Scientists have uncovered nearly 12,000 viruses lurking in a remote stretch of the Pacific Ocean floor, with more than 99% previously unknown to science. Researchers from Chongqing University in China identified 11,662 new microbes in the Clarion-Clipperton Zone, a vast deep-sea region situated between Mexico and Hawaii.
While the deep-sea organisms are not believed to pose any threat to human health, the discovery highlights just how little we understand about underwater ecosystems, which face increasing danger from the extraction of precious metals. The majority of viruses belong to the class Caudoviricetes, commonly known as tailed and head-tail viruses, which target and infect bacteria.
A hidden world beneath the Pacific
The Clarion-Clipperton Zone plunges to depths of up to 6,000 metres and is littered with millions of potato-sized, metal-rich rocks referred to as polymetallic nodules. These rocks contain valuable metals such as cobalt, nickel and manganese, which are highly sought after to satisfy the growing demand for electric vehicle batteries. The zone holds the distinction of being the world's largest deep-sea mineral exploration region.
To examine its concealed viral communities, researchers studied more than 60 seabed sediment samples gathered by the China Ocean Mineral Resources R&D Association. The Chongqing University team wrote in the study paper: "Protein-sharing network and phylogenetic analyses showed extensive benthic viral diversity, with over 99 per cent of viral clusters not represented in current reference databases."
Further genetic comparisons revealed that just 4% of the viruses' protein clusters matched those in global databases, highlighting just how unique these communities truly are.
Why the viruses matter
Despite the darkness, scarce nutrients and toxic heavy metals, the seabed supports complex microbial communities. Viruses play a crucial role in regulating microbes that drive essential cycles involving carbon, nitrogen, phosphorus, sulphur and metals. By infecting their hosts, viruses can help release nutrients that other organisms require.
Some also carry genes that bolster microbial metabolism, while viral gene exchange can help microbes adapt to metal toxicity. This makes these viruses far more than simply a catalogue of unfamiliar discoveries — they play a vital role in maintaining the ecosystem surrounding the nodule fields.
What mining could put at risk
The worry is that industrial mining could disturb these biological networks by churning up the seabed and generating sediment plumes. Disruption to host microbes could, in turn, interfere with the nutrient cycles they sustain. These remain potential risks, rather than evidence that commercial mining has already damaged the viral communities identified in the study.
The International Seabed Authority has issued 17 exploration licences in the area, with China holding five of them. Exploration licences differ from authorisation to commence commercial mining. The discoveries establish a foundation for comprehending this predominantly hidden ecosystem ahead of possible mining disruption - and underscore why scientists are calling for its viral networks to be charted before commercial extraction gets underway.
