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Suzuki Koji
| Faculty of Environmental Earth Science Earth System Science Marine and Atmospheric Geochemistry | Professor |
| Institute for the Promotion of Business-Regional Collaboration | Professor |
Researcher basic information
■ Degree■ URL
researchmap URLホームページURL■ Various IDs
Researcher number
- 40283452
Research Keyword
- Marine phytoplankton
- Ice Algae
- Primary Production
- Biological Oceanography
- Marine Biogeochemistry
- Algal Ecophysiology
- Environmental Science/Agriculture Science, Environmental dynamic analysis, 生物海洋学
- Environmental Science/Agriculture Science, Environmental dynamic analysis, 海洋生物地球化学
- Life Science, Aquatic bioproduction science, 一次生産
- Master's degree program, Graduate School of Environmental Science
- Doctoral (PhD) degree program, Graduate School of Environmental Science
Career
■ CareerCareer
- Oct. 2016 - Present
Hokkaido University, Faculty of Environmental Earth Science, Professor - Apr. 2007 - Sep. 2016
Hokkaido University, Faculty of Environmental Earth Science, Associate Professor - Dec. 2002 - Mar. 2007
Hokkaido University, Graduate School of Environmental Earth Science, Associate Professor - Apr. 2001 - Nov. 2002
Nagoya University, Hydrospheric Atmospheric Research Center, 助手 - Apr. 1996 - Mar. 2001
Nagoya University, 大気水圏科学研究所, Research Associate - Apr. 1993 - Mar. 1996
日本学術振興会, 特別研究員（DC1）
- 2025 - Present
Elsevier, Progress in Oceanography Associate Editor - 2024 - Present
SCOR Working Group 170 PRIMO Full Member - 2021 - Present
Frontiers in Marine Science Associate Editor - 2021 - Present
SCOR Working Group165 MixONET Associate Member - 2021 - Present
日本学術会議地球惑星科学委員会, GEOTRACES小委員会委員 - 2019 - Present
東京大学大気海洋研究所, 共同利用研究運営委員会委員 - 2018 - Present
BioGeoSCAPES International Implementation Committee Member - 2018 - Present
日本学術会議環境学委員会, IMBeR小委員会委員 - 2009 - Present
European Geosciences Union (EGU), Biogeosciences Associate Editor
Research activity information
■ Awards■ Papers
- Interannual variability of pigment-based phytoplankton communities in the temperate coastal waters of Sagami Bay, Japan
Koichi Yano; Robel M. Ashenafi; Yoshiki Takayama; Shinji Shimode; Koji Suzuki; Victor S. Kuwahara
Marine Ecology Progress Series, 780, 1, 19, 05 Mar. 2026, [Peer-reviewed]
English, Scientific journal,
Ocean warming enhances stratification and reduces nutrient availability in the surface mixed layer, potentially altering phytoplankton community structure. Although warming has been reported in temperate coastal waters, studies evaluating its effects on phytoplankton communities remain limited. In the present study, we investigated the interannual variability of phytoplankton communities in relation to environmental factors in the temperate coastal waters of Sagami Bay, Japan. Field surveys were conducted from October 2012 to January 2025, and phytoplankton community composition was analyzed using the pigment-based program ‘phytoclass’. The phytoplankton community exhibited clear seasonal cycles, consistent with previous observations. Diatoms predominated (52-82%) from April to September, accounting for the largest proportion of total chlorophyll
(chl
) concentration. By contrast, nanoeukaryotes and picoeukaryotes (nano-/picoeukaryotes) were predominant (51-72%) from October to March. Multivariate analysis identified sea surface temperature (SST) as the primary driver of seasonal variability in community structure, followed by euphotic zone depth (
), mixed layer depth (MLD), salinity, and silica. Trend analysis revealed a significant increase in SST (p < 0.001), a shoaling of the MLD (p = 0.004), and decreases in nitrite (p < 0.001) and silica (p = 0.005) concentrations. For the phytoplankton community, a significant decreasing trend was observed for dinoflagellates, whereas diatoms, nano-/picoeukaryotes, and cyanobacteria showed no significant trends. These results suggest that warming enhances stratification, which reduces nutrient availability in the surface layer. Further shifts in phytoplankton communities may occur if the current trends persist.
- Machine learning for estimating phytoplankton size structure from satellite ocean color imagery in optically complex Pacific Arctic waters
Hisatomo Waga; Amane Fujiwara; Wesley J. Moses; Steven G. Ackleson; Daniel Koestner; Maria Tzortziou; Kyle Turner; Alana Menendez; Toru Hirawake; Koji Suzuki; Sei-Ichi Saitoh
Biogeosciences, 04 Feb. 2026, [Peer-reviewed]
Scientific journal - Iron dynamics during spring phytoplankton bloom in the southern Sea of Okhotsk: The impact of sea ice melt on iron supply
Momoka Imai; Aiko Murayama; Kazuya Ono; Youhei Yamashita; Koji Suzuki; Tomohiro Nakamura; Kay I. Ohshima; Humio Mitsudera; Jun Nishioka
Progress in Oceanography, Jan. 2026, [Peer-reviewed]
Scientific journal - Formation of marine atmospheric organic aerosols associated with the spring phytoplankton bloom after sea ice retreat in the Sea of Okhotsk
Yuzo Miyazaki; Yunhan Wang; Eri Tachibana; Koji Suzuki; Youhei Yamashita; Jun Nishioka
Atmospheric Chemistry and Physics, 15 Dec. 2025, [Peer-reviewed]
Scientific journal - Photosynthetic carbon fixation capability of diatom communities in the southern Sea of Okhotsk from winter to spring as estimated using their rbcL genes
Yanxu Sun; Jun Nishioka; Takenobu Toyota; Koji Suzuki
Journal of Oceanography, 07 Oct. 2025, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal - Determining dominant phytoplankton assemblages and their controlling factors in the winter sea-ice-covered southern Sea of Okhotsk and the spring open water through a multiple analytical approach
Yanxu Sun; Jun Nishioka; Takenobu Toyota; Koji Suzuki
Marine Environmental Research, Jun. 2025, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal - Phytoplankton community structure in relation to iron and macronutrient fluxes from subsurface waters in the western North Pacific during summer
Huailin Deng; Koji Suzuki; Ichiro Yasuda; Hiroshi Ogawa; Jun Nishioka
Biogeosciences, 19 Mar. 2025, [Peer-reviewed]
Scientific journal - Characteristics of autumn phytoplankton communities in the Chukchi Sea: resuspension of settled diatoms to the surface during strong wind events
Y Fukai; A Fujiwara; S Nishino; S Kimura; M Itoh; K Suzuki
Marine Ecology Progress Series, 752, 35, 50, Inter-Research Science Center, 16 Jan. 2025, [Peer-reviewed], [Last author]
Scientific journal, Phenological changes in microalgal production and community structure are occurring in the Arctic Ocean. In particular, delayed sea ice formation in autumn can extend the microalgal growth season; however, the succession of phytoplankton communities during this longer photoavailable season is poorly understood. Our objective was to relate oceanographic conditions to the variability in total phytoplankton biomass by examining diatom assemblages in the Chukchi Sea during autumn. We combined scanning electron microscopy (SEM) and DNA metabarcoding techniques to characterize diatom communities, including resting spores of the genus Chaetoceros. The upper layer from the shelf slope to the basin is generally well stratified and influenced by sea-ice meltwater. This stratification prevents the supply of nutrients from the lower layers; therefore, the diatom community is characterized by the typical autumn diatom genus Proboscia near the surface. On the southern shelf, the wind modulates the bottom current, and in turn the current induces the resuspension of sediments and microalgae. Therefore, we speculate that strong winds enhance the currents within the benthic boundary layer, which entrains Chaetoceros resting spore-rich sediments and nutrients (including NH4) to the ocean interior, resulting in a seeding potential for autumn phytoplankton blooms. Multiple data from the cruise and the moorings suggest that the resuspension of sediments and microalgae could commonly occur in the shelf during autumn. The enhanced wind activity in the shallow Chukchi Sea could be important for biogeochemical processes by facilitating the supply of nutrients and viable diatoms from the seafloor to the upper water column. - The Dawn of the BioGeoSCAPES Program: Ocean Metabolism and Nutrient Cycles on a Changing Planet
Mak Saito; Woods Hole Oceanographic Institution; Harriet Alexander; Heather Benway; Philip Boyd; Martha Gledhill; Elizabeth Kujawinski; Naomi Levine; Mairead Maheigan; Adrian Marchetti; Ingrid Obernosterer; Alyson Santoro; Dalin Shi; Koji Suzuki; Alessandro Tagliabue; Benjamin Twining; Maria Maldonado
Oceanography, 2024, [Peer-reviewed]
Scientific journal, - Global oceanic diazotroph database version 2 and elevated estimate of global oceanic N2 fixation
Zhibo Shao; Yangchun Xu; Hua Wang; Weicheng Luo; Lice Wang; Yuhong Huang; Nona Sheila R. Agawin; Ayaz Ahmed; Mar Benavides; Mikkel Bentzon-Tilia; Ilana Berman-Frank; Hugo Berthelot; Isabelle C. Biegala; Mariana B. Bif; Antonio Bode; Sophie Bonnet; Deborah A. Bronk; Mark V. Brown; Lisa Campbell; Douglas G. Capone; Edward J. Carpenter; Nicolas Cassar; Bonnie X. Chang; Dreux Chappell; Yuh-ling Lee Chen; Matthew J. Church; Francisco M. Cornejo-Castillo; Amália Maria Sacilotto Detoni; Scott C. Doney; Cecile Dupouy; Marta Estrada; Camila Fernandez; Bieito Fernández-Castro; Debany Fonseca-Batista; Rachel A. Foster; Ken Furuya; Nicole Garcia; Kanji Goto; Jesús Gago; Mary R. Gradoville; M. Robert Hamersley; Britt A. Henke; Cora Hörstmann; Amal Jayakumar; Zhibing Jiang; Shuh-Ji Kao; David M. Karl; Leila R. Kittu; Angela N. Knapp; Sanjeev Kumar; Julie LaRoche; Hongbin Liu; Jiaxing Liu; Caroline Lory; Carolin R. Löscher; Emilio Marañón; Lauren F. Messer; Matthew M. Mills; Wiebke Mohr; Pia H. Moisander; Claire Mahaffey; Robert Moore; Beatriz Mouriño-Carballido; Margaret R. Mulholland; Shin-ichiro Nakaoka; Joseph A. Needoba; Eric J. Raes; Eyal Rahav; Teodoro Ramírez-Cárdenas; Christian Furbo Reeder; Lasse Riemann; Virginie Riou; Julie C. Robidart; Vedula V. S. S. Sarma; Takuya Sato; Himanshu Saxena; Corday Selden; Justin R. Seymour; Dalin Shi; Takuhei Shiozaki; Arvind Singh; Rachel E. Sipler; Jun Sun; Koji Suzuki; Kazutaka Takahashi; Yehui Tan; Weiyi Tang; Jean-Éric Tremblay; Kendra Turk-Kubo; Zuozhu Wen; Angelicque E. White; Samuel T. Wilson; Takashi Yoshida; Jonathan P. Zehr; Run Zhang; Yao Zhang; Ya-Wei Luo
Earth System Science Data, 15, 8, 3673, 3709, Copernicus GmbH, 15 Aug. 2023, [Peer-reviewed]
Scientific journal, Abstract. Marine diazotrophs convert dinitrogen (N2) gas intobioavailable nitrogen (N), supporting life in the global ocean. In 2012, thefirst version of the global oceanic diazotroph database (version 1) waspublished. Here, we present an updated version of the database (version 2),significantly increasing the number of in situ diazotrophic measurements from13 565 to 55 286. Data points for N2 fixation rates, diazotrophic cellabundance, and nifH gene copy abundance have increased by 184 %, 86 %, and809 %, respectively. Version 2 includes two new data sheets for the nifH genecopy abundance of non-cyanobacterial diazotrophs and cell-specific N2fixation rates. The measurements of N2 fixation rates approximatelyfollow a log-normal distribution in both version 1 and version 2. However,version 2 considerably extends both the left and right tails of thedistribution. Consequently, when estimating global oceanic N2 fixationrates using the geometric means of different ocean basins, version 1 andversion 2 yield similar rates (43–57 versus 45–63 Tg N yr−1; rangesbased on one geometric standard error). In contrast, when using arithmeticmeans, version 2 suggests a significantly higher rate of 223±30 Tg N yr−1 (mean ± standard error; same hereafter) compared to version 1(74±7 Tg N yr−1). Specifically, substantial rate increases areestimated for the South Pacific Ocean (88±23 versus 20±2 Tg N yr−1), primarily driven by measurements in the southwestern subtropics,and for the North Atlantic Ocean (40±9 versus 10±2 Tg N yr−1). Moreover, version 2 estimates the N2 fixation rate in theIndian Ocean to be 35±14 Tg N yr−1, which could not be estimatedusing version 1 due to limited data availability. Furthermore, a comparisonof N2 fixation rates obtained through different measurement methods atthe same months, locations, and depths reveals that the conventional15N2 bubble method yields lower rates in 69 % cases compared tothe new 15N2 dissolution method. This updated version of thedatabase can facilitate future studies in marine ecology andbiogeochemistry. The database is stored at the Figshare repository(https://doi.org/10.6084/m9.figshare.21677687; Shao etal., 2022). - Coexistence of Dominant Marine Phytoplankton Sustained by Nutrient Specialization
Takako Masuda; Keisuke Inomura; Jan Mareš; Taketoshi Kodama; Takuhei Shiozaki; Takato Matsui; Koji Suzuki; Shigenobu Takeda; Curtis Deutsch; Ondřej Prášil; Ken Furuya
Microbiology Spectrum, 11, 4, American Society for Microbiology, 17 Jul. 2023, [Peer-reviewed]
Scientific journal, Our manuscript addresses the following fundamental question in microbial ecology: how do different plankton using the same essential nutrients coexist? Prochlorococcus and Synechococcus are the two dominant picocyanobacteria in the low-nutrient surface waters of the subtropical ocean, which support a significant amount of marine primary production. The geographical distributions of these two organisms are largely overlapping, but the basis for their coexistence in these biomes remains unclear. - Different responses of phytoplankton to Fe manipulation in Fe-limited waters with contrasting surface mixed layer depths in the western subarctic Pacific
Kazuhiro Yoshida; Jun Nishioka; Ichiro Yasuda; Koji Suzuki
Journal of Oceanography, Springer Science and Business Media LLC, 15 Jun. 2023, [Peer-reviewed], [Last author, Corresponding author]
Scientific journal - Role of nutrients and temperature in shaping distinct summer phytoplankton and microzooplankton population dynamics in the western North Pacific and Bering Sea
Liu, Kailin; Jun Nishioka; Bingzhang Chen; Koji Suzuki; Shunyan Cheung; Lu, Yanhong; Huijun Wu; Hongbin Liu
Limnology and Oceanography, Wiley, 16 Jan. 2023, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Haptophyte communities along the Kuroshio Current reveal their geographical sources and ecological traits
Hisashi Endo; Yu Umezawa; Shigenobu Takeda; Koji Suzuki
Molecular Ecology, 32, 1, 110, 123, Wiley, 11 Oct. 2022, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
English, Scientific journal, Abstract
Haptophytes are one of the most ecologically successful phytoplankton groups in the modern ocean and tend to maintain balanced and stable communities across various environments. However, little is known about the mechanisms that enable community stability and ecological success. To reveal the community characteristics and interactions among haptophytes, we conducted comprehensive observations from the upstream to downstream regions of the Kuroshio Current. Haptophyte abundance and taxonomy were assessed using quantitative polymerase chain reaction and metabarcoding of 18S rRNA sequences, respectively. The haptophyte community structure changed abruptly at sites on the shelf‐slope of the East China Sea, indicating the strong influence of shelf waters with high phytoplankton biomass on downstream communities. Correlation network analysis combined with the phylogeny suggested that haptophytes can coexist with their close relatives, possibly owing to their nutritional flexibility, thereby escaping from resource competition. Consistently, some noncalcifying haptophyte genera with high mixotrophic capacities such as Chrysochromulina constituted a major component of the co‐occurrence network, whereas coccolithophores such as Emiliania/Gephyrocapsa were rarely observed. Our study findings suggest that noncalcifying haptophytes play crucial roles in community diversity and stability, and in sustaining the food web structure in the Kuroshio ecosystems. - Number‐size distribution and CCN activity of atmospheric aerosols in the western North Pacific during spring pre‐bloom period: Influences of terrestrial and marine sources
Kaori Kawana; Yuzo Miyazaki; Yuko Omori; Hiroshi Tanimoto; Sara Kagami; Koji Suzuki; Youhei Yamashita; Jun Nishioka; Yange Deng; Hikari Yai; Michihiro Mochida
Journal of Geophysical Research: Atmospheres, 127, 19, American Geophysical Union (AGU), 23 Sep. 2022, [Peer-reviewed]
Scientific journal - Photophysiological response of diatoms in surface sediments to light exposure: A laboratory experiment on a diatom community in sediments from the Chukchi Sea
Fukai, Y.; Matsuno, K.; Fujiwara, A.; Suzuki, K.
Frontiers in Marine Science, 9, Frontiers Media {SA}, 15 Sep. 2022, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
Scientific journal - Comparative analyses of nutritional strategies among the species within the genus Paragymnodinium (Gymnodiniales, Dinophyceae)
Koh Yokouchi; Koji Suzuki; Takeo Horiguchi
Journal of Phycology, Wiley, Aug. 2022, [Peer-reviewed]
English, Scientific journal - High biomass turnover rates of endosymbiotic nitrogen-fixing cyanobacteria in the western Bering Sea
Cheung, S.; Liu, K.; Turk-Kubo, K.A.; Nishioka, J.; Suzuki, K.; L; ry, M.R.; Zehr, J.P.; Leung, S.; Deng, L.; Liu, H.
Limnology And Oceanography Letters, 7, 6, 05 Jul. 2022, [Peer-reviewed], ［Internationally co-authored］
Scientific journal - Crocosphaera as a major consumer of fixed nitrogen
Takako Masuda; Keisuke Inomura; Taketoshi Kodama; Takuhei Shiozaki; Satoshi Kitajima; Gabrielle Armin; Takato Matsui; Koji Suzuki; Shigenobu Takeda; Mitsuhide Sato; Ondrej Prasil; Ken Furuya
Microbiology Spectrum, American Society for Microbiology, 30 Jun. 2022, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal,
is as a key nitrogen (N) supplier in marine ecosystems, and it has been estimated to contribute up to half of oceanic N
fixation. Conversely, a recent study reported that
can assimilate combined N and proposed that unicellular diazotrophs can be competitors with non-N
fixing phytoplankton for combined N.
- Performance of primary production algorithm using absorption coefficient of phytoplankton in the Pacific Arctic
Futsuki, R.; Hirawake, T.; Fujiwara, A.; Waga, H.; Kikuchi, T.; Nishino, S.; Isada, T.; Suzuki, K.; Watanabe, Y.W.
Journal of Oceanography, 78, 4, 08 Jun. 2022, [Peer-reviewed]
Scientific journal - Winter microalgal communities of the southern Sea of Okhotsk: A comparison of sea ice, coastal, and basinal seawater
Yan, D.; Nishioka, J.; Toyota, T.; Suzuki, K.
Progress in Oceanography, 204, 102806, 102806, Elsevier {BV}, Jun. 2022, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
English, Scientific journal - Reconstruction of the eukaryotic communities in Beppu Bay over the past 50 years based on sedimentary DNA barcoding
Yudai Segawa; Masanobu Yamamoto; Michinobu Kuwae; Kazuyoshi Moriya; Hitoshi Suzuki; Koji Suzuki
Journal of Geophysical Research: Biogeosciences, 127, 6, American Geophysical Union (AGU), 27 May 2022, [Peer-reviewed], [Last author]
Scientific journal - Relative contributions of photophysiology and chlorophyll-a abundance to phytoplankton group-specific primary production in the Kuroshio region as inferred by satellite ocean color remote sensing
Hirata, T.; Suzuki, K.
Journal of Oceanography, 78, 4, Springer Science and Business Media {LLC}, 27 Mar. 2022, [Peer-reviewed], [Last author]
English, Scientific journal - Evaluation of retrieving chlorophyll a concentration and colored dissolved organic matter absorption from satellite ocean color remote sensing in the coastal waters of Hokkaido, Japan
Tomonori Isada; Stanford B. Hooker; Yukiko Taniuchi; Koji Suzuki
Journal of Oceanography, Springer Science and Business Media {LLC}, 23 Feb. 2022, [Peer-reviewed], [Last author], ［Internationally co-authored］
English, Scientific journal - Verification and Validation of Hybridspectral Radiometry Obtained from an Unmanned Surface Vessel (USV) in the Open and Coastal Oceans
Stanford B. Hooker; Henry F. Houskeeper; Randall N. Lind; Raphael M. Kudela; Koji Suzuki
Remote Sensing, 14, 5, 1084, 1084, {MDPI} {AG}, 23 Feb. 2022, [Peer-reviewed], [Last author], ［Internationally co-authored］, [International Magazine]
Scientific journal - Primary productivity and phytoplankton community structure in surface waters of the western subarctic Pacific and the Bering Sea during summer with reference to bloom stages
Hisatomo Waga; Amane Fujiwara; Toru Hirawake; Koji Suzuki; Kazuhiro Yoshida; Hiroto Abe; Daiki Nomura
Progress in Oceanography, 201, 102738, 102738, Elsevier {BV}, Feb. 2022, [Peer-reviewed]
English, Scientific journal - Disentangling the Ecological Processes Shaping the Latitudinal Pattern of Phytoplankton Communities in the Pacific Ocean
Xu, Z.; Cheung, S.; Endo, H.; Xia, X.; Wu, W.; Chen, B.; Ho, N.H.E.; Suzuki, K.; Li, M.; Liu, H.
mSystems, 7, 1, American Society for Microbiology, 04 Jan. 2022, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Performance of JAXA’s SGLI standard ocean color products for oceanic to coastal waters: chlorophyll a concentration and light absorption coefficients of colored dissolved organic matter
Atsushi Matsuoka; Janet W. Campbell; Stanford B. Hooker; François Steinmetz; Kazunori Ogata; Takafumi Hirata; Hiroto Higa; Victor S. Kuwahara; Tomonori Isada; Koji Suzuki; Toru Hirawake; Joji Ishizaka; Hiroshi Murakami
Journal of Oceanography, Springer Science and Business Media LLC, 23 Oct. 2021, [Peer-reviewed], ［Internationally co-authored］
Scientific journal - Diatoms contributing to new production in surface waters of the northern Bering and Chukchi Seas during summer with reference to water column stratification
Koji Suzuki; Yuta Yoshino; Yuichi Nosaka; Jun Nishioka; Stanford B. Hooker; Toru Hirawake
Progress in Oceanography, 199, 102692, 102692, Elsevier BV, 22 Oct. 2021, [Peer-reviewed], [Lead author, Corresponding author], ［Internationally co-authored］
Scientific journal - One- and Two-Band Sensors and Algorithms to Derive aCDOM(440) from Global Above- and In-Water Optical Observations
Stanford B. Hooker; Henry F. Houskeeper; Randall N. Lind; Koji Suzuki
Sensors, 21, 16, 5384, 5384, {MDPI} {AG}, 09 Aug. 2021, [Peer-reviewed], [Last author], ［Internationally co-authored］
Scientific journal - Impact of sea‐ice dynamics on the spatial distribution of diatom resting stages in sediments of the Pacific Arctic region
Yuri Fukai; Kohei Matsuno; Amane Fujiwara; Koji Suzuki; Mindy L. Richlen; Evangeline Fachon; Donald M. Anderson
Journal of Geophysical Research: Oceans, 126, 7, American Geophysical Union (AGU), 17 Jun. 2021, [Peer-reviewed], ［Internationally co-authored］
Scientific journal - Gamma4: a genetically versatile Gammaproteobacterial nifH phylotype that is widely distributed in the North Pacific Ocean
Cheung, S.; Zehr, J.P.; Xia, X.; Tsurumoto, C.; Endo, H.; Nakaoka, S.-I.; Mak, W.; Suzuki, K.; Liu, H.
Environmental Microbiology, 23, 8, Wiley, 27 May 2021, [Peer-reviewed], [Corresponding author], ［Internationally co-authored］
English, Scientific journal - Spectral modes of radiometric measurements in optically complex waters
Hooker, S.B.; Houskeeper, H.F.; Kudela, R.M.; Matsuoka, A.; Suzuki, K.; Isada, T.
Continental Shelf Research, 219, 104357, 104357, Elsevier {BV}, Apr. 2021, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Low Fe Availability for Photosynthesis of Sea-Ice Algae: Ex situ Incubation of the Ice Diatom Fragilariopsis cylindrus in Low-Fe Sea Ice Using an Ice Tank
Kazuhiro Yoshida; Andreas Seger; Matthew Corkill; Petra Heil; Kristen Karsh; Andrew McMinn; Koji Suzuki
Frontiers in Marine Science, 8, Frontiers Media {SA}, 22 Mar. 2021, [Peer-reviewed], [Last author, Corresponding author], ［Internationally co-authored］
Scientific journal, - Author Correction: New index of organic mass enrichment in sea spray aerosols linked with senescent status in marine phytoplankton (Scientific Reports, (2020), 10, 1, (17042), 10.1038/s41598-020-73718-5)
Miyazaki, Y.; Suzuki, K.; Tachibana, E.; Yamashita, Y.; M{\"u}ller, A.; Kawana, K.; Nishioka, J.
Scientific Reports, 11, 1, 2021
Scientific journal - Are temperature sensitivities of Prochlorococcus and Synechococcus impacted by nutrient availability in the subtropical northwest Pacific?
Liu, K.; Suzuki, K.; Chen, B.; Liu, H.
Limnology and Oceanography, 66, 3, Wiley, 2021, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - New index of organic mass enrichment in sea spray aerosols linked with senescent status in marine phytoplankton
Yuzo Miyazaki; Koji Suzuki; Eri Tachibana; Youhei Yamashita; Astrid Müller; Kaori Kawana; Jun Nishioka
Scientific Reports, 10, 1, Springer Science and Business Media {LLC}, Dec. 2020, [Peer-reviewed]
English, Scientific journal, - Differences in diversity and photoprotection capability between ice algae and under-ice phytoplankton in Saroma-Ko Lagoon, Japan: a comparative taxonomic diatom analysis with microscopy and DNA barcoding
Kazuhiro Yoshida; Hiroshi Hattori; Takenobu Toyota; Andrew McMinn; Koji Suzuki
Polar Biology, 43, 11, 1873, 1885, 25 Nov. 2020, [Peer-reviewed], [Last author, Corresponding author], ［Internationally co-authored］
English, Scientific journal - Evaluation of the Production of Dissolved Organic Matter by Three Marine Bacterial Strains
Shuji Goto; Yuya Tada; Koji Suzuki; Youhei Yamashita
Frontiers in Microbiology, 11, 584419, 584419, Frontiers Media {SA}, 15 Oct. 2020, [Peer-reviewed]
English, Scientific journal, A large part of marine dissolved organic matter (DOM) is considered to be recalcitrant DOM (RDOM) produced by marine bacteria. However, it is still unclear whether differences in bacterial species and/or physiology control the efficiency of RDOM production. Here, batch culture experiments with glucose as the sole carbon source were carried out using three model marine bacterial strains, namely, Alteromonas macleodii (Alt), Vibrio splendidus (Vib), and Phaeobacter gallaeciensis (Pha). Dissolved organic carbon (DOC) concentrations drastically decreased during the exponential growth phases of these bacteria due to the consumption of glucose. The efficiency of bacterial DOC production at the end of incubation was largely different among the strains and was higher for Vib (20%) than for the other two strains (Alt, 4%; Pha, 6%). All strains produced fluorescent DOM (FDOM), including humic-like FDOM which is considered as recalcitrant component in the ocean, even though the composition of bacterial FDOM was also different among the strains. The efficiency of humic-like FDOM production during the exponential growth phase was different among the bacterial strains; that is, Pha produced humic-like FDOM efficiently compared with the other two species. The efficiency of humic-like FDOM production with mineralization of organic matter was lower during the exponential growth phase than during the stationary phase of Alt and Pha. Four processes for the production of bacterially derived recalcitrant humic-like FDOM are suggested from this study: (1) production during active growing (in all strains), (2) production with the reutilization of bacterial DOM (Alt), (3) production with the consumption of cellular materials (Pha), and (4) release from lysis (Vib). Our results suggest that bacterial species and physiology can regulate RDOM production and accumulation in the ocean. - Freezing, Melting, and Light Stress on the Photophysiology of Ice Algae: Ex Situ Incubation of the Ice Algal diatom Fragilariopsis cylindrus (Bacillariophyceae) Using an Ice Tank
Kazuhiro Yoshida; Andreas Seger; Fraser Kennedy; Andrew McMinn; Koji Suzuki
Journal of Phycology, 56, 5, 1323, 1338, 07 Oct. 2020, [Peer-reviewed], [Last author], ［Internationally co-authored］
English, Scientific journal - Physical Forcing Controls the Basin‐Scale Occurrence of Nitrogen‐Fixing Organisms in the North Pacific Ocean
Shunyan Cheung; Risa Nitanai; Chihiro Tsurumoto; Hisashi Endo; Shin‐ichiro Nakaoka; Wee Cheah; Jaime Färber Lorda; Xiaomin Xia; Hongbin Liu; Koji Suzuki
Global Biogeochemical Cycles, 34, 9, American Geophysical Union ({AGU}), 02 Sep. 2020, [Peer-reviewed], [Last author, Corresponding author], ［Internationally co-authored］
Scientific journal - Trophic sources and linkages to support mesozooplankton community in the Kuroshio of the East China Sea
Fukutaro Karu; Toru Kobari; Taiga Honma; Takeru Kanayama; Koji Suzuki; Naoki Yoshie; Gen Kume
Fisheries Oceanography, 29, 5, 442, 456, Sep. 2020, [Peer-reviewed]
English, Scientific journal - Impact of microzooplankton grazing on the phytoplankton community in the Kuroshio of the East China sea: A major trophic pathway of the Kuroshio ecosystem
Takeru Kanayama; Toru Kobari; Koji Suzuki; Naoki Yoshie; Taiga Honma; Fukutaro Karu; Gen Kume
Deep Sea Research Part I: Oceanographic Research Papers, 163, 103337, 103337, Elsevier {BV}, Sep. 2020, [Peer-reviewed]
Scientific journal - Response to Sea Ice Melt Indicates High Seeding Potential of the Ice Diatom Thalassiosira to Spring Phytoplankton Blooms: A Laboratory Study on an Ice Algal Community From the Sea of Okhotsk
Dong Yan; Kazuhiro Yoshida; Jun Nishioka; Masato Ito; Takenobu Toyota; Koji Suzuki
Frontiers in Marine Science, 7, Frontiers Media SA, 24 Jul. 2020, [Peer-reviewed], [Last author, Corresponding author]
Scientific journal - Distribution of Dimethylsulfoniopropionate Degradation Genes Reflects Strong Water Current Dependencies in the Sanriku Coastal Region in Japan: From Mesocosm to Field Study
Yingshun Cui; Shu-Kuan Wong; Ryo Kaneko; Ayako Mouri; Yuya Tada; Ippei Nagao; Seong-Jun Chun; Hyung-Gwan Lee; Chi-Yong Ahn; Hee-Mock Oh; Yuki Sato-Takabe; Koji Suzuki; Hideki Fukuda; Toshi Nagata; Kazuhiro Kogure; Koji Hamasaki
Frontiers in Microbiology, 11, 13 Jul. 2020, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Ice Melting Can Change DMSP Production and Photosynthetic Activity of the Haptophyte Phaeocystis antarctica
Sohiko Kameyama; Maki Otomaru; Andrew McMinn; Koji Suzuki
Journal of Phycology, Wiley, 05 Jun. 2020, [Peer-reviewed], [Last author], ［Internationally co-authored］
Scientific journal - Effects of phytoplankton community composition and productivity on sea surface pCO2 variations in the Southern Ocean
Shintaro Takao; Shin-Ichiro Nakaoka; Fuminori Hashihama; Keishi Shimada; Hisayuki Yoshikawa-Inoue; Toru Hirawake; Jota Kanda; Gen Hashida; Koji Suzuki
Deep Sea Research Part I: Oceanographic Research Papers, 160, 103263, 103263, Jun. 2020, [Peer-reviewed], [Last author]
English, Scientific journal - Phytoplankton growth and consumption by microzooplankton stimulated by turbulent nitrate flux suggest rapid trophic transfer in the oligotrophic Kuroshio
Toru Kobari; Taiga Honma; Daisuke Hasegawa; Naoki Yoshie; Eisuke Tsutsumi; Takeshi Matsuno; Takeyoshi Nagai; Takeru Kanayama; Fukutaro Karu; Koji Suzuki; Takahiro Tanaka; Xinyu Guo; Gen Kume; Ayako Nishina; Hirohiko Nakamura
Biogeosciences, 17, 9, 2441, 2452, Copernicus {GmbH}, 06 May 2020, [Peer-reviewed]
Scientific journal - Community Composition and Photosynthetic Physiology of Phytoplankton in the Western Subarctic Pacific Near the Kuril Islands With Special Reference to Iron Availability
Kazuhiro Yoshida; Suzu Nakamura; Jun Nishioka; Stanford B. Hooker; Koji Suzuki
Journal of Geophysical Research: Biogeosciences, 125, 3, American Geophysical Union ({AGU}), 11 Mar. 2020, [Peer-reviewed], [Last author, Corresponding author], ［Internationally co-authored］
Scientific journal - A global end-member approach to derive aCDOM(440) from near-surface optical measurements
Koji Suzuki
Biogeosciences, 17, 2, 475, 497, Copernicus GmbH, 30 Jan. 2020, [Peer-reviewed], [Corresponding author], ［Internationally co-authored］
Scientific journal, Abstract. This study establishes an optical inversion scheme for deriving the absorption coefficient of colored (or chromophoric, depending on the literature) dissolved organic material (CDOM) at the 440 nm wavelength, which can be applied to global water masses with near-equal efficacy. The approach uses a ratio of diffuse attenuation coefficient spectral end-members, i.e., a short- and long-wavelength pair. The global perspective is established by sampling “extremely” clear water plus a generalized extent in turbidity and optical properties that each span 3 decades of dynamic range. A unique data set was collected in oceanic, coastal, and inland waters (as shallow as 0.6 m) from the North Pacific Ocean, the Arctic Ocean, Hawaii, Japan, Puerto Rico, and the western coast of the United States. The data were partitioned using subjective categorizations to define a validation quality subset of conservative water masses (i.e., the inflow and outflow of properties constrain the range in the gradient of a constituent) plus 15 subcategories of more complex water masses that were not necessarily evolving conservatively. The dependence on optical complexity was confirmed with an objective methodology based on a cluster analysis technique. The latter defined five distinct classes with validation quality data present in all classes, but which also decreased in percent composition as a function of increasing class number and optical complexity. Four algorithms based on different validation quality end-members were validated with accuracies of 1.2 %–6.2 %, wherein pairs with the largest spectral span were most accurate. Although algorithm accuracy decreased with the inclusion of more subcategories containing nonconservative water masses, changes to the algorithm fit were small when a preponderance of subcategories were included. The high accuracy for all end-member algorithms was the result of data acquisition and data processing improvements, e.g., increased vertical sampling resolution to less than 1 mm (with pressure transducer precision of 0.03–0.08 mm) and a boundary constraint to mitigate wave-focusing effects, respectively. An independent evaluation with a historical database confirmed the consistency of the algorithmic approach and its application to quality assurance, e.g., to flag data outside expected ranges, identify suspect spectra, and objectively determine the in-water extrapolation interval by converging agreement for all applicable end-member algorithms. The legacy data exhibit degraded performance (as 44 % uncertainty) due to a lack of high-quality near-surface observations, especially for clear waters wherein wave-focusing effects are problematic. The novel optical approach allows the in situ estimation of an in-water constituent in keeping with the accuracy obtained in the laboratory. - Effects of temperature, light and iron availability on photosynthetic capacity in the diatoms Chaetoceros debilis and Thalassiosira nordenskioeldii dominated in the Northwestern Subarctic Pacific,北西太平洋亜寒帯域で優占する珪藻 Chaetoceros debilis とThalassiosira nordenskioeldii における光合成能に対する温度，光と鉄利用度の効果
Nosaka, Y.; Suzuki, K.
Bulletin of the Plankton Society of Japan, 67, 1, 2020
Scientific journal - 北太平洋亜寒帯域で優占する珪藻Chaetoceros debilisとThalassiosira nordenskioeldiiにおける光合成能に対する温度、光と鉄利用度の効果
野坂裕一; 鈴木光次
日本プランクトン学会報, 67, 1, 18, Jan. 2020, [Peer-reviewed], [Last author] - Community composition and photophysiology of phytoplankton assemblages in coastal Oyashio waters of the western North Pacific during early spring (vol 212, pg 81, 2018)
Kazuhiro Yoshida; Hisashi Endo; Evelyn Lawrenz; Tomonori Isada; Stanford B. Hooker; Ondrej Prasil; Koji Suzuki
ESTUARINE COASTAL AND SHELF SCIENCE, 228, Nov. 2019, [Peer-reviewed]
English - Transportation of Diazotroph Community From the Upstream to Downstream of the Kuroshio
Cheung, S.; Suzuki, K.; Xia, X.; Liu, H.
Journal of Geophysical Research: Biogeosciences, 124, 9, 2680, 2693, American Geophysical Union (AGU), Sep. 2019, [Peer-reviewed], ［Internationally co-authored］
Scientific journal - Increased temperature benefits growth and photosynthetic performance of the sea ice diatom Nitzschia cf. neglecta (Bacillariophyceae) isolated from saroma lagoon, Hokkaido, Japan
Dong Yan; Hisashi Endo; Koji Suzuki
Journal of Phycology, 55, 3, 700, 713, Wiley, 09 Jun. 2019, [Peer-reviewed], [Last author, Corresponding author]
Scientific journal - Diverse Trophic Pathways from Zooplankton to Larval and Juvenile Fishes in the Kuroshio Ecosystem
Okazaki, Y; H. Miyamoto; K. Suzuki; H. Saito; K. Hidaka; T. Ichikawa
Kuroshio Current: Physical, Biogeochemical, and Ecosystem Dynamics, 245, 256, Apr. 2019, [Peer-reviewed]
English, In book - Spatial variations in community structure of haptophytes across the Kuroshio front in the Tokara Strait
Endo, H.; Suzuki, K.
Kuroshio Current: Physical, Biogeochemical, and Ecosystem Dynamics, 207, 221, Apr. 2019, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal - Responses of phytoplankton assemblages to iron availability and mixing water masses during the spring bloom in the Oyashio region, NW Pacific
Isada, T.; Hattori-Saito, A.; Saito, H.; Kondo, Y.; Nishioka, J.; Kuma, K.; Hattori, H.; McKay, R. M. L.; Suzuki, K.
Limnology and Oceanography, 64, 1, 197, 216, Wiley, 2019, [Peer-reviewed], [Last author], ［Internationally co-authored］
Scientific journal - Corrigendum − Yoshida et al., 2018 (Estuarine, Coastal and Shelf Science (2018) 212 (80–94), (S0272771417310107), (10.1016/j.ecss.2018.06.018))
Yoshida, K.; Endo, H.; Lawrenz, E.; Isada, T.; Hooker, S.B.; Pr{\'a}?il, O.; Suzuki, K.
Estuarine, Coastal and Shelf Science, 228, 2019
Scientific journal - Kuroshio current: Physical, biogeochemical, and ecosystem dynamics
Nagai, T.; Saito, H.; Suzuki, K.; Takahashi, M.
Kuroshio Current: Physical, Biogeochemical, and Ecosystem Dynamics, Kuroshio Current: Physical, Biogeochemical, and Ecosystem Dynamics, 2019
Scientific journal - Latitudinal and Vertical Variation of Synechococcus Assemblage Composition Along 170° W Transect From the South Pacific to the Arctic Ocean
Xia, X.; Cheung, S.; Endo, H.; Suzuki, K.; Liu, H.
Microbial Ecology, 77, 2, 333, 342, 2019, [Peer-reviewed], ［Internationally co-authored］
Scientific journal - Ion concentrations in ice wedges: An innovative approach to reconstruct past climate variability
Iizuka, Yoshinori; Miyamoto, Chihiro; Matoba, Sumito; Iwahana, Go; Horiuchi, Kazuho; Takahashi, Yoshio; Kanna, Naoya; Suzuki, Koji; Ohno, Hiroshi
Earth and Planetary Science Letters, 515, 58, 66, 2019, [Peer-reviewed]
Scientific journal - Chemical transfer of dissolved organic matter from surface seawater to sea spray water-soluble organic aerosol in the marine atmosphere
Yuzo Miyazaki; Youhei Yamashita; Kaori Kawana; Eri Tachibana; Sara Kagami; Michihiro Mochida; Koji Suzuki; Jun Nishioka
Scientific Reports, 8, 1, Springer Nature, 05 Oct. 2018, [Peer-reviewed]
Scientific journal - Contrasting biogeography and diversity patterns between diatoms and haptophytes in the central Pacific Ocean
Hisashi Endo; Hiroyuki Ogata; Koji Suzuki
Scientific Reports, 8, 1, 10916, Springer Science and Business Media {LLC}, 19 Jul. 2018, [Peer-reviewed], [Last author, Corresponding author]
Scientific journal - Determination of the freshwater origin of Coastal Oyashio Water using humic-like fluorescence in dissolved organic matter
Mizuno, Yu; Nishioka, Jun; Tanaka, Takahiro; Tada, Yuya; Suzuki, Koji; Tsuzuki, Yuta; Sugimoto, Atsuko; Yamashita, Youhei
Journal of Oceanography, 74, 5, 1, 13, Springer Tokyo, 2018, [Peer-reviewed]
English, Scientific journal - Community composition and photophysiology of phytoplankton assemblages in coastal Oyashio waters of the western North Pacific during early spring
Yoshida, Kazuhiro; Endo, Hisashi; Lawrenz, Evelyn; Isada, Tomonori; Hooker, Stanford B.; Prášil, Ondřej; Suzuki, Koji
Estuarine, Coastal and Shelf Science, 212, 80, 94, 2018, [Peer-reviewed], [Last author, Corresponding author], ［Internationally co-authored］
English, Scientific journal - Changes in phytoplankton community structure during wind-induced fall bloom on the central Chukchi shelf
Fujiwara, Amane; Nishino, Shigeto; Matsuno, Kohei; Onodera, Jonaotaro; Kawaguchi, Yusuke; Hirawake, Toru; Suzuki, Koji; Inoue, Jun; Kikuchi, Takashi
Polar Biology, 41, 6, 1279, 1295, Springer Verlag, 2018, [Peer-reviewed]
English, Scientific journal - Biogenic sulfur compounds in spring phytoplankton bloom in the western North Pacific off the coast of northern Japan
Nagao, Ippei; Eum, Young-Joon; Iwamoto, Yoko; Tada, Yuya; Suzuki, Koji; Tsuda, Atsushi; Toratani, Mitsuhiro; Hamasaki, Koji; Uematsu, Mitsuo
Progress in Oceanography, 165, 145, 157, Elsevier Ltd, 2018, [Peer-reviewed]
English, Scientific journal - Phylogenetic diversity and distribution of bacterial and archaeal amoA genes in the East China Sea during spring
Kataoka, T.; Suzuki, K.; Irino, T.; Yamamoto, M.; Higashi, S.; Liu, H.
Arch Microbiol, 200, 2, 329, 342, Springer Verlag, 2018, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Metagenomic Insights Into the Microbial Community and Nutrient Cycling in the Western Subarctic Pacific Ocean
Li, Yingdong; Jing, Hongmei; Xia, Xiaomin; Cheung, Shunyan; Suzuki, Koji; Liu, Hongbin
Frontiers in Microbiology, 9, Frontiers Media S.A., 2018, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - 衛星による海洋基礎生産力の推定
平譯享; 高尾信太郎; 鈴木光次; 西岡純; 渡邉豊; 伊佐田智規
海の研究, 26, 65, 77, May 2017, [Peer-reviewed] - Characterization of the synoptic-scale diversity, biogeography, and size distribution of diatoms in the North Pacific
Koji Sugie; Koji Suzuki
Limnology and Oceanography, 62, 3, 884, 897, Wiley Blackwell, 01 May 2017, [Peer-reviewed], [Last author]
English, Scientific journal - Highly heterogeneous diazotroph communities in the Kuroshio Current and the Tokara Strait, Japan
Cheung, S.; Suzuki, K.; Saito, H.; Umezawa, Y.; Xia, X.; Liu, H.
PLoS One, 12, 10, e0186875, 2017, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Phytoplankton community responses to iron and CO2 enrichment in different biogeochemical regions of the Southern Ocean
Endo, Hisashi; Hattori, Hiroshi; Mishima, Tsubasa; Hashida, Gen; Sasaki, Hiroshi; Nishioka, Jun; Suzuki, Koji
Polar Biology, 40, 11, 2143, 2159, 2017, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal - Production and Reutilization of Fluorescent Dissolved Organic Matter by a Marine Bacterial Strain, Alteromonas macleodii
Goto, S.; Tada, Y.; Suzuki, K.; Yamashita, Y.
Front Microbiol, 8, 507, 507, 2017, [Peer-reviewed]
English, Scientific journal - Phylogeography and pigment type diversity of Synechococcus cyanobacteria in surface waters of the northwestern pacific ocean
Xia, X.; Partensky, F.; Garczarek, L.; Suzuki, K.; Guo, C.; Yan Cheung, S.; Liu, H.
Environ Microbiol, 19, 1, 142, 158, 2017, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Influence of hydrography on the spatiotemporal variability of phytoplankton assemblages and primary productivity in Funka Bay and the Tsugaru Strait
Isada, Tomonori; Hirawake, Toru; Nakada, Satoshi; Kobayashi, Tsukuru; Sasaki, Ken'ichi; Tanaka, Yoshiyuki; Watanabe, Shuichi; Suzuki, Koji; Saitoh, Sei-Ichi
Estuarine, Coastal and Shelf Science, 188, 199, 211, 2017, [Peer-reviewed]
English, Scientific journal - Geographic Distribution of Ammonia-Oxidizing Archaea along the Kuril Islands in the Western Subarctic Pacific
Jing, Hongmei; Cheung, Shunyan; Xia, Xiaomin; Suzuki, Koji; Nishioka, Jun; Liu, Hongbin
Frontiers in Microbiology, 8, 2017, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Dynamics and Origin of Transparent Exopolymer Particles in the Oyashio Region of the Western Subarctic Pacific during the Spring Diatom Bloom
Nosaka, Yuichi; Yamashita, Youhei; Suzuki, Koji
Frontiers in Marine Science, 4, Frontiers Media S. A, 2017, [Peer-reviewed], [Last author]
English, Scientific journal - Distinct bacterial community and diversity shifts after phytoplankton-derived dissolved organic matter addition in a coastal environment
Tada, Yuya; Nakaya, Rie; Goto, Shuji; Yamashita, Youhei; Suzuki, Koji
Journal of Experimental Marine Biology and Ecology, 495, 119, 128, 2017, [Peer-reviewed], [Last author]
English, Scientific journal - Differences in Rate and Direction of Shifts between Phytoplankton Size Structure and Sea Surface Temperature
Waga, Hisatomo; Hirawake, Toru; Fujiwara, Amane; Kikuchi, Takashi; Nishino, Shigeto; Suzuki, Koji; Takao, Shintaro; Saitoh, Sei-Ichi
Remote Sensing, 9, 3, 222, 222, 2017, [Peer-reviewed]
English, Scientific journal - Basin-scale distribution of prokaryotic phylotypes in the epipelagic layer of the Central South Pacific Ocean during austral summer
Tada, Y.; Shiozaki, T.; Ogawa, H.; Suzuki, K.
Journal of Oceanography, 73, 2, 145, 158, 2017, [Peer-reviewed], [Last author]
English, Scientific journal - Influence of timing of sea ice retreat on phytoplankton size during marginal ice zone bloom period on the Chukchi and Bering shelves
A. Fujiwara; T. Hirawake; K. Suzuki; L. Eisner; I. Imai; S. Nishino; T. Kikuchi; S.-I. Saitoh
Biogeosciences, 13, 1, 115, 131, 15 Jan. 2016, [Peer-reviewed]
English, Scientific journal - Changes in the community structure of free-living heterotrophic bacteria in the open tropical Pacific Ocean in response to microalgal lysate-derived dissolved organic matter
Tada, Y.; Suzuki, K.
FEMS Microbiology Ecology, 92, 7, 2016, [Peer-reviewed], [Last author]
English, Scientific journal - Response of Spring Diatoms to CO2 Availability in the Western North Pacific as Determined by Next-Generation Sequencing
Endo, H.; Sugie, K.; Yoshimura, T.; Suzuki, K.
PLoS One, 11, 4, e0154291, 2016, [Peer-reviewed], [Last author]
English, Scientific journal - Rapid and highly sensitive analysis of chlorophylls and carotenoids from marine phytoplankton using ultra-high performance liquid chromatography (UHPLC) with the first derivative spectrum chromatogram (FDSC) technique
Koji Suzuki; Akiko Kamimura; Stanford B. Hooker
Marine Chemistry, 176, 96, 109, Nov. 2015, [Peer-reviewed], [Lead author, Corresponding author], ［Internationally co-authored］
English, Scientific journal - A new marine araphid diatom, Thalassionema kuroshioensis sp nov., from temperate Japanese coastal waters
Koji Sugie; Koji Suzuki
DIATOM RESEARCH, 30, 3, 237, 245, Jul. 2015, [Peer-reviewed], [Last author]
English, Scientific journal - Size of Dominant Diatom Species Can Alter Their Evenness
Koji Sugie; Koji Suzuki
PLOS ONE, 10, 6, Jun. 2015, [Peer-reviewed], [Last author]
English, Scientific journal - Hyperspectral optical discrimination of phytoplankton community structure in Funka Bay and its implications for ocean color remote sensing of diatoms
Tomonori Isada; Toru Hirawake; Tsukuru Kobayashi; Yuichi Nosaka; Masafumi Natsuike; Ichiro Imai; Koji Suzuki; Sei-Ichi Saitoh
REMOTE SENSING OF ENVIRONMENT, 159, 134, 151, Mar. 2015, [Peer-reviewed]
English, Scientific journal - Effects of CO2 and iron availability on rbcL gene expression in Bering Sea diatoms
H. Endo; K. Sugie; T. Yoshimura; K. Suzuki
BIOGEOSCIENCES, 12, 7, 2247, 2259, 2015, [Peer-reviewed], [Last author]
English, Scientific journal - Organic matter production response to CO2 increase in open subarctic plankton communities: Comparison of six microcosm experiments under iron-limited and -enriched bloom conditions
Takeshi Yoshimura; Koji Sugie; Hisashi Endo; Koji Suzuki; Jun Nishioka; Tsuneo Ono
DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS, 94, 1, 14, Dec. 2014, [Peer-reviewed]
English, Scientific journal - Phytoplankton community composition and photosynthetic physiology in the Australian sector of the Southern Ocean during the austral summer of 2010/2011
Shintaro Takao; Toru Hirawake; Gen Hashida; Hiroshi Sasaki; Hiroshi Hattori; Koji Suzuki
POLAR BIOLOGY, 37, 11, 1563, 1578, Nov. 2014, [Peer-reviewed], [Last author]
English, Scientific journal - Distributions of dissolved organic carbon and nitrogen in the western Okhotsk Sea and their effluxes to the North Pacific
Rumi Sohrin; Kunimatsu Imanishi; Yoshimi Suzuki; Kenshi Kuma; Ichiro Yasuda; Koji Suzuki; Takeshi Nakatsuka
PROGRESS IN OCEANOGRAPHY, 126, 168, 179, Aug. 2014, [Peer-reviewed]
English - Bio-optical properties during the summer season in the Sea of Okhotsk
Shintaro Takao; Takahiro Iida; Tomonori Isada; Sei-Ichi Saitoh; Takafumi Hirata; Koji Suzuki
PROGRESS IN OCEANOGRAPHY, 126, 233, 241, Aug. 2014, [Peer-reviewed], [Last author]
English - High-resolution observations of dissolved isoprene in surface seawater in the Southern Ocean during austral summer 2010-2011
Sohiko Kameyama; Satoshi Yoshida; Hiroshi Tanimoto; Satoshi Inomata; Koji Suzuki; Hisayuki Yoshikawa-Inoue
JOURNAL OF OCEANOGRAPHY, 70, 3, 225, 239, Jun. 2014, [Peer-reviewed]
English, Scientific journal - Photosynthetic Competence of the Marine Aerobic Anoxygenic Phototrophic Bacterium Roseobacter sp under Organic Substrate Limitation
Yuki Sato-Takabe; Koji Hamasaki; Koji Suzuki
MICROBES AND ENVIRONMENTS, 29, 1, 100, 103, Apr. 2014, [Peer-reviewed], [Last author]
English, Scientific journal - Light utilization efficiency of phytoplankton in the Western Subarctic Gyre of the North Pacific during summer
Yuichi Nosaka; Tomonori Isada; Isao Kudo; Hiroaki Saito; Hiroshi Hattori; Atsushi Tsuda; Koji Suzuki
JOURNAL OF OCEANOGRAPHY, 70, 1, 91, 103, Feb. 2014, [Peer-reviewed], [Last author]
English, Scientific journal - Development and verification of SGLI/GCOM-C1 ocean algorithms
Hirata, T.; Hirawake, T.; Sakaida, F.; Yamaguchi, A.; Suzuki, K.; Murakami, H.; Ishizaka, J.; Kobayashi, H.; Fujiwara, A.; Toratani, M.; Saitoh, S.-I.
Journal of the Remote Sensing Society of Japan, 34, 4, 278, 285, 2014, [Peer-reviewed]
Scientific journal - Timing of sea ice retreat can alter phytoplankton community structure in the western Arctic Ocean
A. Fujiwara; T. Hirawake; K. Suzuki; I. Imai; S. -I. Saitoh
BIOGEOSCIENCES, 11, 7, 1705, 1716, 2014, [Peer-reviewed]
English, Scientific journal - Spatial variability in iron nutritional status of large diatoms in the Sea of Okhotsk with special reference to the Amur River discharge
K. Suzuki; A. Hattori-Saito; Y. Sekiguchi; J. Nishioka; M. Shigemitsu; T. Isada; H. Liu; R. M. L. McKay
BIOGEOSCIENCES, 11, 9, 2503, 2517, 2014, [Peer-reviewed], [Lead author, Corresponding author], ［Internationally co-authored］
English, Scientific journal - Decadal Vision in Oceanography (III) : Discussions in the biological oceanography subgroup of the future planning committee, The Oceanographic Society of Japan(Decadal Vision in Oceanography-Special issue of "Oceanography in Japan"-)
Koji Hamasaki; Joji Ishizaka; Hiroaki Saito; Hiroya Sugisaki; Koji Suzuki; Kazutaka Takahashi; Sanae Chiba
海の研究 = Umi no Kenkyu (Oceanography in Japan), 22, 6, 253, 272, 日本海洋学会, 15 Nov. 2013, [Peer-reviewed]
Japanese, 海洋生物を中心とする視点から,海洋学の過去10年程度の研究の進展を総括するとともに,今後10年間でわが国として取り組むべき研究の方向性と必要とされる研究基盤について論じた。特に,「生物多様性」を生物海洋学,海洋生物学を特徴づけるに最もふさわしい言葉として,その解明ならびに地球システムとの関係について重要と考えられる課題毎に論じた。生物多様性の解明においては,動植物プランクトン及び微生物群集多様性の解明,鍵種の生物学,非優占種の役割,多様性と生物間相互作用を重要課題とした。生物多様性と地球システムとの関係については,気候変動による影響と気候へのフィードバック,複合生態系としての沿岸域,生物多様性とモニタリング,生態系・生物地球化学統合モデルを重要課題とした。Progress in oceanographic research in the past decade is reviewed and future directions and required infrastructures in the Japanese oceanographic research in the next decade are discussed, mainly from the biological oceanographic perspective. Particularly, we chose "Biodiversity" as the best keyword representing the nature of biological oceanography and marine biology, and discussed important issues in the study of biodiversity and its relation to the Earth system. In the study of biodiversity, important issues to reveal are the diversity of phytoplankton, zooplankton and microbial communities, biology of key species, the role of minor species and biological interaction. In the study of relationship between biodiversity and the Earth system, important issues are the effect of climate change and feedbacks to the climate, integrated ecosysetms in the coastal area, monitoring biodiversity, and integrated ecosystem-biogeochemical models. - Vertical Profiles of Bacteria in the Tropical and Subarctic Oceans Revealed by Pyrosequencing
Hongmei Jing; Xiaomin Xia; Koji Suzuki; Hongbin Liu
PLOS ONE, 8, 11, Nov. 2013, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Synergistic effects of pCO2 and iron availability on nutrient consumption ratio of the Bering Sea phytoplankton community
K. Sugie; H. Endo; K. Suzuki; J. Nishioka; H. Kiyosawa; T. Yoshimura
Biogeosciences, 10, 10, 6309, Copernicus {GmbH}, Oct. 2013, [Peer-reviewed] - Impacts of elevated CO2 on particulate and dissolved organic matter production: microcosm experiments using iron-deficient plankton communities in open subarctic waters
Takeshi Yoshimura; Koji Suzuki; Hiroshi Kiyosawa; Tsuneo Ono; Hiroshi Hattori; Kenshi Kuma; Jun Nishioka
JOURNAL OF OCEANOGRAPHY, 69, 5, 601, 618, Oct. 2013, [Peer-reviewed]
English, Scientific journal - Strong relationship between dimethyl sulfide and net community production in the western subarctic Pacific
Sohiko Kameyama; Hiroshi Tanimoto; Satoshi Inomata; Hisayuki Yoshikawa-Inoue; Urumu Tsunogai; Atsushi Tsuda; Mitsuo Uematsu; Masao Ishii; Daisuke Sasano; Koji Suzuki; Yuichi Nosaka
GEOPHYSICAL RESEARCH LETTERS, 40, 15, 3986, 3990, Aug. 2013, [Peer-reviewed]
English, Scientific journal - Influence of Amur River discharge on phytoplankton photophysiology in the Sea of Okhotsk during late summer
Tomonori Isada; Takahiro Iida; Hongbin Liu; Sei-Ichi Saitoh; Jun Nishioka; Takeshi Nakatsuka; Koji Suzuki
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 118, 4, 1995, 2013, Apr. 2013, [Peer-reviewed], [Last author], ［Internationally co-authored］
English, Scientific journal - The MAREDAT global database of high performance liquid chromatography marine pigment measurements
J. Peloquin; C. Swan; N. Gruber; M. Vogt; H. Claustre; J. Ras; J. Uitz; R. Barlow; M. Behrenfeld; R. Bidigare; H. Dierssen; G. Ditullio; E. Fernandez; C. Gallienne; S. Gibb; R. Goericke; L. Harding; E. Head; P. Holligan; S. Hooker; D. Karl; M. Landry; R. Letelier; C. A. Llewellyn; M. Lomas; M. Lucas; A. Mannino; J. C. Marty; B. G. Mitchell; F. Muller-Karger; N. Nelson; C. O'Brien; B. Prezelin; D. Repeta; W. O. Smith Jr.; D. Smythe-Wright; R. Stumpf; A. Subramaniam; K. Suzuki; C. Trees; M. Vernet; N. Wasmund; S. Wright
Earth System Science Data, 5, 1, 109, 123, 25 Mar. 2013, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Growth stimulation and inhibition of natural phytoplankton communities by model organic ligands in the western subarctic Pacific
Yoshiko Kondo; Shigenobu Takeda; Jun Nishioka; Mitsuhide Sato; Hiroaki Saito; Koji Suzuki; Ken Furuya
JOURNAL OF OCEANOGRAPHY, 69, 1, 97, 115, Feb. 2013, [Peer-reviewed]
English, Scientific journal - Effects of CO2 and iron availability on phytoplankton and eubacterial community compositions in the northwest subarctic Pacific
H. Endo; T. Yoshimura; T. Kataoka; K. Suzuki
Journal of Experimental Marine Biology and Ecology, 439, 160, 175, Jan. 2013, [Peer-reviewed], [Last author]
English, Scientific journal - Photobleaching as a factor controlling spectral characteristics of chromophoric dissolved organic matter in open ocean
Y. Yamashita; Y. Nosaka; K. Suzuki; H. Ogawa; K. Takahashi; H. Saito
BIOGEOSCIENCES, 10, 11, 7207, 7217, 2013, [Peer-reviewed]
English, Scientific journal - Evaluation of using unfiltered seawater for underway measurement of dimethyl sulfide in the ocean by online mass spectrometry
Yuko Omori; Hiroshi Tanimoto; Satoshi Inomata; Sohiko Kameyama; Shintaro Takao; Koji Suzuki
Limnology and Oceanography: Methods, 11, 549, 560, 2013, [Peer-reviewed]
English, Scientific journal - Photosynthetic characteristics of marine aerobic anoxygenic phototrophic bacteria Roseobacter and Erythrobacter strains
Yuki, S.-T.; Hamasaki, K.; Suzuki, K.
Archives of Microbiology, 194, 5, 331, 341, May 2012, [Peer-reviewed], [Last author]
Scientific journal - Variations of net primary productivity and phytoplankton community composition in the Indian sector of the Southern Ocean as estimated from ocean color remote sensing data
S. Takao; T. Hirawake; S. W. Wright; K. Suzuki
BIOGEOSCIENCES, 9, 10, 3875, 3890, 2012, [Peer-reviewed], [Last author], ［Internationally co-authored］
English, Scientific journal - Dissolved methane distribution in the South Pacific and the Southern Ocean in austral summer
Osamu Yoshida; Hisayuki Y. Inoue; Shuichi Watanabe; Koji Suzuki; Shinichiro Noriki
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 116, Jul. 2011, [Peer-reviewed]
English, Scientific journal - Population dynamics of phytoplankton, heterotrophic bacteria, and viruses during the spring bloom in the western subarctic Pacific
Koji Suzuki; Akira Kuwata; Naoki Yoshie; Akira Shibata; Kyoko Kawanobe; Hiroaki Saito
DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS, 58, 5, 575, 589, May 2011, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal - Effects of Mn and Fe on growth of a coastal marine diatom Talassiosira weissflogii in the presence of precipitated Fe(III) hydroxide and EDTA-Fe(III) complex
Satomi Ushizaka; Kenshi Kuma; Koji Suzuki
FISHERIES SCIENCE, 77, 3, 411, 424, May 2011, [Peer-reviewed], [Last author]
English, Scientific journal - Importance of intracellular Fe pools on growth of marine diatoms by using unialgal cultures and on the Oyashio region phytoplankton community during spring
Koji Sugie; Kenshi Kuma; Satoshi Fujita; Satomi Ushizaka; Koji Suzuki; Tsutomu Ikeda
JOURNAL OF OCEANOGRAPHY, 67, 2, 183, 196, Apr. 2011, [Peer-reviewed]
English, Scientific journal - Synoptic relationships between surface Chlorophyll-a and diagnostic pigments specific to phytoplankton functional types
T. Hirata; N. J. Hardman-Mountford; R. J. W. Brewin; J. Aiken; R. Barlow; K. Suzuki; T. Isada; E. Howell; T. Hashioka; M. Noguchi-Aita; Y. Yamanaka
BIOGEOSCIENCES, 8, 2, 311, 327, 2011, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Remote sensing of size structure of phytoplankton communities using optical properties of the Chukchi and Bering Sea shelf region
A. Fujiwara; T. Hirawake; K. Suzuki; S. -I. Saitoh
BIOGEOSCIENCES, 8, 12, 3567, 3580, 2011, [Peer-reviewed]
English, Scientific journal - Application of PTR-MS to an incubation experiment of the marine diatom Thalassiosira pseudonana
Sohiko Kameyama; Hiroshi Tanimoto; Satoshi Inomata; Koji Suzuki; Daisuke D. Komatsu; Akinari Hirota; Uta Konno; Urumu Tsunogai
GEOCHEMICAL JOURNAL, 45, 5, 355, 363, 2011, [Peer-reviewed]
English, Scientific journal - Impacts of elevated CO2 on organic carbon dynamics in nutrient depleted Okhotsk Sea surface waters
Takeshi Yoshimura; Jun Nishioka; Koji Suzuki; Hiroshi Hattori; Hiroshi Kiyosawa; Yutaka W. Watanabe
JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY, 395, 1-2, 191, 198, Nov. 2010, [Peer-reviewed]
English, Scientific journal - Primary productivity and its bio-optical modeling in the Oyashio region, NW Pacific during the spring bloom 2007
Tomonori Isada; Ai Hattori-Saito; Hiroaki Saito; Tsutomu Ikeda; Koji Suzuki
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 57, 17-18, 1653, 1664, Sep. 2010, [Peer-reviewed], [Last author]
English, Scientific journal - Distributions of short-lived iodocarbons and biogenic trace gases in the open ocean and atmosphere in the western North Pacific
M. K. Kurihara; M. Kimura; Y. Iwamoto; Y. Narita; A. Ooki; Y. -J. Eum; A. Tsuda; K. Suzuki; Y. Tani; Y. Yokouchi; M. Uematsu; S. Hashimoto
MARINE CHEMISTRY, 118, 3-4, 156, 170, Feb. 2010, [Peer-reviewed]
English, Scientific journal - Community compositions of Bacteria and Archaea in the Sea of Okhotsk during summer
Hongmei Jing; Hongbin Liu; Koji Suzuki; Rumi Sohrin; Jun Nishioka
AQUATIC MICROBIAL ECOLOGY, 61, 2, 191, 204, 2010, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Iron deficiency in micro-sized diatoms in the Oyashio region of the Western subarctic Pacific during spring
Ai Hattori-Saito; Jun Nishioka; Tsuneo Ono; R. Michael L. McKay; Koji Suzuki
Journal of Oceanography, 66, 1, 105, 115, Jan. 2010, [Peer-reviewed], [Last author], ［Internationally co-authored］
English, Scientific journal - Temporal and spatial variations in photosynthetic physiology of diatoms during the spring bloom in the western subarctic Pacific
Naoki Yoshie; Koji Suzuki; Akira Kuwata; Jun Nishioka; Hiroaki Saito
MARINE ECOLOGY PROGRESS SERIES, 399, 39, 52, 2010, [Peer-reviewed]
English, Scientific journal - Mesozooplankton selective feeding in subtropical coastal waters as revealed by HPLC pigment analysis
Hongbin Liu; Mianrun Chen; Koji Suzuki; Chong Kim Wong; Bingzhang Chen
MARINE ECOLOGY PROGRESS SERIES, 407, 111, 123, 2010, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Determination of total N2 fixation rates in the ocean taking into account both the particulate and filtrate fractions
U. Konno; U. Tsunogai; D. D. Komatsu; S. Daita; F. Nakagawa; A. Tsuda; T. Matsui; Y. -J. Eum; K. Suzuki
BIOGEOSCIENCES, 7, 8, 2369, 2377, 2010, [Peer-reviewed]
English, Scientific journal - Response of lower trophic organisms to nutrient input and effects on carbon budget: A mesocosm experiment
Atsushi Tsuda; Kimio Fukami; Hiroshi Kiyosawa; Koji Suzuki; Shigenobu Takeda; Jun Nishioka; Masayuki Takahashi; Keith Johnson; Chi-Shing Wong
Plankton and Benthos Research, 5, 4, 144, 155, 2010, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Temporal changes in community composition of heterotrophic bacteria during in situ iron enrichment in the western subarctic Pacific (SEEDS-II)
Takafumi Kataoka; Koji Suzuki; Maki Hayakawa; Isao Kudo; Seigo Higashi; Atsushi Tsuda
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 56, 26, 2779, 2787, Dec. 2009, [Peer-reviewed]
English, Scientific journal - Responses of DMS in the seawater and atmosphere to iron enrichment in the subarctic western North Pacific (SEEDS-II)
Ippei Nagao; Shinya Hashimoto; Koji Suzuki; Shuji Toda; Yasushi Narita; Atsushi Tsuda; Hiroaki Saito; Isao Kudo; Shungo Kato; Yoshizumi Kajii; Mitsuo Uematsu
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 56, 26, 2899, 2917, Dec. 2009, [Peer-reviewed]
English, Scientific journal - Production and air-sea flux of halomethanes in the western subarctic Pacific in relation to phytoplankton pigment concentrations during the iron fertilization experiment (SEEDS II)
Shinya Hashimoto; Shuji Toda; Koji Suzuki; Shungo Kato; Yasusi Narita; Michiko K. Kurihara; Yoko Akatsuka; Hiroshi Oda; Takahiro Nagai; Ippei Nagao; Isao Kudo; Mitsuo Uematsu
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 56, 26, 2928, 2935, Dec. 2009, [Peer-reviewed]
English, Scientific journal - Primary productivity, bacterial productivity and nitrogen uptake in response to iron enrichment during the SEEDS II
Isao Kudo; Yoshifumi Noiri; William P. Cochlan; Koji Suzuki; Takafumi Aramaki; Tsuneo Ono; Yukihiro Nojiri
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 56, 26, 2755, 2766, Dec. 2009, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Iron-induced alterations of bacterial DMSP metabolism in the western subarctic Pacific during SEEDS-II
Martine Lizotte; Maurice Levasseur; Isao Kudo; Koji Suzuki; Atsushi Tsuda; Ronald P. Kiene; Michael G. Scarratt
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 56, 26, 2889, 2898, Dec. 2009, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Community structure and photosynthetic physiology of phytoplankton in the northwest subarctic Pacific during an in situ iron fertilization experiment (SEEDS-II)
Koji Suzuki; Hiroaki Saito; Tomonori Isada; Ai Hattori-Saito; Hiroshi Kiyosawa; Jun Nishioka; R. Michael. L. McKay; Akira Kuwata; Atsushi Tsuda
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 56, 26, 2733, 2744, Dec. 2009, [Peer-reviewed], [Lead author, Corresponding author], ［Internationally co-authored］
English, Scientific journal - Biogeochemical cycling of N and Si during the mesoscale iron-enrichment experiment in the western subarctic Pacific (SEEDS-II)
Hiroaki Saito; Atsushi Tsuda; Yukihiro Nojiri; Takafumi Aramaki; Hiroshi Ogawa; Takeshi Yoshimura; Keiri Imai; Isao Kudo; Jun Nishioka; Tsuneo Ono; Koji Suzuki; Shigenobu Takeda
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 56, 26, 2852, 2862, Dec. 2009, [Peer-reviewed]
English, Scientific journal - Photosynthetic features and primary productivity of phytoplankton in the Oyashio and Kuroshio-Oyashio transition regions of the northwest Pacific
Tomonori Isada; Akira Kuwata; Hiroaki Saito; Tsuneo Ono; Masao Ishii; Hisayuki Yoshikawa-Inoue; Koji Suzuki
JOURNAL OF PLANKTON RESEARCH, 31, 9, 1009, 1025, Sep. 2009, [Peer-reviewed], [Last author]
English, Scientific journal - Detection of UVBR-sensitive and -tolerant bacteria in surface waters of the western North Pacific
Takafumi Kataoka; Yoshikuni Hodoki; Koji Suzuki; Hiroaki Saito; Seigo Higashi
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY, 95, 2, 108, 116, May 2009, [Peer-reviewed]
English, Scientific journal - Tempo-spatial patterns of bacterial community composition in the western North Pacific Ocean
Takafumi Kataoka; Yoshikuni Hodoki; Koji Suzuki; Hiroaki Saito; Seigo Higashi
JOURNAL OF MARINE SYSTEMS, 77, 1-2, 197, 207, Apr. 2009, [Peer-reviewed]
English, Scientific journal - Phytoplankton growth and microzooplankton grazing in the Sea of Okhotsk during late summer of 2006
Hongbin Liu; Koji Suzuki; Jun Nishioka; Rumi Sohrin; Takeshi Nakatsuka
DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS, 56, 4, 561, 570, Apr. 2009, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Phylogenetic diversity of marine Synechococcus spp. in the Sea of Okhotsk
Hongmei Jing; Hongbin Liu; Koji Suzuki
AQUATIC MICROBIAL ECOLOGY, 56, 1, 55, 63, 2009, [Peer-reviewed], [Last author], ［Internationally co-authored］
English, Scientific journal - Differences in cell viabilities of phytoplankton between spring and late summer in the northwest Pacific Ocean
Maki Hayakawa; Koji Suzuki; Hiroaki Saito; Kazutaka Takahashi; Shin-ichi Ito
JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY, 360, 2, 63, 70, Jun. 2008, [Peer-reviewed]
English, Scientific journal - Evidence for the grazing hypothesis: Grazing reduces phytoplankton responses of the HNLC ecosystem to iron enrichment in the western subarctic pacific (SEEDS II)
Atsushi Tsuda; Shigenobu Takeda; Hiroaki Saito; Jun Nishioka; Isao Kudo; Yukihiro Nojiri; Koji Suzuki; Mitsuo Uematsu; Mark L. Wells; Daisuke Tsumune; Takeshi Yoshimura; Tatsuo Aono; Takafumi Aramaki; William P. Cochlan; Maki Hayakawa; Keiri Imai; Tomoshi Isada; Yoko Iwamoto; William K. Johnson; Sohiko Kameyama; Shungo Kato; Hiroshi Kiyosawa; Yoshiko Kondo; Maurice Levasseur; Ryuji J. Machida; Ippei Nagao; Fumiko Nakagawa; Takahiro Nakanish; Seiji Nakatsuka; Akira Narita; Yoshifumi Noiri; Hajime Obata; Hiroshi Ogawa; Kenji Oguma; Tsuneo Ono; Tomofumi Sakuragi; Motoki Sasakawa; Mitsuhide Sato; Akifumi Shimamoto; Hyoe Takata; Charles G. Trick; Yutaka W. Watanabe; Chi Shing Wong; Naoki Yoshie
JOURNAL OF OCEANOGRAPHY, 63, 6, 983, 994, Dec. 2007, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Iron supply to the western subarctic Pacific: Importance of iron export from the Sea of Okhotsk
Jun Nishioka; Tsuneo Ono; Hiroaki Saito; Takeshi Nakatsuka; Shigenobu Takeda; Takeshi Yoshimura; Koji Suzuki; Kenshi Kuma; Shigeto Nakabayashi; Daisuke Tsumune; Humio Mitsudera; W. Keith Johnson; Atsushi Tsuda
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 112, C10, Oct. 2007, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Effect of high iron concentrations on iron uptake and growth of a coastal diatom Chaetoceros sociale
Shouei Iwade; Kenshi Kuma; Yutaka Isoda; Masahiko Yoshida; Isao Kudo; Jun Nishioka; Koji Suzuki
AQUATIC MICROBIAL ECOLOGY, 43, 2, 177, 191, Jun. 2006, [Peer-reviewed]
English, Scientific journal - Role of heterotrophic dinoflagellate Gyrodinium sp in the fate of an iron induced diatom bloom
H Saito; T Ota; K Suzuki; J Nishioka; A Tsuda
GEOPHYSICAL RESEARCH LETTERS, 33, 9, May 2006, [Peer-reviewed]
English, Scientific journal - Distribution and sources of organic matter in surficial sediments on the shelf and slope off Tokachi, western North Pacific, inferred from C and N stable isotopes and C/N ratios
T Usui; S Nagao; M Yamamoto; K Suzuki; Kudo, I; S Montani; A Noda; M Minagawa
MARINE CHEMISTRY, 98, 2-4, 241, 259, Feb. 2006, [Peer-reviewed]
English, Scientific journal - Nutrient and phytoplankton dynamics during the stationary and declining phases of a phytoplankton bloom induced by iron-enrichment in the eastern subarctic Pacific
Hiroaki Saito; Atsushi Tsuda; Yukihiro Nojiri; Jun Nishioka; Shigenobu Takeda; Hiroshi Kiyosawa; Isao Kudo; Yoshifumi Noiri; Tsuneo Ono; Yousuke Taira; Koji Suzuki; Takeshi Yoshimura; Philip W. Boyd
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 53, 20-22, 2168, 2181, 2006, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - Responses of phytoplankton and heterotrophic bacteria in the northwest subarctic Pacific to in situ iron fertilization as estimated by HPLC pigment analysis and flow cytometry
K Suzuki; A Hinuma; H Saito; H Kiyosawa; HB Liu; T Saino; A Tsuda
PROGRESS IN OCEANOGRAPHY, 64, 2-4, 167, 187, 2005, [Peer-reviewed], [Lead author, Corresponding author], ［Internationally co-authored］
English - Responses of microzooplankton to in situ iron fertilization in the western subarctic Pacific (SEEDS)
H Saito; K Suzuki; A Hinuma; T Ota; K Fukami; H Kiyosawa; T Saino; A Tsuda
PROGRESS IN OCEANOGRAPHY, 64, 2-4, 223, 236, 2005, [Peer-reviewed]
English - Community structure and dynamics of phytoplankton in the western subarctic Pacific Ocean: A synthesis
HB Liu; K Suzuki; H Saito
JOURNAL OF OCEANOGRAPHY, 60, 1, 119, 137, Feb. 2004, [Peer-reviewed], ［Internationally co-authored］
English - A mesoscale iron enrichment in the western Subarctic Pacific induces a large centric diatom bloom
A Tsuda; S Takeda; H Saito; J Nishioka; Y Nojiri; Kudo, I; H Kiyosawa; A Shiomoto; K Imai; T Ono; A Shimamoto; D Tsumune; T Yoshimura; T Aono; A Hinuma; M Kinugasa; K Suzuki; Y Sohrin; Y Noiri; H Tani; Y Deguchi; N Tsurushima; H Ogawa; K Fukami; K Kuma; T Saino
SCIENCE, 300, 5621, 958, 961, May 2003, [Peer-reviewed]
English, Scientific journal - Long-term monitoring of the sedimentary processes in the central part of Sagami Bay, Japan: rationale, logistics and overview of results
H Kitazato; T Nakatsuka; M Shimanaga; J Kanda; W Soh; Y Kato; Y Okada; A Yamaoka; T Masuzawa; K Suzuki; Y Shirayama
PROGRESS IN OCEANOGRAPHY, 57, 1, 3, 16, 2003, [Peer-reviewed]
English - Isotopic composition of suspended particulate nitrogen (δ15Nsus) in surface waters of the Atlantic Ocean from 50°N to 50°S
Yoshihisa Mino; Toshiro Saino; Toshiro Saino; Koji Suzuki; Emilio Maranón
Global Biogeochemical Cycles, 16, 4, 7, 1, 01 Dec. 2002, [Peer-reviewed], ［Internationally co-authored］ - East-west gradients in the photosynthetic potential of phytoplankton and iron concentration in the subarctic Pacific Ocean during early summer
K Suzuki; HB Liu; T Saino; H Obata; M Takano; K Okamura; Y Sohrin; Y Fujishima
LIMNOLOGY AND OCEANOGRAPHY, 47, 6, 1581, 1594, Nov. 2002, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal - Picoplankton community structure in the subarctic Pacific Ocean and the Bering Sea during summer 1999
HB Liu; K Suzuki; C Minami; T Saino; M Watanabe
MARINE ECOLOGY PROGRESS SERIES, 237, 1, 14, Jul. 2002, [Peer-reviewed]
English, Scientific journal - Grazing impact of microzooplankton on a diatom bloom in a mesocosm as estimated by pigment-specific dilution technique
K Suzuki; A Tsuda; H Kiyosawa; S Takeda; J Nishioka; T Saino; M Takahashi; CS Wong
JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY, 271, 1, 99, 120, May 2002, [Peer-reviewed], [Lead author, Corresponding author], ［Internationally co-authored］
English, Scientific journal - Measurement of phytoplankton photosynthetic activity using chlorophyll fluorescence
SUZUKI Koji; YOSHIKAWA Takashi; FURUYA Ken; SAINO Toshiro
Bulletin of the Plankton Society of Japan, 49, 1, 27, 36, 日本プランクトン学会, Feb. 2002, [Peer-reviewed], [Lead author, Corresponding author]
Japanese, Scientific journal - Phytoplankton growth, and microzooplankton grazing in the subarctic Pacific Ocean and the Bering Sea during summer 1999
HB Liu; K Suzuki; T Saino
DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS, 49, 2, 363, 375, Feb. 2002, [Peer-reviewed]
English, Scientific journal - Temporal and spatial patterns of chemotaxonomic algal pigments in the subarctic Pacific and the Bering Sea during the early summer of 1999
K Suzuki; C Minami; HB Liu; T Saino
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 49, 24-25, 5685, 5704, 2002, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal - Seasonal variability of picophytoplankton and bacteria in the western subarctic Pacific Ocean at station KNOT
HB Liu; K Imai; K Suzuki; Y Nojiri; N Tsurushima; T Saino
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 49, 24-25, 5409, 5420, 2002, [Peer-reviewed]
English, Scientific journal - Measurement of the Absorption Coefficient of Seawater
Kishino Motoake; Furuya Ken; Taguchi Satoru; Hirawake Toru; Suzuki Koji; Tanaka Akihiko
Umi no Kenkyu (Oceanography in Japan), 10, 6, 537, 559, 日本海洋学会, 01 Nov. 2001, [Peer-reviewed]
Japanese, The absorption coefficient of seawater is one of the most crucial parameters in studies of primary production in the sea and ocean-color remote sensing. A considerable number of studies have been done on the measurement of the absorption coefficient so far. This article is a reviw of the principle and problems of each method of absorption measurement, and a step toward a protocol for measuring the absorption coefficient of plytoplankton - A Protocol for Measuring the Absorption Coefficient of Phytoplankton using QFT (Quantitative Filter Technique) and a Submersible Spectrophotometer.
Hirawake Toru; Suzuki Koji; Kishino Motoaki; Furuya Ken; Taguchi Satoru; Saitoh Sei-ich; Saino Toshiro; Matsumoto Kazuhiko; Harimoto Takashi; Sasaki Hiroaki; Fujiki Tetsuichi; Kobara Shinichi; Kashiwa Toshiyuki
Journal of the Oceanographical Society of Japan, 10, 6, 471, 484, The Oceanographic Society of Japan, 2001, [Peer-reviewed]
Japanese, The absorption coefficient of phytoplankton is one of the most important parameters in studies of primary production in the sea and ocean-color remote sensing. This report presents protocol for measuring the absorption coefficient with QFT(quantitative filter technique). The protocol was discussed at three workshops, where some experiments were conducted to standardize its methodology ; (1) with an emphasis on comparisons between spectrophotometers, and techniques for pigment extraction ; (2) comparison between the absorption coefficients of phytoplankton determined by different analytical techniques ; and (3) establishment of a reliable database. In addition, in situ absorption measurement with a submersible spectrophotometer(ac-9, WET Labs)was also discussed at the workshops, and its analytical procedure recommended is briefly reported here. The absorption coefficients as measured with this protocol enable data obtained by different researchers to be compared directly. - Spatial and temporal variabilities of phytoplankton community structure in the northern North Pacific as determined by phytoplankton pigments
Yumiko Obayashi; Eiichiro Tanoue; Koji Suzuki; Nobuhiko Handa; Yukihiro Nojiri; Chi Shing Wong
Deep-Sea Research Part I: Oceanographic Research Papers, 48, 2, 439, 469, 2001, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal - The distribution of Fe in the Australian sector of the Southern Ocean
Y Sohrin; S Iwamoto; M Matsui; H Obata; E Nakayama; K Suzuki; N Handa; M Ishii
DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS, 47, 1, 55, 84, Jan. 2000, [Peer-reviewed]
English, Scientific journal - Seasonal phytodetritus deposition and responses of bathyal benthic foraminiferal populations in Sagami Bay, Japan: Preliminary results from 'Project Sagami 1996-1999'
H. Kitazato; Y. Shirayama; T. Nakatsuka; S. Fujiwara; M. Shimanaga; Y. Kato; Y. Okada; J. Kanda; A. Yamaoka; T. Masuzawa; K. Suzuki
Marine Micropaleontology, 40, 3, 135, 149, 2000, [Peer-reviewed]
English, International conference proceedings - Short term variability of particle fluxes and its relation to surface processes detected by ADEOS/ OCTS off Sanriku, northwestern North Pacific in the spring of 1997
Saino, T.; Shang, S.; Mino, Y.; Suzuki, K.; Nomura, H.; Miyake, H.; Masuzawa, T.; Harada, K.
Journal of Oceanography, 54, 1998
Scientific journal - Short term variability of particle fluxes and its relation to variability in sea surface temperature and chlorophyll a field detected by Ocean Color and Temperature Scanner (OCTS) off Sanriku, northwestern North Pacific in the spring of 1997
Toshiro Saino; Shaoling Shang; Yoshihisa Mino; Koji Suzuki; Hideaki Nomura; Sei-Ichi Saitoh; Hideo Miyake; Toshiyuki Masuzawa; Koh Harada
Journal of Oceanography, 54, 5, 583, 592, Terra Scientific Publishing Company, 1998, [Peer-reviewed]
English, Scientific journal - Chlorophyll-specific absorption coefficients and pigments of phytoplankton off Sanriku, Northwestern North Pacific
Koji Suzuki; Motoaki Kishino; Kousei Sasaoka; Sei-Ichi Saitoh; Toshiro Saino
Journal of Oceanography, 54, 5, 517, 526, Terra Scientific Publishing Company, 1998, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal - Temporal and spatial distribution of phytoplankton pigments in the central Pacific Ocean along 175°E during the boreal summers of 1992 and 1993
Koji Suzuki; Nobuhiko Handa; Hiroshi Kiyosawa; Joji Ishizaka
Journal of Oceanography, 53, 4, 383, 396, Oceanographic Society of Japan, 01 Aug. 1997, [Peer-reviewed], [Lead author, Corresponding author]
English - Estimation of phytoplankton succession in a fertilized mesocosm during summer using high-performance liquid chromatographic analysis of pigments
K Suzuki; N Handa; T Nishida; CS Wong
JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY, 214, 1-2, 1, 17, Jul. 1997, [Peer-reviewed], [Lead author, Corresponding author], ［Internationally co-authored］
English, Scientific journal - Sporadic increase of particle sedimentation at the ice edge of the Antarctic Ocean during the austral summer 1994-1995
H. Sasaki; H. Suzuki; M. Tanaka; K. Suzuki; N. Handa; S. Kudoh; M. Fukuchi
Proc. NIPR Symp. Polar Biol., 10, 50, 55, National Institute of Polar Research, 1997, [Peer-reviewed]
English, International conference proceedings, Time-series sediment traps were deployed at depths of 537 m, 796 m, 1259 m, 1722 m and 2727 m at ice edge of the Antarctic Ocean (64°42'S, 139°58'E) from 26 December 1994 to 20 January 1995. During a short period from 7 to 9 January, a sporadic flux increase within a few days in terms of total dry weight of 774 mg m^<-2>d^<-1> at 537 m was observed. The mass of sinking particles forming the flux maximum sank down to the deepest trap (2727 m) within 7-11 days, indicating that about 5% of these particles were transported downward to the bottom with the sinking rate of 199-313 m d^<-1> (mean 243 m d^<-1>). The considerable particle loss rate (13% [100 m]^<-1>) below the mesopelagic layers in a short period suggests the occurrence of consumption processes induced by the sporadic supply of freshly produced particles from above. - Ultraviolet radiation induced changes in the production of organic compounds in Antarctic marine phytoplankton
J. I. Goes; N. Handa; K. Suzuki; S. Taguchi; T. Hama
Proc. NIPR Symp. Polar Biol., 10, 25, 38, National Institute of Polar Research, 1997, [Peer-reviewed]
English, International conference proceedings, Experiments were conducted during January 1995 in the Southern Ocean to examine the impact of enhanced solar ultraviolet-B radiation (UVBR) on the biosynthesis and composition of organic compounds in Antarctic marine phytoplankton. Our results revealed distinct changes in the biochemical composition of phytoplankton attributable to UVBR exposure. Fatty acid concentrations increased in the presence of UVBR, mainly on account of a large increase in the content of saturated fatty acids within the cells. On the other hand, polyunsaturated fatty acids declined in cells exposed to UVBR. Amino acid concentrations were higher in the UVBR exposed samples, attributable largely to a UVBR induced increase in cellular concentrations of glutamic' acid (glutamic acid+glutamine) and aspartic acid. Monosaccharide constituents of cellular storage and structural carbohydrates, however, showed a decline in the cells exposed to UVBR. Except for the decline in structural monosaccharides, these changes in the patterns of organic compounds observed in Antarctic phytoplankton were remarkably similar but, greater in magnitude in comparison to those observed in temperate phytoplankton exposed to UVBR. - Size and taxonomic plankton community structure and carbon flow at the equator, 175 degrees E during 1990-1994
J Ishizaka; K Harada; K Ishikawa; H Kiyosawa; H Furusawa; Y Watanabe; H Ishida; K Suzuki; N Handa; M Takahashi
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 44, 9-10, 1927, 1949, 1997, [Peer-reviewed]
English, Scientific journal - Distribution of the prochlorophyte Prochlorococcus in the central Pacific Ocean as measured by HPLC
Koji Suzuki; Nobuhiko Handa; Hiroshi Kiyosawa; Joji Ishizaka
Limnology and Oceanography, 40, 5, 983, 989, 1995, [Peer-reviewed], [Lead author, Corresponding author]
English
- Characteristics of transparent exopolymer particles (TEP) distribution in the Oyashio during diatom bloom period in spring of 2010
NOSAKA YUICHI; SUZUKI KOJI; YAMASHITA YOUHEI; SAITO HIROAKI; TAKAHASHI KAZUTAKA, Abstracts of Annual Meeting of the Geochemical Society of Japan, 58, 0, 273, 273, 2011
2010年4月および6月の親潮域において，植物プランクトンの群集組成と光合成特性と共に，透明細胞外重合体粒子（TEP）分布の特徴を調査した．4月は珪藻ブルームが発生し，表層（5m深）における植物プランクトンの光合成活性が相対的に高かったのに対し，6月は珪藻ブルームが終焉し，光合成活性も低かった．4月における表層のTEP濃度は，6月と比較して，2-3倍高かった．観測期間中，表層のTEP濃度とSi(OH)<sub>4</sub>/NO<sub>3</sub>比の間に高い相関（r = 0.94, p < 0.01, n = 6）がみられたことから，珪藻類の栄養塩取り込み活性がTEP生産を支配していたことが示唆された．, GEOCHEMICAL SOCIETY OF JAPAN
- The 5th Workshop on High-Performance Liquid Chromatography (HPLC) Intercomparison on Phytoplankton Pigments (HIP)
Canuti, E.; Allerup, M.; Bracher, A.; Brotas, V.; Capellacci, S.; Carabelli, C.; Casabianca, S.; Develoouse, I.; Dias, A.; Dimier, C.; Flander-Putrle, V.; Laloux, M.; Lami, A.; Kenemer, C.; Kumar, S.; Peeken, I.; Penna, A.; Raman, M.; Ras, J.; Ricci, F.; Salaün, J.; Schluter, L.; Suzuki, K.; Thomas, C.; Tirkey, A.; Tracana, A.; Uitz, J.; Vijaya; Krishna, A.; Vlaemnick, B.; Zaccagnini, A.
Jan. 2025, 9789268238752, [Joint work] - Kuroshio Current: Physical, Biogeochemical, and Ecosystem Dynamics
Takeyoshi Nagai; Hiroaki Saito; Koji Suzuki; Motomitsu Takahashi
Wiley - American Geophysical Union, Jun. 2019, 9781119428428, 1 online resource (x, 312 p., [8] p. of plates), English, [Peer-reviewed], [Joint editor] - Advances in Above- and In-Water Radiometry, Vol. 3: Hybridspectral Next-Generation Optical Instruments
Hooker, S.B; R.N. Lind; J.H. Morrow; J.W. Brown; R.M. Kudela; H.F. Houskeeper; K. Suzuki
NASA Scientific and Technical Information Program, NASA Goddard Space Flight Center, Nov. 2018, ［Internationally co-authored］, [Joint work] - Advances in Above- and In-Water Radiometry, Vol. 2: Autonomous Atmospheric and Oceanic Observing Systems
Hooker, S.B; R.N. Lind; J.H. Morrow; J.W. Brown; R.M. Kudela; H.F. Houskeeper; K. Suzuki
NASA Scientific and Technical Information Program, NASA Goddard Space Flight Center, Nov. 2018, ［Internationally co-authored］, [Joint work] - Advances in Above- and In-Water Radiometry, Vol. 1: Enhanced Legacy and State-of-the-Art Instrument Suites
Hooker, S.B; R.N. Lind; J.H. Morrow; J.W. Brown; K. Suzuki; H.F. Houskeeper; T. Hirawake; E.R. Maúre
NASA Scientific and Technical Information Program, NASA Goddard Space Flight Center, Nov. 2018, ［Internationally co-authored］, [Joint work] - 海洋生態学
日本生態学会編; 鈴木光次, 基礎生産過程; 海洋生態系の食物関係
共立出版, Feb. 2016, 9784320057456, xi, 305p, 図版 [4] p, Japanese, [Contributor] - 環境分析ガイドブック
日本分析化学会編; 鈴木光次, 植物プランクトン
丸善, Jan. 2011, 9784621082775, xx, 823p, 図版 [4] p, Japanese, [Contributor] - 地球温暖化の科学
北海道大学大学院環境科学院編; 鈴木光次, 地球温暖化による海洋生態系の変化
北海道大学出版会, Mar. 2007, 9784832981812, xii, 246p, Japanese, [Contributor] - オゾン層破壊の科学
北海道大学大学院環境科学院編; 鈴木光次, 紫外線による海洋生態系への影響; 水中の放射伝達
北海道大学出版会, Mar. 2007, 9784832981799, vi, 408p, Japanese, [Contributor] - 第5版 実験化学講座 環境化学
日本化学会編; 鈴木光次, 植物プランクトン
丸善, Jan. 2007, 9784621078068, xiii, 519p, Japanese, [Contributor] - 地球環境調査計測事典第3巻沿岸域編
鈴木光次, 逆相高速液体クロマトグラフィーによるクロロフィルとカロチノイドの測定及びフィコビリンタンパク質の測定; 蛍光法による基礎生産速度の測定
フジ・テクノシステム, 2002, 4938555891, 3冊, Japanese, [Contributor]
- 対流圏化学特論, 2024年, 修士課程, 環境科学
- 大気海洋化学基礎論, 2024年, 修士課程, 環境科学院
- 生物地球化学基礎論, 2024年, 修士課程, 環境科学院
- 環境と人間, 2024年, 学士課程, 全学教育
- American Geophysical Union
- Phycological Society of America
- Association for the Sciences of Limnology and Oceanography
- 日本海洋学会
- 日本地球化学会
- European Geosciences Union
- Evaluation of the role of gel particles in oceanic material cycles
Grants-in-Aid for Scientific Research
01 Apr. 2025 - 31 Mar. 2028
野坂 裕一; 鈴木 光次; 伊佐田 智規
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Tokai University, 25K15420 - 広域高頻度高精度観測から解明する微細藻類の動態変化
2023 - 2028
鈴木 光次
人為起源二酸化炭素の増加に伴い、海洋の主要一次生産者である微細藻類（植物プランクトン）の動態の変化が危惧されています。本研究では、協力商船と研究船を用いた前例の無い高頻度、高精度観測を通して、世界の海の中でも生産力の高い北太平洋中高緯度域の炭素隔離能力に対して重要な働きをする植物プランクトンの現存量、群集組成、生産力の季節変化と年々変化を把握し、温暖化と海洋酸性化の影響を定量的に明らかにします。
科学技術振興機構, 戦略的な研究開発の推進/戦略的創造研究推進事業/CREST, 23829302 - 北太平洋中高緯度域の新生産に貢献するケイ藻類と窒素固定ラン藻類の動態変化の解明
科学研究費助成事業
01 Apr. 2023 - 31 Mar. 2027
鈴木 光次; 高尾 信太郎
北太平洋を定期的に航行する協力商船New Century 2（トヨフジ海運株式会社）を用いて、航海中、船底から船内実験室まで汲み上げられた表層海水を昼間に毎日1回採取した。ケイ藻類および窒素固定ラン藻類の動態を評価するための植物プランクトン色素試料と遺伝子（DNAおよびRNA）試料については、海水の濾過を行い、得られたフィルター試料を冷凍保存した。水温、塩分、光合成有効放射量、硝酸塩濃度、海水中の二酸化炭素分圧については、同商船に備えた各種センサーで連続測定した。硝酸塩センサーデータの検証・校正等のための海水栄養塩試料は、冷凍保存し、陸上で分析した。また、2023年6月に学術研究船白鳳丸（海洋研究開発機構）を用いた西部北太平洋亜寒帯域KH-23-2次研究航海に参加し、協力商船観測と同様の試料および環境データを取得した。
上記の協力商船および研究船で取得した植物プランクトン色素試料を超高速液体クロマトグラフィー（UHPLC）で解析を行った。また、2014年以後に上記の協力商船で取得した遺伝子試料について、ケイ藻類と窒素固定ラン藻類に特有の遺伝子断片のコピー数を定量PCR法で評価した。さらに、次世代シーケンサーによるアンプリコンシーケンス解析を行い、ケイ藻類とその群集組成の把握を行った。ケイ藻類の現存量、組成、生産力に対する各環境因子（水温、塩分、硝酸塩とそれ以外の栄養塩（リン酸塩、ケイ酸塩等）の濃度とそれらの比、海水炭酸系パラメータ、中規模渦運動エネルギー、海面高度等）の影響を評価した。
日本学術振興会, 基盤研究(B), 北海道大学, 23K28206 - Elucidation of microbial factors that control the amount and physicochemical properties of atmospheric organic nitrogen aerosols in the subarctic ocean
Grants-in-Aid for Scientific Research
01 Apr. 2023 - 31 Mar. 2026
宮崎 雄三; 鈴木 光次; 山下 洋平
秋季の南部オホーツク海上で学術研究船新青丸により大気・表層海水試料を採取し、前年度までに同海域で採取済みの試料と併せ、化学組成分析を行った。その結果、微小エアロゾル質量に対し有機物が約50%を占め支配的であり、水溶性成分の割合が大きいことが明らかになった。さらに有機物の安定炭素同位体比の測定から、観測されたエアロゾルのうち、海氷後退後の春季の植物プランクトンブルーム期で71%、ブルーム衰退期で64% が海洋起源であると推定された。エアロゾル中の水溶性有機炭素（WSOC）と分子トレーサー濃度との相関関係から、観測された海洋由来のWSOCの大部分は、海水飛沫による一次生成ではなく、α-ピネンや硫化ジメチルの酸化生成物に関連する前駆物質からの二次生成の寄与が大きいことが示唆された。さらにブルーム期の水溶性有機エアロゾル中のC:N平均比はブルーム衰退期の平均比より有意に低く、海洋表層の微生物活動に関連した有機態窒素エアロゾル生成の影響が大きいことが示唆された。実際、表層海水においてブルーム期の溶存態有機炭素（DOC）:溶存態有機窒素（DON）の平均比（12.8）もブルーム衰退期の平均比（14.7）より有意に低く、ブルーム期のDOCとDONはオホーツク海で研究期間に優占的な珪藻類であるFragilariopsis cylindrusのようなアイスアルジーに関係していることが示唆された。これらの結果から、領域的な海洋表層から大気に放出生成される有機物の領域的な気候影響を評価する上で、植物プランクトンブルーム期のアイスアルジーに由来する有機物のエアロゾル二次生成の重要性が明らかになった。
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 23K28207 - Formation of water nutritional property including iron and silicate at the termination of global ocean conveyor belt
Grants-in-Aid for Scientific Research
05 Jul. 2021 - 31 Mar. 2026
西岡 純; 中村 知裕; 三寺 史夫; 山下 洋平; 鈴木 光次; 小畑 元; 近藤 能子; 安田 一郎; 三角 和弘; 南 秀樹
2006年、2007年、2010年、2011年、2014年、2018年に北海道大学低温科学研究所とロシア極東海洋気象学研究所の共同研究として実施したロシア船を用いたオホーツク海とベーリング海の観測データを、1998年から2017年までに北太平洋で実施した観測航海のデータと統合し、各測点の水柱内の塩分、水温、密度、溶存酸素、Fe、Si、N、Pデータを含む栄養物質データセットを作成整備しHPで公開した。上記データセットを用いた解析を実施し、東経155度の北太平洋中層水（NPIW）から表層に向けた上向きのFeおよび主要栄養塩のフラックスと、HPLC植物色素データから得られる表層の生物種組成情報を比較した。生物種組成情報を取り出してフラックスとの関係を見ると、下層から表層への栄養物質フラックスと珪藻の現存量との間には良い相関がみられた。亜寒帯ジャイア域と黒潮・親潮移行域でNPIW循環から表層に供給されるFeやSiなどの栄養物質によって、珪藻の増殖が支えられていることが初めて示された。また、堆積物由来溶存鉄の長距離輸送メカニズムの解明を目指して、NPIW循環域における溶存Feの化学形態別分布を解析した。その結果、オホーツク海陸棚堆積物から運ばれてくるFeは、粒子状やコロイド状が主な形態であるのに対し、中層水循環により長距離輸送されるFeは腐植錯体Feであることを示唆した
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (S), Hokkaido University, 21H05056 - Exploratory research on new source of atmospheric reactive nitrogen focusing on marine nitrogen-fixing organisms
Grants-in-Aid for Scientific Research
09 Jul. 2021 - 31 Mar. 2023
Miyazaki Yuzo
This study aimed to elucidate the contribution of marine nitrogen-fixing microorganism (Trichodesmium) to the formation of atmospheric reactive nitrogen by a laboratory incubation experiment. During the incubation period of approximately two months, it was observed that dissolved nitrogen was exuded from Trichodesmium during the exponential phase of the growth stage. Throughout the experiment, ammonium/ammonia and water-soluble organic nitrogen (WSON) were the major reactive nitrogen components in both particulate and gas phases. Overall results showed that the atmospheric emission of acidic WSON was more evident during the exponential and stationary growth phases, while the emissions of basic reactive nitrogen were more significant during the decline and death phases. This study demonstrated the sea-to-air emissions of ammonia and WSON associated with the growth and decline of nitrogen-fixing microorganism for the first time.
Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Research (Exploratory), Hokkaido University, 21K19835 - Organic nitrogen aerosol in the marine atmosphere: Which factors control the amount of organic nitrogen in marine microbial activity?
Grants-in-Aid for Scientific Research
Apr. 2019 - Mar. 2022
Miyazaki Yuzo
Shipboard measurements of atmospheric aerosols and surface seawater in the subtropical North Pacific indicated that organic nitrogen, produced and exuded by nitrogen-fixing microorganisms in surface seawater, significantly contributed to the formation of atmospheric organic nitrogen aerosols. Laboratory experiments of incubation of nitrogen-fixing microorganisms followed by atmospheric measurements confirmed sea-to-air emissions of organic nitrogen associated with the growth of nitrogen-fixing microorganisms. Furthermore, the experiment revealed that the emission of organic nitrogen, mainly consisted of highly-volatile, basic components, increased during the decay of microorganisms.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 19H04233 - Toward understanding changes in the photosynthetic capability of microalgae with their vulnerable species after sea ice melt
Grants-in-Aid for Scientific Research
Apr. 2018 - Mar. 2021
Suzuki Koji
In this study, we carried out laboratory incubation experiments using a representative, isolated diatom strain of sea ice microalgae, and clarified changes in the photosynthetic capability of the strain during the formation, frozen or melting periods of sea ice. Additionally, we collected sea ice with ice algae from the Sea of Okhotsk in winter, and then performed an ice melt study. During the latter experiment, morphological changes, decreases in photosynthetic pigment concentration and so on were observed in microalgal cells immediately after sea ice melt. Then cell viability of pennate diatoms became lower. On the other hand, most centric diatoms fully recovered until approximately 3 days after sea ice melt, and they were able to photosynthesize and grow actively. Based on the results obtained from this study, we published 9 original papers from international journals.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 18H03352 - Biogeochemical linkage in the polar - subarctic region via sea ice melting water
Grants-in-Aid for Scientific Research
Apr. 2017 - Mar. 2021
Nishioka Jun
We conducted field observations in the northwestern Bering Sea and the Sea of Okhotsk, which are subpolar marginal seas, and adjacent subarctic waters, and evaluated the effects of the inflow of melting water from the sea ice on the distribution of nutrient such as iron and nutrients, and the growth of phytoplankton species. The results suggest that the East Sakhalin Current within the Sea of Okhotsk and sea ice meltwater carry iron from continental shelf origin over a wide area of the southern Sea of Okhotsk and coastal Oyashio waters, and forming water masses characterized by high nutrient and iron concentrations, which have a significant impact on phytoplankton growth during the spring season. The results of observational studies of the western Bering Sea to East Sakhalin Current showed that the western Bering Sea is an important region that links the subarctic and polar regions through nutrient cycling.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 17H00775 - Algorithm development for the identification of Phytoplankton Functional Types (PFTs) with optical hyperspectral data in the coastal waters
Grants-in-Aid for Scientific Research
Apr. 2016 - Mar. 2019
ISADA Tomonori; TANIUCHI Yukiko; SUZUKI Koji
We developed the algorithm for identification of Phytoplankton Functional Types (PFTs) with optical hyperspectral data of phytoplankton absorption to better understand marine biogeochemical cycles and to accelerate its implications for ocean color remote sensing applications. We selected four PFTs (diatoms, cyanobacteria, green algae, and dinoflagellates) as target PFTs. Our results indicate that an optical hyperspectral data with a derivative spectroscopy/similarity index (SI) method is a promising approach to identify the dominance of each PFT in the ocean. Additionally, we found that derivative spectra of phytoplankton absorption coefficients could be a useful indicator of bio-optical provinces.
Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Hokkaido University, 16K16182 - Establishment of New Ecozones in the Oceans by Meta-genetic Community Analysis
Grants-in-Aid for Scientific Research
28 Jun. 2012 - 31 Mar. 2017
Tsuda Atsushi; HIRAI Junya; ENDO Hiroshi; SUZUKI Shotaro; TACHIBANA Aiko
The goal of this project is to clarify the biogeography and biodiversity of micro-organisms, phytoplankton and zooplankton by meta-genomic method using a high throughput sequencer. The metagenomic methods have established for bacteria, archaea, diatoms, haptophytes and calanoid copepods, which were ten-times faster than classical method such as microscopic one without effects of individual's skills and experiences. Using these methods for samples collected from wide areas of the Pacific, we found that phytoplankton and zooplankton were distributed along with the surface current system. However, bacteria and archaea were more effected by their life styles (free-living and attached).
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area), The University of Tokyo, 24121004 - Elucidation of thermohaline/biogeochemical circulation systems connecting the Sea of Okhotsk with subarctic North Pacific Ocean
Grants-in-Aid for Scientific Research
Apr. 2010 - Mar. 2015
WAKATSUCHI Masaaki; MITSUDERA Humio; NISHIOKA Jun; NAKAMURA Tomohiro; EBUCHI Naoto; WATANABE Yutaka; SUZUKI Koji; KURODA Hiroshi; OHSHIMA Keiichiro; TSUMUNE Daisuke; MATOBA Sumito
We investigated the thermohaline/biogeochemical circulation systems, connecting the Sea of Okhotsk with the North Pacific, to elucidate a ‘miraculous mechanism’ that supports abundant fisheries resources in the Okhotsk and Oyashio regions. Salinity of the dense shelf water (DSW) over the northern shelf of the Okhotsk Sea controls the strength of the thermohaline circulation of the North Pacific Ocean. DSW salinity is determined by relative contribution among the salinity anomaly that propagates long distance from the subarctic gyre, freshwater anomaly by precipitation, and saline water anomaly rejected during sea ice formation. DSW entrains nutrients such as iron, originating in the Amur River and deposited over the continental shelf, and spreads these materials to the North Pacific Ocean. This study has revealed an exquisite thermohaline-biogeochemical system coupled through DSW and tidal mixing, which controls primary production in the large area of the subarctic North Pacific.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (S), Hokkaido University, 22221001 - Understanding the production of transparent exopolymer particles and its controlling factors during the spring bloom in Oyashio waters
Grants-in-Aid for Scientific Research
2010 - 2012
SUZUKI Koji; SAITO Hiroaki
Much attention has recently been paid to the dynamics of transparent exopolymer particles (TEP) in seawater, because TEP can play an important role in determining the capability of ocean carbon fixation as adhesives for aggregating marine organic matters. However, no such information has ever been available from the Oyashio region, NW Pacific where biological production is relatively high among the world’s oceans. In this study, we obtained crucial results of TEP production and its controlling factors during the spring bloom in Oyashio waters through field observations and laboratory experiments.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 22310002 - Ecosystem responses by epipelagic organisms to dust flux and its feedback to climate
Grants-in-Aid for Scientific Research
2006 - 2010
TSUDA Atsushi; MICHIDA Yutaka; SAITO Hiroaki; TAKAHASHI Kazutaka; SUZUKI Koji
This group provided the biological information to the group who studied the biogenic gasses such as DMS to understand the mechanisms of the variation. Some on-deck incubation experiments showed that diatoms are most important phytoplankton enhanced by typhoon passing and suggested possibilities of altering the carbon cycling and food web structure. Argo-floats with a chlorophyll sensor were deployed. Although we have not observed a typhoon passing, some anomalies of high chlorophyll concentration have been observed. We also found that many copepod species showed seasonal vertical migration behavior, which had recognized as characteristic behavior to polar zooplankton. These results suggest that biological production in the subtropical Pacific is largely depend on the unpredictable spatial and temporal variability of primary production.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research on Priority Areas, The University of Tokyo, 18067008 - Clarifying the characteristics of primary production and their physiological mechanisms during spring Oyashio diatom blooms
Grants-in-Aid for Scientific Research
2007 - 2009
SUZUKI Koji; MINAGAWA Jun
We obtained the data of phytoplankton photosynthesis and iron in the Oyashio region of the NW Pacific during the spring blooms. Coastal Oyashio waters, which contained relatively high amount of iron, stimulated the photosynthetic activity of phytoplankton, especially diatoms. However, diatoms were generally stressed by low iron availability even in the spring blooms. We also determined the effects of temperature, light, and iron availability on photosynthetic features of the representative bloom-forming diatom species isolated from Oyashio waters, through batch culture experiments.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 19510001 - Iron behavior and sources regulating primary production in marginal seas (Bering Sea, Okhotsk Sea, Japan Sea)
Grants-in-Aid for Scientific Research
2006 - 2009
KUMA Kenshi; SAITOH Seiichi; ISODA Yutaka; NAGAO Seiya; NAKATSUKA Takeshi; SUZUKI Koji; WATANABE yutaka; NISHIOKA Jun
Surface mixed layer of the basin region in the Bering Sea is under a typical iron-deficient and nutrient-rich condition with low primary production because of low atmospheric iron input. However, phytoplankton bloom (Breen Belt) is observed at the shelf break region of the Southeastern Bering Sea for a long period in summer. It is suggested that the Green Belt is maintained by the supply of nutrient-rich basin water and iron-rich shelf deep water to the surface water of the shelf break. The tidal mixing in the straits of the Kuril Islands is an important role on supplying nutrient and iron to the surface water of the northwestern North Pacific Ocean and maintaining the high primary production in the Oyashio region. On the contrary, the surface mixed layer in the Japan Sea is characterized by low nutrient and high iron concentrations, resulting from high atmospheric iron input to nutrient-depleted surface water of the Japan Sea close to the Asian continent.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 18201001 - Interaction between Metallome and Proteome in the Marine Ecosystem
Grants-in-Aid for Scientific Research
2004 - 2006
SOHRIN Yoshiki; OKAMURA Kei; NORISUYE Kazuhiro; SUZUKI Koji; HASEGAWA Hiroshi; SOHRIN Rumi
1.Development of chemical speciation and in situ determination of bioactive trace metals
(1)Determination of suspended particulate Co, Ni, Cu, Zn, Cd and Pb has been developed.
(2)Determination of dissolved and acid-dissolvable Zr, Hf, Nb, Ta and W has been developed.
(3)In-situ flow analysis of alkalinity and total carbonate has been developed.
2.Development of analytical methods for enzymes and proteins of phytoplankton and bacteria
(1)Detection of Fe-S protein PsaC and PsbA(D1) in photosynthetic system has been developed.
(2)Anti-ferredoxin and anti-flavodoxin antibodies, which cross-react with ferredoxin and flavodoxin of marine diatoms, respectively, have been developed using synthetic peptides in order to estimate their Fe stress.
3.Observation of the variation and relationship of metallome and proteome
(1)Different distributions of Fe, Co, Ni, Cu, Zn and Cd in seawater between the Sulu Sea, South China Sea and Pacific Ocean were observed.
(2)During the second mesoscale iron enrichment experiments in the western subarctic North Pacific (SEEDS-II), the effects of iron enrichment on the phytoplankton community structure and the speciation of bioactive trace metals were examined.
(3)On the basis of analysis of photosynthetic proteins, Fe in seawater has been proved to be a major factor controlling the spring bloom of diatoms in the Oyashio region.
(4)Diurnal dynamics of biomass of nano-flagellates and ciliates in Suruga Bay was investigated.
(5)The effects of trace metals on the activity of extracellular enzymes of microbes have been proved.
4.Study on metal uptake mechanism of phytoplankton in culture
(1) The size distribution of Fe in culture media of phytoplankton was investigated. Fe ligands exuded from phytoplankton were analyzed by LC-MS.
(2)Membrane proteins revealed in red tide forming phytoplankton Prymnesium parvum under Fe deficiency were analyzed.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Kyoto University, 16204046 - 北西太平洋亜寒帯域における植物プランクトンの死亡とその物質循環過程とのかかわり
科学研究費助成事業
2003 - 2005
鈴木 光次
近年、海洋植物プランクトンが海洋表層から取り除かれる要因として、沈降や動物プランクトンによる捕食以外に、海洋表層での植物プランクトンの細胞死の重要性が指摘されるようになってきた。しかし,北太平洋における植物プランクトンの細胞死に関する報告は無い。そこで本年度は、春および晩夏の北西太平洋亜寒帯域の親潮域および黒潮親潮移行域の植物プランクトンの細胞生存率(総細胞数に占める生細胞数の割合)の比較を行った。水産総合研究センター若鷹丸によるWK0309航海(2003年9月2日〜21日)およびWK0505航海(2005年5月10日〜29日)において、親潮域および黒潮親潮移行域で、細胞消化法を用いて、植物プランクトンの細胞生存率の見積もりを行なった。2003年の晩夏ではSynechococcus spp.の生存率が59〜75%、真核ウルトラ植物プランクトン(体長<10μm)の生存率が21〜41%であり、真核ウルトラ植物プランクトンはSynechococcus spp.よりも致死率(総細胞数に占める死細胞数の割合)が有意に高かった(p<0.01)。一方、2005年の春では,Synechococcus spp.の約80%、真核ウルトラ植物プランクトンの70%以上が生細胞として検出された。さらに、フコキサンチンを含む植物プランクトン(主に珪藻類とプリムネシオ藻類)の細胞生存率は100%に近い値であった。以上の結果から、本調査海域において、植物プランクトンの細胞生存率に季節変化があることが初めて明らかとなった。また、本調査海域の植物プランクトンの除去過程を考える上で、特に晩夏の植物プランクトンの細胞死は決して無視できない過程であることが示唆された。以上の結果をまとめて、国際誌に投稿するための論文を作成した。
日本学術振興会, 若手研究(A), 北海道大学, 15681001 - Dynamics of trace bioelements and their effects on the ecosystem in the marine environment
Grants-in-Aid for Scientific Research
2001 - 2003
SOHRIN Yoshiki; HASEGAWA Hiroshi; SUZUKI Koji; OKAMURA Kei
1. An analytical method for the determination of trace metals in seawater has been developed on the basis of chelating adsorbent column extraction-ICP mass spectrometry. The distributions of Fe, Co, Ni, Cu, Zn, Cd, and Pb in the North Pacific have been observed. The concentration of acid-dissolvable Fe is higher than that of dissolved Fe, showing the dominance, of labile particulate Fe in seawater. Although dissolved Fe and Zn in summer surface water are depleted in the subarctic North Pacific, they are abundant in the subtropical North Pacific.
2. We have found that there was an east-west gradient in the photosynthetic, competence of phytoplankton in the subarctic North Pacific in the summer of 1999 and that the difference was probably caused by Fe levels in seawater. A dramatic floristic shift was found by pigment signatures.
3. We have participated a mesoscale Fe enrichment in the western subarctic North Pacific (SEEDS2001). The photochemical quantum efficiency of algal photosystem suggested that the phytoplankton community was suffered from Fe stress and the Fe enrichment improved the physiological condition. There was some 5 nM of labile particulate Fe in the field. It had been supplied by aeolian dust, but it was not readily available for phytoplankton. The decrease in dissolved Co, Ni, Cu, Zn, and Cd occurred during the phytoplankton bloom.
4. A sensitive analytical method has been developed using chelating ligand exchange-adsorptive cathodic stripping voltammetry, and Fe ligands derived from eukaryotic phytoplankton have been detected.
5. We have developed a technique to separate and purify RNA from phytoplankton under Fe stress. The composition change in membrane proteins of Fe-stressed phytoplankton has been observed.
6. Incubation experiments of phytoplankton have shown that the growth of phytoplankton is controlled by the species and concentrations of co-existing organic ligands.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Kyoto University, 13440166 - Bio phile element composition and species composition of marine phytoplaskton
Grants-in-Aid for Scientific Research
1997 - 1999
MASUZAWA Toshiyuki; HAMA Takeo; SUZUKI Koji
Products of biological production by phytoplankton (organic matter, calcium carbonate and opal) in the euphotic layer of the oceans are starting materials from material cycling of both major (N, P, Si, Ca, etc.) and minor biophile elements in the oceans. The data on elemental compositions from major to trace elements of these marine biological products have been quite limited. The purposes of this study are : to collect marine phytoplankton samples from the subarctic north Pacific and Bering Sea area with a specially designed non-metal NORPAC net, to develop a simple stepwize leaching method for major component analysis and for fractionation of major and trace elements into each major component phases, to obtain multi-element compositions of marine phytoplanlkton samples and to compare the elemental composition and species composition of phytoplankton samples.
We sampled phytoplankton samples mainly composed of diatom with a size range of 25-335 μm from the subarctic North Pacific and Bering Sea area, developed a simple stepwize leaching method to analyze sea salt, calcium carbonate, organic matter, opal and residual aluminosilicate, determined the fractionation of major and trace elements in to these major components. Species compositions of these phytoplankton samples were identified microscopically. As the results we showed the 12 major and trace element compositions in biogenic phase of these samples and estimated the association of these elements with biogenic phases. The analytical method developed here will become an effective method to clarify the behaviors of these elements associating with biological production in marine environments.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Nagoya University, 09440191 - 海洋植物プランクトンの生化学組成と基礎生産力に対する紫外線の影響
科学研究費助成事業
1997 - 1998
鈴木 光次
今年度は、南極産の中心目珪藻Chatoceros dichaeta、羽状目珪藻Nitzscha sp.、プリムネシオ藻Phaeocysris sp.のバッチ培養株に白色光線(PAR)及び紫外線(UVA+UVB)を人工的に照射し、各株の光合成系IIの光化学反応の量子収率(F_v/F_m)、有効光吸収断面(σ_)、第一電子受容体(Q_A^-)の酸化時定数(τQ_A^-)に対する紫外線の影響をFast Repetition Rate Fluorometer(FRRF)を用いて調査した。その際、全光エネルギーが約25W/m^2になるように、UVB/PAR比を0.01%、0.25%、2.94%と変化させて、3つの光環境を設定した(以後、それぞれの光環境を順にL1、L2、L3と呼ぶ)。全ての株において、UVB/PAR比のF_v/F_m、σ_ 、τQ_A^-値をLlのそれぞれの値と比較した結果、これらの間に統計的な有意差は認められなかった。この事は、L2ではこれら株の光合成系IIの反応中心に対してUVBの影響がなかったことを示唆している。しかしながら、L3では、全ての株において、光化学変換効率の指標であるF F mが、LlやL2のそれと比べて、明らかに低下した。また、同様に、L3のτQ_A^-はLlやL2のそれと比較して大きくなった事から、L3では光合成系2と系1間の電子伝達効率が低下したことを示唆している。これらの事から、L3では全ての株の光合成系IIの反応中心がUVBにより損傷を受けたと考えられる。LlやL2において、Phaeocystis sp.のF F mはNitzschiasp.のそれと同程度であったが、L3ではNitzschia sp.のF F m?がPhaeocystis sp.のそれに比べて大きく低下した。このような植物プランクトンのUVBに対する耐性の差は、今後、地上に到達するUVBが増加した場合、植物プランクトン群集構造の変化、延いては海洋の食物連鎖や物質循環の構造を変える事に繋がるかもしれない。この実験の他にも、紫外線照射による生化学物質の合成速度を調べる実験を同時に行い、現在、試料を分析中である。以上をまとめて、投稿論文を早急に作成する予定である。
日本学術振興会, 奨励研究(A), 名古屋大学, 09780492
