DNA metabarcoding data reveals harmful algal-bloom species undescribed previously at the northern Antarctic Peninsula region

Introduction of non-indigenous microbial organisms is forecast to pose a significant threat to the northern Antarctic Peninsula (NAP) marine environments, but reliable data are still lacking. In order to explore the diversity of phytoplankton community, especially discover harmful bloom species that never reported in early studies due to the paucity of molecular investigation in the NAP, we collected plankton samples from the north of South Shetland Islands to east of the South Orkney Islands and sequenced their 18S rRNA gene V4 region metabarcoding. The dominate groups in the samples were dinoflagellates, diatoms, cryptophytes, and haptophytes. We discovered 1340 amplicon sequence variants (ASVs) associated with the Dinophyceae, and 742 ASVs of which were categorized to the genus or species level using the DINOREF database. Dinophyceae Gyrodinium, Warnowia, Ptychodiscus, Gymnodinium, Karenia, Brachidinium, Polarella, Islandinium, and Scrippsiella were the dominate taxa, accounting for 75 percent of the dinoflagellate reads. Karenia papilionacea and Scrippsiella acuminata were first-ever detected in the NAP, and they might be carried in from outside the Antarctic by shipping activities. Their relative abundance suggests that there is a risk of harmful blooms emerging in the northern Antarctic Peninsula as a result of climate change and human activities.