DNA barcoding enhances large-scale biodiversity initiatives for deep-pelagic crustaceans within the Gulf of Mexico and adjacent waters

Abstract

Abstract The application of DNA barcoding represents a complementary and efficient approach to identifying specimens at all stages of their life cycle when used in combination with traditional morphological methods. Due to difficulties obtaining samples from the deep sea (> 200 m), these methods have been less frequently applied to deep-water taxa. We used DNA-barcoding techniques to enhance large-scale biodiversity initiatives for deep-pelagic crustaceans within the Gulf of Mexico, a region that has recently been identified as one of the world’s four most hyperdiverse ocean ecosystems. This study was conceptualized in direct response to the Deepwater Horizon Oil Spill in 2010, which identified major knowledge gaps in our understanding of deep-sea biodiversity. We employed traditional Sanger sequencing and a genomic skimming approach to target the mitochondrial ribosomal large subunit 16S and the protein-coding cytochrome oxidase subunit 1 (COI). Alongside these molecular approaches, traditional taxonomic investigations allowed for advancements in biodiversity, evolutionary relationships, cryptic species complexes, and distributional records across four abundant and common deep-pelagic orders (Amphipoda, Euphausiacea, Lophogastrida, and Decapoda). DNA barcodes were successfully obtained from 82 species for a total of 158 and 169 new 16S and COI sequences, respectively. Evidence of cryptic diversity has been found in the genera EucopiaDana, 1852 (Lophogastrida) and Allosergestes Judkins & Kensley, 2008 (Decapoda). New records for the Gulf of Mexico of species of LanceolaSay, 1818 (Amphipoda), Eupasiphae Wood-Mason in Wood-Mason & Alcock, 1893, PasiphaeaSavigny, 1816, and MeningodoraSmith, 1882 (Caridea) are presented. Preliminary results allow us to reconsider the current classification and evolutionary relationships of several lineages. The urgency to document biodiversity in the deep-pelagic is pressing against a backdrop of future threats including oil spills and deep-sea drilling.