Scientists test the impact of deep-sea mining on over a third of seabed animals

Recent research has revealed that mechanical mining operations in the deep ocean can severely disrupt life on the seabed. Scientists conducting the largest study of its kind discovered that the number of animals within the paths of mining vehicles dropped by 37% compared to untouched regions.

The team recorded over 4,000 seafloor animals in a remote area of the Pacific Ocean, with approximately 90% of these species previously unknown to science.

While the deep ocean holds vast reserves of minerals essential for green technology, mining in international waters remains controversial and is currently restricted until the environmental consequences are fully understood.

Research conducted by the Natural History Museum in London, the UK National Oceanography Centre, and the University of Gothenburg was initiated at the request of The Metals Company, a deep-sea mining firm. The scientists emphasized that their findings were independent; the company reviewed the data before publication but could not modify the results.

The study compared biodiversity levels two years prior to mining and two months after machines traveled 80 km along the seafloor. It focused on animals between 0.3 mm and 2 cm, including worms, sea spiders, snails, and clams. Within the machine tracks, species diversity fell by 32% in addition to the 37% decline in animal numbers.

"The machinery removes roughly the top five centimeters of sediment, which is home to most seafloor organisms. Naturally, removing this layer eliminates the animals living there," explained lead author Eva Stewart, a PhD student at the Natural History Museum and the University of Southampton.

Researchers also noted that mining-related pollution could gradually affect more fragile species, even if they survive the initial disturbance. Some animals may move away temporarily, but whether they return remains uncertain, according to Dr. Guadalupe Bribiesca-Contreras from the National Oceanography Centre.

Interestingly, areas surrounding the machine tracks, where displaced sediment settled, did not experience a reduction in animal numbers. "We observed changes in species dominance, but the overall abundance remained stable," said Dr. Adrian Glover, research scientist at the Natural History Museum.

A spokesperson for The Metals Company commented that the data suggested biodiversity impacts were largely confined to the mined areas and did not extend far beyond them.

However, some experts warn that these findings are not encouraging for commercial deep-sea mining. Dr. Patrick Schrder from Chatham House stated, "The tests demonstrate that current harvesting methods are too destructive for large-scale operations. Scaling this up would likely cause even greater damage."

The research was conducted in the Clarion-Clipperton Zone, a 6 million km area of the Pacific Ocean believed to contain over 21 billion tonnes of nickel, cobalt, and copper-rich polymetallic nodules. These minerals are critical for renewable energy technologies such as solar panels, wind turbines, and electric vehicles, with global demand projected to at least double by 2040.

Despite their importance, deep-sea mining raises serious environmental concerns. Scientists and environmental organizations caution that the largely unexplored ecosystems of the deep ocean could be irreversibly harmed before they are fully understood.

The International Seabed Authority, responsible for regulating activities in international waters, has yet to approve commercial mining, though 31 exploration licenses have been issued. Thirty-seven countries, including the UK and France, support a temporary ban on mining, and Norway recently delayed its plans for Arctic operations. Conversely, some initiatives in the US aim to accelerate mineral extraction for strategic purposes.

If current mining methods are deemed excessively harmful, companies may pursue less invasive techniques for extracting nodules. The study is published in Nature Ecology & Evolution.

Author: Harper Simmons