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A schematic showing the potential impacts of deep-sea mining on marine ecosystems. Schematic not to scale.
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Rising demand for minerals and metals, including for use in the technology sector, has led to a resurgence of interest in exploration of mineral resources located on the seabed. Such resources, whether seafloor massive (polymetallic) sulfides around hydrothermal vents, cobalt-rich crusts (CRCs) on the flanks of seamounts or fields of manganese (pol...
Citations
... Although no commercial-scale deep-sea mining has occurred, many mining operations are active in the shallow waters (Miller et al., 2018). Exact resource assessment can be challenging in the deep ocean due to the harsh environment and the difficulties in accessing the seabed (Weaver et al., 2022). ...
... Due to their ecological significance, seamounts have become important areas for deep-sea fisheries, with concerns raised about the impact of bottom trawling on the slow-growing, long-lived benthic communities inhabiting seamounts . The exploration and exploitation of deep-sea mineral resources pose a potential threat to seamount benthos in the future (Miller et al. 2018). Effective deep-sea spatial planning, based on habitat classification, is crucial for supporting the conservation of deepsea ecosystems (McQuaid, Bridges, and Howell 2023). ...
The oligotrophic tropical western Pacific region is characterized by a high density of seamounts, with the Kyushu‐Palau Ridge (KPR) being the longest seamount chain here. Effective spatial management plans for seamount ecosystems necessitate an understanding of distribution patterns and key environmental factors influencing benthic communities. However, knowledge regarding deep‐sea biodiversity patterns over intricate topography remains limited. In this study, we investigated a seamount with a water depth of 522 m at the summit located in the southern section of KPR. Survey transects were conducted from 522 m to 4059 m. By analyzing video‐recorded data obtained by a human‐occupied vehicle (HOV) during dives and environmental variables derived from bathymetry, distinct assemblages were identified through noise clustering. α‐ and β‐diversity patterns within the seamount megabenthic community were analyzed across the depth gradient, along with investigation of their environmental drivers. A total of 10,596 megafauna individuals were documented, categorized into 88 morphospecies and statistically separated into six distinct community clusters using noise clustering analysis. Species abundance and richness were highest within the 700–800 m water depth range, declining notably beyond 2100 m, indicating a critical threshold for habitat classification in this region. The β‐diversity of megabenthic communities was high (0.836). Although β‐diversity patterns along the depth gradient were mostly dominated by differences in species richness, the contribution of species replacement increased with depth, becoming dominant at depths greater than 3000 m. Depth emerged as the primary driver of spatial variation in community structure, while near‐bottom current velocity, topographic parameters (bathymetric position index, slope), and substrate type also influenced the formation of microhabitats. The study highlights the depth gradients, thresholds, and other intricate environmental factors shaping the spatial heterogeneity of these communities. It provides valuable insights for the future development of effective survey and conservation strategies for benthic biodiversity on the KPR.
... Geologist Professor John Rogers photographed abyssal habitats using a camera in an underwater housing in 1998 (see Figure 3), with evidence of manganese nodules in the South African abyss. Although these deep systems are not currently targeted by any human activities in South Africa, there is increasing global efforts and interest in mining such minerals, both in international (ISA 2021; Petersen et al. 2016) and national waters (Miller et al. 2018). ...
After more than a century of global research in the deep ocean, many international collaborations and rapid expansion in deep-sea research outputs, the deep sea in South Africa remains poorly studied with insufficient information, funding, infrastructure, specialists, capacity, and expertise to support deep-sea research and management. This situation not only prevents sound environmental management but limits South Africa's potential to derive benefits from the deep sea. Key obstacles that limit exposure to and participation in the field of deep-sea research include financial, technical and academic capacity challenges, cultural barriers, limited exposure to the deep sea, a lack of access to ships and deep-sea research infrastructure, the perceived irrelevance of the deep sea, and uniform standards in competitive grants and the publication process that disregard current imbalances in skills, capacity and academic leadership. Key pathways of entry and enablers to improve deep-sea research and management capacity include exposure to the ocean and deep sea, dedicated financial support, access to vessels and training, diversity in training approaches and models, academic champions, and mentorship. Further recommendations to support capacity development and transformation in South African deep-sea research are detailed and include five key themes: • Mainstreaming to raise the profile and clarify benefits of deep-sea research and effective management • Exposure and diverse training opportunities to improve ocean literacy and lasting capacity building • Funding to increase opportunities for education, training, collaboration, monitoring and job security • Partnerships and research collaboration that promote co-developed, co-led and co-published research • Technology and infrastructure development, sharing and access
... About 290 MTs of nickel and 121 MTs of cobalt have been identified in polymetallic nodules on the abyssal seafloor (4.5 km below the surface) of the ocean. On the slopes and summits of seamounts, ferromanganese crusts are rich in cobalt [171,172]. However, extraction of these valuable metals from the ocean faces both technical and legal challenges. ...
With the booming of renewable clean energies towards reducing carbon emission, demands for lithium-ion batteries (LIBs) in applications to transportation vehicles and power stations are increasing exponentially. As a consequence, great pressures have been posed on the technological development and production of valuable elements key to LIBs, in addition to concerns about depletion of natural resources, environmental impacts, and management of waste batteries. In this paper, we compile recent information on lithium, nickel, and cobalt, the three most crucial elements utilized in LIBs, in terms of demands, current identified terrestrial resources, extraction technologies from primary natural resources and waste. Most nickel and cobalt are currently produced from high-grade sulfide ores via a pyrometallurgical approach. Increased demands have stimulated production of Ni and Co from low-grade laterites, which is commonly performed through the hydrometallurgical process. Most lithium exists in brines and is extracted via evaporation–precipitation in common industrial practice. It is noteworthy that at present, the pyrometallurgical process is energy-intensive and polluting in terms of gas emissions. Hydrometallurgical processes utilize large amounts of alkaline or acidic media in combination with reducing agents, generating hazardous waste streams. Traditional evaporation–precipitation consumes time, water, and land. Extraction of these elements from deep seas and recycling from waste are emerging as technologies. Advanced energy-saving and environmentally friendly processes are under extensive research and development and are crucial in the process of renewable clean energy implementation.
... As noted in the introduction, estimates suggest that the reserves of polymetallic nodules in these deep-sea locales are vast. While the reserves of polymetallic sulphides and cobalt-rich crusts are substantial, their total potential is less precisely known (Miller et al., 2018). Boschen et al., 2013 Cobalt-rich ferromanganese crusts These crusts accumulate on underwater mountain flanks, ridges, and plateaus. ...
... DSM can significantly disrupt seafloor habitats, resulting in biodiversity loss and the potential extinction of unique marine species (Levin et al., 2016;Miller et al., 2018). The resilience of deepsea ecosystems is low, with recovery from mining disturbances expected to take decades, if not centuries (Glover and Smith, 2003;Ramirez-Llodra et al., 2010). ...
... The novelty of this paper lies in its multidisciplinary analysis, integrating aspects that are often treated separately in existing literature. Previous studies have predominantly focused on the technical and environmental facets of DSM (Hein et al., 2013;Miller et al., 2018;McLellan, 2015). However, this research uniquely combines these with geopolitical and economic considerations, offering a holistic perspective on DSM's impact on global energy security. ...
In the context of a global shift towards low-carbon energy systems, this paper provides an in-depth analysis of deep-sea mining's (DSM) potential role in enhancing global energy security. Addressing the growing demand for critical minerals essential for clean energy technologies, electric vehicles (EVs), and energy storage systems, the paper examines how DSM can diversify the global mineral supply and reduce reliance on geopolitically sensitive sources. It explores DSM's capacity to recalibrate energy prices, influence the competitive landscape of clean energy technologies, and shift geopolitical dynamics. The paper delves into the multi-faceted impacts of DSM on energy security, including geopolitical shifts, supply chain diversification, and environmental trade-offs. By providing a holistic view that links mineral supply security to sustainable energy transitions, this study extends beyond prior research focused mainly on the technical and environmental aspects of DSM. The findings illustrate DSM's intersection with international politics, its effect on energy pricing strategies, and the balance between resource exploitation and environmental stewardship. Strategic policy recommendations are offered to optimize DSM's benefits while minimizing its ecological impacts, aligning the emerging DSM industry with global sustainability goals. In addition to identifying challenges, the paper proposes actionable solutions, contributing a unique perspective to the discourse on DSM and energy security.
... When assessing environmental effects, the first step consists of defining the characteristics of the activity or disturbance (nature/intensity, spatial footprint and frequency/timing) and of the receptor under consideration (spatial extent/distribution, sensitivity, ability to recover) ( Table 2). In the context of deep-seabed mining, numerous potential disturbances exist (see Miller et al., 2018;Weaver and Billett, 2019;Jones et al., 2020) -here we illustrate a few to demonstrate their role in the framework. The intensity of the disturbance may relate to the areas of seabed disturbed directly by the mining footprint of nodule extraction, disturbance from the sediment plumes created by the nodule collector near the seabed or in the water column, direct disturbance of mining equipment, ship noise and light, release of chemicals from the seabed, and discharge release from the mining equipment (processing waste into the water column) and ships (at the surface). ...
Interest in deep seafloor mineral exploitation has been developing over the last few decades, and especially recently as the potential application of metals and elements in these mineral deposits has become more relevant for clean energy technology. The mineral resources located in areas beyond national jurisdiction ("the Area") are under the regulatory control of the International Seabed Authority (ISA), which is required to protect the marine environment from the harmful effects of seabed mining activities and make recommendations to avoid serious harm to the marine environment. However, there is currently no agreed operational definition of serious harm for the Area. Noting that we neither support or disapprove of deep-sea mining, we propose a scientifically-focused risk framework approach for defining serious harm in the context of polymetallic nodule mining based on ISA documentation, as well as international and national criteria, and approaches developed for managing deep-sea resources. A three-tier "traffic light" scheme is proposed, with a threshold level between detectable (green) and significant harm (orange), and a further limit beyond which significant harm becomes serious harm (red). The green, orange and red sectors are associated with no additional management, additional management required, and stopping mining operations, respectively. We further provide illustrations of the type of criteria that could be used in defining levels of harmful effects, and further discuss aspects related to ensuring definitions and their application are fit-for-purpose. The framework proposed here provides a blueprint of an adaptive process that can be applied to the management of any mineral resource, although we focus in some specifics on polymetallic nodule mining. The work bridges the gap between earlier attempts at defining serious harm in the context of deep-sea mining and the need for a clear and consistent approach to operationalise the concept of serious harm.
... PMS are more frequent on abyssal plains and are associated with both active and inactive deep-sea hydrothermal vents along Mid-Ocean Ridges, while most CFCs occur on the slopes and summits of seamounts. (Boschen-Rose and Colaço, 2021;Miller et al., 2018). Deepsea mining industrial operations will involve habitat removal, seafloor compaction, discharges and emissions of plumes, vibration and noise, among other impacts (Christiansen et al., 2020). ...
... Marine ferromanganese (Fe-Mn) crusts, nodules, and hydrothermal deposits commonly host a wide range of critical and strategic metals (e. g., Bi, Co, Cu, Li, Mo, Ni, Pt, Te, V, W, Zr, rare earth elements and yttrium (REY)), resources essential to the burgeoning green-and high-tech industries, and which can also be used for genetic classification of the Fe -Mn precipitates . Detailed assessments have been conducted on the major occurrences (Miller et al., 2018), mineralogy Knaack et al., 2020;Post, 1999), the geochemical behaviour of the major and minor elements present in Fe-Mn precipitates (Hein et al., 2000;Koschinsky and Hein, 2003), and genetic classification schemes have been developed (Bau et al., 2014;Bonatti et al., 1972;Josso et al., 2017). Three main processes are responsible for the formation of Fe-Mn precipitates: (1) hydrogenetic growth, i.e., the slow (mm/Ma) accretion of metals directly from seawater; (2) diagenetic growth, the accretion of remobilized metals from sediment pore fluids; and (3) relatively fast (mm/ka), diffuse-flow hydrothermal growth, in which ascending metal-rich fluids mix with seawater, cement and partly to pervasively replace the host sediment/rock, forming stratabound deposits (Chen and Owen, 1989;Goldberg and Arrhenius, 1958;Hein et al., 2008;Lynn and Bonatti, 1965). ...
... In addition, the availability of food can be critical and sometimes limiting except for chemosynthetic ecosystems (Vecchione et al., 2023). The deep-ocean floor is mostly abyssal plain at depths between 3000 and 6000 m but comprises other features such as canyons, seamounts, midocean ridges and trenches, underwater volcanoes, or hydrothermal vents (Miller et al., 2018). ...
... However, DSM raises so many issues and valid concerns as it will harvest non-renewable resources from the deep ocean and cause many disturbances to the environment, such as light, vibration and noise. The necessary machineries working on the deep seafloor will remove the seafloor habitat and associated organisms, with potential to disrupt food webs and ecosystem health, as well as modify the substrate, disrupting the biogeochemical processes, with implication to carbon cycling (Hallgren and Hansson, 2021;Hauton et al., 2017;Miller et al., 2018;Simon-Lledó et al., 2019). In addition, the generation and release of sediment plumes and metals, potential sub-lethal impacts of chronic exposure, rises of seawater temperature by metal washing, and other cumulative effects should be considered (Hallgren and Hansson, 2021;Hauton et al., 2017;Miller et al., 2018;Simon-Lledó et al., 2019). ...
... The necessary machineries working on the deep seafloor will remove the seafloor habitat and associated organisms, with potential to disrupt food webs and ecosystem health, as well as modify the substrate, disrupting the biogeochemical processes, with implication to carbon cycling (Hallgren and Hansson, 2021;Hauton et al., 2017;Miller et al., 2018;Simon-Lledó et al., 2019). In addition, the generation and release of sediment plumes and metals, potential sub-lethal impacts of chronic exposure, rises of seawater temperature by metal washing, and other cumulative effects should be considered (Hallgren and Hansson, 2021;Hauton et al., 2017;Miller et al., 2018;Simon-Lledó et al., 2019). Consequently, these may cause irreversible damage to these unique ecosystems. ...
... Dumping large amounts of carbon, whether as liquid CO 2 , macroalgae, crop waste, or phytoplankton, would alter geochemical conditions in the deep ocean, modify substrate, and smother life at the seabed 25 . DSM would damage life on the seafloor and in the water by removal, disruption, smothering by sediment plumes, noise, light, and contamination 26 . Both DSM-and mCDR-induced changes in water chemistry and marine ecosystems at the seafloor and in the water column would impact natural components of the marine carbon cycle including the biological pump, with likely unknown and unintended consequences for the ocean's natural absorption, transfer, and storage of carbon. ...