MiningImpact project partners publish new study in Scientific Reports | JPI OCEANS

MiningImpact project partners publish new study in Scientific Reports

2019.06.26

MiningImpact project partners publish new study in Scientific Reports

The publication shows that the impacts of seabed mining on deep-sea ecosystems can persist for decades.
In the first JPI Oceans MiningImpact project scientists revisited a site nearly 30 years after it had been exposed to simulated deep-sea mining activity to assess seabed and ecosystem recovery. With a robot submarine the seafloor in the disturbed area was mapped and photographed in unprecedented detail. The images were combined into a seafloor photo-mosaic completely covering 11 hectares of seabed, the largest photo-mosaic of the abyssal ocean ever obtained. Tracks on the seafloor caused by the simulated mining were still clearly visible, and the impacts on marine life initially observed in 1989 persist.
 
The study, published on 29 May 2019 in Scientific Reports, was able to pinpoint individual animals over a wide area and relate their abundance and distribution to the seafloor perturbation. While mobile species, such as sea cucumbers and sea stars, were able to recolonise impacted areas, animals such as sponges and sea anemones that live attached to the seafloor are restricted to undisturbed areas but remain virtually absent from directly disturbed seabed. Given the important role of these animals in abyssal ecosystems, the results of the study suggest that impacts of large-scale commercial mining could lead to an irreversible loss of key ecosystem functions, especially in the directly disturbed mining tracks.
 
 
The impacts of mining may be further exacerbated by removing the home for many animals. The target of this type of deep-sea mining is polymetallic nodules, potato-shaped rocks rich in copper, cobalt, nickel and manganese. These nodules provide a stable anchoring point for colonisation with anemones, soft corals, and sponges, and promote the development of surprisingly diverse communities on otherwise muddy seabed. The nodules take millions of years to form. Removal or burial of nodules from mining activities will remove the home of many of these filter-feeding animals, constraining their capacity to recolonise impacted zones and further impairing ecosystem recovery.
 
The site investigated is known as the “DISturbance and reCOLonization experiment” (DISCOL), and lies in the deep Pacific Ocean off Peru at around 4000 metres water depth. The seafloor was disturbed as an experiment in 1989 by a team of German researchers. This is still to date the largest disturbance experiment carried out in an abyssal environment. With mining activities potentially on the horizon, long-term experiments such as this are critical to providing the body of knowledge needed to assess and improve the sustainability of the developing deep-sea mining industry.
 
Erik Simon-Lledo, the lead author of the study said “The clear lack of recovery that we observed in the DISCOL site should be taken as a warning of the real disturbance potential of commercial mining in the deep ocean, which we are still far from fully understanding. Further experiments are urgently needed to generate the baseline knowledge that is required for efficient regulation of deep-sea mining activities”.
 
The study is the result of a collaboration between the UK National Oceanography Centre and the GEOMAR Helmholtz Centre for Ocean Research in Kiel (Germany) in the MiningImpact project, funded under the framework of JPI Oceans.

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