Vertical distribution of oceanic tintinnid (Ciliophora: Tintinnida) assemblages from the Bering Sea to Arctic Ocean through Bering Strait

Knowledge on the distribution of plankton species is fundamental to understand planktonic ecosystem structure and function. To understand the difference of tintinnid vertical distribution pattern in the Bering Sea and the Arctic Ocean and their connection through the Bering Strait, we reported the vertical distribution of tintinnid assemblages from the Bering Sea to the Arctic Ocean. Bering Sea-dominant species (Codonellopsis frigida, Ptychocylis obtusa, Parafavella spp., Acanthostomella norvegica) had abundance peak in the upper 50 m. In the Arctic Ocean, abundance peak of dominant species (P. urnula) occurred in surface and deep chlorophyll a maximum layers. Salpingella acuminata and S. faurei occurred from 50 to 80 m in Bering Sea and Arctic Ocean oceanic waters. Bering Strait-dominant species (P. acuta, Parafavella spp., A. norvegica) occurred from the surface to the bottom. Both S. acuminata and S. faurei were absent in Bering Strait at depths shallower than 120 m. Bering Sea-dominant species (C. frigida, P. obtusa, Parafavella spp., A. norvegica) disappeared successively northward. Ptychocylis urnula occurred in the northern part of Bering Strait at depths exceeding 50 m. The size of P. acuta (only occurring in Bering Strait) was between that of P. urnula and P. obtusa. Bering Sea-dominant species had wide temperature but narrow salinity ranges (32.7–33.3); their successive northward disappearance might reflect difference in the salinity tolerance. Ptychocylis urnula had a wide salinity but narrow temperature range in the Arctic Ocean. Its distribution through Bering Strait is likely limited by temperature (− 1.8 to 1.2 °C). The vertical distribution of S. acuminata and S. faurei might correlate with depth. Our results contribute to a better understanding of the vertical distribution of the microbial food web and serve as a baseline for future studies on the pelagic community change in the Arctic.