Deep beneath the rolling waves of the Pacific, an invisible drama is unfolding—one that could shape the fate of the world’s fisheries and, ultimately, the food on our dinner tables. A new peer-reviewed study, published November 6, 2025 in Nature Communications, has cast a spotlight on the environmental stakes of deep-sea mining, warning that the impacts could ripple far beyond the ocean floor.
At the heart of the controversy lies the pursuit of polymetallic nodules—potato-sized rocks scattered across the seafloor, packed with critical minerals like copper, iron, and zinc. These metals are in hot demand for electric vehicles, renewable energy infrastructure, and even military technology, fueling a global race to tap into the ocean’s hidden riches. While commercial-scale mining hasn’t yet begun, the groundwork is being laid, with several exploration contracts already granted by the International Seabed Authority, as reported by the Associated Press.
But what happens when we disturb the deep? That’s the question University of Hawaii researchers set out to answer, focusing their attention on the ocean’s so-called "twilight zone"—an enigmatic layer stretching from 650 to 5,000 feet (200 to 1,500 meters) below the surface. Here, in a realm beyond the reach of sunlight, tiny creatures form the foundation of a vast and intricate food web.
According to the study, the process of mining isn’t just about scraping the seafloor. Once the mineral-laden nodules are hauled up, companies must release excess seawater, sediment, and ocean floor dirt back into the depths. This waste forms a murky plume, filled with particles that are eerily similar in size to the natural food consumed by zooplankton—the minuscule, drifting animals that make up more than half of the ocean’s zooplankton population.
"If these organisms eat the waste particles—what senior study author Brian Popp called ‘junk food’—then that affects 60% of micronekton that eat the zooplankton," the Associated Press explained. It’s a domino effect: undernourished zooplankton mean hungry micronekton (small fish and shrimp), which in turn threatens the larger fish that depend on them, such as mahi mahi and tuna. The study’s lead author, oceanography graduate student Michael Dowd, put it bluntly: "Surface fish can dive down deep into the water, they feed on organisms down at depth. If these organisms down at depth are no longer present because their food web has collapsed, then that can impact higher food webs and more commercial interests."
This isn’t just an academic concern. Commercial fisheries worldwide rely on the health of these deep-sea ecosystems, and any disruption could have real-world consequences for food security and livelihoods. The study’s findings suggest that the risks of deep-sea mining extend far beyond the immediate area of extraction, potentially spreading across entire regions if multiple companies operate simultaneously for years on end.
While previous research has mostly focused on the seafloor itself, this study shifts the lens to the mid-water column—a zone teeming with life that often goes overlooked. The researchers warn that simply changing the depth at which waste is released may not solve the problem. Returning dirty water and sediment to the ocean floor or other depths could be just as disruptive, albeit in different ways.
As the debate intensifies, some scientists and environmentalists are urging caution, emphasizing the need for more research before the industry ramps up. "It was well laid out in the study that the impacts wouldn’t necessarily be just the depth that the plume is released," said Sheryl Murdock, a deep-sea postdoctoral researcher at Arizona State University, who was not involved in the research. "The question being: Is it worth a few minerals to potentially destroy the way that the oceans function?"
Diva Amon, a marine biologist and postdoctoral researcher at the University of California, Santa Barbara, echoed those concerns. "All of this could lead to species illness, species movement, species death. And depending on the scale of this, that could have graver repercussions, like species extinctions," she told the Associated Press. "There’s a lot more research that needs to be done to be able to make an informed decision about how to manage this industry, if it does start, in a way that will prevent, essentially, serious harm to the ocean and ocean ecosystem."
Given the potential for widespread disruption, the study’s authors advocate for a careful, science-based approach to managing mining waste. They stress the importance of determining the right depth and quality standards for returning waste to the ocean, to minimize harm to vulnerable marine communities. But even with improved practices, some researchers question whether deep-sea mining is necessary at all.
Brian Popp, one of the study’s senior authors, points to alternative sources of critical minerals, such as recycling batteries and electronics or reprocessing mining waste and tailings from existing operations. "Digging up the deep sea might not be necessary," Popp suggested, hinting at a future where the circular economy could help meet mineral demand without sacrificing the health of the ocean.
Still, the momentum for deep-sea mining continues to build. In the United States, former President Donald Trump signed an executive order in April 2025, directing the National Oceanic and Atmospheric Administration (NOAA) to expedite the permitting process for ocean floor mining. Just a month later, the administration floated the idea of selling leases for mineral extraction near American Samoa. By October, NOAA had sent a draft rule to the White House aimed at streamlining mining operations.
These moves come amid tense trade relations with China, which controls a significant share of the world’s critical mineral supply. As nations jockey for access to these resources, the pressure to tap into the ocean’s mineral wealth is only likely to increase.
Environmental groups, meanwhile, are sounding the alarm—not just about the direct harm to marine life, but also about the potential release of planet-warming carbon dioxide currently locked away in the ocean and its floor. The disturbance of these natural carbon sinks could have unforeseen consequences for the global climate, adding another layer of complexity to an already thorny issue.
"If only a single company is mining in one single spot, it’s not going to affect a huge fishery. It’s not going to affect a huge amount of water. But if many companies are mining for many years and outputting a lot of material, this is going to spread across the region," Dowd observed. "And the more mining occurs, the more a problem it could be."
For now, the future of deep-sea mining hangs in the balance. The new research underscores the urgent need for robust scientific inquiry, transparent decision-making, and a willingness to consider alternatives before plunging headlong into the unknown. As the world weighs the promise of mineral riches against the risks to ocean life, one thing is clear: the stakes have never been higher.
