Dynamics of cold-water dinoflagellates in the northern Baltic Sea based on 18S rRNA gene metabarcoding

Cold-water dinoflagellates contribute significantly to spring blooms in temperate coastal waters. In the northern Baltic Sea, Peridiniella catenata, Apocalathium malmogiense, Gymnodinium corollarium, and Biecheleria baltica predominate the dinoflagellate spring blooms. Spring dynamics of cold-water dinoflagellates have been previously studied using cyst sedimentation data. Here, we utilize time-series data based on amplicons of the V4 region of the 18S rRNA gene spanning from autumn 2012 to spring 2013 and describe dynamics and habitat preferences of the relatively most abundant dinoflagellates in the northern Baltic Sea. Our results indicate that these species preferred either sea ice, under-ice water, or deeper water columns during the ice-covered season and that they shifted in temporal dominance during our sampling period.