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Underwater upheaval: The ecological impact of deep-sea mining

In a world first, Japan managed to successfully extract cobalt crusts from deep-sea mountains in a pilot test. Their goal was to unearth cobalt, a mineral critical for manufacturing electric vehicle batteries. But researchers have discovered a disturbing side effect of this feat. They found that animals quickly vacated the areas surrounding deep-sea mining operations.

The study, published in the journal Current Biology, reveals that marine animal populations appear to have plummeted in and around the mining area.

The impacts were not limited to the direct mining zones but also emerged across broader regions. According to the researchers, the broader impacts were linked to sediment plumes stirred up by the mining activities.

Deep-sea mining regulations 

Regulations regarding deep-sea mining, which falls under the jurisdiction of the International Seabed Authority (ISA) outside a country’s territorial waters, remain a work in progress. 

Even so, starting July 9, the ISA must either finalize its exploitation regulations or consider mining operations under the umbrella of existing international laws. This looming deadline highlights the urgency for comprehensive research and informed decisions.

“These data are really important to get out,” said study lead author Travis Washburn, a benthic ecologist working with the Geological Survey of Japan. “A set of regulations is supposed to be finalized soon, so a lot of these decisions are happening now.”

What the researchers discovered 

The research team embarked on a deep-sea investigation. They conducted surveys at the Takuyo-Daigo seamount site before, a month after, and a year following the initial mining test. Using data collected by a remotely operated vehicle, they scrutinized video footage captured from the ocean floor. There, they found worrying signs. 

A year after the mining test, they observed a 43 percent decline in fish and shrimp density in areas directly hit by sediment pollution. Surprisingly, the areas surrounding the mining site also showed a significant 56 percent decrease in these marine species. While the team believes the contamination of food sources might be the culprit, they admit that more research is needed to validate this theory.

Less mobile marine species like corals and sponges seemed to be less affected by the short, two-hour mining test. However, the researchers cautioned against jumping to conclusions. They point out that longer-term mining activities might still inflict serious harm on these stationary organisms.

“I had assumed we wouldn’t see any changes because the mining test was so small. They drove the machine for two hours, and the sediment plume only traveled a few hundred meters,” said Washburn. “But it was actually enough to shift things.”

Further research is urgently needed 

With these startling discoveries, the researchers call for more in-depth, repeated studies. Scientists need to ascertain the real ecological impact of deep-sea mining. They emphasize the need for gathering data over several years before the actual mining tests. This will help account for natural fluctuations in marine animal communities.

“We’re going to need more data regardless, but this study highlights one area that needs more focus,” said Washburn. “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.”

More about deep-sea mining 

Deep-sea mining is the process of extracting valuable minerals and metals from the ocean floor. This process is largely driven by the demand for these resources, many of which are used in high-technology applications.

There are three types of resources typically targeted by deep-sea mining:

Polymetallic nodules

These are rounded accretions of minerals, typically manganese, nickel, copper, and cobalt, found on the abyssal plains of the deep ocean.

Polymetallic sulphides

These are formed by hydrothermal vents on the seafloor, where hot, mineral-rich water spews out from beneath the Earth’s crust. These vents can create deposits rich in copper, zinc, lead, and precious metals like gold and silver.

Cobalt-rich crusts

These are found on the flanks of seamounts, and are a potential source of cobalt, manganese, and other trace metals.

Environmental concerns of deep-sea mining

While deep-sea mining holds the promise of accessing valuable resources, it also presents significant environmental concerns. 

The deep ocean is a poorly understood and fragile ecosystem, and mining activities could have a significant impact, including the destruction of habitats, loss of species, and disruption of ecosystem functions. Noise and light pollution, as well as the potential release of toxic substances, are also concerns.

Furthermore, the legal and regulatory aspects of deep-sea mining are complex. The United Nations Convention on the Law of the Sea (UNCLOS) designates the International Seabed Authority (ISA) to regulate mining in international waters, but national laws apply within countries’ exclusive economic zones.

Given the environmental risks associated with this practice, it’s crucial that any advancement in deep-sea mining is matched with rigorous environmental protections and sustainable practices.


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