Diversity and life-cycle analysis of Pacific Ocean zooplankton by video microscopy and DNA barcoding: Crustacea

Determining the DNA sequencing of a small element in the mitochondrial DNA (DNA barcoding) makes it possible to easily identify individuals of different larval stages of marine crustaceans without the need for laboratory rearing. It can also be used to construct taxonomic trees, although it is not yet clear to what extent this barcode-based taxonomy reflects more traditional morphological or molecular taxonomy. Collections of zooplankton were made using conventional plankton nets in Newport Bay and the Pacific Ocean near Newport Beach, California (Lat. 33.628342, Long. -117.927933) between May 2013 and January 2020, and individual crustacean specimens were documented by video microscopy. Adult crustaceans were collected from solid substrates in the same areas. Specimens were preserved in ethanol and sent to the Canadian Centre for DNA Barcoding at the University of Guelph, Ontario, Canada for sequencing of the COI DNA barcode. From 1042 specimens, 544 COI sequences were obtained falling into 199 Barcode Identification Numbers (BINs), of which 76 correspond to recognized species. For 15 species of decapods (Loxorhynchus grandis, Pelia tumida, Pugettia dalli, Metacarcinus anthonyi, Metacarcinus gracilis, Pachygrapsus crassipes, Pleuroncodes planipes, Lophopanopeus sp., Pinnixa franciscana, Pinnixa tubicola, Pagurus longicarpus, Petrolisthes cabrilloi, Portunus xantusii, Hemigrapsus oregonensis, Heptacarpus brevirostris), DNA barcoding allowed the matching of different life-cycle stages (zoea, megalops, adult). The results show the utility of DNA barcoding for matching life-cycle stages as well as for documenting the diversity of this group of organisms.