A deep-sea mining rush appears closer than ever to getting underway. Deep-sea mining, which requires extracting minerals and metals from the seafloor, has scientists and environmentalists worried because a growing body of research suggests its environmental damages are likely to be long-lasting and severe.
In international waters, a United Nations body called the International Seabed Authority (ISA) has granted 30 exploration contracts for an area of the underwater abyss three-times the size of California. These seabed parcels are split between 22 countries and companies hoping to extract mineral riches, including cobalt, copper, nickel and rare earth elements used in manufacturing cell phones, batteries and electric cars.
The 1989 experiment involved plowing an area of seafloor 13,615 feet below the surface to simulate the disturbance of mining. Since then, scientists have revisited the area to assess its response.
A 2019 study published in the journal Nature found many species had not returned to the plowed area even 26 years after the undersea dust had settled. The authors wrote that if their results were representative of deep-sea mining activities that the industry’s impacts might be “greater than expected, and could potentially lead to an irreversible loss of some ecosystem functions.”
The new study focused on even smaller organisms: the microbes buried in the sediments of the plowed tracks. A combination of photos and samples taken from the site in 2015 revealed that plowing new tracks slashed microbial community by half and that even the 26 year old tracks had still only recovered two-thirds of their microbes. This reduction in overall numbers of microbes also translated to a 75 percent slowdown of various microbial processes. Overall, the team calculated that it would take a full 50 years for the microbes in the simulated mining area to return to normal.
Drazen is one of a select few scientists who have explored the abyssal plain ecosystem of the Clarion-Clipperton Zone (CCZ), where the majority of the ISA’s undersea mining contracts are located. The CCZ covers 1.7 million square miles between Hawaii and Mexico and its seafloor is littered with polymetallic nodules, potato-like lumps of metal that contain cobalt, manganese, nickel and copper.
This new research gives a taste of the potential fallout of sending a mining machine in the deep sea, but the impacts are not limited to compacted seafloor and smothering sediment plume. The very things being mined also appear important for deep-sea life.
“Half of the species we have observed appear to rely on the nodules, even mobile animals seem to prefer them,” Drazen told me of the species in the CCZ. “The nodules are precisely what make this habitat unique.” And the nodules aren’t replaceable in any normal sense of the word: “When you lift them off the seafloor, you’re removing a habitat that took 10 million years to grow,” Drazen tells Wil Hylton of the Atlantic.
https://www.smithsonianmag.com/smart-news/deep-sea-minings-environmental-toll-could-last-decades-180974791/