Posters

Poster Session 2, Tuesday,  October  4, 10:40–12:40

Poster 102

Optical Characterization of the Phytoplankton Community in the Temperate Coastal Waters of Sagami Bay, Japan

Ocean color remote sensing platforms are essential to improve spatial and temporal estimates of phytoplankton communities from space. In order to improve the optical characterization of phytoplankton communities, the light absorption coefficient of particulates associated with varying phytoplankton assemblages requires investigation. Further, characteristics of nonalgal particles and colored dissolved organic matter that mask phytoplankton contributions to measured optical signals require evaluation. Therefore, the purpose of this study is to characterize the temporal variability of the phytoplankton community in relation to the light absorption coefficient in the temperate coastal waters of Sagami Bay, Japan. The specific objectives are to (1) determine the temporal variability of the phytoplankton community composition and size distribution estimated from diagnostic pigment concentrations, and (2) characterize co-varying light absorption coefficients. Field observations were conducted from May 2016 to May 2022 at St. M in Sagami Bay, Japan. Preliminary results by hierarchical cluster analysis and non-metric multidimensional scaling (NMDS) show three (3) significantly different phytoplankton community clusters based on diagnostic pigments: (1) diatom dominant, (2) chlorophyte dominant, and (3) cyanobacteria dominant (ANOSIM, R = 0.86, p < 0.001). The results also suggest the phytoplankton absorption coefficients could also be divided into similar co-varying clusters when the diagnostic pigments are translated into phytoplankton size classes. This study shows the bio-optical relationship between the temporal succession of phytoplankton communities and light absorption coefficients in a temperate coastal area, and provide further insight towards observing phytoplankton diversity by remote sensing.

*Koichi Yano, Soka University, [email protected]

Masahiko Kaji, Graduate School of Science and Engineering, Soka University, [email protected] 

Shinji Shimode, Manazuru Marine Center for Environmental Research and Education, Graduate School of Environment and Information Sciences, Yokohama National University, [email protected] 

Sayaka Sogawa, Japan Fisheries Research and Education Agency, [email protected]

Toru Hirawake, National Institute of Polar Research, [email protected] 

Victor S. Kuwahara, Graduate School of Science and Engineering, Soka University, [email protected]