Threat from mining waste disrupts twilight zone ocean food webs

Threat from mining waste disrupts twilight zone ocean food webs
by Simon Mansfield
Sydney, Australia (SPX) Nov 07, 2025

A new study led by the University of Hawaii at Manoa, published in Nature Communications, presents the first evidence that waste discharged from deep-sea mining in the Pacific's Clarion-Clipperton Zone could disrupt marine life in the midwater "twilight zone" between 200 and 1,500 meters depth. Particle plumes created during mining threaten food sources for 53 percent of zooplankton and 60 percent of micronekton - organisms vital to oceanic food chains and predators higher up.

Michael Dowd, lead author and oceanography graduate student at UH Manoa, said, "When the waste released by mining activity enters the ocean, it creates water as murky as the mud-filled Mississippi River. The pervasive particles dilute the nutritious, natural food particles usually consumed by tiny, drifting Zooplankton." Micronekton - small shrimp, fish, and other swimming animals - feed on zooplankton and are preyed upon by fish, seabirds, and marine mammals. Dowd added, "Zooplankton's exposure to junk food sediment has the potential to disrupt the entire food web."

Sampling conducted during a 2022 mining trial found released waste particles had far lower amino acid concentrations than naturally occurring marine detritus, reducing their nutritional value for twilight zone species. Erica Goetze, co-author and oceanography professor, stated, "We found that many animals at the depth of discharge depend on naturally occurring small detrital particles - the very food that mining plume particles replace."

The study underscores the twilight zone's role in supporting diverse marine life and facilitating carbon transfer from surface waters to the deep ocean, with broad implications for Pacific fisheries. Jeffrey Drazen, co-author and SOEST oceanography professor, explained, "Our research suggests that mining plumes don't just create cloudy water - they change the quality of what's available to eat, especially for animals that can't easily swim away. It's like dumping empty calories into a system that's been running on a finely tuned diet for hundreds of years."

With commercial mining not yet active in the CCZ, the authors urge policymakers to consider environmental safeguards. Brian Popp, co-author and earth sciences professor, commented, "If we don't understand what's at stake in the midwater, we risk harming ecosystems we're only just beginning to study." Expanded research and thoughtful regulations are needed to protect the vertical layers of ocean life exposed to mining waste.

Drazen concluded, "Before commercial deep-sea mining begins, it is essential to carefully consider the depth at which mining waste is discharged. The fate of these mining waste plumes and their impact on ocean ecosystems varies with depth, and improper discharge could cause harm to communities from the surface to the seafloor."

Research Report:Deep-sea mining discharge can disrupt midwater food webs