The impact of new deep-sea mining plans on ocean ecosystems is much more severe than most people think. A new study is hoping to dispel any misconceptions.

As precious mineral resources on Earth are depleted year after year, commercial mining companies are beginning to look underwater for more. Mining the seas may sound straightforward enough, but sadly it appears that the environmental impact could be disastrous.

A new publication from the University of Hawai’i at Mānoa is seeking to dispel scientific misconceptions that severely underestimate the impact of deep-sea mining on local ecosystems.

What is deep-sea mining?

Simply put, deep-sea mining is the process of retrieving minerals from the ocean floor. This occurs at depths below 200 metres (650 feet), and can reach as far down as 5,000 metres. Depending on the type of mineral deposit found, resources such as nickel, copper, cobalt and even gold can be extracted. These precious metals are notably important in high-tech industries.

The process of deep-sea mining is simple in theory. Often, a remotely-operated vehicle (ROV) is first used to drill into the seabed to find evidence of precious minerals. If the minerals are present then mining may begin in that area.

Following this, a mining ship will deploy a collector vehicle to the ocean floor. This vehicle then scrapes the top 10 to 15 centimetres of the seabed, pumping the sediment up to the surface vessel via a connected pipeline. Any unwanted sediment is then dumped back into the ocean.

A visualisation of this process, created by MIT, can be seen here. While no major deep-sea mining operations have taken place yet, many plans are taking shape.

The environmental impacts

The deep sea contains some of the most diverse and extreme ecosystems on the planet. Mining operations have the potential to wipe out habitats and cause the extinctions of multiple fragile species.

A dense pink coral garden was found at nearly 1800 meters on Mendellsohn Seamount.
A dense pink coral garden was found at nearly 1800 meters on Mendellsohn Seamount. Many of the colonies were exceptionally large. (Credit: NOAA OER)

For oceanography professor Craig Smith, this is no joke. “The bottom line is that many deep-sea ecosystems will be very sensitive to seafloor mining, are likely to be impacted over much larger scales than predicted by mining interests, and that local and regional biodiversity losses are likely, with the potential for species extinctions.”

Sea cucumber nearly 3 miles down  in the deep-sea.
Sea cucumber nearly 3 miles deep [5000 meters]. (Credit: Deep CCZ Project)

Along with the already-known impacts of the intended mining operations, many misconceptions have begun to arise. These have been carefully addressed in the new study led by professor Smith.

The big misconceptions about deep-sea mining

1. The sensitivity of deep-sea ecosystems

Smith and his team have revealed that the ecosystems on the deep-sea floor are far more sensitive than most people realise. This means the impact of mining could more severe than previously thought. “We found underestimates of mining footprints and a poor understanding of the sensitivity and biodiversity of deep-sea ecosystems, and their potential to recover from mining impacts,” Smith said.

“All the authors felt it was imperative to dispel misconceptions and highlight what is known and unknown about deep seabed mining impacts.”

The team also revealed that many of habitats affected will be destroyed permanently, with no chance of recovery.

2. The reliability of simulations

Although major mining operations underwater are yet to take place, many computer simulations have attempted to assess its potential impacts. Professor Smith says that these simulations are unreliable. “All the simulations conducted so far do not come close to duplicating the spatial scale, intensity and duration of full-scale mining.”

“Further, the computer models use ecosystem sensitivities derived from shallow-water communities that experience orders of magnitude higher levels turbidity and sediment burial (mining-type perturbations) under natural conditions than the deep-sea communities targeted for mining.”

3. The sheer scale of mining operations

The physical environmental footprint of the mining will be far larger than most people realise. But just how much of the ocean floor is going to be mined?

Professor Smith explained that the proposed plans “may ultimately impact 500,000 square kilometres of deep seafloor in the Pacific, an area the size of Spain, yielding perhaps the largest environmental footprint of a single extractive activity by humans.”

The future

Deep-sea mining is bound to be a very lucrative venture. It will give us access to precious materials on a scale we haven’t seen for a very long time. It is also a very dangerous prospect for biodiversity. Whichever way we look at it, it seems it is inevitable.

Smith’s team is aiming to work closely with regulators and officials to make sure that deep-sea mining operations don’t go ahead until the environmental risks are fully appreciated. While it can’t be stopped, hopefully the impacts can be minimised. Only time will tell.

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