Biodiversity, biogeography, and connectivity of polychaetes in the world's largest marine minerals exploration frontier

The abyssal Clarion-Clipperton Zone (CCZ), Pacific Ocean, is an area of commercial importance owing to the growing interest in mining high-grade polymetallic nodules at the seafloor for battery metals. Research into the spatial patterns of faunal diversity, composition, and population connectivity is needed to better understand the ecological impacts of potential resource extraction. Here, a DNA taxonomy approach is used to investigate regional-scale patterns of taxonomic and phylogenetic alpha and beta diversity, and genetic connectivity, of the dominant macrofaunal group (annelids) across a 6 million km2 region of the abyssal seafloor. We used a combination of new and published barcode data to study 1866 polychaete specimens using molecular species delimitation. Both phylogenetic and taxonomic alpha and beta diversity metrics were used to analyse spatial patterns of biodiversity. Connectivity analyses were based on haplotype distributions for a subset of the studied taxa. DNA taxonomy..., Complete description of the DNA taxonomy pipeline used in the collection of samples new to this study is provided in Glover et al. (2016). Abyssal benthic specimens were collected from UK-1, OMS, and APEI-6 using a variety of oceanographic sampling gear including box cores, epibenthic sledges (EBS), remotely operated vehicle (ROV), and multi-cores. Live-sorted specimens were stored in individual microtube vials containing an aqueous solution of 80% non-denatured ethanol, numbered, barcoded into a database, and kept chilled until return to the Natural History Museum, London, UK.
Extraction of DNA was done with DNeasy Blood and Tissue Kit (Qiagen) using a Hamilton Microlab STAR Robotic Workstation. Approximately 450 bp of 16S, and 650 bp of cytochrome c oxidase subunit I (COI) were amplified using primers listed in Table S1. PCR mixtures contained 1 μl of each primer (10 μM), 2 μl template DNA and 21 μl of Red Taq DNA Polymerase 1.1X MasterMix (VWR) in a mixture of a total of 25 μl. The P...,