The subarctic Pacific includes the coast of Hokkaido in the west to the Gulf of Alaska in the east. This region is known as one of the worlds major high nutrient low chlorophyll ocean areas. Despite its importance, little information is available about the east-west differences in the microplankton communities of this region. This study examined east-west differences in the microplankton community structure along the transect of 47°N latitude in the subarctic Pacific during July-August 2021. The microplankton cell density at each station ranged between 2.3 and 117.8 cells mL-1. The microplankton community was classified into A, B, and C1-C4 groups at a 48.1% similarity level. Groups A and B, dominated by dinoflagellates, occurred at the ends of the transect’s eastern and western regions, respectively. The groups C1-C4, dominated by diatoms, were seen between groups A and B in the middle of the transect. The spatial distribution of each subgroup (C1-C4) was separated from east to west. Group C1 had the highest cell density, predominated by Pseudo-nitzschia spp., which was seen for the two adjacent stations at 175.0-171°W. This group is considered to have arisen due to the effect of mesoscale eddies originating from the coast of the Gulf of Alaska.
Egashira et al. (Sun,) studied this question.