Abstract
The Clarion-Clipperton Zone (CCZ), located in the abyssal equatorial Pacific, has been subject to intensive international exploration for polymetallic nodule mining over the last four decades. Many studies have investigated the potential effects of mining on deep-sea ecosystems and highlighted the importance of defining environmental baseline conditions occurring at potential mining sites. However, current information on biodiversity and species distributions in the CCZ is still scarce and hampers the ability to effectively manage and reduce the potential impacts of mining activities. As part of the regulatory regimes adopted by the International Seabed Authority, concession holders are required to conduct an environmental impact assessment and gather baseline data on biodiversity and community structure in relation to their license areas. In the present study, we used an integrative molecular and morphological approach to assess species richness and genetic variation of deep-sea scavenging amphipods collected in two nodule-mining exploration areas (UK-1 and OMS-1 areas) and one Area of Particular Environmental Interest (APEI-6) in the eastern part of the CCZ. We analyzed the DNA sequences of the cytochrome c oxidase subunit I gene of 645 specimens belonging to ten distinct morphospecies. Molecular data uncover potential cryptic diversity in two investigated species, morphologically identified as Paralicella caperesca Shulenberger & Barnard, 1976 and Valettietta cf. anacantha (Birstein & Vinogradov, 1963). Our study highlights the importance of using molecular tools in conjunction with traditional morphological methods for modern biodiversity assessment studies, particularly to evaluate morphologically similar individuals and incomplete specimens. The results of this study can help determine species identity and ranges, information which can feed into environmental management.
Highlights
Polymetallic nodules, commonly referred to as manganese nodules, are probably one of the most attractive mineral resources as they contain economically relevant metals, such as copper, nickel, and cobalt, and can be found in large quantities on the ocean floor (Halbach et al 1975; Halbach and Fellerer 1980; Clark et al 2013)
As part of the ABYSSal baseLINE (ABYSSLINE) project, this study aims to gather baseline information on diversity and genetic variation of scavenging amphipods collected in two exploration areas, UK’s contract area, licensed to UK Seabed Resources (UKSR), and Singapore’s contract area, licensed to Ocean Mineral Singapore (OMS), plus one Area of Particular Environmental Interest (APEI-6, formerly known as APEI-4), in the eastern part of the Clarion-Clipperton Zone (CCZ) (Fig. 1)
We have demonstrated that in large, specimen-rich datasets, combining traditional approaches with molecular data, can speed up morphospecies assignment and enable cost-efficient and reliable species delimitation
Summary
Polymetallic nodules, commonly referred to as manganese nodules, are probably one of the most attractive mineral resources as they contain economically relevant metals, such as copper, nickel, and cobalt, and can be found in large quantities on the ocean floor (Halbach et al 1975; Halbach and Fellerer 1980; Clark et al 2013). The Clarion-Clipperton Zone (CCZ), situated in the central equatorial Pacific basin between two geological submarine fracture zones, holds major portions of manganese nodule deposits and is subject to intense exploration for future deep-sea mining activities (ISA 2010). Contractors are required to acquire environmental baseline data on biodiversity as well as community structure and standing stocks in relation to their license area (ISA 2013b). For biological communities, these baseline data requirements (section 15 (e)), include to “.... Collect data on the sea floor communities relating to megafauna, macrofauna, meiofauna, microfauna, demersal scavengers and fauna associated directly with the resource, both in the exploration area and in areas that may be impacted by operations (e.g. the operational and discharge plumes)” These baseline data requirements (section 15 (e)), include to “.... collect data on the sea floor communities relating to megafauna, macrofauna, meiofauna, microfauna, demersal scavengers and fauna associated directly with the resource, both in the exploration area and in areas that may be impacted by operations (e.g. the operational and discharge plumes)” (ISA 2013b, p. 5)
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