Mining the Deepest Ocean for Rare Earth Metals Could Push Worms Living in the Abyss to Extinction, Study Warns

Mining for rare earth metals in some of the deepest parts of the ocean could lead to the extinction of creatures living in the abyss, researchers have warned. By analyzing the lives of worms living at the bottom of the Clarion Clipperton Fracture Zone (CCFZ), in the Eastern Pacific, the team discovered these animals are highly sensitive to changes in the environment, so may not survive activities disturbing their habitat.

Rare earth metals are a group of 17 chemical elements that while relatively abundant, are rarely found in concentrations high enough to be easily extracted. Over recent decades they have become increasingly important. Rare earth metals are now crucial to many technology industries, including the manufacturing of smart phones and car batteries. They are also critical to national defense, being used to make night-vision goggles, communication equipment and GPS devices.

As land-based reserves are depleted and demand increases, other parts of the planet are now being looked at for their potential—the bottom of the ocean.

Rare earth metals are known to be abundant in polymetallic nodules. These are layers of iron and manganese hydroxides that form on the seafloor. This has made them of great interest to businesses looking to exploit this resource.

The CCFZ, which sits over 2.5 miles beneath the surface of the ocean, has the largest known reserve of polymetallic nodules. It spans an area covering over 1.7 million square miles. It is currently being explored for its mining potential by nations across the world, including China, Russia, the U.K., France and Germany, among others, according to a 2018 report from the French Institute of International Relations.

Scientists are now taking part in a research project to better understand the biological baseline of the CCFZ so they can assess the potential impact of mining activities in the region. Lara Macheriotou, from Ghent University, Belgium, is part of a team looking at this impact.

"One only has to look at the rate of human population growth to get a notion of how the demand for rare earth metals is rising, and will continue to rise," she told Newsweek in an email. "These metals are used not just in our personal devices such as smartphones, computers and hybrid cars, but also in the technologies being developed to reduce our dependency on nonrenewable energy sources, such as solar panels and wind turbines."

Macheriotou and colleagues have now published a study in the Proceedings of the Royal Society B: Biological Sciences that examines the impact mining the CCFZ would have on nematode worms—the most abundant invertebrates of the CCFZ.

The team looked at how the worms live in their environment—with their survival driven by competition with other similar species, or because of their suitability to the environmental conditions. A species driven more by environmental conditions would be more sensitive to environmental changes than those structured by competition. Researchers examined nematode assemblages and distribution, assessing the patterns to see which of these parameters they are structured by, finding environmental conditions was key to the structure of their communities.

Macheriotou said she was not entirely surprised by these findings. She said at the low population densities coupled with the low level of nutrients available at the bottom of the CCFZ makes it hard to imagine a competition-led system.

the ccfz
The CCFZ. Researchers say nematode worms living there would be at risk of extinction if mining for rare earth metals began. GEOMAR

If mining were to take place, the team says nematode worms would be at risk of extinction. "Local extinction of species with a narrow geographic distribution will likely be instantaneous following mining operations, depending on the size of the area affected," she said.

"The strongest impacts of deep-sea mining activities on nematode communities are predicted from 1.) the direct removal of the upper ~10 cm [3.9 inches] of sediment, which contains the majority of the assemblage 2.) blanketing of extensive areas by sediment that has been stirred up by the mining vehicle operations and 3.) sediment compaction due to the weight of the nodule collector. All three will result in either immediate mortality, increased stress, displacement and overall perturbations to communities that have been stable for potentially hundreds of thousands of years."

Nematode worms are hugely important to the food web in the CCFZ, providing high quality food for larger animals in an area that is largely nutrient poor. What impact mining the CCFZ could have is hard to predict, she said, as it is one of the least explored ecosystems on the planet.
"What we can confidently say is that the local extinction of nematodes will bring about an overall reduction of biodiversity which will not be confined to just the nematodes but also to larger organisms as these biological components are interlinked."

Terrestrial sources for rare earth metals have not yet been exhausted, but they are becoming rarer and requiring deeper and more numerous mines. This, Macheriotou says, comes with severe environmental and socio-economic impacts. Asked whether mining the CCFZ should go ahead, she said the desire to keep pristine ecosystems intact is set against the realities of the industry.

"[I] cannot turn a blind eye to the insufferable working conditions imposed on mine workers across the globe, nor the environmental destruction these operations are causing," she said. "We are at a moment now where industrial interest and scientific concern are involved in a conversation, something which has never happened before. It is an unprecedented opportunity to define 'best practices' and to set up monitoring frameworks that will ensure the longevity of these deep-sea ecosystems; in this way, deep-sea mining may offer an alternative that is free of human cost, and thus worthy of consideration."

The team is now continuing its work assessing the impact of mining at the CCFZ. Now they have collected data, they hope to identify how it will be disturbed and recover from any activities.