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.

极夜（Polar Night）是北极高纬度地区的全黑暗时段，在此期间，数周至6个月不等的周期内无太阳活动驱动初级生产力生成，无法为海洋生态系统提供能量支撑。尽管如此，近期已有研究发现，多种海洋生物在极夜期间仍可进行活跃的摄食、生长与繁殖行为。本研究针对历史上长期被学界忽视的底栖无脊椎动物早期远洋生命阶段（阶段性浮游生物，meroplankton）的极夜多样性展开阐述。我们于2023年1月在斯瓦尔巴群岛的孔斯峡湾（Kongsfjorden）采用浮游生物拖网采样，对阶段性浮游幼体的分类单元丰富度进行了评估。尽管阶段性浮游生物的密度低于其他季节，但通过对细胞色素c氧化酶亚基I（COI）与16S基因位点进行脱氧核糖核酸（DNA）条形码分析，我们仍得以评估其分类单元丰富度——本次观测到的丰富度远高于此前其他研究与其他季节的结果，共发现隶属于6个门的48个独特分类单元。未来应开展针对性研究，聚焦极夜（Polar Night），以更深入地阐明海洋生物繁殖与发育的季节动态规律。