Meroplanktonic larvae collected during the polar night in Kongsfjorden, Svalbard (January 2023)

The Polar Night is a period of complete darkness in the high Arctic, meaning that for a period ranging from several weeks to 6 months there is no solar activity fueling primary production to support the marine ecosystem. Despite this, recent studies have found evidence of active feeding, growth, and reproduction in multiple marine organisms during this period. Here, we describe the polar night diversity of early pelagic life stages of benthic invertebrates (meroplankton), a group that has historically been largely overlooked. We assessed the taxa richness of meroplanktonic larvae in January 2023 in Kongsfjorden, Svalbard, using plankton tows. Although meroplankton densities were lower than in other seasons, deoxyribonucleic acid (DNA) barcoding of the cytochrome c oxidase subunit I (COI) and 16S loci allowed us to assess richness, which was much higher than other studies and seasons, with 48 unique taxa belonging to 6 phyla observed. Further targeted research should focus on the Polar Night to better understand seasonal patterns in reproduction and development.