mining could provide vital resources for our transition to renewable energy, its implications on marine ecosystems cannot be overlooked, underscoring the urgent need for sustainable practices.
