Deep-Sea Mining Waste Threatens Vital Ocean Life and Food Chains

A groundbreaking study from the University of Hawaii at Manoa reveals that waste from deep-sea mining operations poses a significant threat to marine life in the Pacific’s biodiverse Clarion-Clipperton Zone (CCZ). Published in Nature Communications on November 6, 2025, the research highlights the potential for mining discharge to disrupt the intricate food webs in the ocean’s midwater “twilight zone,” which ranges from 200 to 1,500 meters beneath the surface.

The study indicates that more than 53% of zooplankton and 60% of micronekton—small swimming creatures that feed on zooplankton—could be adversely affected by the mining waste. This disruption could have cascading effects on higher predators, including fish, seabirds, and marine mammals.

Lead author Michael Dowd, a graduate student in oceanography at the School of Ocean and Earth Science and Technology (SOEST), described the findings, stating, “When the waste released by mining activity enters the ocean, it creates water as murky as the mud-filled Mississippi River.” The study underscores that the particles released dilute the nutritious food particles that sustain the drifting zooplankton, fundamentally altering the food chain.

Impact of Mining Waste on Ocean Ecosystems

The research, titled “Deep-sea mining discharge can disrupt midwater food webs,” examines the effects of waste released during a 2022 mining trial in the CCZ. This region is under exploration for deep-sea polymetallic nodules, which contain critical minerals such as cobalt, nickel, and copper. Researchers found that water samples from the mining discharge contained significantly lower concentrations of amino acids—an essential indicator of nutritional value—compared to naturally occurring particles that sustain life in these depths.

Co-author Erica Goetze, an oceanography professor at SOEST, emphasized the broader implications, stating, “This isn’t just about mining the seafloor; it’s about reducing the food for entire communities in the deep sea.” The findings are particularly concerning as they highlight the reliance of many deep-sea organisms on natural detrital particles that could be replaced by mining plume particles.

The study arrives at a critical juncture as several countries seek to meet the rising global demand for metals essential for electric vehicle batteries and other low-carbon technologies. Currently, approximately 1.5 million square kilometers of the CCZ are licensed for mining activities, raising urgent questions about the environmental impact of such operations.

Regulatory Gaps and Future Implications

During deep-sea mining, nodules are collected alongside seawater and sediment, which are then transported to collection ships. The sediment waste, along with finely pulverized nodule particles, must be returned to the ocean. The depth at which this waste is discharged remains unclear, and some operators have proposed midwater discharge within the twilight zone. This lack of clarity has left the impacts of mining waste on midwater communities poorly understood, contributing to a significant regulatory gap in the industry.

The twilight zone is home to a remarkable diversity of marine life, including krill, fish, squid, and gelatinous species such as jellyfish. These organisms play a crucial role in the ocean’s carbon transport system, which is vital for both oceanic and human health. Co-author Jeffrey Drazen, a deep-sea ecologist at SOEST, noted, “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.”

The findings raise urgent concerns about the long-lasting effects of large-scale commercial mining if executed without adequate environmental protections. Fisheries operating in the CCZ, particularly those targeting tuna, may be directly affected, potentially impacting global food supplies.

Co-author Brian Popp, a professor of earth sciences at SOEST, remarked, “Deep-sea mining has not yet begun at a commercial scale, so this is our chance to make informed decisions.” The authors advocate for a thorough understanding of the midwater ecological impacts before any commercial mining begins.

The research aims to influence international regulatory decisions currently being formed by the International Seabed Authority, as well as the National Oceanic and Atmospheric Administration in the United States, which oversees environmental assessments of deep-sea mining initiatives. The authors are also calling for enhanced research to protect the full vertical extent of ocean ecosystems.

As Jeffrey Drazen concluded, “Before commercial deep-sea mining begins, it is essential to carefully consider the depth at which mining waste is discharged.” The consequences of improper discharge could jeopardize communities ranging from the surface to the seafloor, highlighting the urgency of establishing robust environmental safeguards in the face of expanding mining operations.