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研究者情報

マスター

アカウント（マスター）

  • 氏名

    大西　広二(オオニシ　ヒロジ), オオニシ　ヒロジ

所属（マスター）

  • 水産科学研究院　海洋生物資源科学部門　海洋環境科学分野

所属（マスター）

  • 水産科学研究院　海洋生物資源科学部門　海洋環境科学分野

独自項目

syllabus

  • 2021, 一般教育演習(ﾌﾚｯｼｭﾏﾝｾﾐﾅｰ), Freshman Seminar, 学士課程, 全学教育, 海洋環境、水圏生態、水産資源、海洋物理学、海洋化学、プランクトン、イカ、耳石
  • 2021, 物理海洋学・気象学, Physical Oceanography and Meteorology, 学士課程, 水産学部, 地球流体、海洋環境、海洋循環、大気循環、気候変動
  • 2021, 基礎乗船実習, Basic On-board Training of Fisheries Sciences, 学士課程, 水産学部, 水産科学，野外実習，海洋生物，海洋環境，調査手法，生物採集法，船内生活，協調性，自主性
  • 2021, 一般教育演習(ﾌﾚｯｼｭﾏﾝｾﾐﾅｰ), Freshman Seminar, 学士課程, 全学教育, フィールド，海洋環境，自然，グループ学習，課題発見，問題解決，プレゼンテーション，おしょろ丸
  • 2021, 海洋資源科学実験Ⅰ, Laboratory Work on Marine Resources Ⅰ, 学士課程, 水産学部, 海洋音響学、漁具工学、地球流体、情報処理技術、室内実験
  • 2021, 水産科学英語Ⅱ, English for Fisheries Sciences II, 学士課程, 水産学部, 論文講読，プレゼンテーション，海洋資源科学

researchmap

プロフィール情報

学位

  • 博士（水産科学）（北海道大学）

プロフィール情報

  • 姓

    大西, オオニシ

  • 名

    広二, ヒロジ

  • ID各種

    200901050742078472

対象リソース

業績リスト

研究キーワード

  • 海洋物理学   水産海洋学   Physical Oceanography(4402)   Marine Science(6301)   

研究分野

  • 自然科学一般 / 大気水圏科学
  • ライフサイエンス / 水圏生産科学

学歴

  •         - 1992年   北海道大学   水産学研究科   漁業学専攻
  •         - 1992年   北海道大学
  •         - 1990年   北海道大学   水産学部   特設専攻科
  •         - 1990年   北海道大学
  •         - 1989年   北海道大学   水産学部   漁業学科
  •         - 1989年   北海道大学

受賞

  • 2001年04月 日本海洋学会 日高論文賞
     
    受賞者: 大西 広二

論文

  • Sachi Umezawa, Manami Tozawa, Yuichi Nosaka, Daiki Nomura, Hiroji Onishi, Hiroto Abe, Tetsuya Takatsu, Atsushi Ooki
    Biogeosciences 20 2 421 - 438 2023年01月27日 
    Abstract. We conducted repetitive observations in Funka Bay,Hokkaido, Japan, on 15 February, 4 and 15 March, and 14 April 2019. Thediatom spring bloom peaked on 4 March and started declining on 15 March.Funka Bay winter water remained below 30 m depth, which was below thesurface mixed-layer and dark-layer depth (0.1 % of the surface photosynthetically active radiation, PAR, depth) on 4and 15 March. In the subsurface layer at depths of 30–50 m, concentrationsof NO3-, PO43-, and Si(OH)4 decreased by halfbetween these dates, even in the dark. Incubation experiments using thediatom Thalassiosira nordenskioeldii showed that this diatom could consume added nutrients in the dark atsubstantial rates after pre-culturing to deplete nutrients. Incubationexperiments using natural seawater collected in the growing phase of the bloom on 8 March 2022 also showed that nutrient-depleted phytoplankton could consumeadded nutrients in the dark. We excluded three physicalprocess – water mixing, diffusive transport, and subduction – as possible mainreasons for the decrease in nutrients in the subsurface layer. We concludethat the nutrient reduction in the subsurface layer (30–50 m) between 4 and15 March 2019 could be explained by nutrient consumption by diatoms in the dark in thatlayer.
  • Takumi Teraoka, Kanako Amei, Yutaka Fukai, Kohei Matsuno, Hiroji Onishi, Atsushi Ooki, Tetsuya Takatsu, Atsushi Yamaguchi
    Plankton and Benthos Research 17 4 369 - 382 2022年11月30日
  • Michinobu Kuwae, Narumi Tsugeki, Bruce P. Finney, Yukinori Tani, Jonaotaro Onodera, Mako Kiyoto, Mitsukuni Kusaka, Takuya Sagawa, Yugo Nakamura, Hiroji Onishi, Hiroshi Kuroda, Noboru Okuda, Tamihisa Ohta, Minoru Ikehara, Tomohisa Irino
    Quaternary Research 107 27 - 42 2022年05月 
    Abstract Little is known about the dynamics of marine food chains spanning primary to higher trophic levels on centennial and longer timescales, especially where the supply of dissolved iron limits primary productivity. To elucidate the long-term dynamics of biological productivity in the Coastal Oyashio (CO), which is a major pathway for transporting dissolved iron into the western North Pacific from winter to spring, we reconstructed the lower trophic level productivity over the last 3000 years in the CO. Our results demonstrate that the concentrations and mass accumulation rates of both Chl-a (chlorophyll a and its derivatives) and biogenic opal used as proxies of primary productivity, and steryl chlorin esters (SCEs) used as that of zooplankton productivity, show a millennial-scale increasing trend and centennial-scale variability beginning ca. AD 400. SCEs were positively correlated with Chl-a, indicating that changes in zooplankton productivity were induced by bottom-up control of primary productivity. The Chl-a and SCEs showed synchronous centennial-scale patterns with a relative abundance of sea-ice-associated diatom species transported by CO, and with a ventilation index in the Okhotsk Sea Intermediate Water. This synchronous pattern indicates that lower trophic-level productivity during the spring bloom responded to the intensity of iron-replete CO.
  • Sachi Umezawa, Manami Tozawa, Yuichi Nosaka, Daiki Nomura, Hiroji Onishi, Hiroto Abe, Tetsuya Takatsu, Atsushi Ooki
    2022年01月06日 [査読有り]
     
    Abstract. We conducted time-series observations in Funka Bay, Hokkaido, Japan, from 15 February to 14 April 2019. The diatom spring bloom peaked on 4 March and started declining on 15 March. Funka Bay winter water remained below 30-m depth, which was below the surface mixed-layer and dark-zone depths on both dates. At depths of 30–50 m, concentrations of NO3–, PO43–, and Si(OH)4 decreased by half between these dates even in darkness. Incubation experiments using the diatom Thalassiosira nordenskioeldii showed that this diatom could consume nutrients in darkness at substantial rates. We conclude that the nutrient reduction in the subsurface layer (30–50 m) could be explained by dark consumption by diatoms that had been growing in the surface waters and then sank to the subsurface layer. We believe that this is the first study to present observational evidence for the consumption of the main nutrients by diatoms in the dark subsurface layer during the spring bloom. Nutrient consumption in this layer might have a substantial influence on the primary production during and after the spring bloom.
  • Atsushi Ooki, Naoya Miyashita, Sachi Umezawa, Manami Tozawa, Yuichi Nosaka, Daiki Nomura, Hiroji Onishi, Hiroto Abe, Tetsuya Takatsu
    GEOCHEMICAL JOURNAL 56 5 142 - 150 2022年
  • Mamoru Tanaka, Jiro Yoshida, Keunjong Lee, Yasutaka Goto, Takahiro Tanaka, Hiromichi Ueno, Hiroji Onishi, Ichiro Yasuda
    JOURNAL OF OCEANOGRAPHY 77 3 431 - 446 2021年06月 
    A recent linear stability analysis and a numerical simulation suggest that diffusive convection (DC), a regime of the double-diffusive convection, plays a potential role in onset of thermohaline-shear instability, implying that DC could contribute to turbulence production in the oceans. However, an existence of such a thermohaline-shear instability has not been examined in real oceans. We examine if this newly proposed instability mechanism exists in the subarctic North Pacific by analyzing our fine- and micro-scale turbulence measurement data. Vertical inversions were cautiously detected in seawater density profiles and used as a proxy for instability events for gradient Richardson number larger than the critical value of 1/4. We found that a portion of inversions were associated with active DC. Such DC-related inversions exhibited elevated levels of turbulent kinetic energy dissipation rate even for gradient Richardson number largely exceeding 1/4. Our estimate suggested that the thermohaline-shear instability contributes to roughly only 10% of the dissipation of turbulent kinetic energy in the diffusively convective layer in our observation site.
  • M. Higuchi, M. Anongponyoskun, J. Phaksopa, H. Onishi
    Agriculture and Natural Resources 54 2 2020年 [査読有り]
  • Atsushi Ooki, Ryuta Shida, Masashi Otsu, Hiroji Onishi, Naoto Kobayashi, Takahiro Iida, Daiki Nomura, Kota Suzuki, Hideyoshi Yamaoka, Tetsuya Takatsu
    Journal of Oceanography 75 2019年06月 [査読有り][通常論文]
  • Bungo Nishizawa, Hiroji Onishi, Yutaka Watanuki
    Fisheries Science 85 1 53 - 60 2019年01月 [査読有り]
  • Shimizu Yusaku, Ooki Atsushi, Onishi Hiroji, Takatsu Tetsuya, Tanaka Seiji, Inagaki Yuta, Suzuki Kota, Kobayashi Naoto, Kamei Yoshihiko, Kuma Kenshi
    JOURNAL OF ATMOSPHERIC CHEMISTRY 74 2 205 - 225 2017年06月 [査読有り][通常論文]
     
    Volatile organic iodine compounds (VOIs) emitted from the ocean surface to the air play an important role in atmospheric chemistry. Shipboard observations were conducted in Funka Bay, Hokkaido, Japan, bimonthly or monthly from March 2012 to December 2014, to elucidate the seasonal variations of VOI concentrations in seawater and their sea-to-air iodine fluxes. The bay water exchanges with the open ocean water of the North Pacific twice a year (early spring and autumn). Vertical profiles of CH2I2, CH2ClI, CH3I, and C2H5I concentrations in the bay water were measured bimonthly or monthly within an identified water mass. The VOI concentrations began to increase after early April at the end of the diatom spring bloom, and represented substantial peaks in June or July. The temporal variation of the C2H5I profile, which showed a distinct peak in the bottom layer from April to July, was similar to the PO4 (3-) variation profile. Correlation between C2H5I and PO4 (3-) concentrations (r = 0.93) suggests that C2H5I production was associated with degradation of organic matter deposited on the bottom after the spring bloom. CH2I2 and CH2ClI concentrations increased substantially in the surface and subsurface layers (0-60 m) in June or July resulted in a clear seasonal variation of the sea-to-air iodine flux of the VOIs (high in summer or autumn and low in spring).
  • Sachiko Suzuki, Keiko Sekiguchi, Yoko Mitani, Hiroji Onishi, Takehiko Kamito
    Zoological Science 33 5 491 - 491 2016年10月01日 [査読有り]
  • Saito Rui, Yasuda Ichiro, Komatsu Kosei, Ishiyama Hiromu, Ueno Hiromichi, Onishi Hiroji, Setou Takeshi, Shimizu Manabu
    OCEAN DYNAMICS 66 5 605 - 621 2016年05月 [査読有り][通常論文]
     
    Aleutian eddies are mesoscale anticyclonic eddies formed within the Alaskan Stream region between 180A degrees meridian and 170A degrees E south of the Aleutian Islands. They propagate southwestward after the isolation from the Alaskan Stream and pass through the Western Subarctic Gyre. We compared hydrographic structures of three Aleutian eddies observed during summer, west of 170A degrees E (Eddy A) and east of 170A degrees E (Eddies B and C). In each eddy, a subsurface dichothermal water (3.0-4.0 A degrees C) was observed above a subsurface mesothermal water (4.0-4.5 A degrees C). The minimum temperature in the dichothermal water at around a depth of 100 m was colder in Eddy A (2.8 A degrees C) than in Eddies B and C (3.0-3.2 A degrees C). This difference could be ascribed to wintertime cooling and influence of surrounding waters during spring warming period. The wintertime cooling makes the dichothermal water colder for eddies isolated from the Alaskan Stream region for a longer time. Particle-tracking experiments using re-analysis products from a data-assimilative eddy resolving ocean model suggested that the dichothermal water within Eddy A was cooled by the entrainment of surrounding colder water even during the spring warming period. The mesothermal waters at depth around 250 m demonstrated similarity among the observed eddies, and the maximum temperature in the mesothermal water within Eddy A (4.3 A degrees C) was close to that of Eddies B and C (4.2 A degrees C) in the in situ observations. These results indicated that the dichothermal water of Aleutian eddies modifies over time, whereas the mesothermal water maintains the original feature as they propagate southwestward from the Alaskan Stream region to the Western Subarctic Gyre.
  • べーリング海南東部陸棚縁辺域での潮汐混合と溶存鉄輸送
    田中雄大, 安田一郎, 久万健志, 西岡純, 田中祐希, 大西広二, 上野洋路, 増島雅親
    月刊海洋 号外 58 47 - 55 2016年 [査読無し][通常論文]
  • Hioki Nanako, Kuma Kenshi, Morita Yuichiroh, Miura Daichi, Ooki Atsushi, Tanaka Seiji, Onishi Hiroji, Takatsu Tetsuya, Kobayashi Naoto, Kamei Yoshihiko
    JOURNAL OF OCEANOGRAPHY 71 6 703 - 714 Springer 2015年12月 [査読有り][通常論文]
     
    We studied iron remobilization and nutrient regeneration in bottom water of Funka Bay, Japan, bimonthly from August 2010 to December 2011. The bay basin (bottom depth, 92-96 m) is separated from the northwest Pacific Ocean at its mouth by a sill with a depth of 60 m. After a spring phytoplankton bloom during early March-early April, nutrients in bay bottom water tended to accumulate with time until August-September, and to increase gradually with depth during April-October, by the oxidative decomposition of settling particulate organic matter on the bay bottom. In contrast, the process of iron remobilization into bottom water of the bay is remarkably different from nutrient regeneration. The much higher concentrations of dissolved and total dissolvable iron near the bottom and the seasonally variable relationship between dissolved iron concentration and apparent oxygen utilization in bay bottom water likely reflect a balance between dissolved iron input and removal processes within the bay bottom water. The release of soluble Fe(II) from reducing bay sediments might induce the high concentrations of dissolved and total dissolvable iron in deep-bottom waters of Funka Bay and might be one of the most important sources of iron in Funka Bay. The upward transport of iron from the bay bottom to the surface water during the winter vertical mixing may play an important role in the supply of bioavailable iron for phytoplankton growth in the coastal waters.
  • T. Tanaka, I. Yasuda, H. Onishi, H. Ueno, M. Masujima
    JOURNAL OF OCEANOGRAPHY 71 1 1 - 17 2015年02月 [査読有り][通常論文]
     
    Tide-induced vertical mixing along the shelf break in the eastern Bering Sea is considered one of the main physical processes that sustain local summertime high biological production. However, observations based on microstructure measurements that show enhanced tidal mixing are scarce. In this study, repeated casts of current and turbulence in the vicinity of the shelf break within Pribilof Canyon were conducted over a day in June 2012, enabling us to evaluate the representativeness of the vertical mixing intensity during one day and to detect the relationship between turbulence and tidal current. The cross-sectional distributions of the one-day averaged vertical diffusivity and the turbulent energy dissipation rate showed that strong vertical mixing occurred at the subsurface within about 15 km of the shelf break and near the seabed of the outer shelf. This result agrees with prior observations that were made by us and based on a single profile at each station, which indicated that the observed spatial pattern of turbulence is robust. Diurnal and semidiurnal tidal currents dominated the flow variations off the shelf break, and a statistically significant positive correlation was detected between the vertical shear of the horizontal tidal currents and the turbulent energy dissipation rate. This result suggests that the high turbulent energy dissipation and the enhanced vertical mixing off the shelf break were induced by the strong vertical shear of tidal currents.
  • 清水 悠作, 大木 淳之, 久万 健志, 大西 広二, 亀井 佳彦, 小林 直人
    日本地球化学会年会要旨集 62 89 - 89 一般社団法人日本地球化学会 2015年 
    CH2I2、C2H5Iなど揮発性有機ヨウ素化合物（volatile organoiodine compound:VOI）は、海から大気へヨウ素を供給するキャリアーとして機能する。本研究では、VOIと生物生産性や有機物分解との関係を調べるために、北海道噴火湾で2012年3月から2014年12月の隔月に海水を採取し、海水中VOI濃度をパージ＆トラップ-ガスクロマトグラフ-質量分析法で測定した。
    春季植物プランクトンブルーム終了後の5月以降にVOI濃度は急激に増加し始め、6月から7月に年間ピークに達した。ピーク深度はVOI成分により異なった。このようなピーク深度の違いは、生成メカニズムの違いを示しており、こうした海水中VOIの生成メカニズムの違いは、大気への放出特性にも反映されると考えられる。
  • Keiko Sekiguchi, Hiroji Onishi, Hiroko Sasaki, Shota Haba, Yuka Iwahara, Daisuke Mizuguchi, Mayuko Otsuki, Daisuke Saijo, Bungo Nishizawa, Hirona Mizuno, Naoki Hoshi, Takehiko Kamito
    MARINE MAMMAL SCIENCE 30 3 1199 - 1209 2014年07月 [査読有り][通常論文]
  • 清水 悠作, 大木 淳之, 久万 健志, 大西 広二, 亀井 佳彦, 小林 直人
    日本地球化学会年会要旨集 61 202 - 202 一般社団法人日本地球化学会 2014年 
    CH2I2などの海水中の揮発性有機ヨウ素化合物(Volatile organoiodine compound；VOI)は、海洋から大気へのヨウ素の主なキャリアーとして知られるが、生成過程などは明らかになっていない。本研究では、VOIと生物生産性や有機物分解との関係を明らかにするため、VOIと生物化学パラメータのモニタリングを行った。北海道噴火湾にて、VOI（CH2I2、CH3I、CH2ClI）濃度や、生物科学パラメータの定点測定を、2012年3月から2014年6月まで行った。春季の植物プランクトンブルームが終焉し、植物プランクトンが老化、死滅する時期に、VOIが多量に生成されることがわかった。CH2I2増分が2013年は2012年の半分であったことより、VOI生成量には経年差がみられた。
  • Rui Saito, Atsushi Yamaguchi, Ichiro Yasuda, Hiromichi Ueno, Hiromu Ishiyama, Hiroji Onishi, Ichiro Imai
    JOURNAL OF PLANKTON RESEARCH 36 1 117 - 128 2014年01月 [査読有り][通常論文]
     
    Mesoscale anticyclonic eddies have been observed south of the Aleutian Islands. Eddies farther east, in the Gulf of Alaska, are known to transport coastal water and coastal zooplankton to the offshore open ocean. The impacts of mesoscale anticyclonic eddies formed south of the western Aleutian Islands (Aleutian eddies) on the zooplankton community are not fully understood. In the present study, we describe zooplankton population structures within an Aleutian eddy and outside the eddy during July 2010. Based on the sea-level anomaly, the Aleutian eddy was formed south of Attu Island (172 degrees 54'E) in February 2010, and it moved southeastward in the next 5 months. Large oceanic copepods, Neocalanus cristatus, Eucalanus bungii and Metridia pacifica were more abundant inside the eddy than the outside. Inside the eddy, the life stage distribution of N. cristatus was more advanced than that outside, and Neocalanus spp. had accumulated more lipids. These conditions probably reflect the greater primary production in the eddy, production enhanced by nutrients advected into the eddy. The Aleutian eddy contained mostly oceanic copepods because it was formed in the offshore water and/or eddy-eddy interaction occurred after its formation. The sufficient food condition in the eddy presumably resulted in higher growth and survival rates of these oceanic copepods, resulting in the greater abundance, advanced development stages and greater lipid accumulation.
  • Hiromichi Ueno, Ichiro Yasuda, Sachihiko Itoh, Hiroji Onishi, Yutaka Hiroe, Toshio Suga, Eitarou Oka
    JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS 117 2012年08月 [査読無し][通常論文]
     
    A Kenai eddy was studied through analyses of satellite altimeter data and hydrographic data from shipboard and Argo float observations. This eddy formed in December 2006 south of the Kenai Peninsula and propagated southwestward along the Alaskan Stream. The eddy held horizontally uniform warm core water in January 2007. In late winter 2007, this core water was cooled from the top and a subsurface temperature maximum was formed around 26.5 sigma(theta). Two years later in summer 2009, warm and low-dissolved-oxygen (low- DO) water characterized by a temperature maximum around 26.5 sigma(theta) was observed again in the eddy core and was likely the remnant of original core water. At the same time, cold and high-DO water intrusions occurred in the eddy core, suggesting that strong modification of core water was ongoing. After summer 2009, the core water was fully changed through interaction with another eddy.
  • UENO Hiromichi, YASUDA Ichiro, ITOH Sachihiko, ONISHI Hiroji, HIROE Yutaka, SUGA Toshio, OKA Eitarou
    J Geophys Res 117 C8 C08032-C08032-11 - n/a 2012年08月 [査読有り][通常論文]
  • Takuzo Abe, Keiko Sekiguchi, Hiroji Onishi, Kota Muramatsu, Takehiko Kamito
    Marine Biology 159 5 1173 - 1176 2012年05月 [査読有り]
  • 上野洋路, 安田一郎, 伊藤幸彦, 大西広二, 廣江豊, 廣江豊, 須賀利雄, 須賀利雄, 岡英太郎
    月刊海洋 43 12 756 - 762 2011年12月 [査読無し][通常論文]

MISC

  • 田中雄大, 安田一郎, 久万健志, 西岡純, 田中祐希, 大西広二, 上野洋路, 増島雅親 月刊海洋 47‐55 2016年11月01日 [査読無し][通常論文]
  • 松本健太郎, 有馬大地, 松野孝平, 山?康裕, 大西広二, 大木淳之, 平譯享, 山口篤, 今井一郎 北大水産彙報 66 (1) 29 -38 2016年 [査読無し][通常論文]
     
    The spring phytoplankton community in the western North Pacific is characterized by large variability in both the horizontal and verical dimensions. To evaluate this variability, phytoplankton communitiesat 39°30'N-44°00'N along 155°E were investigated in situ using a multi-excitation fluorometer during May 2014. The sea surface chlorophyll a(Chi. a) level was high and composed mainly of diatoms near 43°30'N-42'N, while it was low and composed of dinoflagellates south of 40°N. Based on seven fixed-station investigations, the phytoplanklton communities were classified into 4 types : a low Chl. a level before bloom (44°N), massive diatom bloom(42°N-43°N), low Chl. a level with dinoflagellates(40°N-41°N) and lowest Chl.a(at the southernmost station at 39°30'N). These phytoplankton communities corresponded with the formation of a water mass separating the Subartctic front(SAF) and Subarctic boundary(SAB). Multi-excitation fluorometry data showed a high correlation with Chl. a measurements obtained via Thrmo-salinometer and biovolume microscopic analyses(r²=0.67-0.97,p<0.05). Thus, we concluded that a multi-excitation fluorometer can be applied for the evaluation of detailed spatial and temporal changes in the phytoplankton community at various locations.
  • 齋藤類, 安田一郎, 小松幸生, 石山宙夢, 上野洋路, 大西広二, 山口篤 日本海洋学会大会講演要旨集 2014 102 2014年03月10日 [査読無し][通常論文]
  • 齋藤類, 山口篤, 安田一郎, 上野洋路, 石山宙夢, 大西広二, 今井一郎 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 2013 115 2013年09月26日 [査読無し][通常論文]
  • 齋藤類, 山口篤, 安田一郎, 上野洋路, 大西広二, 今井一郎 日本海洋学会大会講演要旨集 2013 237 2013年08月30日 [査読無し][通常論文]
  • 大木淳之, 三輪一爾, 大西広二, 亀井佳彦, 小林直人, 久万健志 分析化学(Bunseki Kagaku) 62 (12) 1071 -1078 2013年 [査読無し][通常論文]
     
    A shipboard observation was conducted in Funka Bay of Hokkaido from October 2011 to August 2012. Volatile organic halogenated compounds (halocarbons) in seawater collected at coastal, basin and sea shore sampling sites were measured by purge and trap GC-MS method. The spatial and temporal distributions of bromoform (CHBr3) were obtained, and we analyzed the origin of the compound. The minimum concentration of bromoform (15 pmol L< sup> -1< /sup> ) was found in December. The bromoform concentration in the basin area increased from 20 pmol L< sup> -1< /sup> to 25 pmol L< sup> -1< /sup> at a rate of 5 pmol L< sup> -1< /sup> month< sup> -1< /sup> during the phytoplankton spring bloom period (March-April). This increase would have been derived from the phytoplankton production of bromoform. The concentration increased from April to August at a rate of 4 pmol L< sup> -1< /sup> month< sup> -1< /sup> , and the maximum concentration of 42 pmol L< sup> -1< /sup> in basin area was found in August. Much higher concentrations were found in the coastal area (125 pmol L< sup> -1< /sup> ) and the sea shore (up to 1800 pmol L< sup> -1< /sup> ). The late summer bromoform maximum found in the basin area would be derived from macro algal production near the sea shore. © 2013 The Japan Society for Analytical Chemistry.
  • 齋藤類, 山口篤, 上野洋路, 大西広二, 今井一郎 日本海洋学会大会講演要旨集 2012 76 2012年03月13日 [査読無し][通常論文]
  • 高橋孝三, 朝日博史, 小野寺丈尚太郎, 岡崎裕典, 筒井英人, 池上隆仁, 兼松芳幸, 大西広二 日本海洋学会大会講演要旨集 2012 72 2012年03月13日 [査読無し][通常論文]
  • 上野洋路, 大西広二 月刊海洋 44 (12) 2012年
  • Hiromichi Ueno, William R. Crawford, Hiroji Onishi JOURNAL OF OCEANOGRAPHY 66 (3) 319 -328 2010年06月 [査読無し][通常論文]
     
    The impact of the Alaskan Stream (AS) eddies on the chlorophyll a (chl-a) distribution in the central subarctic North Pacific was investigated through analysis of chl-a and altimetry data from satellite observations. Altimetry observations provided the locations of mesoscale eddies in time and space within the maps of chlorophyll distributions. The climatological chl-a distributions averaged in the area and time showing presence of AS eddies suggested that AS eddies contributed significantly to the chl-a distribution in the deep-sea region of the subarctic North Pacific. The chl-a distribution was closely related to the AS eddies regardless of whether the eddy was located in or detached from the AS. A combination of two or three AS eddies sometimes formed high chl-a concentration belts that injected chlorophyll and coastal nutrient-rich waters southward from the Aleutian Islands far into the deep-sea region of the subarctic North Pacific. These results indicate that chl-a distribution in the central subarctic North Pacific was strongly impacted by AS eddies.
  • Kenai渦の変質過程
    月刊海洋・海洋出版株式会社 2010年 [査読無し][通常論文]
  • アラスカンストリームの流域特性と変動
    月刊海洋・海洋出版株式会社 2010年 [査読無し][通常論文]
  • Current property and variability of the Alaskan Stream
    2010年 [査読無し][通常論文]
  • Hiromichi Ueno, Howard J. Freeland, William R. Crawford, Hiroji Onishi, Eitarou Oka, Kanako Sato, Toshio Suga JOURNAL OF PHYSICAL OCEANOGRAPHY 39 (4) 934 -951 2009年04月 [査読無し][通常論文]
     
    Anticyclonic eddies propagating southwestward in the Alaskan Stream (AS) were investigated through analysis of altimetry data from satellite observations during 1992-2006 and hydrographic data from profiling float observations during 2001-06. Fifteen long-lived eddies were identified and categorized based on their area of first appearance. Three eddies were present at the beginning of the satellite observations; another three formed in the eastern Gulf of Alaska off Sitka, Alaska; and four were first detected at the head of the Gulf of Alaska near Yakutat, Alaska. The other five eddies formed along the AS between 157 degrees and 169 degrees W, and were named AS eddies. While the eddies that formed in the Gulf of Alaska mainly decayed before exiting the Gulf of Alaska, the AS eddies mostly crossed the 180 degrees meridian and reached the western subarctic gyre. Four of five AS eddies formed under negative or weakly positive wind stress curls, which possibly caused AS separation from the coast. Comparison of eddy propagation speeds in the AS with the bottom slope showed that eddies propagated faster over steeper slopes, although eddy speeds were slower than those predicted by the topographic planetary wave dispersion relation. An AS eddy was observed by profiling floats in the western subarctic gyre after it detached from the AS. Intermediate-layer water near the eddy center had low potential vorticity compared with the surrounding water, suggesting that AS eddies provided the western subarctic gyre with water just south of the Aleutian Islands.
  • 小野寺丈尚太郎, 高橋孝三, 大西広二, 簗田満 海の研究 18 (5) 307 -322 2009年 [査読無し][通常論文]
     
    珪藻沈降群集フラックスと海洋環境変動との対応関係を探るために,Station AB(ベーリング海)とStation SA(北太平洋北部中央亜寒帯)において,1990年8月から1999年1月上旬までに得られたセディメントトラップ試料を分析した。全珪藻フラックス変動の極大は,多くの年は両Stationともに春と秋のどちらか年一回か,春と秋の年2回観察された。しかし,年によっては特異なフラックス変動が観測され,そのタイミングはStations ABとSAで異なっていた。これらの経年変動は,おそらく冬季鉛直混合と,それに引き続く夏季成層構造の発達度合いとタイミングの違いが影響していると思われる。珪藻沈降群集の優占種はNeodenticula seminaeで,8年間を通した平均優占率はABで80%,SAで82%に達した。8年間を通して,珪藻沈降群集組成に若干の変化が両Stationで見られたが,これらの変動傾向が長期的な海洋環境変動と関係しているかどうかについては,9年目以降の試料分析を通して考察する必要がある。In order to decipher the relationship between the changes in diatom floral fluxes and the oceanographic conditions, we've deployed sediment traps at Stations AB (the Aleutian Basin) and SA (the central subarctic Pacific) from August of 1990 to the present. For the first eight years, we've conducted a diatom flux study. Total diatom fluxes (TDF) at both stations usually showed spring and/or fall peaks in a year. However, significant interannual variations of TDF were observed at both stations. At Station SA, significant correlation coefficient was obtained between mean TDF of each year and Pacific Decadal Oscillation index. These interannual variations are possibly due to the differences in the strength and timing of winter mixing and the subsequent summer stratification. The dominant species at both stations was Neodenticula seminae with mean abundances of 80% (Station AB) and 82% (Station SA) of TDF throughout the sampled duration. Coastal species were more abundant at Station AB than Station SA. At Station SA, relatively small numbers of Chaetoceros resting spores occurred in summers of some years as the result of lateral advection from the Aleutian Islands. During the eight years, the slight changes of diatom sinking flora were observed at both stations. Whether or not these trends suggest the changes in oceanographic condition for long-term, a further observation is warranted and to be continued.
  • Otobe Hirotaka, Onishi Hiroji, Inada Masakatsu, MICHIDA Yutaka, TERAZAKI Makoto Coastal Marine Science 33 (1) 78 -86 2009年 [査読無し][通常論文]
     
    In order to understand the seasonal water circulation system of Otsuchi Bay, direct current measurements were taken by using bottom-mounted Acoustic Doppler Current Profilers (ADCPs) during two periods, from October 2003 to March 2004 and from May 2004 to October 2004. During the first observation period, a remarkable estuary-type vertical circulation was observed. An anti-clockwise circulation, flowing into the bay along the northern coast and out along the southern coast was dominant during the second observation period. It was found that this clear seasonal variation was generated by both seasonal changes of wind and tide-induced residual current.
  • 小野寺 丈尚太郎, 高橋 孝三, 大西 広二, 簗田 満, Jonaotaro Onodera, Kozo Takahashi, Hiroji Onishi, Mitsuru Yanada, Center for Advanced Marine Core Research Kochi University, Department of Earth and Planetary Sciences Kyushu University, Graduate School of Fisheries Science Hokkaido University, Graduate School of Fisheries Science Hokkaido University 海の研究 = Umi no Kenkyu (Oceanography in Japan) 18 (5) 307 -322 2009年 [査読無し][通常論文]
     
    珪藻沈降群集フラックスと海洋環境変動との対応関係を探るために,Station AB(ベーリング海)とStation SA(北太平洋北部中央亜寒帯)において,1990年8月から1999年1月上旬までに得られたセディメントトラップ試料を分析した。全珪藻フラックス変動の極大は,多くの年は両Stationともに春と秋のどちらか年一回か,春と秋の年2回観察された。しかし,年によっては特異なフラックス変動が観測され,そのタイミングはStations ABとSAで異なっていた。これらの経年変動は,おそらく冬季鉛直混合と,それに引き続く夏季成層構造の発達度合いとタイミングの違いが影響していると思われる。珪藻沈降群集の優占種はNeodenticula seminaeで,8年間を通した平均優占率はABで80%,SAで82%に達した。8年間を通して,珪藻沈降群集組成に若干の変化が両Stationで見られたが,これらの変動傾向が長期的な海洋環境変動と関係しているかどうかについては,9年目以降の試料分析を通して考察する必要がある。In order to decipher the relationship between the changes in diatom floral fluxes and the oceanographic conditions, we've deployed sediment traps at Stations AB (the Aleutian Basin) and SA (the central subarctic Pacific) from August of 1990 to the present. For the first eight years, we've conducted a diatom flux study. Total diatom fluxes (TDF) at both stations usually showed spring and/or fall peaks in a year. However, significant interannual variations of TDF were observed at both stations. At Station SA, significant correlation coefficient was obtained between mean TDF of each year and Pacific Decadal Oscillation index. These interannual variations are possibly due to the differences in the strength and timing of winter mixing and the subsequent summer stratification. The dominant species at both stations was Neodenticula seminae with mean abundances of 80% (Station AB) and 82% (Station SA) of TDF throughout the sampled duration. Coastal species were more abundant at Station AB than Station SA. At Station SA, relatively small numbers of Chaetoceros resting spores occurred in summers of some years as the result of lateral advection from the Aleutian Islands. During the eight years, the slight changes of diatom sinking flora were observed at both stations. Whether or not these trends suggest the changes in oceanographic condition for long-term, a further observation is warranted and to be continued.
  • Shoichi Kizu, Hiroji Onishi, Toshio Suga, Kimio Hanawa, Tomowo Watanabe, Hiroshi Iwamiya DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS 55 (4) 571 -586 2008年04月 [査読無し][通常論文]
     
    The fall rates of the current types of expendable conductivity-temperature-depth (XCTD) profilers and one under development are evaluated based on a series of co-located measurements with conventional conductivity-temperature-depth (CTD) profilers in the North Pacific. The types of probes investigated are the XCTD-1, the XCTD-2, the XCTD-3, and the XCTD-5 manufactured by Tsurumi Seiki Co., Ltd. It is confirmed that the present manufacturer's fall-rate coefficients for the XCTD-1/2 satisfy the accuracy guarantee of 2% of depth, at depth greater than 20 in. The coefficients of all XCTD types tested Lire dependent on water temperature, and the probes tend to fall slightly faster in warmer water. New sets of coefficients are given for the individual types, in a form that includes a correction for water temperature. It is also found that the ring hood structure of the XCTD-1/2 is effective in stabilizing the fall rates. The newer XCTD-3/5, which lack the hood, show larger scatter in the fall rate and occasionally violates the guaranteed depth accuracy. (c) 2008 Elsevier Ltd. All rights reserved.
  • 表層水塊および成層構造の時空間変動に関する研究の進展と今後の展開
    須賀利雄, 上野洋路, 大西広二, 林和彦, 斎藤寛子, 鋤柄千穂, 遠山勝也 月刊海洋 39 (7) 2007年07月 [査読無し][通常論文]
  • Hiromichi Ueno, Eitarou Oka, Toshio Suga, Hiroji Onishi, Dean Roemmich GEOPHYSICAL RESEARCH LETTERS 34 (5) L05603 -L05603 2007年03月 [査読無し][通常論文]
     
    Hydrographic data from profiling float observations for 2001 - 2005 and from expendable bathythermograph observations for 1993 - 2005 were analyzed to study the formation and variation of temperature inversions (T-inversions) in the eastern subarctic North Pacific ( SNP). The formation and variation of T-inversions differed significantly between the northern and southern regions of the eastern SNP. In the northern region, the temperature minimum (T-min) at the top of T-inversions outcropped to the sea surface and was cooled in the mixed layer nearly every winter. This process caused a seasonal cycle in the magnitude of T-inversions (DT), with a maximum in winter. In the southern region, the winter T-min outcropped relatively infrequently and the DT did not exhibit a significant maximum in winter during most years. The T-min in the southern region was likely to outcrop upstream near the date line roughly one year earlier and was then advected to the southern region.
  • Comparison of the current measured by electromagnetic current meter and bottom mounted ADCP in Otsuchi bay
    Coastal Marine Science 30 (2) 459 -463 2006年 [査読無し][通常論文]
  • H Ueno, E Oka, T Suga, H Onishi GEOPHYSICAL RESEARCH LETTERS 32 (20) L20603 -L20603 2005年10月 [査読無し][通常論文]
  • 橋本 洋平, 磯田 豊, 大西 広二, 坂岡 桂一郎 海の研究 14 (4) 513 -525 2005年 [査読無し][通常論文]
  • 北太平洋亜寒帯海域におけるArgoデータの利用
    月刊海洋・海洋出版株式会社 2005年 [査読無し][通常論文]
  • 大西 広二, Hiroji Onishi 海の研究 = Umi no Kenkyu (Oceanography in Japan) 11 (2) 358 -358 2002年03月05日 
    北太平洋中央部の亜寒帯海域において,北海道大学のおしょろ丸によるCTD観測が毎年6月の下旬に行われている。1990～1998年の9年間,180°の経度線に沿って,48°N～51.2°Nの間に9観測点が設けられた。このデータセットを用いて,水温,塩分,密度,地衡流速(3,000m基準)についての平均断面図や標準偏差断面図などを作成した。さらにEOF解析を用いて断面構造における空間分布と時間変動の解析を行った。流速断面のEOF第1モード(寄与率37.6%)は,西向きのアラスカンストリームと東向きの亜寒帯海流の強弱を表わす空間分布を示した。このモードの振幅関数では,1991年と1997年に正の極大値を持ち,亜寒帯海流の東向き輸送量の変動とよい一致を示した。また,この変動は,Ridge Domainにおける深層水の湧昇の度合いが強く関与していることが示された。
  • H. Onishi Journal of Oceanography 57 (1) 79 -91 2001年 [査読無し][通常論文]
     
    In the central North Pacific Subarctic Gyre, CTD hydrographic measurements were carried out yearly in late June from 1990 to 1998 at 9 stations along 180° meridian from 48°N to 51.2°N. Vertical sections of 9-year means, anomalies for each year and others of potential temperature, salinity, potential density and geostrophic velocity (referred to 3000 m) were calculated based on this data set. Empirical Orthogonal Function (EOF) analysis was adopted in the investigation of spatial characteristics and its temporal variation in vertical sections. The spatial distribution of the 1st mode EOF of velocity shows the westward Alaskan Stream and the eastward Subarctic Current. This mode explains 37.6% of the total variance. Two positive maxims appear in its amplitude in 1991 and 1997, which is similar to the variation in volume transport of the eastward Subarctic Current. These variations are closely related to the vertical movement of Ridge Domain deep water.
  • Onishi Hiroji, Ohtsuka Shintaro, Anma Gen Bull. Fac. Fish. Hokkaido Univ. 51 (1) 31 -43 2000年 [査読無し][通常論文]
  • Hiroji Onishi, Kiyotaka Ohtani Journal of Oceanography 55 (5) 597 -608 1999年10月 [査読無し][通常論文]
     
    The Alaskan Stream is the westward boundary current of the North Pacific subarctic gyre. In the central region of the North Pacific, the Alaskan Stream serves as a connection between the Alaskan gyre, Western subarctic gyre and Bering Sea gyre. Its volume transport is very important in estimating the magnitude of the subarctic circulation in the North Pacific. In order to clarify its seasonal and interannual variation, we conducted observations along a north-south section at 180°during June from 1990 to 1997. Moorings were deployed from 1995 to 1997. Hydrographic casts were made at intervals of ~37 km to a depth of 3000 m. Moorings were set between CTD stations, with Moor1 (Moor2) at the center (southern edge) of the Alaskan Stream. Geostrophic volume transport (referred to 3000 m) revealed large interannual variability in the Alaskan Stream. Average volume transport over the 8 years was 27.5 x 106 m3s-1 with a standard deviation of 6.5 x 106 m3s-1. Maximum transport was 41.0 x 106 m3s-1 (1997) and minimum was 21.7 x 106 m3s-1 (1995). Stable westward flows were observed at Moor1 1500 m (259°, 11.7 cm s-1) and 3000 m (240°, 3.7 cm s-1, 1996-1997 year average). The ratio of eddy to mean kinetic energy (KE'/KE) was very small (< 0.6) throughout the year. A relatively weak and unstable westward flow was observed at Moor2 at 3000 m depth. Conversely, the average flow direction at Moor2 5000 m was eastward.
  • Seasonal and interannual variability of the Alaskan Stream in the central North Pacific
    IOC-WESPAC The Fourth International Sciencetific Symposium, Okinawa, Japan 43 -52 1998年 [査読無し][通常論文]
  • Baroclinic Flow Referred to the 3000m Reference Level across the 180° Transect in the Subarctic Pacific
    Bull. Fac. Fish. Hokkaido Univ. 48 53 -64 1997年 [査読無し][通常論文]
  • 「北太平洋西部亜寒帯海域の平均海洋構造と変動」
    『水産海洋研究』 60 78 -83 1996年 [査読無し][通常論文]
  • 北太平洋亜寒帯循環の東西輸送
    月刊海洋・海洋出版株式会社 1992年 [査読無し][通常論文]

所属学協会

  • 日本海洋学会   水産海洋学会   海洋気象学会   

Works（作品等）

共同研究・競争的資金等の研究課題

  • 日本学術振興会：科学研究費助成事業
    研究期間 : 2006年 -2008年 
    代表者 : 古谷 研, 黒倉 寿, 武田 重信, 岸 道郎, 大西 広二, 小河 久朗, 斉藤 宏明
     
    三陸沿岸域におけるホタテ、マガキなどの無給餌養殖生産の内湾環境依存性を、大槌湾と大船渡湾の対比から明らかにした。大船渡湾では、大槌湾よりも閉鎖性が強いため湾内外の海水交換が悪く、湾外からの栄養塩供給は湾奥には至らない。両湾ともに、貝類養殖は現状の養殖密度がほぼ妥当であるが、養殖貝類の成長速度は養殖実施場所によって異なることから、養殖実施場所の選択により増産の可能性があることが明らかになった。
  • 日本学術振興会：科学研究費助成事業
    研究期間 : 2003年 -2006年 
    代表者 : 簗田 満, 高橋 孝三, 大西 広二, 朝日 博史
     
    北太平洋亜寒帯海域における基礎生産過程を研究する手法としてセジメント・トラップ実験を導入し,長期間にわたるこの研究の継続を通じて基礎生産過程の経年変動を引き起こす環境要因,特にアラスカンストリームなどの海洋物理的要因を解明し,近未来の海洋環境の変遷を予想することを本研究の最終目的とし,研究代表者および研究分担者の3名〜4名は,平成15年度〜平成18年度に北大水産学部所属練習船「おしょろ丸」の北洋航海(6〜8月)に乗船し,中央北太平洋亜寒帯海域(49°N,174°W)およびベーリング海盆(53.5°N,178°W)において,セジメント・トラップの回収と設置を行った。 得られた沈降粒子については,全沈降粒子量,炭素/窒素含有量,タンパク質アミノ酸,非タンパクアミノ酸,ヘキソサミン,安定同位体比,生物起源炭酸カルシウム,生物起源オパールの同定・定量を行なった。また,顕微鏡観察による珪藻,放散虫,有孔虫および円石藻類の定量および種組成の解析が行われた。さらに,CTDおよびXCTDを用いてアラスカンストリームおよび亜寒帯海流の流量および熱・塩分輸送量を解析し,また,Argoフロートのデータ解析により物理的海洋環境変動を解析した。 以上の分析および解析の結果から,2003年春期のベーリング海における珪藻を主体とする高い沈降粒子フラックスのピーク,北太平洋亜寒帯海域における有孔虫類や円石藻類を主体とする炭酸塩物質による沈降粒子フラックスの最大ピークの時間的ずれなど,過去(1990年〜2001年)に認められたそれらの季節変動および年変動と大きく異なることが明らかとなった。これらの変動は,表層水温や表面水温偏差の変動と密接に関与していると考えられた。
  • 日本学術振興会：科学研究費助成事業
    研究期間 : 2003年 -2005年 
    代表者 : 大西 広二
     
    本年度は研究期間の3年目の最終年にあたり、一昨年度導入した観測機器を利用した夏期の観測準備を行った。また、限られた観測時間の有効利用を図るため、1950m深まで観測可能なXCTD2プローブを購入し、CTD観測の充実を図った。 夏期(6月下旬〜8月下旬)に行われた、北海道大学水産学部附属練習船おしょろ丸の北洋航海には、研究代表者が乗船し、海洋観測に携わった。海洋観測は、時間的制約の中で、アラスカンストリーム海域・亜寒帯海流海域を横断する観測断面を3断面に渡って行うことが出来た。観測結果から、3断面のうちアラスカンストリームの上流域にあたる西経165度と170.5度では流域幅は広いものの流量は少なく、経度180度では流域幅は狭いものの構造が深く、多くの西向き流量が求められた。この結果から、アラスカンストリームが流下方向に増大する傾向は過去の観測結果と一致し、深層水湧昇域の密度傾斜の形状が大きく空間的に変化する事が流速構造や流量の変化に繋がっていることが確かめられた。 この結果を踏まえて、今後は東西循環を繋ぐ流量、外部との流入・流出量に着目し、ADCPデータや水塊分析データを基に解析結果をまとめる予定である。さらにArgoフロートデータ、衛星データや気象データとの対応も図り、本研究で得られた成果がよりグローバルな海洋環境の変化と密接に係わっている事を確かめ、長期にわたるアラスカンストリームのモニター観測を一層重要な物と位置づけて行きたいと考える。 本年度の成果の一部は、2005年日本海洋学会春季大会シンポジウムで発表・報告した。これからも更なる成果を公表し、広く意見を求めて研究のまとめにつなげたい。
  • 日本学術振興会：科学研究費助成事業
    研究期間 : 1996年 -1998年 
    代表者 : 大谷 清隆, 大西 広二, 松石 隆, 桜井 泰憲
     
    本研究は平成8-10年度の3年間に渡って、亜寒帯海域の中長期変化と生態系の応答の検出を目的に行ったものである。歴史的資料に研究期間中に得た資料を加えてこの間に得られた主な成果を列記すると以下のようである。 1) 亜寒帯海域の海洋変動はアリューシャン低気圧システムに連動した変動を示し、べーリング海とオホーツク海の海氷滞在指数は負の相関関係を示し大気変動に生じる10年規模の変動とENSOに対応する大きな変動が認められた。2) アラスカンストリームの流量も1990年と1997年に30svを越すピークを持つ変動があり、1998年は14svと1990年以後で最も小さい値であった。3) 移行領域以北海域でシロサケ個体群の密度効果が体サイズの小型化と成熟年齢の高齢化に影響することが明らかになった。4) 同様に、アカイカ豊度はアカイカ流し網漁業が廃止された1994年以降増加していたが、1997年に固体サイズが大型になり豊度が減少した。その要因としてエルニーニョによる再生産率の低下とこれによる餌環境の好転が推定された。5) サンマの生活史を親子モデル計算から求めた所、寿命2年で1.5歳、と2歳で産卵するモデルが過去の漁獲量やサイズ組成に最も適合した。6) 体重組成によるコホート解析法に基づく資源量推定法はタラ資源量変動と適正漁獲量サイズ・時期を決めるのに有効である事を初めて明らかにした。
  • 日本学術振興会：科学研究費助成事業
    研究期間 : 1995年 -1997年 
    代表者 : 大谷 清隆, 大西 広二, 志賀 直信, 中谷 敏邦, 斉藤 誠一, 桜井 泰憲, NORCROSS B.L, ESLINGER D.L, PAUL A.J., WEINGARTNER ティー.ジェイ, ALEXANDER V., TYLER A.L., 小達 恒夫, 石井 清彦, 磯田 豊, 簗山 満, 三宅 秀男, WEINGARTNER ティー.ジェイ.
     
    本国際共同研究は、ベーリング海生態系の重要な鍵種であるスケトウダラを含む魚類の再生産機構に関わる生物生産と、大気・海洋変動との応答の解明を目的として、アラスカ大学フェアバンクス校水産・海洋学部との大学間協定に基づく共同研究として実施した。具体的には、平成7年度から9年度までの3年間、北海道大学練習船「おしょろ丸」による7、8月の北洋実習航海を利用して、南東ベーリング海およびセントローレンス島の南側の冷水域であるポリニヤ海域で、海洋環境とプランクトン調査およびトロール試験操業による生物採集を行い、環境の変動と指標生物であるスケトウダラとホッキョクダラなどのタラ科魚類の資源量調査、餌生物調査を行った。得られた成果の詳細は、1998年夏に出版される北大水産学部紀要に、「親潮域とベーリング生態系の比較研究-気候変動に関係した鍵種の生産構造と新規加入」とし公表する。成果の概要は次の通りである。(1)セントローレンス島南のポリニア海域での沿岸湧昇を衛星と船舶調査により確認した。さらに、(2)ポリニア海域における尾虫類の分布の経年変化と生態系における役割、(3)南東ベーリング海におけるスケトウダラ新規加入の経年変化とそれに関連する生物・物理過程、(4)極域生態系の環境変動指標種としてのホッキョクダラの卵・稚仔魚期の生残に関わる環境要因、(5)ポリニア海域における底魚魚類群集構造と食性に対する底冷水の経年変化との対応などを明らかにした。
  • 北部北太平洋亜寒帯循環の物質・熱輸送量の評価

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