A single pass of a nodule-collecting machine across the Pacific seafloor wiped out more than a third of the animals living in its path, according to a peer-reviewed study published in Nature Ecology & Evolution that provides the first direct measurement of biodiversity loss from an industrial-scale deep-sea mining system.
The research, which drew international attention when it appeared in May 2025, documents what happened after a tracked collector vehicle vacuumed polymetallic nodules from the abyssal plain of the Clarion-Clipperton Zone, a vast stretch of ocean floor between Hawaii and Mexico that sits more than 4,000 meters below the surface. Within the machine’s tracks, macrofaunal density dropped 37% and species richness fell 32%.
Those numbers now sit at the center of an intensifying global debate. The Metals Company, the Canadian-listed firm that operated the collector during an October 2022 trial, is pushing to become the first company to commercially extract nodules rich in nickel, cobalt, and manganese from international waters. Those metals are essential components of electric vehicle batteries and grid-scale energy storage, and demand projections continue to climb.
What the study found
Researchers used a Before-After-Control-Impact (BACI) design, comparing biological samples collected before and after the trial at both disturbed and undisturbed reference sites within the NORI-D contract area. BACI protocols control for natural background variation by measuring changes at both impacted and reference sites over the same period, making them well suited for isolating cause and effect in field ecology.
The team analyzed 4,350 individual organisms pulled from sediment cores, identifying species including polychaete worms, crustaceans, and mollusks that form the base of deep-sea food webs. For a deep-ocean study, where every sample requires expensive remotely operated vehicle deployments, that dataset carries unusual statistical weight.
“The results were stark,” said Travis Washburn, a deep-sea ecologist at the National Oceanography Centre and lead author of the study, in a statement released by the NOC. “We found a significant decrease in the abundance of animals and the number of species within the collector tracks.”
One finding complicated a straightforward narrative of destruction. In the sediment plume zone, the area adjacent to the tracks where fine particles settled after being churned up by the collector, overall animal abundance did not decline. But the composition of species shifted. Different organisms dominated the community after the disturbance, a change that could alter nutrient cycling, carbon storage, and food availability for larger deep-sea creatures.
The distinction matters: direct physical contact with the collector proved far more lethal than the secondary sediment cloud, at least over the timeframe the study captured.
Recovery is the unanswered question
The study documents immediate impact. It does not answer the question regulators and conservation scientists most urgently need resolved: how long will recovery take?
Life on the abyssal plain grows and reproduces at extraordinarily slow rates. Temperatures hover just above freezing, food drifts down from the sunlit surface in sparse, unpredictable pulses, and pressure exceeds 400 atmospheres. Previous research on disturbance at comparable depths, including studies of experimental plow tracks from the 1980s and 1990s, has found that biological communities showed incomplete recovery even after multiple decades. The authors of the new paper did not include quantitative recovery data, leaving the permanence of the measured losses an open question.
The plume zone findings carry their own uncertainties. A community with the same total number of animals but a reshuffled species roster may function very differently. Whether those compositional shifts persist, reverse, or deepen over time is unknown. And in a full commercial operation, sediment plumes would blanket areas orders of magnitude larger than those generated by a single trial run.
The commercial and regulatory backdrop
The Metals Company disclosed the collector trial in its annual report filed with the U.S. Securities and Exchange Commission for fiscal year 2022, describing the test as part of its path toward commercial production. SEC filings are legally accountable documents; material misstatements expose the company to liability. The filing confirms that this was not a small academic experiment but a trial of industrial equipment intended for scaled-up extraction.
Oversight of deep-sea mining in international waters falls to the International Seabed Authority, a United Nations body based in Kingston, Jamaica. The ISA has been negotiating a comprehensive mining code for years but has not finalized one. A self-imposed July 2023 deadline passed without agreement, and negotiations through 2024 and into 2025 have continued to stall over environmental standards, benefit-sharing with developing nations, and liability frameworks. Without a completed code, exploration contractors like The Metals Company operate under existing contracts that require environmental monitoring but lack clearly defined thresholds for acceptable harm or mechanisms to halt operations if damage exceeds expectations.
Meanwhile, a growing coalition of nations has called for a moratorium or precautionary pause on deep-sea mining. As of early 2025, more than 30 countries, including France, Germany, Canada, Brazil, and several Pacific Island states, had voiced support for slowing or stopping the process until more is known about ecological consequences. Major corporations including BMW, Volvo, Google, and Samsung SDI have also pledged to avoid using deep-sea minerals in their supply chains.
How the baseline shifts the burden of proof
The 37% and 32% figures are empirical measurements from a specific trial at a specific site. They do not automatically predict what would happen across the full 6-million-square-kilometer Clarion-Clipperton Zone under commercial mining. Environmental conditions, nodule density, and baseline biodiversity vary across the region, and different collector designs or operating speeds could produce different outcomes.
But the numbers do establish something that the debate has lacked until now: a concrete, peer-reviewed baseline for what a single collector pass does to the animals in its direct path. That baseline gives regulators a benchmark against which future mitigation claims can be tested. If a company argues that a redesigned collector or modified track layout reduces harm, the burden of proof now has a quantified starting point.
For investors evaluating The Metals Company, the documented biodiversity losses translate into regulatory risk, reputational exposure, and potential legal liability, particularly as the ISA mining code remains unfinished and international opposition grows. The company’s SEC filing discusses environmental risks in general terms, as publicly traded firms are required to do, but does not contain a specific response to the biodiversity findings published in the Nature study.
For policymakers weighing the promise of seabed minerals against the cost to ocean ecosystems, the study offers the most rigorous field data yet produced. It confirms that industrial collection equipment can substantially reduce both the abundance and diversity of life on the seafloor in a single pass, while leaving subtler but still measurable changes in surrounding areas. It also makes plain how much remains unknown: long-term recovery trajectories, cumulative effects of repeated mining over large areas, and whether any regulatory framework can adequately manage the risks. Those gaps will not close quickly. The abyssal plain does nothing quickly.
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*This article was researched with the help of AI, with human editors creating the final content.
