Size spectra data from marine phytoplankton and zooplankton can provide deep insights into material transfer in lower trophic levels. In this study, we quantified size spectra data of phytoplankton and zooplankton in the subarctic (SA) and transitional (TR) domains in the western North Pacific during May 2023. Phytoplankton and zooplankton data were obtained using FlowCam and ZooScan imaging instruments, respectively. Significantly normalized biovolume size spectra (NBSS) were detected for all samples in both taxa. There were no regional differences in abundance or biovolume. A large regional pattern was detected for the size spectra of phytoplankton at the sea surface. In samples from the TR, the mean biovolume per cell was larger, the slope of NBSS was flatter, and the size diversity was higher than in those in the SA. The NBSS slope and size diversity both showed higher variation in phytoplankton than in zooplankton. Based on the combination of phytoplankton and zooplankton at the same station, NBSS covering the whole planktonic size range are presented. In both taxa, a large discrepancy, e.g., missing NBSS area, was present from 10-5 to 10-1 mm3 ind.-1 in the biovolume. Methods to fill this gap in future studies are discussed.
Wang et al. (Sun,) studied this question.