Chlorophyll-specific absorption coefficients and pigments of phytoplankton off Sanriku, northwestern North Pacific

Abstract

Keywords: ⋅Phytoplankton absorption, ⋅phytoplankton pigments, The variety in shape and magnitude of the in vivo chlorophyll-specific absorption spectra of phytoplankton was investigated in relation to differences in pigment composition off Sanriku, northwestern North Pacific. Site-to-site variations of the absorption coefficients, a*ph(λ), and pigment composition were clearly observed. At warm-streamer stations, higher values of a*ph (440) and a*ph (650) were found with relatively high concentrations of chlorophyll b (a green algae marker). At stations located in the Oyashio water (cold streamer), a*ph (440) values were lower and fucoxanthin (a diatom marker) concentra- tions were higher, compared to the other stations. The peak in the absorption spectra at the Oyashio stations was shifted toward shorter wavelengths, which was probably due to the presence of phaeopigments. In a Kuroshio warm-core ring, the magnitude of a*ph (440) was in between those at the warm-streamer and Oyashio stations, and the diagnostic pigment was peridinin (a dinoflagellate marker). These findings indicated that major differences in phytoplankton absorption spectra of each water mass were a result of differences in the phytoplankton pigment composition of each water mass, which was probably related to the phytoplankton community.