New Zealand scientists stress harm of deep-sea mining

Deep-sea mining not only physically disturbs the seafloor, mechanically damaging organisms, but also creates sediment plumes that can be transported outside the immediately mined area and impact marine organisms far away from the mined site, a New Zealand scientist said on Saturday.

"Seamounts are important biodiversity hotspots in generally deeper water environments and there is increasing interest globally in mining seamounts for valuable minerals," said James Bell, professor of the School of Biological Sciences at Victoria University of Wellington.

Bell made the statement in response to an investigation on the environmental impact of deep-sea mining, published Friday in the journal Current Biology, which reports a decrease of 43 percent in ocean animals, such as fish and shrimp density, both in and around the mining zone of the Takuyo-Daigo Seamount near Japan.

In 2020, Japan performed the first successful test extracting cobalt crusts from the top of deep-sea mountains to mine cobalt -- a mineral used in electric vehicle batteries. Not only do directly mined areas become less habitable for ocean animals, but mining also creates a plume of sediment that can spread through the surrounding water, which prompted ocean animals to vacate areas both around and outside deep-sea mining operations.

Bell said given that seabed mining is being considered by many countries including New Zealand, due to the increasing demand for consumer electronics and other commercial products, it is vitally important for us to understand the impacts of mining on seamount communities.

"The deep sea is full of life. These habitats seem extreme to us, but life has survived, thrived, and diversified here for billions of years," said Kat Bolstad, associate professor at the Department of Environmental Science of Auckland University of Technology.

"Many of these lives are conducted across time scales that we have trouble imagining -- some microbes may divide only once every thousand years. Some fish live for centuries," Bolstad said, adding that abrupt disturbances are rare, and deep-sea life has evolved within these stable conditions.

This study shows disruptions to the ecosystem last far beyond the immediate mining event, Bolstad said.
An increasing number of countries including New Zealand and indigenous groups are calling for a moratorium or outright ban on commercial-scale deep-sea mining.