According to new research published today in the journal Nature Communications, the waste generated during the process of obtaining battery minerals from seabed mining may deprive marine life of a key food source and may affect large fish, including tuna, on which humans depend. The study comes as former President Trump sought to circumvent international law and allow companies to engage in commercial deep-sea mining. In fact, the first company to apply for an international mining license from the Trump administration funded this research, and the results once again sounded the alarm for deep-sea mining.
The researchers found that if mining waste is released into the "twilight zone" of water, which is between about 200 and 1,500 meters from the sea surface, it will cause microscopic animals such as zooplankton and the creatures that prey on them to starve. This would have serious consequences for the entire food web, and scientists believe further research should be conducted on how to avoid potential risks.
"We want to slow down this process," said lead author Michael Dowd, a graduate student in the University of Hawai'i School of Ocean and Earth Sciences and Technology. "The current plan will have serious consequences."
The Trump administration aims to mine polymetallic nodules rich in nickel, cobalt and manganese, minerals that can be used to make rechargeable lithium-ion batteries. Canadian start-up The Metals Company (TMC), in partnership with Nauru, is the first to attempt to commercially mine such nodules, pushing the International Seabed Authority (ISA) to develop mining regulations to protect marine resources regarded as the "common wealth of mankind".
At the same time, more than 900 marine scientists and policy experts around the world issued public statements calling for a moratorium on deep-sea development, warning that mining could lead to multi-generational and irreversible loss of biodiversity and ecosystem functions.
In 2025, the US government and TMC decided not to wait for the introduction of ISA mining specifications. Trump signed an executive order to accelerate the pace of seabed mining in US and international waters, and TMC quickly submitted relevant applications. Critics pointed out that the move violated international law, and ISA Secretary-General Leticia Reis de Carvalho said that unilateral mining would undermine the global ocean governance system.
The mining process transports seafloor nodules along with seawater and sediment through pipelines to ships, where the metals are separated and the waste is discharged back into the ocean. Exactly where the waste should be dumped is currently undecided. The "twilight zone" is an option considered by the industry. Although the sunlight is sparse, there are abundant life activities, including small fish, crustaceans, micro-swimming animals and their food - zooplankton. Zooplankton feed on sinking organic particles. If the waste forms a large amount of sediments of similar particle sizes here, it will cause zooplankton to replace the original food with "junk food" with much lower nutritional value.
The University of Hawaii team collected water and pellet samples and measured amino acid concentrations to assess nutritional value before and after TMC's small-scale test mining in the Pacific in 2022. Results showed that the nutritional value of waste pellets is 10 to 100 times lower than natural pellets, and is described as "junk food with almost no organic matter."
"This will affect the food chain from the bottom up, with zooplankton first affected, and then affecting higher-level microswimmers and even large fish such as whales and tuna," Daode said. Zooplankton migrate through different water layers and are an important food source for a variety of predators. They also help transport carbon to the deep sea and regulate the earth's climate. A large number of "garbage particles" may cause a chain reaction in various water layers.
If waste is discharged into shallower waters, the risk to high trophic level predators may be greater. The scientific community currently has no data on the impact in deeper water, where some species migrate to escape shallow water predators. Scientists suggest that if companies insist on mining, the harm may be mitigated by returning sediment waste to the seabed where it was originally mined. However, this will increase complexity and cost, and the scientific community is concerned that "cutting corners" may damage the marine ecology.
The authors of the paper emphasize that despite receiving corporate funding, the research was completed independently and unaffected. TMC responded that it would discharge waste at a depth of 2,000 meters, which is lower than the twilight zone studied in the paper, and that there are fewer zooplankton at that water depth and particles can spread quickly. "There are public concerns about the impact on midwaters, but the data has changed and the discussion should adjust accordingly," said TMC project manager Michael Clarke.
In addition, innovations in battery technology and the development of electronic waste recycling can reduce the need for mining of new minerals. Car companies such as Tesla, BYD and Ford have adopted new battery solutions to reduce nickel and cobalt consumption. Establishing a more complete recycling system can also prevent the new energy industry from triggering new environmental crises. "We can recycle e-waste and mine our own waste without having to dig deep into the ocean floor for a green revolution," concluded co-author Brian Pope, a professor at the University of Hawaii.