Habitats of shark, ray and chimaera species overlap with potential proposed deep-sea mining areas, new study finds
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In recent years, deep-sea mining has become an increasingly common – and contentious – topic of conversation when thinking about planetary resources. While some tout its uses for mining valuable minerals, others question the environmental impacts it may pose for both ecosystems and marine life.
Now, in new research published by University of Hawai‘i at Mānoa oceanographers, such environmental impacts are becoming more fully realised. In their study, researchers found the habitat of 30 species of sharks, rays and chimaeras – also known as ghost sharks –overlap with areas where proposed deep sea mining may occur.
Already, nearly two-thirds of these species are threatened with extinction due to human impacts. Deep-sea mining is projected to disrupt the seafloor and discharge large plumes of sediment into the water above. Sediment plumes can lead to the suffocation and smothering of a variety of species, elevating their extinction risk.
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Researchers overlayed global maps of species ranges created by the IUCN alongside those displaying areas allocated for deep-sea mining by the International Seabed Authority. As well as this, researchers accounted for how each species reproduces and how deep they dive, in order to measure their vulnerability to mining impacts.
For example, species such as skate and chimaera lay eggs on the seafloor – an area which is heavily frequented by mining vehicles, posing a threat to nurseries.
The species assessed in the study include whale shark, manta rays and the megamouth shark. In their findings, researchers discovered 30 species could be impacted by discharge plumes, and 25 of these 30 species could also be impacted by seafloor disruptions associated with mining.
‘Sharks and their relatives are the second most threatened vertebrate group on the planet, mostly from overfishing,’ said study senior author Jeff Drazen. ‘Because of their vulnerability, they should be considered in ongoing discussions of the environmental risks from deep-sea mining, and those responsible for monitoring their health should be aware that mining could pose an additional risk.’
To protect these species from any harmful impacts, researchers recommend a range of solutions – such as establishing monitoring programs, creating protected areas and including such species in environmental assessments.
Why is deep-sea mining so harmful?
Deep-sea mining is set to occur in the Clarion-Clipperton Zone, a large abyssal plan area spanning from the waters around Hawaii into the eastern Pacific Ocean. However, this zone has recently been revealed as a hotspot for new species: researchers discovered more than 5,000 species there that are new to science.
Yet these new species face the threat of being killed through direct contact with heavy mining equipment deployed on the seabed, or via plumes of sediment.
In the long term, mining activities could impair the feeding and reproduction of deep-sea species through intense noise and light pollution in what is an otherwise dark and silent environment. Since many deep-sea species already reproduce very slowly, this poses a real risk to their viability.
As well as the impacts toward marine life, deep-sea mining also poses challenges onshore. The deep-sea mining industry would need shoreline facilities for processing and shipping materials, requiring development of these areas. Historically, such changes have affected coastal communities depending on marine resources.
