Metabarcoding analysis of zooplankton under sea ice in the Okhotsk Sea

The Okhotsk Sea is a semi-closed marine area characterized by unique environments, including seasonal sea ice during winter, and is expected to harbor distinct zooplankton diversity. However, zooplankton communities beneath sea ice remain inadequately researched, primarily because of sampling and methodological challenges. This project used the Okhotsk Tower and icebreakers Garinko II/III, typically used for sightseeing, to collect zooplankton samples during the sea-ice season off the coast of Mombetsu, Hokkaido, Japan. We carried out DNA metabarcoding of mitochondrial cytochrome oxidase subunit I (COI) and nuclear small ribosomal subunit (18S) genes to assess species- and population-level diversity. For each gene, three technical replicates were prepared to eliminate erroneous sequences.