POSTER SESSION 1
15:30–17:30, Monday, September 14
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
ABSTRACT 1139 | POSTER 93
EVALUATION OF PARTICLE SIZE DISTRIBUTION OF SURFACE SEAWATER CONTINUOUSLY MEASURED WITH FLOW IMAGING MICROSCOPY IN THE SOUTHERN OCEAN
The particle size distribution (PSD) of suspended matter in seawater determines the size and number of trophic levels, as well as the efficiency of biological pumps. While phytoplankton groups with large cell size represented by diatoms dominate in the Southern Ocean, especially in the sea ice zone, their size may decrease due to recent marine heat waves and sea ice reduction. Therefore, monitoring of PSD in the Southern Ocean is important to know the response of phytoplankton to these extreme phenomena. In the Southern Ocean, little is known about data from flow imaging microscopy (FIM) which can automatically continuously image particles and measure their size. In this study, we operated a FlowCam which is one of the FIMs and investigate the latitudinal changes in PSD in the Southern Ocean. The PSD spectra of the FlowCam followed a power law. Large-sized particles more than 20 μm found in the waters south of 63S were consistent with the significantly high chlorophyll a concentration and dominance of diatoms. In contrast, there was no apparent relationship among them in the waters north of 63S. The numbers of small and large particles were almost in similar range and higher in comparison with previous studies, respectively. Consequently, mean size spectral slope was smaller (2.5) than the previous study (3.99). This is mainly due to the large size particles getting stuck in the cell and being counted multiple times. By using AI-based particle identification capabilities currently under development, these obstacles are expected to be overcome.
Toru Hirawake, National Institute of Polar Research, [email protected], https://orcid.org/0000-0003-0274-6642
Ryosuke Makabe, National Institute of Polar Research, [email protected]
Shintaro Takao, National Institute for Environmental Studies, [email protected], https://orcid.org/0000-0002-0118-6447
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