Deep-sea mining holds the promise of vast mineral wealth, but a new study reveals a chilling consequence that could reverberate through ocean ecosystems: starvation. While seabed scraping disrupts deep-ocean life on the seafloor itself, shallower waters may be affected by sediment plumes released during mining. These plumes contain particles too similar in size to plankton’s usual food source—but critically lacking essential nutrients.
Plankton, microscopic organisms forming the base of the ocean food web, rely on organic matter drifting near the surface. They consume these small particles and are then eaten by larger creatures like fish and whales. A team led by oceanographer Michael Dowd from the University of Hawaii at Mānoa set out to understand how deep-sea mining could disrupt this delicate balance.
They traveled to the Clarion-Clipperton Zone in the Pacific, a region rich in polymetallic nodules—lumps of rock containing valuable metals like cobalt and copper. During their three expeditions, they collected plankton samples at depths between 800 and 1,500 meters. Analyzing these samples revealed that plankton preferentially consume particles around 6 micrometers wide.
A third trip coincided with a pilot mining operation conducted by The Metals Company. Here, the researchers collected sediment particles from within the plume created by mining equipment. These particles were alarmingly similar in size to the plankton’s usual food, but lacked crucial nutrients like protein. Essentially, they were “junk food” for these vital organisms.
This finding paints a disturbing picture: If widespread deep-sea mining takes place, sediment plumes could inundate vast areas where plankton reside. If these creatures replace nutritious organic matter with nutrient-poor mineral particles, they will likely suffer from starvation. This cascade effect would then impact the entire food web, potentially leaving larger predators vulnerable as well.
The study underscores that the environmental costs of deep-sea mining extend far beyond the immediate seafloor devastation. It highlights the crucial need for thorough ecological assessments and stringent regulations before this resource extraction industry scales up dramatically.
