Study spotlights deep-sea mining’s impact on species

The largest study yet on the ecological impacts of deep-sea mining – commissioned by its leading proponent, The Metals Co. (Nasdaq: TMC) – has found a steep drop in seabed life during an industrial trial in the eastern Pacific, sharpening concerns over proposed nodule harvesting.

Scientists from the Natural History Museum in London, the University of Gothenburg in Sweden and the U.K.’s National Oceanography Centre tracked a mining vehicle over two years at 4,280 metres, using baseline data from 3,000 tonnes of disturbed polymetallic nodules.

The five-year project, built on more than 160 days at sea and three years of lab work, offers the most detailed picture to date of how mining reshapes deep-ocean ecosystems. Results published last week in Nature Ecology & Evolution show macrofaunal density falling 37% and species richness dropping 32% within the mined tracks.

“Being able to study these remote and poorly known deep-sea regions is extremely important as we consider the potential impacts of deep-sea mining,” said Eva Stewart, a Ph.D. student at the Museum and University of Southampton and lead author of the study.

“Finally, we have good data on what the impacts of a modern commercial deep-sea mining machine might be.”

New species

The study was requested by Nauru Ocean Resources (NORI), a wholly owned subsidiary of The Metals Company, which has been looking to mine the Clarion–Clipperton Zone (CCZ) – a 6-million-sq.-km area of the central Pacific Ocean.

Shares in The Metals Company gained more than 10% to $7.56 apiece on Thursday afternoon in New York, valuing the company at $3.13 billion. The stock has surged from about $1 each in January as the Trump administration has moved to ease the path for deep sea mining and international bodies haven’t agreed on terms to regulate it. 

Stewart and other authors also noted that the expedition yielded discoveries, including a new species of marine animal (a solitaire coral) and how the abyssal ecosystem can naturally change over time.

A total of 4,350 sediment macrofaunal animals were collected across four expeditions, from which 788 species were identified by the collective efforts of the institutions involved in the study. The animals found were mainly marine worms (polychaete annelids), closely followed by crustaceans (isopods, tanaids, amphipods) and molluscs such as snails and clams.

Given that most of the animals were macrofaunal organisms living in sediment, it remains to be seen how deep-sea mining would impact other types of marine life. Still, the study points to a potentially large disturbance of the ecosystem based on its tracking on nodule-living animals alone.

Concerns 

The study results cast further doubts on whether mining the ocean floor presents a viable option to expand the global quest to extract critical minerals such as cobalt, nickel and rare earths, which are found in abundance in polymetallic nodules. The CCZ alone is estimated to hold over 21 billion tonnes of these minerals.

Greenpeace, an environmental organization that has long fought against the idea of deep-sea mining and companies like The Metals Co., said the study serves as further scientific evidence of the significant damage mining activities can have on the ocean ecosystem.

“A test with machines only half the size of those intended to be used reduced the number of animals found in the tracks by 37%. Deep-sea mining will devastate the unique and newly discovered marine creatures in the high seas,” Greenpeace said.

“We are just beginning to understand this deep-sea ecosystem, and yet the overwhelming evidence continues to point to the fact that deep-sea mining will cause irreversible harm.”