The sediment waste from deep-sea mining could potentially displace or kill the small ocean organisms that are foundational to the marine food web, a new study finds.
The study, published in the journal Nature Communications, is the first to examine the wastewater discharges of seabed mining, where vacuum-like submersible vessels recover mineral-rich nodules from the ocean floor and bring them to ships on the surface.
Those “polymetallic nodules” are separated from water and sediment, which is returned to the ocean at depths between 1,000 and 3,000 meters below the surface.
But researchers sampling ocean water from discharge plumes during trials of seabed mining technology in 2022 found the practice is not benign at depths of 1,200 meters (4,000 feet) below sea level. Rather, the discharge created large sediment clouds in a strata of the ocean known to be rich in zooplankton, tiny organisms that are the first link in the marine food chain.
