"Sediment plumes from deep-sea mining could pollute vast swaths of the ocean, scientists say", 20 July 2020

[...] [D]eep-sea mining, a new activity intended to extract minerals from the seafloor, could seriously threaten the midwater ecosystem, a new paper suggests.

While deep-sea mining has not yet begun, numerous companies are interested in exploring for  minerals near hydrothermal vents, seamounts, and the abyssal plains where polymetallic nodules are found. [...]

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These activities would generate two types of “environmentally detrimental plumes,” [...] These plumes, according to the authors, will introduce heavy metals into the pelagic food chain, which could even contaminate the human seafood supply; clog organisms’ filtration and breathing structures; and introduce visual and mobility barriers that could prevent organisms from properly functioning.

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[...] Mongabay also contacted several organizations currently licensed to explore the seabed for minerals, including Lockheed Martin, the parent company of UK Seabed Resources; Dredging, Environmental and Marine Engineering NV (DEME), the parent company of Global Sea Mineral Resources NV; Japan Oil, Gas and Metals National Corporation; and the Federal Institute for Geosciences and Natural Resources of Germany. However, none responded to our request for an interview.

[...] Gregory Stone, chief scientist and a director of DeepGreen [Metals], told Mongabay that the company’s mining activities probably wouldn’t have a big impact on the midwater column or surrounding ocean.

“Our major strategy is to isolate our activities from the water column as much as we can,” Stone said.

Nevertheless, Stone said that the company will be spending the next three years researching the effects of deep-sea mining on the midwater ecosystem. “The way we approach this is we want to remove every impact we can,” Stone said. “And then we want to minimize every impact we cannot remove.”

“If we do discover something, and it’s really bad, we won’t do it,” he added.

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