Abyssal fauna of the UK-1 polymetallic nodule exploration area, Clarion-Clipperton Zone, central Pacific Ocean: Mollusca

Abstract

We present the first DNA taxonomy publication on abyssal Mollusca from the Clarion-Clipperton Zone (CCZ), central Pacific ocean, using material collected as part of the Abyssal Baseline (ABYSSLINE) environmental survey cruise ‘AB01’ to the UK Seabed Resources Ltd (UKSRL) polymetallic-nodule exploration area ‘UK-1’ in the eastern CCZ. This is the third paper in a series to provide regional taxonomic data for a region that is undergoing intense deep-sea mineral exploration for high-grade polymetallic nodules.Taxonomic data are presented for 21 species from 42 records identified by a combination of morphological and genetic data, including molecular phylogenetic analyses. These included 3 heterodont bivalves, 5 protobranch bivalves, 4 pteriomorph bivalves, 1 caudofoveate, 1 monoplacophoran, 1 polyplacophoran, 4 scaphopods and 2 solenogastres. Gastropoda were recovered but will be the subject of a future study. Seven taxa matched published morphological descriptions for species with deep Pacific type localities, and our sequences provide the first genetic data for these taxa. One taxon morphologically matched a known cosmopolitan species but with a type locality in a different ocean basin and was assigned the open nomenclature ‘cf’ as a precautionary approach in taxon assignments to avoid over-estimating species ranges. One taxon is here described as a new species, Ledella knudseni sp. n. For the remaining 12 taxa, we have determined them to be potentially new species, for which we make the raw data, imagery and vouchers available for future taxonomic study. The Clarion-Clipperton Zone is a region undergoing intense exploration for potential deep-sea mineral extraction. We present these data to facilitate future taxonomic and environmental impact study by making both data and voucher materials available through curated and accessible biological collections.

Larval assemblages over the abyssal plain in the Pacific are highly diverse and spatially patchy

“…The meroplankton richness captured by metabarcoding, with representatives from 12 phyla, 23 classes, 46 orders, and 65 families, included many organisms that have been previously reported from the CCZ or other deep-sea regions in the Pacific. Taxa such as Porcellanaster ceruleus , Oneirophanta setigera , Ophryotrocha, or Yoldiella have previously been observed as adults in related studies of megafauna/macrofauna from the same CCZ claim areas, while others ( Parameiropsis , Laonice, Macrostylis ) were recorded in other areas of the eastern and central CCZ (Cho, Wi & Suh, 2016; Amon et al, 2017b; Amon et al, 2017c; De Smet et al, 2017; Wiklund et al, 2017; Table 2). Sampled taxa that are known to occur in other areas of the deep Pacific include numerous polychaetes and several gastropods, as well as groups that are more infrequently reported as part of the meroplankton, such as scaphopods, entoprocts (parasitic/commensal), or myzostomids (parasitic) (Table 1, Fig.…”

“…Within the CCZ, variations in benthic community structure and function are primarily driven by north-south and east-west gradients in overlying productivity (Glover et al, 2002; Smith et al, 2008a; Wedding et al, 2013; Sweetman et al, 2018), and the diversity of meio—to macrofaunal invertebrates is high. Under-sampling and incomplete taxonomic information limit our understanding of abyssal biodiversity and biogeography (Smith et al, 2008a; McClain & Hardy, 2010), with many recent descriptions of new species and/or new distributional records for mega-, macro-, and meiofauna greatly increasing our knowledge of the CCZ fauna (e.g., Glover et al, 2016; Dahlgren et al, 2016; Wiklund et al, 2017; Goineau & Gooday, 2017; Taboada et al, 2018).…”

Significant taxon sampling gaps in DNA databases limit the operational use of marine macrofauna metabarcoding

“…As an example, for abyssal plains (54% of Earth's surface), a staggering 90% of the infauna species found in a typical survey are new to science (Ebbe et al 2010). Recent work in the central Pacific Ocean-where DNA barcoding has not been implemented to any noteworthy degree-points to the significant effort needed to establish even a preliminary taxonomic baseline for DNA-based species identification (Dahlgren et al 2016;Glover et al 2016;Wiklund et al 2017;Wiklund et al 2019). In contrast to most deep ocean basins, shelf areas are better understood.…”

Access to Marine Genetic Resources (MGR): Raising Awareness of Best-Practice Through a New Agreement for Biodiversity Beyond National Jurisdiction (BBNJ)

“…Records are published on the Natural History Museum London data portal (Scott et al, 2019), with global unique identifiers (GUIDS) linking the museum database to the specimen permanent record. Taxonomic data papers are published in the open access journals, Biodiversity Data Journal and ZooKeys Glover et al, 2016;Wiklund et al, 2017;Wiklund et al, accepted). These journals are formatted to maximise interoperability: semantically enhanced with embedded links to databases such as GenBank.…”