CLIMATEWIRE | Even minor deep sea mining operations can have a major impact on marine biodiversity.
A new study finds that ocean animals decline in mining zones — and they stay gone even up to a year after operations cease.
Published Friday in the scientific journal Current Biology, the research presents a case study on a 2020 Japanese mining test on the Takuyo-Daigo Seamount off the coast of Honshu, Japan’s largest island. The first of its kind, the test was aimed at extracting cobalt-rich crusts from the ocean floor, a key mineral used in battery manufacturing.
The test lasted only about two hours, the researchers say, and involved an underwater machine traversing the bottom of the sea. Yet even this small operation sent marine animals fleeing.
The researchers observed that swimming animals, such as fish, shrimp and jellyfish, started to vanish from the mining site and surrounding areas shortly after the operation ended. And a year later, the declines were still pronounced. Swimmers had decreased by 43 percent in the direct mining zone and by 56 percent in the surrounding areas.
Sessile organisms, on the other hand — animals that stay in one place, such as sea sponges and anemones — remained relatively stable.
That was a surprise to the scientists. Studies of other kinds of deep-sea disturbances, including deep-sea trawling and oil and gas operations, have suggested that sessile animals are especially vulnerable, sometimes taking decades to recover. Swimming animals, on the other hand, are usually more resilient.
The new study indicates that mining operations may present a different kind of threat to deep-sea animals. Many sessile organisms feed on organic material that drifts down from upper layers in the water column. These food sources may be less likely to be disturbed by mining operations.
But deep-sea swimmers tend to get their food from the bottom of the ocean, feeding on sediments and organic matter in the seafloor or on other animals. Mining operations can easily contaminate these food sources with drill cuttings or other mining byproducts. When an area’s food quality declines, fish tend to migrate into new areas with better options.
Mining also stirs up plumes of sediments and other materials lodged in the seafloor, including heavy metals and other potentially toxic substances. The new study didn’t observe abnormally high levels of toxic metals after the mining test was complete, but the researchers note that fish can be sensitive to even small concentrations.
The researchers conclude that swimming animals “may be stronger indicators of mining impacts” than scientists previously believed.
“We’re going to need more data regardless, but this study highlights one area that needs more focus,” said lead study author Travis Washburn, a scientist with the Geological Survey of Japan, in a statement. “We’ll have to look at this issue on a wider scale, because these results suggest the impact of deep-sea mining could be even bigger than we think.”
Deep-sea mining is currently the subject of major international interest — and growing controversy.
Proponents say deep-sea mining is an essential way to secure minerals critical for manufacturing batteries and other renewable energy technologies. These include minerals such as cobalt, nickel, manganese, copper and zinc. Currently, most of these minerals are mined from terrestrial sources around the world, and they’re often linked to human rights abuses.
But critics counter that deep-sea mining presents a major threat to fragile ocean ecosystems.
Most interest at the moment revolves around the mineral-rich Clarion-Clipperton Zone, a region of the Pacific Ocean spanning about 2 million square miles between Hawaii and Mexico. There’s no mining currently happening there; an intergovernmental body known as the International Seabed Authority is responsible for designating the rules about mining operations and approving mining contracts in international waters.
The ISA so far has awarded more than 30 exploration contracts to countries and companies allowing them to assess potential mining opportunities in the CCZ. But the ISA has yet to agree upon industry rules for deep sea mining, and until recently it was not considering mining applications at all.
That changed in 2021 when the island nation of Nauru triggered a treaty provision known as the “two-year rule,” which obligates the ISA to allow mining to begin within 24 months whether or not it’s established industry regulations by that point.
That deadline expired on July 9, meaning the ISA is now obliged to begin accepting mining applications. But it still hasn’t finalized industry rules, raising alarms among environmentalists.
ISA negotiators are meeting this month in an attempt to finalize the rules, but it’s unclear how quickly they’ll be able to reach an agreement. Meanwhile, the council also must consider how to proceed if the ISA receives a mining application before the rules are complete.
Scientists, environmentalists and world leaders have urged caution. Hundreds of marine scientists and policy experts signed an open letter in 2021 calling for a pause on deep-sea mining. Environmentalists, activists and member states belonging to the International Union for the Conservation of Nature voted in support of a moratorium on deep sea mining in the same year.
Countries including Germany, France and New Zealand also have called for a pause on deep sea mining until scientists conduct more research on its environmental impacts. Brazil reportedly became the most recent nation to join the chorus during this month’s ISA negotiations, asking for at least a 10-year pause.
The new study is the latest to raise concerns about the potential impacts of deep-sea mining on marine ecosystems and biodiversity. A separate study, published in May, warned that mineral-rich regions of the ocean also are home to thousands of species that might be affected by mining operations. It found that the mineral-rich Clarion-Clipperton Zone is home to more than 5,000 unique species, most of them entirely new to science.
“We are on the eve of some of the largest deep sea mining operations potentially being approved,” study co-author Adrian Glover, a researcher at the Natural History Museum in London, said in a statement when the study was released. “It is imperative that we work with the companies looking to mine these resources to ensure any such activity is done in a way that limits its impact upon the natural world.”
Reprinted from E&E News with permission from POLITICO, LLC. Copyright 2023. E&E News provides essential news for energy and environment professionals.