show Abstracthide AbstractDetection of marine organisms based on environmental DNA (eDNA) has resulted in more detailed knowledge of their diversity, distribution, and appearance patterns. In combination with time series sampling and environmental monitoring, the eDNA-based datasets support the detection of changes in biodiversity and facilitate the discovery of interactions among organisms and with abiotic parameters. In this study, we used plankton diversity data generated based on eight years of weekly sampling from a single location in the northwestern Pacific to detect as much diversity present as possible. In total, > 2500 operational taxonomic units (OTUs) associated with unique species from nine supergroups were detected based on five primer pairs. From all the markers, universal primers targeting 18S and 28S ribosomal RNA (rRNA) genes detected the highest number of unique OTUs. Additional unique taxa were detected even during the last two years of sampling demonstrating the need for long-term monitoring. The diversity detected was mainly structured by the dominating current patterns that have significantly different characteristics in terms of temperature, salinity, and nutrient concentrations. We could also detect three types of appearance patterns among the OTUs associated with a single species ranging from sporadical appearance to seasonal or continuous presence. The clear seasonal pattern provides a detailed understanding of the plankton community variability on a multiannual scale in combination with environmental parameters. Simultaneous detection of hundreds of unique OTUs associated with various taxa also allowed investigation of their co-appearance patterns. As the monitoring continues, the dataset will expand and support the investigation of long-term changes in the plankton community of the northwestern Pacific as well as AI-based prediction of species appearances.