Data Set Thaler et al. 2024

In the Arctic, the biogeography of marine microeukaryotes is expected to be impacted by changes in local environmental conditions and advective processes. We used amplicon sequencing of the V4 variable region of the 18S rRNA gene in summer pelagic eukaryote communities in the western (Canada Basin) and eastern (Nares Strait) extremes of the Canadian High Arctic to detect and classify sequences of Acantharia, a taxonomically and functionally diverse group of large planktonic protists. Acantharia contribute to food webs in global oceans as predators of smaller microzooplankton, and some clades capture algal cells that allow them to contribute to inorganic carbon fixation as well. However, owing to difficulties preserving their bio-mineralized strontium sulfate (SrSO₄) skeletons, little is known about the origin, depth distribution and autecology of these uncultivated clades. Arctic acantharians in our study were dominated by two clades belonging to cyst-forming groups. Their detection in deeper samples near the end of summer was consistent with swarmer formation. The distribution of one clade suggested successful advective transport from the Beaufort Gyre to southern Nares Strait, with cells remaining active along the northern shelf of the Canadian Arctic. The other clade appeared to be a resident taxon of the Canada Basin whose distribution was correlated to local environmental conditions.