Abstract
To protect the range of habitats, species, and ecosystem functions in the Clarion Clipperton Zone (CCZ), a region of interest for deep-sea polymetallic nodule mining in the Pacific, nine Areas of Particular Environmental Interest (APEIs) have been designated by the International Seabed Authority (ISA). The APEIs are remote, rarely visited and poorly understood. Here we present and synthesise all available observations made at APEI-6, the most north eastern APEI in the network, and assess its representativity of mining contract areas in the eastern CCZ. The two studied regions of APEI-6 have a variable morphology, typical of the CCZ, with hills, plains and occasional seamounts. The seafloor is predominantly covered by fine-grained sediments, and includes small but abundant polymetallic nodules, as well as exposed bedrock. The oceanographic parameters investigated appear broadly similar across the region although some differences in deep-water mass separation were evident between APEI-6 and some contract areas. Sediment biogeochemistry is broadly similar across the area in the parameters investigated, except for oxygen penetration depth, which reached >2 m at the study sites within APEI-6, deeper than that found at UK1 and GSR contract areas. The ecology of study sites in APEI-6 differs from that reported from UK1 and TOML-D contract areas, with differences in community composition of microbes, macrofauna, xenophyophores and metazoan megafauna. Some species were shared between areas although connectivity appears limited. We show that, from the available information, APEI-6 is partially representative of the exploration areas to the south yet is distinctly different in several key characteristics. As a result, additional APEIs may be warranted and caution may need to be taken in relying on the APEI network alone for conservation, with other management activities required to help mitigate the impacts of mining in the CCZ.
Highlights
The Clarion-Clipperton Zone (CCZ) is a seabed area of approximately 6 million km2, receiving scientific and commercial interest for its vast resources of polymetallic nodules (Lodge et al, 2014)
Two of the Areas of Particular Environmental Interest (APEIs) were moved by the International Seabed Authority (ISA) from the central area, with the area designated as APEI-6 moved to the northeast corner of the CCZ (Wedding et al, 2013)
CTD profiles at APEI-6 indicate the presence of lowsalinity (34.86 SA) and low-oxygen (2.65 mL L-1) North Pacific Deep Water (NPDW) around 3600 m (Θ > 1.30 ◦C), and the eastward penetration of saline and more oxygen-rich Lower Circumpolar Water (LCPW) below the NPDW layer extending as far as UK1 (117◦W)
Summary
The Clarion-Clipperton Zone (CCZ) is a seabed area of approximately 6 million km, receiving scientific and commercial interest for its vast resources of polymetallic nodules (Lodge et al, 2014). As the CCZ is predominantly seabed beyond national jurisdiction, the mineral resources are regulated by the International Seabed Authority (ISA). The ISA has divided the CCZ into various mining exploration contract areas assigned to state-sponsored contractors. The ISA has produced a spatial management plan for the CCZ that includes nine Areas of Particular Environmental Interest (APEIs), with original locations designed to be areas represen tative of the region expected to sustain mining impacts (Wedding et al, 2013). The recent Friday Harbor workshop (International Seabed Authority, 2020) high lighted the importance of sampling at the APEI sites
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