An Overview of Seabed Mining Including the Current State of Development, Environmental Impacts, and Knowledge Gaps

Abstract

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 (polymetallic) nodules on the abyssal plains, cannot be considered in isolation of the distinctive, in some cases unique, assemblages of marine species associated with the same habitats and structures. In addition to mineral deposits, there is interest in extracting methane from gas hydrates on continental slopes and rises. Many of the regions identified for future seabed mining are already recognized as vulnerable marine ecosystems (VMEs). Since its inception in 1982, the International Seabed Authority (ISA), charged with regulating human activities on the deep-sea floor beyond the continental shelf, has issued 27 contracts for mineral exploration, encompassing a combined area of more than 1.4 million km 2 , and continues to develop rules for commercial mining. At the same time, some seabed mining operations are already taking place within continental shelf areas of nation states, generally at relatively shallow depths, and with others at advanced stages of planning. The first commercial enterprise, expected to target mineral-rich sulfides in deeper waters, at depths between 1,500 and 2,000 m on the continental shelf of Papua New Guinea, is scheduled to begin early in 2019. In this review, we explore three broad aspects relating to the exploration and exploitation of seabed mineral resources: (1) the current state of development of such activities in areas both within and beyond national jurisdictions, (2) possible environmental impacts both close to and more distant from mining activities and (3) the uncertainties and gaps in scientific knowledge and understanding which render baseline and impact assessments particularly difficult for the deep sea. We also consider whether there are alternative approaches to the management of existing mineral reserves and resources, which may reduce incentives for seabed mining.

Population genetic structure of the deep‐sea mussel Bathymodiolus platifrons (Bivalvia: Mytilidae) in the Northwest Pacific

“…Together with several recent studies (Breusing et al., , ), this study exemplified the usefulness of SNP data especially from high‐throughput sequencing for population genetic studies of chemosynthetic ecosystems. More importantly, the results from this study will lay a foundation for an effective determination of biogeographic regions, establishment of informed management plans, and designation of deep‐sea reserves in the Pacific Ocean, in preparation for an upcoming era of deep‐sea resource exploitation (Miller et al., ; Sigwart, Chen, & Marsh, ).…”

“…Most marine benthic animals, including those in the deep ocean, have a biphasic life with a pelagic larval stage through which they achieve connectivity across different habitats (Cowen & Sponaugle, ). Knowledge on population connectivity of vent and seep animals sheds light on the scale, direction, and frequency of dispersal, which will not only enhance our understanding of the mechanisms shaping their global and regional biogeography, but also provide key insights into their recovery potential in response to environmental and anthropogenic disturbances (Baco et al., ; Kinlan & Gaines, ; Miller, Thompson, Johnston, & Santillo, ; Rogers et al., ).…”

Measurement and modelling of deep sea sediment plumes and implications for deep sea mining

“…Such studies have led to considerable speculation about extensive and widespread impacts of deep sea mining activities (e.g. 18,[20][21][22] ), which may not be merited.…”

Regional‐scale patterns of deep seafloor biodiversity for conservation assessment

“…This is an important knowledge gap as anthropogenic activities are increasingly targeting deep‐sea habitats (Glover & Smith, ; Ramirez‐Llodra et al, ), where inadequate data limit effective environmental impact assessment (Clark, Durden, & Christiansen, ). There are plans to mine the deep sea for polymetallic nodules on oceanic abyssal plains, cobalt‐rich ferromanganese crusts on seamounts and polymetallic sulphide deposits on volcanically active continental margins and mid‐ocean ridges (Miller, Thompson, Johnston, & Santillo, ). Deep‐sea sedimentary basins on continental margins are also of interest to the oil and gas industry (Zou et al, ), while renewable energy and aquaculture increasingly look to offshore areas to dilute environmental and social concern.…”

“…This is an important knowledge gap as anthropogenic activities are increasingly targeting deep-sea habitats (Glover & Smith, 2003;Ramirez-Llodra et al, 2011), where inadequate data limit effective environmental impact assessment (Clark, Durden, & Christiansen, 2019). There are plans to mine the deep sea for polymetallic nodules on oceanic abyssal plains, cobalt-rich ferromanganese crusts on seamounts and polymetallic sulphide deposits on volcanically active continental margins and mid-ocean ridges (Miller, Thompson, Johnston, & Santillo, 2018).…”