An international study on the impact of deep-sea mining on the seafloor has found it causes a 32 per cent reduction in marine species.
The plume created by mining also increases the dominance of some animals in the areas affected.
The paper, "Impacts of an industrial deep-sea mining trial on macrofaunal biodiversity," is published in the journal Nature Ecology and Evolution.
Scientists involved captured baseline data, tracking natural changes and assessing the impacts of a polymetallic nodule mining machine in what is billed as the largest study of the impacts of deep-sea mining on seafloor animals.
“Taking into consideration natural fluctuations, the study found that after the test, there was a 37% reduction in the number of macrofaunal animals living within the sediment directly impacted by the tracks of the deep-sea mining machine,”the scientists say.
Macrofaunal animals are organisms visible to the naked eye (0.3mm–2 cm in size), such as polychaete worms, crustaceans, snails and clams. No impact on animal abundance was detected in regions covered by a sediment plume from the mining machine.
The research was led by scientists from the Deep-Sea Research Lab at the Natural History Museum in London, and co-led by the University of Gothenburg and the National Oceanography Centre.
The project took five years to complete, with the team spending more than 160 days at sea in the Pacific and three years of careful analytical work in the laboratory.
Eva Stewart, lead author and PhD student at the Natural History Museum and University of Southampton, said that “being able to study these remote and poorly known deep-sea regions is extremely important as we consider the potential impacts of deep-sea mining”.
“Finally, we have good data on what the impacts of a modern commercial deep-sea mining machine might be. We have also discovered many new species and shown how the abyssal ecosystem changes naturally over time,” she said.
Earlier this month, Norway’s Labour government announced it will not issue a single deep-sea mining licence in its Arctic waters before the end of 2029.
It will also cut all public funding for seabed mineral mapping.
The major reversal of policy comes almost two years after Norway became the first country to formally approve deep-sea mining in its national waters, with plans to open 280,000 square kilometres of Arctic seabed for extraction.
Licences were expected to be issued by Norway this year, but scientists, NGOs and four opposition parties called for a pause on deep-sea mining.
