Over five years and 160 days at sea, researchers pulled 4,350 animals from the deep Pacific seafloor and sorted them into 788 species. The vast majority had never been recorded by science. The collection site, a licensed exploration block called NORI-D in the Clarion-Clipperton Zone, sits four kilometers below the surface in a region where companies want to scrape up metal-rich nodules for battery production. A peer-reviewed study published in Nature Ecology and Evolution in early 2026 lays out the full species inventory and delivers a blunt finding: a single mining trial in the same area cut animal abundance by 37 percent.
A census of the abyss
The Clarion-Clipperton Zone, or CCZ, is a belt of abyssal plain stretching roughly 4.5 million square kilometers between Hawaii and Mexico. Its floor is carpeted with polymetallic nodules, potato-sized mineral lumps rich in cobalt, nickel, and manganese. Those metals are central to lithium-ion batteries and other green-energy technologies, which is why the International Seabed Authority (ISA), the United Nations body that governs mineral activities on the international seabed, has issued exploration contracts covering large swaths of the zone.
NORI-D is one of those contract areas, held by Nauru Ocean Resources Inc., a subsidiary of The Metals Company. The research team ran multiple expeditions there, collecting every macrofauna specimen larger than 0.3 millimeters from sediment and nodule surfaces. The result was the most detailed species-level census ever assembled for a single CCZ block: 788 species from a single licensed area, most of them new to science.
That number is striking not because deep-sea biologists expected the CCZ to be barren, but because previous sampling had been so sparse that no one could say with confidence how many species actually lived there. The new dataset replaces guesswork with a documented baseline.
Why the nodules matter biologically
Polymetallic nodules are not just geological curiosities. A separate peer-reviewed study in Scientific Reports established that they function as required habitat for portions of the abyssal epifauna in CCZ nodule fields. On a seafloor otherwise dominated by soft sediment, nodules provide the only hard substrate available for organisms that need something solid to anchor to, feed from, or reproduce on.
One concrete example is the hard coral Deltocyathus zoometallicus, formally described by researchers at the National Oceanography Centre in the United Kingdom. The coral was found growing directly on polymetallic nodules in the CCZ, making it entirely dependent on the very objects that mining operations would vacuum off the seafloor. Its existence puts a name and a face on a broader pattern: many of the 788 documented species are not spread evenly across the mud but clustered around nodules and other hard structures. Remove the nodules, and you remove the foundation of the community.
Nodule formation is measured in millions of years. From any practical human or regulatory standpoint, a nodule field that has been harvested is a nodule field that is gone.
What a single mining trial did
In 2022, The Metals Company conducted a collector test in the NORI-D block, dragging a prototype mining vehicle across a patch of seafloor. Post-test surveys by the research team recorded a 37 percent reduction in macrofaunal abundance at the disturbed site. For an ecosystem where organisms grow slowly, reproduce infrequently, and colonize new ground over centuries or millennia, losing more than a third of the animals in a single pass is a severe shock.
That figure comes with important caveats. The specific monitoring methodology, sample sizes at each time point, and confidence intervals are detailed in the full Nature Ecology and Evolution paper rather than in press summaries. No publicly available peer-reviewed follow-up has yet established whether the decline persists for years, decades, or longer. And no long-term recovery data from any deep-sea mining trial, anywhere in the world, has been published as of mid-2026. The 37 percent number is not part of a trend line. It is a single data point from an early-stage industrial experiment, and it is the best data point anyone has.
What scientists still do not know
The gaps in the evidence are nearly as important as the findings. Many of the 788 species identifications rely on morphological sorting rather than full DNA-based taxonomic work. Genetic analysis sometimes splits one apparent species into several, pushing counts higher, but it can also merge superficially different specimens into one. Until more molecular data are available, 788 should be read as a well-supported estimate, not a final inventory.
The ecological roles of most newly recorded species remain poorly understood. Researchers know that sponges, worms, crustaceans, and corals attach to nodules, but how those organisms fit into broader abyssal food webs, whether they serve as prey for mobile predators or drive nutrient cycling, has not been established in published work. For Deltocyathus zoometallicus, no peer-reviewed study has modeled population viability under different mining scenarios. The same is true for the rest of the NORI-D assemblage: reproductive strategies, dispersal distances, and tolerance to disturbance are largely inferred rather than measured.
Then there is the question of scale. A prototype collector disturbing a small patch of seafloor is not the same as a commercial operation running for decades across thousands of square kilometers. Sediment plumes kicked up by collectors could travel tens of kilometers before settling, potentially smothering filter feeders and altering water-column chemistry far from the mining tracks. Quantitative data on plume spread, particle size, and biological responses in the CCZ remain scarce. Without those measurements, extrapolating from one test to a full industrial campaign is guesswork.
A rich ecosystem on the edge of an industrial decision
The ISA has been working for years on a regulatory framework, known as the Mining Code, that would govern commercial extraction of nodules from the international seabed. Negotiations have repeatedly stalled over environmental concerns, and as of June 2026 no final code has been adopted. Meanwhile, The Metals Company has signaled its intent to begin commercial-scale collection, and several Pacific Island nations that sponsor exploration contracts are weighing the economic benefits against ecological risk.
What the Nature Ecology and Evolution study adds to that debate is not a policy prescription but a factual foundation. The CCZ is not an empty plain waiting to be harvested. It supports a complex, largely undescribed community of animals whose existence depends on the same nodules the industry wants to extract. A single, limited disturbance test cut animal numbers by more than a third, and no evidence exists to show that recovery is possible on any timeline relevant to human decision-making.
For regulators weighing whether to green-light large-scale mining, the research offers no blueprint for safe exploitation. It offers something more uncomfortable: documented proof that the seafloor holds far more life than anyone had cataloged, that much of it is found nowhere else, and that the first attempt to mine it did measurable damage whose permanence no one can yet rule out.
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*This article was researched with the help of AI, with human editors creating the final content.
