Scientists have discovered almost 12,000 viruses hidden in a remote stretch of the Pacific seabed, 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 between Mexico and Hawaii.
Although the deep-sea bugs are not thought to pose a risk to human health, the revelation highlights how little is known about underwater ecosystems, which are under threat from the mining of valuable metals. Most of the viruses belong to the class Caudoviricetes, known as tailed and head-tail viruses, which infect bacteria.
Hidden world beneath the Pacific
The Clarion-Clipperton Zone lies at depths of up to 6,000 metres and is scattered with millions of potato-sized, metal-rich rocks known as polymetallic nodules. These contain metals such as cobalt, nickel and manganese, sought after to meet demand for electric vehicle batteries. The zone is the world's largest deep-sea mineral exploration region.
To investigate its hidden viral communities, researchers analysed more than 60 seabed sediment samples collected by the China Ocean Mineral Resources R&D Association.
Distinctive viral communities
“Protein-sharing network and phylogenetic analyses showed extensive benthic viral diversity, with over 99 percent of viral clusters not represented in current reference databases,” the Chongqing University team wrote in the study paper. Further genetic comparisons found that just 4% of the viruses' protein clusters matched those in global databases, underlining how distinctive these communities are.
Despite the darkness, scarce nutrients and toxic heavy metals, the seabed supports complex microbial communities. Viruses help regulate microbes that drive essential cycles involving carbon, nitrogen, phosphorus, sulphur and metals. By infecting their hosts, viruses can help release nutrients that other organisms need. Some also carry genes that support microbial metabolism, while viral gene exchange can help microbes adapt to metal toxicity.
What mining could put at risk
The concern is that industrial mining could disturb these biological networks by churning up the seabed and creating sediment plumes. Disruption to host microbes could, in turn, interfere with the nutrient cycles they support. These are potential risks, not evidence that commercial mining has already damaged the viral communities identified in the study.
The International Seabed Authority has granted 17 exploration licences in the zone, five of them held by China. Exploration licences are not the same as permission to begin commercial mining. The findings provide a baseline for understanding this largely unseen ecosystem before potential mining disturbance - and highlight why scientists want its viral networks mapped before commercial extraction begins.
