The deep sea as a target for exploitation

The deep sea has always been an important area for human exploitation: resources such as fish, oil and gas have been taken from the sea for many decades, and more recently the marine environment has been targeted as a source of renewable energy. The recognition that metalliferous deposits on the seafloor could provide a valuable source of scare metals has become increasingly widespread in the past 5 years, though the concept of deep-sea mining was first introduced in the 1960's. Over the past decade the demand for precious metals for advancing technologies has rocketed, making deep-sea deposits increasingly attractive to commercial operators. The most likely targets for deep-sea mining are polymetallic sulphides, manganese nodules and  cobalt-rich ferromanganese crusts . On a longer time scale, rare earth elements (REEs) in deep-sea muds may also become important, and there has long been interest in the extraction of gas hydrates as a source of hydrocarbons.


Map showing location of current ISA licensed exploration areas


Mineral exploration activities have already taken place in prospective areas of the ocean beyond national jurisdiction under license from the International Seabed Authority, most notably around the Clarion-Clipperton Zone in the Pacific Ocean, parts of the Indian Ocean and along the Mid-Atlantic Ridge (see map, right). In territorial waters, commercial activity has progressed more rapidly and the extraction of gold, copper and silver from deep water deposits offshore Papua New Guinea is close to becoming a reality.



The extraction of deep-sea mineral resources will have a significant impact on the marine environment, particularly its ecosystems. The scale and nature of these impacts remains uncertain and depends on the target resource and its associated ecosystems, and the technology used to extract the ore. Deep-sea mining will potentially affect extensive areas of seabed and will likely produce near-bottom, mid-water or near-surface sediment plumes. Seabed mining at sea may result in the emission of toxic materials into the ocean, or the discharge of fine particulate material that can smother benthic communities. There is therefore an urgent need to assess the nature and scales of the potential impacts of mining, and how they will affect deep-sea ecosystems. 



Swarms of the shrimp Rimicaris exoculata bathing in warm waters of an hydrothermal vent of the Mid-Atlantic Ridge. Image couresy Ifremer, Exomar cruise 2005.



Many deep-sea habitats extend over large areas, but the extent of individual species and habitat ranges are largely unknown. Some habitats, such as hydrothermal vents (shown right), are highly localised and may be particularly vulnerable to mining impacts. Greater knowledge is needed on the diversity, resilience, species ranges, life cycles and ecosystem functioning of deep-sea fauna. Only then will it be possible to safeguard and conserve future prosperity from deep-sea ecosystem services. This research has pressing importance as commercial, political and public interest in the extraction of metals from the deep sea increases.





MIDAS will identify the potential scale and impact of each of these activities in European seas and in the global ocean, focusing on the scale of physical impacts, the dynamics of particle-laden hydrodynamic plumes, and the potential toxins that may be released in the mining process. We will assess the potential effects of these impacts on deep-sea ecosystems, including the possible loss of species and ecosystem functions, and propose targets for their protection, monitoring and restoration.