Climate change, population growth, urbanization and clean energy are some of the major challenges the world faces in the years ahead. Metals like nickel, cobalt, copper and manganese are essential to address these needs. On land, they are becoming increasingly difficult to access, or even scarce. This is one of the reasons for the growing interest in mineral exploitation in the deep-sea (Roche and Feenan, 2013).
The deep-sea is a vast and largely unknown area. Its abyssal plains in depths of > 3000 m cover more than half of the Earth’s surface. In these areas, large amounts of mineral deposits known as polymetallic nodules can be found. They contain increased concentrations of the above mentioned minerals and rare-earth elements which are needed for most of our current technology. These round or cauliflower-shaped small rocks are scattered on the surface of the abyssal sediment in all ocean basins where sedimentation rates are extremely low (lower than 20 mm per thousand years) (Petersen et al., 2016).
Ghent University has been involved in a number of international and interdisciplinary European projects such as the MIDAS project (Managing Impacts of Deep-Sea Resource Exploitation) and the Joint Programming Initiative (JPI) “Ecological impacts of Deep-Sea Mining”, aiming to unravel the impacts of deep-sea mining on the marine environment. Indeed, polymetallic nodules also fulfil a major role as providers of hard substrate in the otherwise soft environment of the abyssal seafloor. Mining of these hard substrates would threaten the sessile epifauna including sponges, corals, crinoids or sea pens, but also the associated mobile fauna including isopods, ophiuroids or octopods (Vanreusel et al., 2016).
The largest density of economically valuable polymetallic nodules is found in the Clarion-Clipperton Fracture Zone. This is an area in the subtropical North-East Pacific Ocean, located between Hawaii and Mexico, about 5.000 meters beneath the ocean level. The Clarion-Clipperton Fracture Zone is a 6.000 km by 1.000 km tract between two of the long, straight fracture zones that were created by the stresses of plate tectonics in the crust. It is one of the areas managed by the International Seabed Authority (ISA), an independent legislative body regulating activities regarding the deep seafloor. As of 2018, the ISA has issued sixteen 15-year contracts of approximately 75.000 km² for the exploration of polymetallic nodules in the Clarion-Clipperton Fracture Zone. One of these contractors is the Belgian dredging company DEME with its in-house deep-sea exploration and exploitation specialist Global Sea Mineral Resource (GSR). Ghent University and GSR are working together on environmental baseline studies and environmental risk assessments. Through several expeditions to the Clarion-Clipperton Fracture Zone, GSR was able to gather large amounts of biological, oceanographic, geological and mineral resource information. They were also able to test their first small-scale mining prototype Patania I in May 2017. While this device was built to gather information of how larger robots can move across the seafloor, its successor, Patania II will have a larger size to mimic a more realistic scenario.
In 2019, the testing of Patania II will be closely monitored and valuable information about impacts such as sediment plume dispersal, nodule removal and sediment compaction will be gathered. This will happen in collaboration with an international scientific consortium within a new JPI Oceans project, including Ghent University. The test will not only inform about the technological feasibility of deep-sea mining but also about ecosystem responses to a large-scale disturbance and the testing and standardizing of appropriate monitoring techniques of this seafloor disturbance. With this information, mining regulations that are drafted by the ISA can be updated and adjusted to ensure that deep-sea mining will cause least harm to the environment.
Roche, C., Feenan, J., 2013. Drivers for the development of deep-sea minerals in the Pacific, in: Baker, E., Beaudoin, Y. (Eds.), Deep Sea Minerals and the Green Economy. Secretariat of the Pacific Community, Fiji, pp. 22–40.
Vanreusel, A., Hilario, A., Ribeiro, P.A., Menot, L., Arbizu, P.M., 2016. Threatened by mining, polymetallic nodules are required to preserve abyssal epifauna. Scientific Reports 6, 26808. https://doi.org/10.1038/srep26808
DEME/GSR, website: https://www.deme-group.com/gsr/
International Seabed Authority, website: https://www.isa.org.jm