Research activity information

• Simulating CO2 dynamics in Brackish Lake Obuchi, Japan: Low pCO2 maintenance through diverse nutrient inputs
  Kazuhiro Misumi; Takaki Tsubono; Daisuke Tsumune; Takeshi Yoshimura; Shinji Ueda
  Progress in Earth and Planetary Science, 12, 1, Springer Science and Business Media LLC, 20 Aug. 2025
  Scientific journal, Abstract
  
  Coastal waters play a crucial role as a pathway for the transport of terrestrial chemical constituents to marine environments. Carbon cycling in coastal areas is essential for understanding climate change. Here, we used a three-dimensional hydrodynamic-ecosystem model to investigate CO₂ dynamics and its controlling factors in Lake Obuchi, a brackish lake in Aomori Prefecture, Japan. The model successfully reproduced the seasonal variations in water temperature, salinity, nutrients, chlorophyll-a, and carbonate system components in the lake. The simulation results show that the partial pressure of CO₂ (pCO₂) in Lake Obuchi remained below atmospheric levels throughout the year, suggesting that the lake functions as a CO₂ sink. The pCO₂ variability is dominated by spatially uniform seasonal patterns (90% of variance) driven by temperature changes, while summer periods exhibit distinct spatial patterns (6.0% of variance) that vary with river discharge magnitude. In Lake Obuchi, pCO₂ is maintained at low levels because of the carbonate system components of water masses formed by mixing river water and seawater. Additionally, primary production within these water masses further reduces pCO₂. This primary production is sustained by nitrogen-rich river water, combined with seasonal phosphorus supply from sediments during summer and autumn and from the sea during winter and spring. Our findings reveal that the seasonal combination of these nutrient sources maintains year-round primary production, which in turn contributes to the reduction in pCO₂ in Lake Obuchi.
• Diurnal to weekly dynamics of partial pressure of carbon dioxide revealed from high-frequency observation in brackish ecosystem, Lake Obuchi-numa in Japan
  Leona Higashi; Atsushi Kubo; Taichi Hosaka; Takeshi Yoshimura; Tatsunori Fukumaki; Daisuke Tsumune; Takaki Tsubono; Kazuhiro Misumi; Shinji Ueda
  Bulletin on Coastal Oceanography, 13 May 2025, [Peer-reviewed]
  Japanese, Scientific journal
• Development of Multiparametric Standard Seawater (MSSW) for CO2 Parameters, Dissolved Oxygen, and Density of Seawater
  Hiroshi Uchida; Akihiko Murata; Masahide Wakita; Hitoshi Mitsuda; Yasuhiro Nagasawa; Tatsuya Tanaka; Yohei Kayukawa; Kazuhiko Takeda; Kazuaki Ito; Takeshi Yoshimura; Daisuke Sasano
  Springer Oceanography, 203, 235, Springer Nature Singapore, 23 Mar. 2025
  In book, Abstract
  
  Multiparametric Standard Seawater (MSSW) is being developed based on the technology used to manufacture the reference material for nutrients in seawater (RMNS), without adding mercuric chloride to sterilize it, but by adopting aluminum bottles and plastic inner caps with high impermeability to gas and water vapor. The history, current status, and future plans for the development of MSSW for measurements of Practical Salinity, density, dissolved inorganic carbon, total alkalinity, pH, dissolved oxygen (DO), and dissolved organic matter are discussed. Substances that interfere with the Winkler method for DO determination (nitrite, iodate, and hydrogen peroxide) were evaluated for MSSW. The values of the parameters of interest were relatively homogeneous, but the concentrations of dissolved organic carbon depended on the serial number in the lot tested. Long-term stabilities were good in most cases, but DO concentrations began to gradually decrease immediately after production and appeared to stabilize a few years later. The Practical Salinity also tended to decrease (–0.00015 year^–1), and the cause of the decreasing trend urgently needs to be clarified. One possibility is an increasing trend (about +0.00015 year^–1) of the Practical Salinity of IAPSO standard seawater for salinity measurements.
• Development of Dissolved Organic Matter Reference Material
  Dennis A. Hansell; Takeshi Yoshimura
  Springer Oceanography, 277, 287, Springer Nature Singapore, 23 Mar. 2025
  In book, Abstract
  
  Dissolved organic matter (DOM) is an important component for the cycling of bioactive elements such as carbon, nitrogen, and phosphorus. However, confidence in the measurement of dissolved organic carbon (DOC), nitrogen (DON), and phosphorus (DOP) in marine systems is limited compared to inorganic nutrients due to complex analytical processes, the absence of certified standards, and the associated uncertainty of analytical results. To improve the latter issue, reference materials have been developed for DOC and total dissolved nitrogen and distributed by the Hansell laboratory at the University of Miami, but not yet for DON and DOP. Here we begin with a description and history of the DOC reference material (RM) program, then consider progress and needs in the development of RMs necessary for organic nutrients. Although currently available RMs for inorganic nutrients were expected to function as RMs for DOM, our previous work negates this option. We have sought an appropriate bottle container material for a DOM-RM, successfully for DOP but still to be developed for simultaneous achievement for DOC, DON, and DOP. We found a potential in both perfluoroalkoxy and glass bottles to achieve DOM-RM that remains to be examined. On the other hand, producing a single-purpose DOP-RM may make a significant contribution to elevating the comparability of DOP data, which are of growing interest among marine research communities.
• Impacts of Fly-Ash-Shell-Blocks on pH and Nutrient Environments in Seawater
  深瀬健斗; 芳村毅; 水田浩之; 日恵井佳子; 砂賀茂夫; 山本武志; 大塚拓; 森永祐加; 小林卓也
  水環境学会誌(Web), 48, 2025
• Kelp dissolved organic carbon release is seasonal and annually enhanced during senescence
  Andrew Kalani Carlson; Takeshi Yoshimura; Isao Kudo
  Journal of Phycology, 2024, [Peer-reviewed]
  Scientific journal
• Contribution of ammonium oxidizing archaea and bacteria to intensive nitrification during summer in Mutsu Bay, Japan
  Akari Aizawa; Yuka Watanabe; Kaori Hashioka; Aya Kadoya; Satoru Suzuki; Takeshi Yoshimura; Isao Kudo
  Regional Studies in Marine Science, 63, Oct. 2023, [Peer-reviewed]
  Scientific journal
• WATER EXCHANGE BETWEEN LAKE AND OCEAN FROM NUMERICAL MODEL REPRODUCTIVITY OF SALT IN BRAKISH LAKE OBUCHI
  Takaki TSUBONO; Daisuke TSUMUNE; Kazuhiro MISUMI; Takeshi YOSHIMURA
  Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering), 78, 2, I_625, I_630, Japan Society of Civil Engineers, May 2022, [Peer-reviewed]
  Japanese, Scientific journal
• Preface: Assessment of impacts of coastal and marine ecosystems to ocean acidification, deoxygenation, and global warming on marine ecosystem
  藤井賢彦; 芳村毅; 小埜恒夫
  月刊海洋, 53, 6, 2021, [Domestic magazines]
  Scientific journal
• Current situation and future perspective for environmental standards of seawater: commencing with Certified Reference Materials (CRMs) for nutrients
  村田昌彦; 青山道夫; 青山道夫; チョン千香子; 三浦勉; 藤井武史; 光田均; 北尾隆; 笹野大輔; 中野俊也; 永井直樹; 児玉武稔; 葛西広海; 清本容子; 瀬藤聡; 小埜恒夫; 横川真一朗; 有井康博; 曽根知実; 石川賀子; 芳村毅; 内田裕; 田中辰弥; 粥川洋平; 脇田昌英
  海の研究, 29, 5, 2020, [Peer-reviewed]
  Scientific journal
• Mechanisms of radiocesium depuration in Sebastes cheni derived by simulation analysis of measured 137Cs concentrations off southern Fukushima 2014–2016
  Takashi Ishimaru; Yutaka Tateda; Daisuke Tsumune; Michio Aoyama; Yasunori Hamajima; Nobue Kasamatsu; Manabu Yamada; Takeshi Yoshimura; Takuji Mizuno; Jota Kanda
  Journal of Environmental Radioactivity, 203, 200, 209, Elsevier BV, Jul. 2019, [Peer-reviewed], [International Magazine]
  English, Scientific journal, The cesium depuration mechanisms were studied in Japanese rockfish Sebastes cheni off Fukushima, in which the radiocesium level remains higher than in other teleost. Samples were collected approximately 5 km south from the nuclear power plant during 2014-2016, and the 137Cs concentrations in fish, stomach content and prey species were measured. The stable cesium content in fish was also analyzed and compared with fish age which was determined by annual ring analysis in otoliths. The 137Cs concentrations in the dominant prey species, mysids and brown shrimp, were several Bq kg-w.w.-1; indicating that transfer via the food chain was substantial compared to that from seawater during the study period. The 137Cs concentrations in S. cheni decreased from 2014 to 2016 due to the metabolic excretion and the rate of decrease in its diet. Biokinetic model analyses confirmed the slower turnover of stable cesium in S. cheni, represented as a biological half-life (Tb1/2) of 140-215 d, and was associated with stable Cs levels in food of 5-7 ng g-w.w.-1. The 137Cs levels in S. cheni were also simulated, which showed that the 137Cs depuration in fish exposed to the initial contaminated plume in 2011 resulted from slower metabolic excretion, while the 137Cs levels in fish born after 2012 could be regarded as equilibrated with the environmental levels of 137Cs. Furthermore, the simulation results suggest that 137Cs depuration in S. cheni population was also caused by the alternation of generation, which can be substantial by the addition of new year class population hatched after 2012 that were not contaminated by the initial contaminated plume from the 2011 accident.
• Sunlight caused interference in outdoor N, N-diethyl-p-phenylenediamine colorimetric measurement for residual chlorine and the solution for on-site work
  Takeshi Yoshimura
  Ecotoxicology and Environmental Safety, 169, 640, 644, 01 Mar. 2019, [Peer-reviewed]
  English, Scientific journal, Chlorination is the most common method to control water qualities, in some case on-site outdoor measurements are required to measure easily-decaying residual chlorine concentration appropriately without delay. In this study sunlight-induced unexpected colour development (UCD) of N, N-diethyl-p-phenylenediamine (DPD) colorimetric measurement was studied under several sun exposure conditions. The colour development level was evaluated with reference to chlorine concentration (mg/L) and relationships between colour development rate (mg/L min) and intensities of solar were investigated. UCD was found to be related to both exposure intensity and time. By means of exposure experiment under specific wavelength of ultraviolet (UV), it was confirmed that both middle and short wavelength of UV radiation being responsible for such an unexpected measurement. Consequently, a simple device was designed using three commercially available anti-UV films, one of which could effectively prevent the UCD from direct sun exposure.
• Impact of CO2 on the elemental composition of the particulate and dissolved organic matter of marine diatoms emerged after nitrate depletion
  Koji Sugie; Takeshi Yoshimura; Masahide Wakita
  Limnology and Oceanography, Wiley, Sep. 2018, [Peer-reviewed]
  Scientific journal
• 海洋酸性化と地球温暖化に対する沿岸・近海域の生態系の応答
  芳村毅; 小埜恒夫; 藤井賢彦
  月刊海洋, 50, 5, 195, 199, 2018
  Japanese, Scientific journal
• Dynamics of particulate and dissolved organic and inorganic phosphorus during the peak and declining phase of an iron-induced phytoplankton bloom in the eastern subarctic Pacific
  Takeshi Yoshimura; Jun Nishioka; Hiroshi Ogawa; Atsushi Tsuda
  JOURNAL OF MARINE SYSTEMS, 177, 1, 7, Jan. 2018, [Peer-reviewed]
  English, Scientific journal
• Response of Spring Diatoms to CO2 Availability in the Western North Pacific as Determined by Next-Generation Sequencing
  Hisashi Endo; Koji Sugie; Takeshi Yoshimura; Koji Suzuki
  PLOS ONE, 11, 4, Apr. 2016, [Peer-reviewed]
  English, Scientific journal
• Effects of high CO2 levels on the ecophysiology of the diatom Thalassiosira weissflogii differ depending on the iron nutritional status
  Koji Sugie; Takeshi Yoshimura
  ICES JOURNAL OF MARINE SCIENCE, 73, 3, 680, 692, Feb. 2016, [Peer-reviewed]
  English, Scientific journal
• Marine diatom Coscinodiscus wailesii inhibits DPD measurement of residual chlorine in seawater samples
  Yoshimura Takeshi; Yanagawa Toshiharu; Fujiwara Atsushi; Murai Keiji; Nogata Yasuyuki; Furuta Takeshi; Kobayashi Takuya
  Sessile Organisms, 33, 2, 38, 43, THE SESSILE ORGANISMS SOCIETY OF JAPAN, 2016, [Peer-reviewed]
  Japanese, Chlorination of seawater is a common practice to prevent biofouling on maritime structures. To enable control and reduce the environmental impacts of chlorine we measure the residual chlorine in wastewaters. In routine measurements of residual chlorine using N,N-diethyl-p-phenylenediamine (DPD), we found significant color development by DPD in non-chlorinated waters when large-sized phytoplankton appeared in high abundance. Through screening 27 microalgal isolates in laboratory culture, the diatom Coscinodiscus wailesii was shown to be the only species that causes the DPD color development in the procedure for total residual chlorine, although not for free residual chlorine, despite no chlorine additions to the culture medium. The result was also confirmed in field samples. Since two other species of genus Coscinodiscus did not show a similar result, this is considered to be highly species-specific. The color development was prevented by removing the C. wailesii cells using a 100 µm mesh cell strainer. Coscinodiscus wailesii did not react with 3,3′-dimethylbenzidine (o-tolidine), an alternative reagent to measure residual chlorine. We conclude that C. wailesii produces some materials which can oxidize DPD to produce the red color, and C. wailesii blooms in the field interfere with measurements of residual chlorine concentrations in natural and waste seawater.
• Primary productivity and nitrogen assimilation with identifying the contribution of urea in Funka Bay, Japan
  Isao Kudo; Takatsugu Hisatoku; Takeshi Yoshimura; Yoshiaki Maita
  ESTUARINE COASTAL AND SHELF SCIENCE, 158, 12, 19, Jun. 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]
  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
• Dissolved organic phosphorus production and decomposition during open ocean diatom blooms in the subarctic Pacific
  Takeshi Yoshimura; Jun Nishioka; Hiroshi Ogawa; Kenshi Kuma; Hiroaki Saito; Atsushi Tsuda
  MARINE CHEMISTRY, 165, 46, 54, Oct. 2014, [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 Discussions, 11, 12, 18105, Copernicus {GmbH}, 2014
• 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
• Effects of pCO2 and iron on the elemental composition and cell geometry of the marine diatom Pseudo-nitzschia pseudodelicatissima (Bacillariophyceae)
  Koji Sugie; Takeshi Yoshimura
  JOURNAL OF PHYCOLOGY, 49, 3, 475, 488, Jun. 2013, [Peer-reviewed]
  English, Scientific journal
• Culture of the hydrocarbon producing microalga Botryococcus braunii strain Showa: Optimal CO2, salinity, temperature, and irradiance conditions
  Takeshi Yoshimura; Shigeru Okada; Masaki Honda
  BIORESOURCE TECHNOLOGY, 133, 232, 239, Apr. 2013, [Peer-reviewed]
  English, Scientific journal
• Appropriate bottles for storing seawater samples for dissolved organic phosphorus (DOP) analysis: A step toward the development of DOP reference materials
  Takeshi Yoshimura
  LIMNOLOGY AND OCEANOGRAPHY-METHODS, 11, APR, 239, 246, Apr. 2013, [Peer-reviewed]
  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 Discussions, 10, 3, 4331, Copernicus {GmbH}, Mar. 2013
• Wet extraction of hydrocarbons from Botryococcus braunii by dimethyl ether as compared with dry extraction by hexane
  Hideki Kanda; Peng Li; Takeshi Yoshimura; Shigeru Okada
  FUEL, 105, 535, 539, Mar. 2013, [Peer-reviewed]
  English, Scientific journal
• Synergistic effects of p CO2 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, 6321, Copernicus {GmbH}, 2013, [Peer-reviewed]
  English, Scientific journal
• Synergistic effects of pCO(2) 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, 6321, 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]
  English, Scientific journal
• Effect of ocean acidification on marine phytoplankton and biogeochemical cycles
  SUGIE Koji; YOSHIMURA Takeshi; Koji Sugie; Takeshi Yoshimura; Central Research Institute of Electric Power Industry; Central Research Institute of Electric Power Industry
  海の研究 = Umi no Kenkyu (Oceanography in Japan), 20, 5, 101, 148, 日本海洋学会, 15 Sep. 2011
  Japanese, 海洋酸性化が海洋生物に及ぼす影響に関する研究が近年勢力的に行われている。本総説では,先ず,地球史における海水のpHの変遷と現代の海洋酸性化とを対比しながら植物プランクトンの動態について考察した。続いて,海洋酸性化の実験方法および植物プランクトンの生理生態と物質循環に及ぼす影響に関して近年の報告を中心にまとめ,以下の課題を抽出した。(1)過去の海洋酸性化の研究において亜寒帯や寒帯および外洋性の単離培養株が用いられていないこと,生息域や生活環に基づく実験が行われていないことは,自然環境における海洋酸性化の影響を把握する上での知識の欠如となっている。(2)pHの変化によって鉄と錯形成をする有機配位子の化学形態や2価鉄の濃度が変化するため,それらが生態系に及ぼす影響を評価する必要がある。(3)pHの低下により植物プランクトン細胞の有機炭素:リン比は増加する傾向,有機炭素:窒素比はほとんど変化しない傾向にある。一方では,pHの低下が溶存有機物およびケイ素の動態に与える影響には未解明な点が多いため,研究を促進させる必要がある。(4)pHの低下と鉄などの微量元素の利用性との複合作用がシアノバクテリアの窒素固定速度に及ぼす影響を明らかにし,窒素循環過程の理解を深化させる必要がある。Increasing atmospheric CO_2 over the Anthropocene due to human activities has reduced seawater pH and it continues as long as burning fossil fuels. In this review, we summarize and discuss the methodology of ocean acidification study and the effects of ocean acidification on phytoplankton and biogeochemical cycle of nutrients. In addition, we compare the pH variability and phytoplankton dynamics over the past 60 million years with the recent phenomenon of ocean acidification. We found that: (1) there is a significant lack of knowledge on the effect of ocean acidification because previous studies were not examined using subpolar to polar phytoplankton species and also not considered their habitat and life cycle. (2) We should study the effect of pH on dissolved inorganic Fe(II) bioavailability relative to dissolved inorganic Fe(III) species and the availability of Fe(III)-ligand complex. The role of Fe(II) and chemical structure of the ligand are also important issues. (3) Particulate organic carbon to phosphorus ratio increased in response to the decrease in pH whereas particulate organic carbon to nitrogen ratio was unaffected by pH. However, there is a lack of knowledge with regard to the effect of ocean acidification on dissolved organic matter and silicic acid dynamics. (4) We should study further the interactive effects of pH and trace metals especially for iron on N_2 fixation rate by cyanobacteria to improve our knowledge about nitrogen cycle.
• Seasonal phosphorus depletion and microbial responses to the change in phosphorus availability in a subarctic coastal environment
  Takeshi Yoshimura; Isao Kudo
  MARINE CHEMISTRY, 126, 1-4, 182, 192, Sep. 2011, [Peer-reviewed]
  English, Scientific journal
• Oceanic iron supply mechanisms which support the spring diatom bloom in the Oyashio region, western subarctic Pacific
  Jun Nishioka; Tsuneo Ono; Hiroaki Saito; Keiichiro Sakaoka; Takeshi Yoshimura
  JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 116, 2, Feb. 2011, [Peer-reviewed]
  English, Scientific journal
• Oceanic iron supply mechanisms which support the spring diatom bloom in the Oyashio region, western subarctic Pacific
  Jun Nishioka; Tsuneo Ono; Hiroaki Saito; Keiichiro Sakaoka; Takeshi Yoshimura
  Journal of Geophysical Research: Oceans, 116, 2, Blackwell Publishing Ltd, 2011, [Peer-reviewed]
  English, Scientific journal
• Oceanic iron supply mechanisms which supprt the spring diatom bloom in the Oyashio region, western subarctic pacific
  Nishioka J; Ono T; Saito H; Sakaoka K; Yoshimura T
  Journal of Geophysical Research, 116, C2, C02021, 2011, [Peer-reviewed]
  English, Scientific journal
• 夏季ベーリング海における植物プランクトン群集へのCO2と鉄の効果がSiとNの利用比に及ぼす影響.
  杉江恒二; 遠藤寿; 鈴木光次; 芳村毅
  月間海洋, 43, 12, 735, 741, 2011
  Japanese
• Iron nutritional status of the phytoplankton assemblage in the Okhotsk Sea during summer
  Takeshi Yoshimura; Jun Nishioka; Takeshi Nakatsuka
  DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS, 57, 11, 1454, 1464, Nov. 2010, [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
• The annual cycle of surface iron and the source of iron supporting the spring diatom bloom in the Oyashio region, western subarctic Pacific
  Nishioka J; Ono T; Saito H; Sakaoka K; Yoshimura T; Matoba
  AGU Fall Meeting Abstracts, 1, 0331, 2010, [Peer-reviewed]
• Dynamics and elemental stoichiometry of carbon, nitrogen, and phosphorus in particulate and dissolved organic pools during a phytoplankton bloom induced by in situ iron enrichment in the western subarctic Pacific (SEEDS-II)
  Takeshi Yoshimura; Hiroshi Ogawa; Keiri Imai; Takafumi Aramaki; Yukihiro Nojiri; Jun Nishioka; Atsushi Tsuda
  DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 56, 26, 2863, 2874, Dec. 2009, [Peer-reviewed]
  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
• Impacts of elevated CO2 on phytoplankton community composition and organic carbon dynamics in nutrient-depleted Okhotsk Sea surface waters
  Yoshimura T.; Nishioka J.; Suzuki K.; Hattori H.; Kiyosawa H.; Watanabe Y. W.
  Biogeosciences Discussions, 6, 2, 4143, 4163, Copernicus Publications, 15 Apr. 2009
  English, Impacts of the increasing CO2 in seawater (i.e. ocean acidification) on phytoplankton physiology may have various and potentially adverse effects on phytoplankton dynamics and the carbon cycle. We conducted a CO2 manipulation experiment in the Sea of Okhotsk in summer 2006 to investigate the response of the phytoplankton assemblage and dynamics of organic carbon. During the 14-day incubation of nutrient-depleted surface water with a natural phytoplankton assemblage under 150, 280, 480, and 590μatm pCO2, the relative abundance of fucoxanthin-containing phytoplankton such as diatoms and prymnesiophytes decreased with increasing pCO2. The amount of DOC accumulation also decreased with increasing pCO2, while differences in POC accumulation between the treatments were small and did not show a clear trend with the pCO2. Change in the phytoplankton community composition under different pCO2 conditions will alter the organic carbon dynamics as found in the present experiment. Compared to results in the literature from nutrient-replete conditions indicating a potential enhancement of phytoplankton production with elevated pCO2, the present results indicated a different physiological response of phytoplankton under nutrient-depleted conditions. These results indicate that the continuing increase in atmospheric CO2 can significantly affect the structure of marine ecosystems and carbon cycle in nutrient-depleted subpolar surface waters.
• 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]
  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, 10, Blackwell Publishing Ltd, 08 Oct. 2007, [Peer-reviewed]
  English, Scientific journal
• Nutrient regeneration at bottom after a massive spring bloom in a subarctic coastal environment, Funka Bay, Japan
  Isao Kudo; Takeshi Yoshimura; Choon-Weng Lee; Mitsuru Yanada; Yoshiaki Maita
  JOURNAL OF OCEANOGRAPHY, 63, 5, 791, 801, Oct. 2007, [Peer-reviewed]
  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]
  English, Scientific journal
• Distributions of particulate and dissolved organic and inorganic phosphorus in North Pacific surface waters
  Takeshi Yoshimura; Jun Nishioka; Hiroaki Saito; Shigenobu Takeda; Atsushi Tsuda; Mark L. Wells
  MARINE CHEMISTRY, 103, 1-2, 112, 121, Jan. 2007, [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]
  English, Scientific journal
• The uptake and export of silicon and nitrogen in HNLC waters of the NE Pacific Ocean
  FA Whitney; DW Crawford; T Yoshimura
  DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 52, 7-8, 1055, 1067, 2005, [Peer-reviewed]
  English, Scientific journal
• Effect of iron enrichment on the dynamics of transparent exopolymer particles in the western subarctic Pacific
  N Ramaiah; S Takeda; K Furuya; T Yoshimura; J Nishioka; T Aono; Y Nojiri; K Imai; Kudo, I; H Saito; A Tsuda
  PROGRESS IN OCEANOGRAPHY, 64, 2-4, 253, 261, 2005, [Peer-reviewed]
  English
• The decline and fate of an iron-induced subarctic phytoplankton bloom
  PW Boyd; CS Law; CS Wong; Y Nojiri; A Tsuda; M Levasseur; S Takeda; R Rivkin; PJ Harrison; R Strzepek; J Gower; RM McKay; E Abraham; M Arychuk; J Barwell-Clarke; W Crawford; D Crawford; M Hale; K Harada; K Johnson; H Kiyosawa; Kudo, I; A Marchetti; W Miller; J Needoba; J Nishioka; H Ogawa; J Page; M Robert; H Saito; A Sastri; N Sherry; T Soutar; N Sutherland; Y Taira; F Whitney; SKE Wong; T Yoshimura
  NATURE, 428, 6982, 549, 553, Apr. 2004, [Peer-reviewed]
  English, Scientific journal
• Size-fractionated iron distributions and iron-limitation processes in the subarctic NW Pacific
  Jun Nishioka; Shigenobu Takeda; Isao Kudo; Daisuke Tsumune; Takeshi Yoshimura; Kenshi Kuma; Atsushi Tsuda
  GEOPHYSICAL RESEARCH LETTERS, 30, 14, Jul. 2003, [Peer-reviewed]
  English, Scientific journal
• 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
• Riverine Nutrient Loadings and their Impact on Primary Production in Funka Bay, Japan.
  芳村毅; 工藤勲
  海の研究, 12, 2, 185, 193, 05 Mar. 2003
  Japanese
• Seasonal variations in nutrients and a factor limiting phytoplankton growth in Lake Ohnuma
  Takeshi Yoshimura; Isao Kudo
  Japanese Journal of Limnology, 62, 3, 205, 217, Japanese Society of Limnology, 2001, [Peer-reviewed]
  Japanese, Scientific journal
• 噴火湾における春季ブルームの一次生産とその行方
  工藤勲; 芳村毅
  沿岸海洋研究, 38, 1, 47, 54, 25 Aug. 2000
  Japanese
• Exhaustion of nitrate terminates a phytoplankton bloom in Funka Bay, Japan: change in SiO4,: NO3 consumption rate during the bloom
  Kudo, I; T Yoshimura; M Yanada; K Matsunaga
  MARINE ECOLOGY PROGRESS SERIES, 193, 45, 51, 2000, [Peer-reviewed]
  English, Scientific journal
• Change in the water quality in Lake Ohnuma, Hokkaido, Japan: A comparison of 1977 and 1996
  Takeshi Yoshimura; Isao Kudo; Mitsuru Yanada; Katsuhiko Matsunaga
  Limnology, 1, 1, 63, 68, Springer Japan, 2000, [Peer-reviewed]
  English, Scientific journal

• Impacts of Fly-Ash-Shell-Blocks on the Nutrient Environment and pH in Seawaters
  深瀬健斗; 芳村毅; 砂賀茂夫; 寺添斉, 日本水環境学会年会講演集, 58th, 2024
• 気候変動がホタテガイに及ぼす影響とその経済評価
  岩渕啓祐; BERNARDO Lawrence Patrick; 芳村毅; 藤井賢彦, 日本海洋学会大会講演要旨集(Web), 2022, 2022
• 粒子状有機物をサイズ分画して炭素:窒素:リン:ケイ素組成比を測定するための手法の検討
  稲田真夕; 芳村毅; 工藤勲, 日本海洋学会大会講演要旨集(Web), 2022, 2022
• 汽水湖尾駮沼における二酸化炭素分圧の連続観測
  越智千香子; 芳村毅; 津旨大輔; 坪野考樹; 三角和弘; 服巻辰則; 東麗緒菜, 日本海洋学会大会講演要旨集(Web), 2022, 2022
• Sea water acidified conditions in the regions of scallop aquacultures in Northern Japan
  森亜弓美; 芳村毅; 工藤勲, 日本地球惑星科学連合大会予稿集(Web), 2020, 2020
• 湿原起源の鉄の海洋への輸送プロセスの解明
  加藤寛己; 芳村毅; 伊佐田智規; 黒田寛; 白岩孝行; 長尾誠也; 西岡純; 村山愛子; 山下洋平, 日本海洋学会大会講演要旨集, 2020, 2020
• 北日本におけるホタテガイ養殖施設近傍の海洋酸性化の現状把握
  森亜弓美; 芳村毅; 工藤勲; 阪口耕一, 日本海洋学会大会講演要旨集, 2020, 2020
• Variation of aquatic humic substances characteristics in river, brackish lake and coastal marine environment
  宮川和大; 長尾誠也; 芳村毅; 加藤寛己; 伊佐田智規, 日本地球化学会年会要旨集(Web), 67th, 2020
• 汽水湖尾駮沼における二酸化炭素分圧の連続観測とその変動要因
  東麗緒菜; 芳村毅; 津旨大輔; 坪野考樹; 三角和弘; 服巻辰則, 日本地球化学会年会要旨集(Web), 66th, 2019
• 尾駮沼における海水淡水の流出入量計測
  坪野考樹; 三角和弘; 津旨大輔; 芳村毅, 地球環境シンポジウム講演集, 27th, 2019
• サロマ湖における動物プランクトンバイオマスおよび種組成の季節変化
  高星和浩; 芳村毅; 芳村毅, 水産海洋学会研究発表大会講演要旨集, 2019, 2019
• Analysis of submarine groundwater discharge using ²²²Rn in Nanao West Bay
  藤田充司; 長尾誠也; 落合伸也; 杉本亮; 芳村毅; CHARETTE Matthew; HENDERSON Paul, 日本放射化学会討論会(Web), 63rd, 2019
• 尾駮沼の尾駮川を通した海水淡水の流出入量
  坪野考樹; 三角和弘; 津旨大輔; 芳村毅, 地球環境シンポジウム講演集, 26th, 105‐108, 05 Sep. 2018
  Japanese
• 陸奥湾における貧栄養化対策としての海底耕耘の有効性
  市村瞭; 工藤勲; 工藤勲; 芳村毅; 芳村毅, 日本ベントス学会・日本プランクトン学会合同大会講演要旨集, 2018, 2018
• 植物プランクトン群集組成をトレーサーとした秋の道東沿岸海域の水塊分布
  谷内由貴子; 黒田寛; 伊佐田智規; 芳村毅; 葛西広海, 水産海洋学会研究発表大会講演要旨集, 2018, 2018
• 福島第一原子力発電所事故によって海洋へ直接漏洩した放射性物質の領域海洋における長期挙動
  津旨大輔; 坪野考樹; 芳村毅; 三角和弘; 立田穣; 青山道夫, アイソトープ・放射線研究発表会要旨集, 54th, 7, 20 Jun. 2017
  Japanese
• 珪藻の栄養状態によってCO₂の変化が生元素動態に及ぼす影響は変わる
  杉江恒二; 芳村毅; 脇田昌英, 日本海洋学会大会講演要旨集, 2017, 2017
• 水温およびCO₂分圧の増加に対する夏季の日本海沿岸域の植物プランクトン群集組成の変化
  芳村毅; 野尻幸宏; 大森裕子; 谷本浩志; 清沢弘志; 吉川貴志, 日本海洋学会大会講演要旨集, 2017, 2017
• 福島第一原子力発電所事故による放出した放射性物質の沿岸域における5年間の挙動
  津旨大輔; 坪野考樹; 芳村毅; 三角和弘; 立田穣; 青山道夫, アイソトープ・放射線研究発表会要旨集, 53rd, 53, 20 Jun. 2016
  Japanese
• 福島沖における¹³⁷Csの4年半の挙動
  津旨大輔; 立田穣; 芳村毅; 坪野考樹; 三角和弘; 青山道夫; 石丸隆, 日本海洋学会大会講演要旨集, 2016, 201, Mar. 2016
  Japanese
• 夏季の日本海沿岸域のプランクトン群集に対する水温およびCO₂分圧の増加の影響評価
  芳村毅; 野尻幸宏; 野尻幸宏; 大森裕子; 大森裕子; 谷本浩志; 清沢弘志; 吉川貴志, 日本海洋学会大会講演要旨集, 2016, 2016
• 東電福島第一原発事故起源の放射性セシウムの日本沿岸での長期挙動と微細構造
  青山道夫; 芳村毅; 津旨大輔; 浜島靖典, 日本海洋学会大会講演要旨集, 2016, 2016
• 海洋酸性化と温暖化の複合ストレスに因る亜寒帯北太平洋のプランクトン群集動態の変化
  杉江恒二; 亀山宗彦; 芳村毅; 内田裕; 西岡純; 原田尚美; 村田昌彦, 日本海洋学会大会講演要旨集, 2016, 2016
• 福島県沿岸での海水及び魚筋肉中放射性セシウムとトリチウム濃度
  青山道夫; 石丸隆; 立田穣; 津旨大輔; 芳村毅; 浜島靖典; 玉利俊哉; 水野拓治, 日本海洋学会大会講演要旨集, 2015, 2015
• 沿岸域のプランクトン群集に対する水温およびCO₂分圧の増加の影響評価
  芳村毅; 野尻幸宏; 堀田公明, 日本海洋学会大会講演要旨集, 2015, 2015
• 福島県および茨城県沿岸での海水及び魚筋肉中の放射性セシウムとトリチウム濃度
  青山道夫; 浜島靖典; 立田穣; 津旨大輔; 芳村毅; 石丸隆; 玉利俊哉; 水野拓治, アイソトープ・放射線研究発表会要旨集, 52nd, 2015
• 二酸化炭素分圧の変化が春季親潮域における珪藻rbcL遺伝子の発現と系統組成に与える影響
  遠藤寿; 遠藤寿; 鈴木光次; 鈴木光次; 杉江恒二; 杉江恒二; 芳村毅, 日本海洋学会大会講演要旨集, 2015, 2015
• Responses of marine organisms to ocean acidification, part 3-Monoculture experiments using phytoplankton isolates-
  芳村毅; 杉江恒二, 電力中央研究所環境科学研究所研究報告, V13017, 19P, 3,1-13, Apr. 2014
  電力中央研究所, Japanese
• Responses of marine organisms to ocean acidification, part 4-Incubation experiments using open ocean plankton communities-
  芳村毅; 杉江恒二; 鈴木光次; 西岡純, 電力中央研究所環境科学研究所研究報告, V13018, 25P, 3,1-19, Apr. 2014
  電力中央研究所, Japanese
• 円石藻類の増殖に対する水温およびCO₂分圧の増加の影響評価
  芳村毅; 野尻幸宏, 日本海洋学会大会講演要旨集, 2014, 2014
• 東電福島第一原子力発電所事故で海洋に放出された核分裂生成物および中性子放射化生成物の挙動
  青山道夫; 浜島靖典; 芳村毅; 本多牧生; 喜多村稔; HULT Mikael, 日本地球化学会年会講演要旨集, 60th, 2013
• 植物プランクトンの増殖に対するCO₂分圧増加の影響の評価
  芳村毅; 杉江恒二; 杉江恒二; 津旨大輔, 日本海洋学会大会講演要旨集, 2013, 2013
• rbcL遺伝子からみた春季親潮域の珪藻類に対するCO₂の効果
  遠藤寿; 鈴木光次; 杉江恒二; 杉江恒二; 芳村毅, 日本海洋学会大会講演要旨集, 2013, 2013
• Growth model of hydrocarbon producing microalgae Botryococcus braunii strain Showa
  本多正樹; 芳村毅; 岡田茂, 電力中央研究所環境科学研究所研究報告, V11021, 19P, 13,巻頭1-3, Jun. 2012
  電力中央研究所, Japanese
• Growth characteristics of hydrocarbon producing microalga Botryococcus braunii strain Showa (Chlorophyta)
  芳村毅; 本多正樹; 岡田茂, 電力中央研究所環境科学研究所研究報告, V11013, 22P, 16,巻頭1-3, Jun. 2012
  電力中央研究所, Japanese
• Responses of marine organisms to ocean acidification, part 2-Culture experiment using unialgal strain of marine phytoplankton-
  杉江恒二; 芳村毅, 電力中央研究所環境科学研究所研究報告, V11049, 19P, 13,巻頭1-3, May 2012
  電力中央研究所, Japanese
• Responses of marine organisms to ocean acidification (part 2) Culture experiment using unialgal strain of marine phytoplankton
  杉江 恒二; 芳村 毅, 電力中央研究所報告. 研究報告. 電力中央研究所環境科学研究所 編, 0, 11049, 1, 13,巻頭1-3, May 2012
  電力中央研究所, Japanese
• 潮汐混合とオホーツク海・ベーリング海の物理・化学・生物過程―白鳳丸KH09‐4航海・おしょろ丸・クロモフ2006/2007シンセシス―pCO₂と鉄濃度の違いが夏季ベーリング海の植物プランクトン群集によるSiとNの利用比に与える影響
  杉江恒二; 遠藤寿; 鈴木光次; 芳村毅, 月刊海洋, 43, 12, 735, 741, 01 Dec. 2011
  Japanese
• Oceanic iron supply mechanisms which support the spring diatom bloom in the Oyashio region, western subarctic Pacific (vol 116, C04007, 2011)
  Jun Nishioka; Tsuneo Ono; Hiroaki Saito; Keiichiro Sakaoka; Takeshi Yoshimura, JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 116, Apr. 2011, [Peer-reviewed]
  English, Others
• 観測されたSF₆濃度をデータ同化する拡散モデルと水塊追跡への適用
  坪野考樹; 津旨大輔; 芳村毅; 西岡純, 水工学論文集(CD-ROM), 55, ROMBUNNO.204, 22 Feb. 2011
  Japanese
• Fe^*を用いた親潮域中層におけるオホーツク海からの鉄移送量の評価
  西岡純; 小埜恒夫; 齊藤宏明; 坂岡桂一郎; 芳村毅, 日本海洋学会大会講演要旨集, 2010, 73, 25 Aug. 2010
  Japanese
• Survey on use of algae for biofuel production
  本多正樹; 芳村毅; 岡田茂, 電力中央研究所環境科学研究所研究報告, V09025, 38P, 32,巻頭1〜3, May 2010
  電力中央研究所, Japanese
• 観測されたSF₆濃度を用いたグリーン関数による拡散モデルの制御変数の推定
  坪野考樹; 津旨大輔; 芳村毅; 西岡純, 水工学論文集(CD-ROM), 54, ROMBUNNO.189, 22 Feb. 2010
  Japanese
• Responses of marine organisms to ocean acidification-Incubation experiment using a natural plankton assemblage-
  芳村毅; 杉江恒二; 西岡純, 電力中央研究所環境科学研究所研究報告, V09005, 21P, 15,巻頭1〜3, Nov. 2009
  電力中央研究所, Japanese
• グリーン関数法でSF₆濃度結果を拡散方程式にデータ同化する手法を用いた水塊移動の推定
  坪野考樹; 津旨大輔; 芳村毅; 西岡純, 水工学論文集(CD-ROM), 53, ROMBUNNO.249, 22 Feb. 2009
  Japanese
• Ocean acidification induced by increasing atmospheric carbon dioxide-A literature review of the impacts of ocean acidification on oceanic uptake of CO2 by marine plankton-
  芳村毅; 津旨大輔, 電力中央研究所環境科学研究所研究報告, V06019, 27P, 21,巻頭1〜4, May 2007
  電力中央研究所, Japanese
• Projection for change in characteristics of carbon dioxide absorption to the ocean based on the oceanic iron cycle
  津旨大輔; 仲敷憲和; 吉田義勝; 芳村毅; BRYAN Frank O; LINDSAY Keith; MOORE Keith J; DONEY Scott C, 電力中央研究所環境科学研究所研究報告, V06010, 20P, 14,巻頭1〜4, Apr. 2007
  電力中央研究所, Japanese
• 河川由来の栄養物質供給が沿岸海域の生物生産に果たす役割
  芳村毅, 農業電化, 60, 1, 19, 22, 15 Jan. 2007
  農業電化協会, Japanese
• Biological carbon dioxide fixation in the ocean by iron supply; Part 2-Improvement of a tracing method of water mass at an iron fertilization experiment-
  津旨大輔; 芳村毅; 西岡純, 電力中央研究所環境科学研究所研究報告, V05026, 19P, 16,巻頭1〜3, Aug. 2006
  電力中央研究所, Japanese
• 海域毎の鉄散布に対する植物プランクトン増殖の応答性の違いとその要因の検討
  西岡純; 津旨大輔; 芳村毅, 電力中央研究所環境科学研究所研究報告, V04033, 24P, 22,巻頭1〜4, Jun. 2005
  電力中央研究所, Japanese
• Biological carbon fixation during iron enrichment experiments in the subarctic north Pacific
  芳村毅; 西岡純; 津旨大輔, 電力中央研究所環境科学研究所研究報告, V04020, 17P, 12,巻頭1〜3, Jun. 2005
  電力中央研究所, Japanese
• 親潮海域春季ブルーム期における亜酸化窒素の挙動
  今村正裕; 西岡純; 芳村毅; 斉藤宏明; 小埜恒夫, 日本海洋学会大会講演要旨集, 2005, 2005
• 北西部北太平洋亜寒帯と親潮域における鉄,カドミウム及び栄養塩の挙動
  高田兵衛; 久万健志; 西岡純; 芳村毅; 緑川貴; 木村完; 山口篤; 高木省吾; 坂岡桂一郎, 日本海洋学会大会講演要旨集, 2005, 149, 2005
  Japanese
• Dissolved organic matter dynamics during an iron enrichment experiment in the western north Pacific
  芳村毅; 西岡純, 電力中央研究所環境科学研究所研究報告, V04002 (Web), 2004
• Literature surveys on the role of dissolved organic matter in the biological carbon fixation into the ocean.
  芳村毅; 西岡純, 電力中央研究所我孫子研究所報告, U03004, 20P, 15,巻頭1〜4, May 2003
  電力中央研究所, Japanese
• Riverine Nutrient Loadings and their Impact on Primary Production in Funka Bay, Japan
  YOSHIMURA Takeshi; KUDO Isao; Takasi Yoshimura; Isao Kudo; Graduate Scholl of Fisheries Science Hokkaido University; Graduate Scholl of Fisheries Science Hokkaido University, 海の研究 = Umi no Kenkyu (Oceanography in Japan), 12, 2, 185, 193, 05 Mar. 2003
  河川から噴火湾への栄養塩負荷量を明らかにするために,噴火湾に流人する8河川および発電所排水路1か所において,流量および栄養塩濃度を一年にわたり観測した。その結果,河川流量は雪解け時の4月に特異的に高い明瞭な季節変化を示した。また,河川水中の栄養塩濃度は河川によって大きく異なったが,全河川の加重平均濃度は硝酸塩が24μM,アンモニウム塩が2.9μM,リン酸塩が0.30μM,ケイ酸塩が270μMであり. DIN:DIP比が非常に高いことが明らかとなった。河川から噴火湾への一年間の淡水負荷量は2.1×10^9m^3であり,溶存無機窒素,リン酸塩,ケイ酸塩負荷量はそれぞれ57×l0^6mol,0.6.3×10^6mol. 570x10^6molだった。これらの栄養塩負荷量が噴火湾の基礎生産に与える影響は総生産を考慮した場合は非常に小さなものだった。しかしながら,新生産を夏期のリン酸塩の減少量から見積もった結果,河川由来の栄養塩が噴火湾の夏期の新生産の最大10%を支えていることが明らかとなった。Water discharge and milrient concentrations were investigated in eight, rivers and a power plant drainage in order to reveal the nutrient, loadings through rivers into Funka Bay. The river water discharge changed seasonally with a remarkable peak in April. The volume-weighted mean concentrations for all rivers of nitrate, ammonium, phosphate and silicate were 24μM, 2.9μM, 0.30μM, and 270μM, respectively. Annual nutrient loadings of dissolved inorganic nitrogen, phosphate and silicate were 57x10^9mol 0.63×l0^6mol, and 570×l0^6mol, respectively. The river waters had higher DIN:DIP ratios than surface waters in Funka Bay, indicating that the former was highly enriched in nitrogen compared with phosphorus. The contributions of riverine nutrient, loadings to primary production in Funka Bay were only 1% when total annual production was considered. In terms of newproduction, however, riverine nutrient, loadings seem to support a significant part. (10%) of summer new production in Funka Bay., 日本海洋学会, Japanese
• Influence of iron supply to oceanic phytoplankton ecosystem.
  西田純; 津旨大輔; 芳村毅; 武田重信; 津田敦, 電力中央研究所我孫子研究所報告, U02017, 20P, Jan. 2003
  Japanese
• 海洋生物生産の加速と海洋大気 鉄添加による植物プランクトンの応答と細胞内での鉄の機能
  工藤勲; 芳村毅, 月刊海洋, 34, 3, 196, 201, 01 Mar. 2002
  海洋出版, Japanese
• 現代海洋化学 II 3章 海洋表層の生物地球化学 海洋における鉄の生物地球化学
  工藤勲; 芳村毅, 月刊海洋, 78, 82, 01 May 2001
  Japanese
• 海洋における鉄の生物地球化学 (総特集 現代海洋化学・2) -- (3章 海洋表層の生物地球化学)
  工藤 勲; 芳村 毅, 号外海洋, 25, 78, 82, 2001
  海洋出版, Japanese

• サロマ湖はホタテガイを何枚育ててくれるか? : 閉鎖性海域における持続的二枚貝養殖漁業
  門谷, 茂; 阪口, 耕一, 第5章 栄養塩と植物プランクトン量の時間的・空間的な変化
  恒星社厚生閣, Aug. 2024, 9784769917106, vii, 141p, Japanese

• 海洋生物環境学基礎論, 2024年, 修士課程, 環境科学院
• 海洋生物圏環境科学特論Ⅰ, 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
• 海洋学入門, 2024年, 学士課程, 水産学部
• 一般教育演習(ﾌﾚｯｼｭﾏﾝｾﾐﾅｰ), 2024年, 学士課程, 全学教育
• 海洋基礎生産学, 2024年, 学士課程, 水産学部
• 分析化学, 2024年, 学士課程, 水産学部
• 洋上実習Ⅰ, 2024年, 学士課程, 水産学部
• 海洋保全学, 2024年, 学士課程, 水産学部
• 化学海洋学, 2024年, 学士課程, 水産学部
• 分析化学, 2024年, 学士課程, 水産学部
• 海洋生物科学実験Ⅰ, 2024年, 学士課程, 水産学部

• Apr. 2023 - Present
  日本水環境学会
• THE OCEANOGRAPHIC SOCIETY OF JAPAN
• ASLO, Association for the Sciences of Limnology and Oceanography
• 日本地球惑星科学連合
• 日本海洋学会沿岸海洋研究会

• Environmental surveys to support the farming of Mizuhopecten yessoensis in Lake Saroma, Hokkaido
  LASBOS Moodle, 芳村毅, 15 Aug. 2020 - Present

• Spatio-temporal variations in the bioelement composition of particulate organic matters fractionated by plankton size
  Grants-in-Aid for Scientific Research
  01 Apr. 2025 - 31 Mar. 2028
  芳村 毅; 伊佐田 智規; 今井 圭理
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 25K15414
• Revisit a Redfield ratio as a reference value in marine bioactive element cycles
  Grants-in-Aid for Scientific Research
  01 Apr. 2021 - 31 Mar. 2024
  芳村 毅; 工藤 勲; 今井 圭理
  海洋によるCO2の吸収・固定量は植物プランクトンによる炭素と栄養素の利用比率によって変化します。その比率としてレッドフィールド比が良く知られており，気候変化を予測する生態系モデルにおいて固定値として使われていますが，実測データの蓄積は十分ではありません。また，プランクトン群集はサイズの異なる多くの種で形成されますが，それらをひとまとめにした比率しか議論されてきませんでした。海洋環境の変化によりプランクトン群集組成が変化すると予測されていますが，その変化が生態系に与える影響を評価できません。そこで，本研究は有機物粒子のサイズ分画手法を確立したうえで，各サイズ画分の主要4元素組成比（炭素：窒素：リン：ケイ素）に関するデータを取得します。
  研究一年目の2021年度は海水中の有機物粒子をサイズ毎に分画するための手法を検討しました。撹拌式セルを用いた限外ろ過システムを応用した「限外ろ過方式」と，孔径の異なるフィルターに連続的に通過させる「逐次ろ過方式」を並行して検討しました。その結果，限外ろ過方式はフィルター上に粒子が捕捉されてしまい，有機物粒子量を過小評価することがわかりました。有機物粒子のサイズ分画手法としては逐次ろ過方式が適していることがわかりました。逐次ろ過方式はリンおよびケイ素の分析試料を作成するのに適していますが，炭素および窒素を分析するためにはフィルター上に集めた有機物粒子を液体に懸濁させて回収する必要があります。フィルターに付着する有機物粒子を完全に回収する手法を検討した結果，超音波洗浄を利用することで達成できることがわかりました。これらの検討により，孔径の異なるメンブレンフィルターを用いた逐次ろ過方式によって有機物粒子を三つにサイズ分画し，超音波洗浄を活用して回収した有機物粒子の主要4元素を分析することで，各サイズ画分の元素組成比を分析するための道筋が完成しました。
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 21K12219
• The impact of river outflows on the coastal environment
  Grants-in-Aid for Scientific Research
  01 Apr. 2021 - 31 Mar. 2024
  木田 新一郎; 田中 潔; 芳村 毅; 伊佐田 智規
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Kyushu University, 21H03591
• Understanding the Mechanisms of oligotrophication in Mutsu Bay for sustainable bivalve culture
  Grants-in-Aid for Scientific Research
  01 Apr. 2018 - 31 Mar. 2021
  KUDO Isao
  Oligotrophication, a decreasing trend in nutrient concentration has been revealed in Mutsu Bay, where intensive scallop hanging culture is conducted. The objectives of this study are to elucidate the mechanisms of the oligotrophication threatening sustainable biological production in the coastal areas and to propose the effective policies for it. Nutrients were depleted in summer and primary productivity (scallop diet) was depressed by the nutrient deficiency. Bottom sediment cultivation was conducted to examine the enhancement of return of nutrients from the sediment. The amounts of this return were estimated as much as 10-20% of the standing stock in the water column. Thus, the bottom sediment cultivation is an effective option for preventing oligotrophication in this area.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 18K05776
• Transfer and accumulation of radioactive material in marine ecosystem
  Grants-in-Aid for Scientific Research
  28 Jun. 2012 - 31 Mar. 2017
  Kanda Jota; MORIYA Shigeharu; KOBAYASHI Takuya; YOSHIMURA Takeshi; ISHIMARU Takashi; IGARASHI Satoshi; SUGA Jiro; YAMAKAWA Hiroshi; OTSU Hideaki; ITO Yukari; TAKAZAWA Nobue; UCHIYAMA Kaori; KUBO Atshushi
  Radioactive material derived from the Fukushima Daiichi Nuclear Power Plant accident was investigated in marine ecosystem. 1) For radioactive cesium in marine organisms and environment in the coastal area of Fukushima, we obtained a continuous time-series data set by ship observations twice a year. Time-series data set for radioactive cesium in zooplankton was also obtained in several open ocean areas. 2) Examinations of transfer routes of radioactive cesium in coastal rocky seafloor revealed that transition of radioactive cesium from suspended or descending particles, and from organic fraction of sediments was small. 3) Using the on-site observation data, the transition of radioactive cesium in the ecosystem was reproduced by a numerical model, and the model was applied to prediction of the future trend of the radioactivity level of marine organisms.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area), Tokyo University of Marine Science and Technology, 24110005
• A study on inventory and distribution of nutrient in seawater together with higher comparability
  Grants-in-Aid for Scientific Research
  31 May 2011 - 31 Mar. 2014
  AOYAMA Michio; MURATA Akihiko; YOSHIMURA Takeshi; HIOKI Akiharu; CHIDA Hiroshi; HYDES David; DICKSON Andrew; KOSUGI Naohiro
  We create a dataset which is the basic dataset to draw more accurate spatial distribution of nutrients in global ocean. During the study period we conducted 6 cruises in which reference material of nutrients in seawater was used, precision of nutrients analyses is better than 0.2 % and station-station comparability was ensured. We also collected all of the cruises in which nutrients data were available. We did crossover analyses at 243 crossovers where our cruises were reference to decide factors to adjust nutrients concentration obtained in other cruises. In addition we included dissolved oxygen as an additional parameter of the dataset. Finally, we got the dataset of 0.5 deg. by 0.5 deg. mesh, 136 layers up to 6500 meters depth for nitrate, phosphate, silicate and dissolved oxygen, respectively.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (S), 23221003
• Impact estimations of the ocean acidification on the calcium carbonate plankton in the Subarctic Pacific.
  Grants-in-Aid for Scientific Research
  2011 - 2013
  HATTORI HIroshi; SASAKI Hiroshi; YOSHIMURA Takeshi; ONO Tsuneo
  Impact estimation experiments of the ocean acidification being caused by the global warming were carried out using calcium carbonate plankton in the Subarctic Pacific as well as in the Southern Ocean. Biomass and species compositions of phytoplankton (haptophytes: coccolithopholids) in these areas are not completed yet. But, it is clearly observed that the acidification impacts were more obvious on the higher biomass species. We are now making theoretical buck grounds for these evidences. And, we now pay simultaneously attentions of the acidification impacts on the diatoms, dominant species in the Subarctic and Southern Oceans.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Tokai University, 23510013
• Impact of elevated CO2 on phytoplankton growth and organic matter production
  Grants-in-Aid for Scientific Research
  2010 - 2012
  YOSHIMURA Takeshi
  Impacts of elevated CO2 on phytoplankton growth and organic matter production were examined using isolates and in situ plankton communities. Responses to the CO2 increase were species-specific and were altered in different temperature and light conditions. Although in situ plankton communities did not show major responses to the CO2 increase, clear trends to the CO2 increase were observed in some experiments. Future CO2 increase in seawater can play a significant role on altering the dynamics of in situ phytoplankton communities and organic matters.
  Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (A), Central Research Institute of Electric Power Industry, 22681004
• Observational research for iron, biological productivity, and carbon cycle in the subarctic northwestern Pacific
  Grants-in-Aid for Scientific Research
  2004 - 2006
  ONO Tsuneo; KASAI Hiromi; NISHIOKA Jun; WATANABE Yutaka; YOSHIMURA Takeshi
  2-D iron distribution in the subarctic northwestern Pacific was investigated repeatedly from 2003 to 2006 with high spacio-temporal resolution equally to major nutrients. Seasonal and interannual variations of iron observed in the Oyashio domain brought us the following information :
  1] Monthly-mean concentration of dissolved iron (DFe) in the Oyashio mixed layer varies in parallel with nitrate, with its maximum anteceding the Kosa season. Ratio of DFe to the nitrate is fairly constant throughout the year (ΔDFe/ΔN=27×10^<-6>[mol/mol]), and this ratio resembles those of North Pacific intermediate water (NPIW). Based on these observation results and a simple model calculation, it is concluded that the seasonal variation of Dfe in the Oyashio mixed layer is mainly governed by spring-summer biological consumption and winter recirculation from the NPIW. Iron input from the dust deposition is implied to have small effect to the mixed-layer iron cycle, although small-scale high iron patch might sometimes be generated by local iron deposition.
  2] More than half of the DFe data observed in Oyashio mixed layer at the bloom-termination period shows roughly constant value of 0.25 nM, implying that the bloom-forming diatoms incur significant iron limitation below this iron level. In spring, iron reaches this lower-limit faster than nitrate, forming iron-limited ecosystem conditions at the end of spring bloom. In summer, however, the ultimate depletion of mixed layer nitrate occurs faster than that of DFe at July, forming nitrate-limited ecosystem in the summer Oyashio domain.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Fisheries Research Agency, 16310019