Deep-sea mining waste threatens life in ocean’s 'twilight zone,' study warns

ISTANBUL

Waste plumes from deep-sea mining in the Pacific Ocean could starve key marine life and unravel entire food webs in the ocean’s dim “twilight zone,” according to a groundbreaking study published Thursday in Nature Communications.

The study, led by researchers at the University of Hawai'i at Manoa's School of Ocean and Earth Science and Technology (SOEST), is the first to demonstrate how mining discharge—plumes of fine particles released into midwater during mineral extraction—endangers the food sources that sustain life between 200 and 1,500 meters below the surface.

“When the waste released by mining activity enters the ocean, it creates water as murky as the mud-filled Mississippi River,” said lead author Michael Dowd, an oceanography graduate student at UH Manoa. “Zooplankton’s exposure to junk food sediment has the potential to disrupt the entire food web.”

Researchers found that 53% of zooplankton and 60% of micronekton species, which feed on them, could be affected. The waste particles contained far fewer amino acids—essential for marine nutrition—than naturally occurring food sources.

“This isn’t just about mining the seafloor; it’s about reducing the food for entire communities in the deep sea,” said co-author Erica Goetze, professor of oceanography at SOEST.

The Clarion-Clipperton Zone (CCZ), a vast Pacific area rich in minerals such as cobalt and nickel, is now under roughly 1.5 million square kilometers of active mining licenses. Yet, as the study warns, discharging mining waste into the twilight zone—a layer critical for global carbon cycling—could cause cascading ecological harm.

“It’s like dumping empty calories into a system that’s been running on a finely tuned diet for hundreds of years,” added Jeffrey Drazen, deep-sea ecologist and co-author.

With commercial mining still in its infancy, the authors urged urgent regulation. “If we don’t understand what’s at stake in the midwater, we risk harming ecosystems we’re only just beginning to study,” said Brian Popp, SOEST professor of earth sciences.

The team hopes the findings will guide global rulemaking by the International Seabed Authority and the US National Oceanic and Atmospheric Administration, emphasizing the need to manage mining waste with full awareness of its deep-sea impacts.