Paralarval and juvenile cephalopods within warm-core eddies in the North Atlantic

Many descriptions of paralarval and juvenile cephalopods are poor. By using DNA barcoding, a global bioidentification system for animals, along with morphological investigation, we can confirm species identifications. We have a better chance of eliminating misidentifications and, therefore, documenting the correct abundance and distribution of cephalopods within an area by combining morphological and molecular evidence. The central objectives of this study are to: (1) compare morphological vs molecular identification of cephalopods and (2) determine the occurrence of cephalopods within the deep scattering layer (DSL) within warm core eddies. The specimens reported here were collected between 2014 and 2016 during three transatlantic cruises from Galway, Ireland to St John's, Newfoundland, with a focus on assemblages in warm-core mesoscale eddies on the western part of the transect. Samples were collected from the DSL at multiple stations across mesoscale eddies. In total, 301 cephalopods belonging to 29 species were collected. Not only does our study increase the knowledge of abundance and diversity of pelagic cephalopods in this area, but it also provides sequences for species for which no comparative sequences were previously available. By examining the match/mismatch between morphological and molecular identifications, we highlight a need for revisions in some taxonomic groupings such as the family Cranchiidae.