2023-07-17 17:38:00
It’s no coincidence that deep-sea mining is in the news. Negotiations are taking place right now in Kingston, Jamaica, to decide on a framework for regulating this new field of activity.
Like France, some countries want to ban it or, at the very least, introduce a “precautionary break”. A new study released by researchers from the Geological Survey of Japan (Geological Survey of Japan) in the journal Current Biology (July 14, 2023) will perhaps provide an additional argument to the representatives of these countries.
“It is very important that this data is disseminatedunderlined in a communiqué Travis Washburn, researcher in benthic (deep sea) ecology at the Geological Survey of Japan, and first author of this study. A set of regulations should be finalized soon, so a lot of decisions are being made now.”
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A mining test in Japan in 2020
Since deep-sea mining has not (yet) started, the authors of the study relied on a preliminary test.
In 2020, Japan succeeded for the first time in extracting cobalt ore at the top of the Takuyo-Daigo seamount (850 to 1,000 m deep at its highest point), located regarding 1,900 km from the coast. , in the Pacific Ocean. A plume of sediment had then formed in the water, transported by the currents on “a few hundred meters” around the mining site.
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As part of the study, a remotely operated underwater vehicle traveled to the ocean floor and collected videos of “megafauna”, i.e. marine animals larger than one centimeter in size. wingspan. The research team analyzed data from three time periods: one month before the test mining, one month following, and following one year.
Half as many sea animals
Result: one year following the mining test, the researchers observed a 43% drop in the density of fish and crustaceans in the areas directly affected by the sediment plume. The decrease was even more marked in a nearby area (56%).
If other factors can explain the drop in numbers for these marine animals, the authors of the study evoke a possible contamination of their food sources by the sediments released during the mining test.
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On the other hand, sessile animals – fixed to their natural substrate – such as corals and sponges, did not experience any significant change. However, the researchers point out that the test mining lasted only two hours, and that prolonged mining might have had consequences for these groups of species.
A prerequisite for any new mining attempt
Nevertheless, scientific caution remains in order. The researchers believe they will need to repeat their observations on other tests to better understand the impact of deep-sea mining on benthic ecosystems.
According to them, any new mining test should be preceded by several years of collecting data on the animal communities of the area concerned, so that natural variation can be taken into account – and thus determine the effects linked specifically to mining. .
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“We will need more data anyway, but this study highlights an area that needs more focus.insists Travis Washburn in the press release. We will have to examine this question on a larger scale”he concludes:
“Because these results suggest that the impact of deep-sea mining might be even greater than we think.”
On the same topic :
⋙ Law of the sea: who owns the seas and oceans?
⋙ Deep-sea mining: “irreversible” consequences for cetaceans
⋙ What is a “dead zone” in the ocean?
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