Flow cytometric investigation and comparison of Synechococcus spp. pico-, nano- and microplankton in the Arctic and Antarctic polar regions during the summer period of 2019

In the present study, Synechococcus spp. pico-, nano- and microplankton community compositions in the Arctic and Antarctic surface coastal waters were compared during the summer of 2019 using flow cytometry. The average surface water temperatures in Antarctica and the Arctic were −0.29 ± 0.28°C and 3.71 ± 0.71°C, respectively. While plankton abundance in Antarctica exhibited a relative increase with temperature, plankton abundance in the Arctic exhibited a relative decrease with temperature. However, no significant correlation was found between plankton abundance and temperature. Synechococcus spp. cell abundance dominated in both polar regions, followed by picoeukaryotes, microautotrophs and nanoeukaryotes. Overall, plankton abundance across sampling sites was highly variable. In Antarctica, the abundance of Synechococcus spp., picoeukaryotes, nanoeukaryotes and microautotrophs were the highest in S4 (151,400 cells/ml), S1 (2180 cells/ml), S2 (1080 cells/ml) and S4 (6100 cells/ml), respectively. On the other hand, the most abundant stations in the Arctic in terms of Synechococcus spp., picoeukaryotes, nanoeukaryotes and microautotrophs were N2 (19600 cells/ml), N3 (6400 cells/ml), N3 (500 cells/ml) and N4 (6100 cells/ml), respectively. While Synechococcus spp. and nanoeukaryote abundance were higher in Antarctica, only Synechococcus spp. abundance was significantly higher in Antarctica.