Of 11,742 viruses found in a Pacific mining zone, 99% were new to science

Sediment cores lifted from the floor of the Clarion-Clipperton Zone in 2023 and 2024 contained 11,742 distinct viruses, and 99% of them had never been documented before. The count comes from a Nature Communications paper by Bowen Hou and Lilan Zhang of Chongqing University and Dong Sung of China’s Second Institute of Oceanography.

The zone is the stretch of Pacific abyss between Hawaii and Mexico where potato-sized nodules rich in cobalt, manganese, nickel, copper and zinc sit on the mud, and where governments and companies hold licenses to explore for ways to collect them. The viruses were catalogued before commercial collection has begun.

Sediment cores and the sequencing

According to ScienceAlert’s report on the paper, the team collected sediment cores in the polymetallic nodule fields and extracted both DNA and RNA for sequencing, so that viruses with either kind of genome could be counted. From those reads came the 11,742 distinct viruses, of which the authors judged 99% to be previously undocumented species.

The 99% figure is a statement about a reference library as much as about the sea floor. A virus counts as new only when its sequence fails to match anything already deposited, and deep abyssal mud has barely been sampled for viruses, so a near-total miss rate says the library is thin here rather than that the zone harbors some separate viral world. The authors describe the work as “a vital pre-mining baseline of microbial ecosystem for future environmental impact assessments.”

Extracting both nucleic acids matters because the two virus types cannot be caught with one net: DNA viruses show up in a DNA library, while RNA viruses, which carry no DNA at all, are invisible to it. Counting 11,742 distinct viruses across both is a deliberate attempt at breadth, and it is the reason the total runs into five figures from mud alone.

Nature Communications published the work in October 2026.

Seventeen contracts in one zone

The setting explains why a baseline matters. The International Seabed Authority, the body that regulates mineral activity on the international seabed, has granted exploration contracts for nodules, sulphides and crusts. ScienceAlert puts the total at 31 and says 17 of them are in the Clarion-Clipperton Zone, five of those held by China. The authority’s own exploration contracts page now lists 32 contracts with 22 contractors, and confirms that 17 of its 19 nodule contracts sit in this one zone.

The region is huge, roughly six million square kilometers by the figure Mongabay gives, and it is already a case study in how little of the deep is known. A checklist covered by Scientific American counted 5,580 animal species there, 5,142 of them unknown to science, and a team writing in ZooKeys described 24 new amphipod species and a new superfamily, with University of Lodz taxonomist Anna Jażdżewska saying more than 90% of the zone’s species are still unidentified.

The commercial clock is running. Mongabay reports that the U.S. National Oceanic and Atmospheric Administration finalized a rule in January allowing simultaneous applications for exploration licenses and commercial recovery permits, and that The Metals Company has filed a consolidated application covering about 65,000 square kilometers, roughly twice the area of Belgium. Scientific American, separately, noted that the seabed authority was set to begin accepting mining applications in July. Mining at commercial scale has not started, which is exactly the window a baseline survey needs.

Viruses as hosts’ metabolic switchboard

Viruses in sediment are active participants, not passengers. The authors write that they “may modulate host metabolism and survival during infection,” with “potential implications for biogeochemical processes in polymetallic nodule field sediments.” Their analysis tied the viruses to bacterial and archaeal hosts, the microbes that process carbon and other elements in the mud, so a virus that reshapes or kills a host can shift the chemistry around it.

In practice, a viral community acts as a brake and an accelerator on microbial life: infection can burst a cell and spill its contents back into the water, or can rewire the host’s metabolism for the virus’s benefit while the cell is still alive. The paper’s stated reason for cataloguing viruses in nodule sediments is to give future environmental impact assessments something to compare against.

ScienceAlert’s account describes no measurement of what mining would do to the viruses, and it makes no claim that they are at risk. The point is narrower: before collectors scrape the nodule fields, there is now a count of what lives in the sediment beneath them, 11,742 viruses at the starting line, nearly all of them unnamed.

An animal-side counterpart already exists. A study from December 2025, summarized by Mongabay, found that commercial mining tests in the zone reduced animal abundance by 37% inside the machine’s tracks and species diversity by 32%. No matching measurement for viruses appears in the coverage of this paper, which leaves the effect of a collector vehicle on the viral community at 11,742 unknowns.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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