Deep sea mining may lead to loss of biodiversity, scientists warn

Mining the deep ocean floor would inevitably lead to the loss of biodiversity, which cannot be compensated for through biodiversity offsets, 15 marine scientists and legal scholars argue in a letter published on Monday in the journal Nature Geoscience.
The rules that will govern the emerging deep sea mining industry – including environmental protection measures – are currently being drafted by the International Seabed Authority (ISA), an intergovernmental body. The letter’s authors say the ISA must recognise the threat mining poses to marine life, and communicate it clearly to its member states and to the public.
With the deep seabed environment still largely unexplored, mining may lead to the loss of undiscovered species, making biodiversity offsets impossible. Out-of-kind biodiversity offsets, which involve restoring or preserving very different marine habitats like tropical coral reefs, cannot compensate for the loss of unknown deep-sea species.
“With interest in deep sea mining growing exponentially, now is the time to ensure that lasting damage to the unique ecosystems found in the ocean depths can be prevented. The new rules governing deep sea mining must take its full costs to society and the environment into account,” says Kristina Gjerde, IUCN’s Global Marine and Polar Programme senior advisor on High Seas issues and co-author of the letter. “Improved scientific research is essential to better understand the deep sea environment and the potential impacts of mining. We also need to engage all levels of society to weigh the value of deep sea minerals against the unavoidable loss of living systems in the deep sea.”
Deep sea mining is still an experimental field that targets minerals such as copper, nickel and cobalt, used for the production of technologies like wind turbines and hybrid cars. Mining may destroy deep sea habitats, eradicate rare and unique species, and introduce sediment clouds, noise, toxic chemicals, vibration and other forms of pollution into pristine environments. Ecosystem and species recovery may take decades to centuries, if it occurs at all, according to the authors.
Restoring ecosystems damaged by mining is not realistic in a deep-sea environment, the letter states. This is because of the high cost of working on the deep sea floor, the extremely slow recovery of deep sea species and the enormous spatial scales of deep-sea mining for some minerals. A single 30-year licence to mine metal-rich nodules will involve an area the size of Austria, for example.
Biodiversity loss can be reduced with techniques like patchwork extraction, where some sites are set aside, although this does not prevent harmful side-effects. For example, the dispersion of fine and potentially toxic particles in plumes can smother and kill marine species.
According to the UN Convention on the Law of the Sea, the deep seabed and its mineral resources beyond national jurisdiction are the common heritage of mankind, and do not belong to any one country.
Deep-sea scientists and legal experts who co-wrote the peer-reviewed correspondence with IUCN’s Kristina Gjerde include C. L. Van Dover of Duke University, USA; J.A. Ardron and D. Jones of the University of Southampton; M. Gianni of the Deep-Sea Conservation Coalition; A. Jaeckel of Macquarie University; L.A. Levin of Scripps Institution of Oceanography; H. Niner of University College London; C.R. Smith and L. Watling of the University of Hawaii at Manoa; T. Thiele of the London School of Economics; P.J. Turner of Duke; and P.P.E. Weaver of Seascape Consultants.