Deep-Sea Mining Scars Persist 44 Years Later
A University of Liverpool-led study finds seafloor organic matter at a 1979 mining test site remains depleted decades on.
Updated on Nov. 3, 2026 in Environmental
Live Poll
Should deep-sea mining be restricted until its long-term environmental effects are better understood?
Researchers from the University of Liverpool report that effects of a 1979 deep-sea mining test on seafloor organic matter are still measurable 44 years later. The study, published in Elementa: Science of the Anthropocene, links the depleted matter to lower abundance of seafloor organisms at the site.
Why it matters
Interest in mining the deep sea for rare metals raises concern about effects on deep-ocean ecosystems. The findings suggest disturbances from mining may last for decades, underscoring the value of long-term monitoring.
The SMARTEX team sampled sediments over a month-long expedition at around 4,800 meters, comparing a site disturbed by a 100-tonne machine in 1979 with an undisturbed control. How the broader region's organic matter varies remains unknown.
The players
University of Liverpool
A public research university in England whose researchers led the study on deep-sea mining effects.
Ocean Minerals Company
The company that conducted the 1979 deep-sea mining test at the Clarion-Clipperton Zone site.
Natural Environment Research Council
The UK public funding body that supported the SMARTEX research project.
The details
Researchers measured particulate organic matter quantity and quality, using carbon and nitrogen content, lipid biomarkers, and stable isotope analysis. They found differences in composition and particle size at the historic site, along with lower abundance of larger animals and single-celled organisms in the mined sediments.
Timeline
1979: Ocean Minerals Company conducted the deep-sea mining test at the site.
2023: The SMARTEX team collected sediment samples at the site.
November 3, 2026: The study was published in Elementa: Science of the Anthropocene.
Seasonal Patterns
The SMARTEX project, funded by the UK Natural Environment Research Council, extends its sediment studies to a 1979 test site in the Clarion-Clipperton Zone. The work documents disturbance effects persisting across four decades on the deep seafloor.
The findings bear on how deep-sea mining could affect future marine ecosystems and the timelines needed to recover them. Pragmatic applications for mining regulation depend on further monitoring, which the authors call for.
The takeaway
Deep-sea disturbances can leave measurable marks on the seafloor for decades, so assessing mining impacts requires monitoring that extends well beyond the initial activity. Readers following ocean policy should watch how regulators weigh such long-term evidence.
Further reading
For broader context on ocean ecosystems and marine pollution, explore Environmental coverage.
Source note: This article includes information reported by Ocean News & Technology.
Live Poll
Should deep-sea mining be restricted until its long-term environmental effects are better understood?
