Deep sea mining
.png) Deep sea mining is the extraction of minerals from the seabed of the deep sea. The main ores of commercial interest are polymetallic nodules, which are found at depths of 4–6 km (2.5–3.7 mi) primarily on the abyssal plain. The Clarion–Clipperton zone (CCZ) alone contains over 21 billion metric tons of these nodules, with minerals such as copper, nickel, cobalt and manganese making up roughly 30% of their weight.[2] It is estimated that the global ocean floor holds more than 120 million tons of cobalt, five times the amount found in terrestrial reserves.[3] As of July 2024[update], only exploratory licenses have been issued, with no commercial-scale deep sea mining operations yet. The International Seabed Authority (ISA) regulates all mineral-related activities in international waters and has granted 31 exploration licenses so far: 19 for polymetallic nodules, mostly in the CCZ; 7 for polymetallic sulphides in mid-ocean ridges; and 5 for cobalt-rich crusts in the Western Pacific Ocean.[4] There is a push for deep sea mining to commence by 2025, when regulations by the ISA are expected to be completed.[5][6] In April 2025, U.S. President Trump signed an Executive Order instructing the National Oceanic and Atmospheric Administration to expedite permits for companies to mine in both international and U.S. territorial waters, citing the Deep Seabed Hard Minerals Resource Act of 1980.[7] Deep sea mining is being considered in the exclusive economic zone (EEZ) of countries, such as Norway, where in January 2024 the government announced its intention to allow companies to apply for exploration permits in 2025. In December 2024, Norway's plans to begin awarding exploration licenses were temporarily put on hold after the Socialist Left Party (SV) blocked the planned licensing round as part of negotiations over the government budget.[8][9] In 2022, the Cook Islands Seabed Minerals Authority (SBMA) granted three exploration licenses for cobalt-rich polymetallic nodules within their EEZ.[10] In 2025, it was announced that the Cook Islands had signed a deal with China focussed on deep-sea mining.[11] Papua New Guinea was the first country to approve a deep sea mining permit in state waters for the Solwara 1 project, despite three independent reviews highlighting significant gaps and flaws in the environmental impact statement.[12] The most common commercial model of deep sea mining proposed involves a caterpillar-track hydraulic collector and a riser lift system bringing the harvested ore to a production support vessel with dynamic positioning, and then depositing extra discharge down the water column below 2,000 meters. Related technologies include robotic mining machines, as surface ships, and offshore and onshore metal refineries.[13][14] Though largely composed of nickel and manganese which are most widely used as key inputs into the steel industry, wind farms, solar energy, electric vehicles, and battery technologies use many of the deep-sea metals.[13] Electric vehicle batteries are a key driver of the critical metals demand that incentivizes deep sea mining, as well as demands for the production of aerospace and defense technologies, and infrastructure.[15][16] The environmental impact of deep sea mining is controversial.[17][18] Environmental advocacy groups such as Greenpeace and the Deep Sea Mining Campaign[19] claimed that seabed mining has the potential to damage deep sea ecosystems and spread pollution from heavy metal-laden plumes.[20] Critics have called for moratoria[21][22] or permanent bans.[23] Opposition campaigns enlisted the support of some industry figures, including firms reliant on the target metals. Individual countries like Norway, Cook Islands, India, Brazil and others with significant deposits within their exclusive economic zones (EEZ's) are exploring the subject.[24][25] As of 2021, the majority of marine mining used dredging operations in far shallower depths of less than 200 m, where sand, silt and mud for construction purposes is abundant, along with mineral rich sands containing ilmenite and diamonds.[26][27] Deposit typesDeep sea ore deposits are classified into three main types: polymetallic nodules, polymetallic sulfide deposits, and cobalt-rich crusts.[28]: 356 Polymetallic nodules.jpg){kind=logo} _(Pacific_Ocean)_2.jpg) Polymetallic nodules are found at depths of 4–6 km (2.5–3.7 mi) in all major oceans, though due to their metallic composition those in the Pacific Ocean are of greatest commercial interest.[29][30] Nodules may also be found in shallow waters like the Baltic Sea and in freshwater lakes.[31][32] They are the most readily minable type of deep sea ore.[33] These nodules typically range in size from 4–14 cm (1.6–5.5 in) in diameter, though some can be as large as 15 cm (5.9 in). Manganese and related hydroxides precipitate from ocean water or sediment-pore water around a nucleus, which may be a shark's tooth or a quartz grain, forming potato-shaped nodules some 4–14 cm (1.6–5.5 in) in diameter. They accrete at rates of 1–15 mm per million years.[34] These nodules are rich in metals including rare earth elements, cobalt, nickel, copper, molybdenum, and yttrium.[35] The Clipperton fracture zone hosts the world's largest deposit nickel resource. These nodules sit on the seafloor and require no drilling or excavation.[2] Nickel, cobalt, copper and manganese make up nearly 30% of the contents.[2]
Polymetallic sulfidesPolymetallic or sulfide deposits form in active oceanic tectonic settings such as island arcs and back-arcs and mid ocean ridge environments.[37] These deposits are associated with hydrothermal activity and hydrothermal vents at sea depths mostly between 1 and 4 km (0.62 and 2.5 mi) and therefore located in shallower waters to other marine mineral types like polymetallic nodules. These minerals are rich in copper, gold, lead, silver and others.[28]: 356 Polymetallic sulphides appear on seafloor massive sulfide deposits. They appear on and within the seafloor when mineralized water discharges from a hydrothermal vent. The ionic metals and sulfides in the hot, mineral-rich water precipitate upon contact with cold seawater.[34] The stock area of the chimney structures of hydrothermal vents can be highly mineralized. Cobalt-rich crustsCobalt-rich crusts (CRCs) form on sediment-free rock surfaces around oceanic seamounts, ocean plateaus, and other elevated features.[38] The deposits are found at depths of 600–7,000 m (2,000–23,000 ft) and form 'carpets' of metal-rich layers about 30 cm (12 in) thick at the feature surface. Crusts are rich in a range of metals including cobalt, tellurium, nickel, copper, platinum, zirconium, tungsten, and rare earth elements.[28]: 356 Temperature, depth and seawater sources shape how the formations grow. Cobalt-rich formations exist in two categories depending on the depositional environment:[39]
Submarine seamount provinces are linked to hotspots and seafloor spreading and vary in depth. They show characteristic distributions. In the Western Pacific, a study conducted at <1500 m to 3500 m bsl reported that cobalt crusts concentrate on less than 20° slopes. The high-grade cobalt crust in the Western Pacific correlated with latitude and longitude, a region within 150°E–140°W and 30°S–30°N.[40]
Diamonds are mined from the seabed by De Beers and others. Deposit sitesDeep sea mining sites hold polymetallic nodules or surround active or extinct hydrothermal vents at about 3,000–6,500 meters (10,000–21,000 ft) depth.[42][41] The vents create sulfide deposits, which collect metals such as silver, gold, copper, manganese, cobalt, and zinc.[20][43] The deposits are mined using hydraulic pumps or bucket systems. The largest deposits occur in the Clarion–Clipperton zone in the Pacific Ocean. It stretches over 4.5 million square kilometers of the Northern Pacific Ocean between Hawaii and Mexico.[44] Scattered across the abyssal plain are trillions of polymetallic nodules, potato-sized rocklike deposits containing minerals such as manganese, nickel, copper, zinc, and cobalt.[44] The Cook Islands contains the world's fourth largest deposit in the South Penrhyn basin close to the Manihiki Plateau.[35] Though the nodule fields of greatest commercial interest are located in the eastern Pacific,[29][30] polymetallic nodules are also found within the Mid-Atlantic Ridge system, around Papua New Guinea, Solomon Islands, Vanuatu, and Tonga,[28]: 356 and the Peru Basin.[45] Cobalt-rich crusts are found on seamounts in the Atlantic and Indian Ocean, as well as countries such as the Pacific Federated States of Micronesia, Marshall Islands, and Kiribati.[28]: 356 On November 10, 2020, the Chinese submersible Striver reached the bottom of the Mariana Trench 10,909 meters (35,790 feet). Chief designer Ye Cong said the seabed was abundant with resources and a "treasure map" can be made.[46] Promising sulfide deposits (an average of 26 parts per million) were found in the Central and Eastern Manus Basin around Papua New Guinea and the crater of Conical Seamount to the east. It offers relatively shallow water depth of 1050 m, along with a nearby gold refinery.[43] United StatesA 2023 study identified four regions in US territorial waters where deep sea mining would be possible: the Hawaiian Islands, the southeastern Blake Plateau, California, and the Gulf of Alaska. Hawaii has both nodules and CRCs, while the other sites hold CRCs. Each area features distinct risks. Mining Hawaii could generate plumes that could damage important fisheries and other marine life. California's waters host massive ship traffic and communication cables. Alaska waters are rich in bottom-dwelling commercially valuable sea life.[47] In April 2025, U.S. President Trump signed an Executive Order instructing the National Oceanic and Atmospheric Administration to expedite permits for companies to mine in both international and U.S. territorial waters, citing the Deep Seabed Hard Minerals Resource Act of 1980.[7] This would allow mining of the deep seabed for the first time in the country. Deep sea mining projectsHakureiThe world's first large-scale mining of hydrothermal vent mineral deposits was carried out by Japan Oil, Gas and Metals National Corporation (JOGMEC) from August to September 2017,[48] using the research vessel Hakurei,[49] at the 'Izena hole/cauldron' vent field within the hydrothermally active back-arc Okinawa Trough, which contains 15 confirmed vent fields according to the InterRidge Vents Database.[50] Solwara 1The Solwara 1 Project was the first time a legitimate legal contract and framework had been developed on deep sea mining.[51] The project was based off the coast of Papua New Guinea (PNG), near New Ireland province. The project was a joint venture between Papua New Guinea and Nautilus Minerals Inc. Nautilus Minerals held a 70% stake and Papua New Guinea purchased a 30% stake in 2011.[52] PNG's economy relies upon the mining industry, which produces around 30–35% of GDP.[53] Nautilus Minerals is a Canadian deep-sea mining company.[51] The project was approved in January 2011, by PNG's Minister for Mining, John Pundari.[51] The company leased a portion of the seabed in the Bismarck Sea.[54] The lease licensed access to 59 square kilometers. Nautilus was allowed to mine to a depth of 1,600 meters for a period of 20 years.[54][53] The company then began the process of gathering the materials and raising money for the project.[55] The intent was to mine a high grade copper-gold resource from a weakly active hydrothermal vent.[56] The target was 1.3 tons of materials, consisting of 80,000 tons of high-grade copper and 150,000 to 200,000 ounces of gold sulfide ore, over 3 years.[53] The project was to operate at 1600 mbsl[56] using remotely operated underwater vehicles (ROV) technology developed by UK-based Soil Machine Dynamics.[57] Community and environmental activists[21] launched the Deep Sea Mining Campaign[58] and Alliance of Solwara Warriors, comprising 20 communities in the Bismarck and Solomon Seas who attempted to ban seabed mining. Their campaign against the Solwara 1 project lasted for 9 years. Their efforts led the Australian government to ban seabed mining in the Northern Territory.[59] In June 2019, the Alliance of Solwara Warriors wrote the PNG government calling for them to cancel all deep sea mining licenses and ban seabed mining in national waters.[59] They claimed that PNG had no need for seabed mining due to its abundant fisheries, productive agricultural lands, and marine life.[59] They claimed that seabed mining benefited only a small number of already wealthy people, but not local communities and Indigenous populations.[59] Others chose to engage in more artistic forms, such as Joy Enomoto.[60] She created a series of woodcut prints titled Nautilus the Protector. The activist community argued that authorities had not adequately addressed free, prior and informed consent for affected communities and violated the precautionary principle.[61] In December 2017 the company had difficulties in raising money and eventually could no longer pay what it owed to the Chinese shipyard where the "production support vessel" was docked.[52] Nautilus lost access to the ship and equipment.[52] In August 2019, the company filed for bankruptcy, delisted from the Toronto Stock Exchange, and was liquidated.[62] PNG lost over $120 million dollars.[52] Nautilus was purchased by Deep Sea Mining Finance LTD. PNG has yet to cancel the extraction license contract. ShellIn the 1970s Shell, Rio Tinto (Kennecott) and Sumitomo conducted pilot test work, recovering over ten thousand tons of nodules in the CCZ.[63] LicensesLicences for mineral exploration in the area beyond national jurisdiction registered with the International Seabed Authority (ISA) are mostly located in the CCZ.[41] As of June 2025, the ISA has entered into 17 contracts with private companies and national governments for polymetallic nodules in the CCZ, one contract with the Government of India in the Central Indian Ocean Basin (CIOB), and one contract with Chinese contractor Beijing Pioneer Hi-Tech Development Corporation in the Prime Crust Zone (PCZ) in the Western Pacific.[45] Cook IslandsIn 2019, the Cook Islands passed two deep sea mining laws. The Sea Bed Minerals (SBM) Act of 2019 was to enable "the effective and responsible management of the seabed minerals of the Cook Islands in a way that also...seeks to maximize the benefits of seabed minerals for present and future generations of Cook Islanders."[64] The Sea Bed Minerals (Exploration) Regulations Act and the Sea Bed Minerals Amendment Act were enacted in 2020 and 2021, respectively.[65] In February 2022, the Cook Islands government Seabed Minerals Agency (SBMA) announced the award of three five-year licences exploration activities in Cook Islands EEZ to private companies Moana Minerals Limited, the Cook Islands Consortium (CIC), and Cook Islands Investment Corporation - Seabed Resources (CIIC-SR). Moana Minerals is a subsidiary of Ocean Minerals LLC (OML), a US-based private investment firm led by President and CEO Hans Smit. Hans Smit previously led Neptune Minerals, Inc a DSM company interested in SMS exploitation in Papua New-Guinean waters. He also served as managing director of Royal IHC MMP, focused on underwater mining activities, and worked on underwater mining systems used for subsea diamond mining.[66] In 2023, the SBMA announced the results of a technical report on the polymetallic nodule deposit of the Cook Islands' exclusive economic zone, undertaken on its behalf by RSC Mining and Mineral Exploration. The study was based on the analysis of both historical samples from previous scientific cruises, as well as data from recent work undertaken by SBMA PMN exploration contractors CIIC-SR and Moana. RSC produced a JORC Code (2012)-compliant Mineral Resource Statement for parts of the EEZ totalling 6.7 billion tons of polymetallic nodules (wet), grading 0.44% Co, 0.21% Cu, 17.4% Fe, 15.8% Mn, and 0.37% Ni. Of this total resource, 304 million tons of nodules grading 0.5% Co, 0.15% Cu, 18.5% Fe, 15.4% Mn, and 0.25% Ni, are assessed at Indicated Resource, whereas Inferred Resources account for 6.4 billion tons grading 0.4% Co, 0.2% Cu, 17% Fe, 16% Mn, and 0.4% Ni.[67]
In 2025, the Cook Islands announced that it had signed a five-year agreement with China focussed on exploration and research into seabed minerals.[11] The Metals Company (TMC)In 2011, the Republic of Nauru sponsored an ISA exploration contract with exploration activities carried out by Nauruan company, Nauru Ocean Resources Inc (NORI).[68] NORI is a wholly owned subsidiary of Canadian company, The Metals Company.[69][70] Since then, The Metals Company has conducted 22 offshore research campaigns on the NORI exploration area as part of its Environmental and Social Impact Assessment.[71] On June 29, 2021, the Republic of Nauru invoked the 'Two-Year Notice' provision of the 1994 Implementation Agreement requiring the ISA to finalize and adopt a Mining Code within two years.[72] This two year deadline elapsed on July 9, 2023, meaning that The Metals Company and other contractors can submit an application for commercial exploitation at any time.[73] The Metals Company also controls two further ISA exploration licences in the CCZ through Kiribati-based Marawa Research and Exploration Ltd., and through its Tongan subsidiary Tonga Offshore Mining Limited (TOML), which it acquired from Deep Sea Mining Finance Limited in April 2020.[74] In April 2025, following U.S. President Donald Trump's Executive Order on offshore mining, The Metals Company submitted applications for a commercial recovery permit and two exploration licenses under the Deep Seabed Hard Mineral Resources Act and regulations set by the National Oceanic and Atmospheric Administration. The commercial recovery permit covers 25,160 square kilometers while the two exploration licence applications cover a combined 199,895 square kilometers.[75] NorwayIn January 2024 Norway's parliament allowed multiple companies to begin submitting applications to prospect for DSM resources, mainly Seafloor Massive Sulfides (SMS), but also potentially Cobalt-rich crusts in the Norwegian EEZ, as well as on its continental shelf extension, along Mohns and Knipovich ridges Jan Mayen and Svalbard in the North Atlantic.[76] Norway's Institute of Marine Research recommended five to ten years of research before allowing mining. In late April 2024, the Norwegian Offshore Directorate invited interested parties to nominate blocks in this area for a first round of mineral exploration licences.[77] First licence awards are expected for early 2025.[78] Three Norwegian start-up companies, Loke Marine Minerals, Green Minerals, and Adepth Minerals were expected to apply for licenses.[79] In March 2023 Loke acquired Lockheed Martin subsidiary UK Seabed Resources Limited (UKSRL). This saw UKSRL's two PMN exploration licences in the CCZ, as well as its 19.9% stake in Ocean Minerals Singapore (OMS), an ISA contractor for PMNs in the CCZ.[80] OMS is majority-controlled by Singaporean state-owned Keppel Offshore & Marine, now part of also Singaporean state-owned Seatrium.[81][82] Green Minerals is another Norwegian company which has expressed interested in mining seafloor massive sulfide (SMS) deposits in the Norwegian EEZ.[83] In January 2023, Green Minerals signed a memorandum of understanding with the ISA to obtain an exploration licence for PMNs in the CCZ.[84] In its May 2024 Capital Markets Day Presentation, it confirmed its ambitions to commence mining operations on SMS deposits on the Norwegian continental shelf and EEZ by 2028, as well as explore for PMNs in the CCZ in the future.[78] After in April 2024, the Norwegian government opened up an exploration area in the Norwegian and Greenland Seas, the World Wide Fund for Nature (WWF) declared that it would take legal action against the decision. According to the government, the seabed contains many resources including copper, zinc and cobalt, which are necessary for producing mobile phones, wind turbines, computers and batteries but as for now supplies are controlled by China or "authoritarian countries". In June the energy ministry submitted "a proposal to announce the first licensing round on the Norwegian continental shelf for public consultation." According to the government, the aim is to understand if a sustainable deep sea mining there can occur. Otherwise, "deep-sea mining would not be permitted".[85] Extraction methods Robotics and AI technologies used to selectively harvest nodules while minimizing disturbances to the deep sea environment are under development.[86] Remotely operated vehicles (ROVs) are used to collect mineral samples from prospective sites, using drills and other cutting tools. A mining ship or station collects the deposits for processing.[57] The continuous-line bucket system (CLB) is an older approach. It operates like a conveyor-belt, running from the bottom to the surface where a ship or mining platform extracts the minerals, and returns the tailings to the ocean.[87] Hydraulic suction mining instead lowers a pipe to the seafloor and pumps nodules up to the ship. Another pipe returns the tailings to the mining site.[87] Borehole Mining is used for mining of natural resources from below the seafloor. ProcessThe three stages of deep-sea mining are prospecting, exploration and exploitation. Prospecting entails searching for minerals and estimating their size, shape and value. Exploration analyses the resources, testing potential recovery and potential economic/environmental extraction impacts. Exploitation is the recovery of these resources.[88] Resource assessment and pilot mining are part of exploration. If successful, "resources" attain a "reserves" classification.[89] Bottom scanning and sampling use technologies such as echo-sounders, side scan sonars, deep-towed photography, remotely operated vehicles, and autonomous underwater vehicles (AUV). Extraction involves gathering material (mining), vertical transport, storing, offloading, transport, and metallurgical processing. Polymetallic minerals require special treatment. Issues include spatial tailing discharges, sediment plumes, disturbance to the benthic environment, and analysis of regions affected by seafloor machines.[89] Environmental impactsDeep sea mining has significant environmental impacts. Research on deep-sea polymetallic nodule mining has substantially increased in recent years, but the expected level of environmental impact is still being established.[1] Scientists from MIT examined seafloor sediment plumes generated by a prototype mining collector in the Clarion Clipperton Zone and found that the plume forms a low-lying turbidity current which hugs the seafloor.[90] Another MIT-led study found that modelling can reliably predict plume behaviour in the midwater column, and impact is influenced by the quantity of discharged sediment, and the turbulence of the water upon discharge.[1] Meta-analysis of 11 separate disturbance and test mining studies showed that impacts are often severe immediately after mining, with major negative changes in density and diversity of most groups occurring. Almost all studies show some recovery in faunal density and diversity for meiofauna and mobile megafauna, often within one year. However, very few faunal groups return to baseline or control conditions after two decades.[91] Benchmark Mineral Intelligence, commissioned by The Metals Company, conducted a life cycle assessment of the environmental impact of producing critical minerals from polymetallic nodules in the Clarion-Clipperton Zone (CCZ). The study found that the deep-sea model performed better environmentally than traditional land-based methods, showing 54-70% lower Global Warming Potential (GWP) on average, due to renewable energy use, high metal recovery, and efficient processes.[92] Another study in the Journal of Cleaner Production found that the production of 1 billion electric vehicles using nodules would produce 90% less CO2 equivalent than producing the same amount of vehicles through land-based mining.[93] While some environmental consequences (such as sediment plumes, disturbance of the bottom, and toxic effects) are known, the scientific understanding of deep sea ecosystems is currently insufficient to evaluate all possible impacts.[20] Technology is under development to mitigate these issues. This includes selective pick-up technology that leaves alone nodules that contain life and leaves behind some nodules to maintain the habitat.[86] The United Nations Environment Programme (UNEP) emphasizes the need for a comprehensive assessment of the environmental impacts of deep-sea mining, which targets polymetallic nodules at depths of 3–6.5 km (1.9–4.0 mi), polymetallic sulphides at 1–4 km (0.62–2.5 mi), and cobalt-rich ferromanganese crusts between <400 m and 3.5 km. Researchers and governments have raised significant concerns about the potential impacts on unique and fragile ecosystems, with only 24.9% of the deep seabed mapped. These ecosystems are essential for ocean and carbon cycling and are vulnerable to climate change. There are widespread calls for a moratorium on deep-sea mining until its environmental, social, and economic risks are fully investigated. The International Seabed Authority (ISA) aims to finalize exploitation regulations by 2025, and a new agreement under the UN Convention on the Law of the Sea (UNCLOS) on marine biodiversity was adopted on 19 June 2023.[94] Sediment plumesPlumes are caused when seawater and sediment separated from nodules at the surface are is returned to the ocean. As the particles are fine (small and light), they can remain suspended in the water column for extended periods and spread over large areas if regenerated at the surface of the ocean. All proposed projects expect to release sediment at depths of below 2,000 meters below the Oxygen Minimum Zone. Tailings increase water turbidity (cloudiness). Plumes form wherever the tailings are released, typically either near the bottom plumes or at the surface.[41][95] Mining-generated plumes differ significantly from traditional mining tailings, as deep-sea sediment primarily consists of naturally occurring, unprocessed material rather than chemically altered waste. Studies show that most suspended particles settle relatively quickly, with heavy sediment blanketing confined to a limited area near the source. The extent of dispersion depends on local hydrodynamics, sediment properties, and mining technology.[1][96][97] Near-bottom plumes occur when the sediment is pumped back down to the mining site. Depending on particle size and water currents, surface plumes can spread widely.[41][87] In shallow water, sediment can resuspend following storms, starting another cycle of damage. In-situ studies show most seafloor sediment settles rapidly, with 90% depositing within 2 km and the vast majority within 9 km, even under extreme conditions, while heavy sediment blanketing remains confined to a small area near the source.[1][96][97] Benthic disturbanceDisturbing or, in the case of seafloor massive sulfides and cobalt crusts, removing parts of the sea floor impacts the habitat of benthic organisms, albeit to varying degrees.[41][97] A study analyzing data from 11 experimental mining simulations found that deep-sea mining activities cause immediate declines in faunal density and diversity, with mobile and small-sized fauna recovering more quickly. Some ecosystems fail to return to pre-disturbance levels after 26 years, while some faunal groups partially rebound, particularly meiofauna and mobile megafauna. Due to limited testing, comparable assessments for seafloor massive sulfides (SMS) and cobalt-rich crusts remain limited.[98][99] Nodule fields provide hard substrate on the bottom, attracting macrofauna. A study of benthic communities in the CCZ assessed a 350 square mile area with an ROV. They reported that the area contained a diverse abyssal plain megafaunal community.[99] Megafauna (species longer than 20 mm (0.79 in)) included glass sponges, anemones, eyeless fish, sea stars, psychropotes, amphipods, and isopods.[99] Macrofauna (species longer than 0.5mm) were reported to have high species diversity, numbering 80 -100 per square meter. The highest species diversity was found among polymetallic nodules.[99] In a follow-up survey in areas with potential for seabed mining, researchers identified over 1,000 species, 90% previously unknown, with over 50% dependent on polymetallic nodules for survival.[99] Noise and light pollutionDeep sea mining generates ambient noise in normally quiet pelagic environments. However, planned operations will not use sonar and are not expected to make dangerously loud noises, with most noise highly localized and similar to that of typical marine shipping operations.[100] Noise pollution affects deep sea fish species and marine mammals, though due to the low surface productivity of its surface waters the Clarion Clipperton Zone is unlikely to be a feeding or breeding site for large marine mammals.[100] Impacts include behavior changes, communication difficulties, and temporary and permanent hearing damage.[101] Light pollution affects the environment of DSM sites as they are normally pitch dark. Mining efforts may increase light levels to illuminate the bottom. Shrimp found at hydrothermal vents suffered permanent retinal damage when exposed to submersible floodlights.[101] Behavioral changes include vertical migration patterns, ability to communicate, and ability to detect prey.[102] EcosystemPolymetallic nodule fields are hotspots of abundance and diversity for abyssal fauna.[103] Sediment can clog filter-feeding organisms such as manta rays.[95] As they block the sun, they inhibit growth of photosynthesizing organisms, including coral and phytoplankton. Phytoplankton sit at the bottom of the food chain. Reducing phytoplankton reduces food availability for all other organisms.[41][104] Metals carried by plumes can accumulate in tissues of shellfish.[105] This bioaccumulation works its way through the food web, impacting predators, including humans. A recent study claimed that nodules are also important for oxygen production in the absence of light and photosynthesis. Nodules the size of potatoes have shown to be able to produce an electric current that is almost equal to the voltage in an AA-sized battery. This generate electric currents strong enough to perform electrolysis, which splits water molecules into hydrogen and oxygen.[106][107] One report states that biomass loss stemming from deep sea mining is estimated to be significantly smaller than that from mining on land.[108] One estimate of land ore mining reports that it will lead to a loss of 568 megatons of biomass (approximately the same as that of the entire human population)[109] versus 42 megatons of biomass from DSM. In addition, land ore mining will lead to a loss of 47 trillion megafauna organisms, whereas deep-sea mining is e | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||