Researcher Profile and Settings

Affiliation

• School of Fisheries Sciences　Training Ship “Ushio-maru”

Job Title

• Assistant Professor

J-Global ID

• 200901084496500439

Research Interests

• 海洋物理   水産学   Oceanography   Fisheries in General   

Research Areas

• Life sciences / Aquaculture
• Natural sciences / Atmospheric and hydrospheric science
• Environmental science/Agricultural science / Environmental dynamics

Educational Organization

•  Bachelor's degree program　School of Fisheries Sciences

Association Memberships

• THE OCEANOGRAPHIC SOCIETY OF JAPAN   

Research Activities

Published Papers

• Transport and modification processes of dense Soya Current Water in the boundary region between shelf and basin areas off Abashiri

  千葉 彩, 堀尾 一樹, 磯田 豊, 小林 直人

  海の研究 日本海洋学会 30 (2) 15 - 46 0916-8362 2021/03 [Refereed]
  
• Observation and model experiments on an internal-wave packet accompanied by streak bands over the sill topography of Tsugaru Strait

  Yamaguchi Takuya, Isoda Yutaka, Itoh Umihiko, Mukai Touru, Kobayashi Naoto

  Oceanography in Japan 日本海洋学会 29 (3) 71 - 90 0916-8362 2020 [Refereed]
   

  The Synthetic Aperture Radar (SAR) around the western entrance of the Tsugaru Strait has yielded well-defined images of an internal-wave packet accompanied by two or three surface-streaks (surface convergence within the same water mass), which is active during the stratified season, and whose wavelength is in the order of several hundred meters. Most of the waves in the packet were observed near the topographically shallow parts of the sill. Temporal changes were repeatedly observed in the internal waves confined to the sill using a high-frequency echosounder profiler within one-day in the summer 2017. The acoustic images suggest that a wave packet of extraordinary amplitude (> 150 m) has developed transiently around the downstream side of the sill at the ascending passage flow. This wave packet consists of two or three successive streak bands, with very disturbed sea surface conditions overlying wave troughs, i.e., strong downwelling areas. The dynamics of such waves developing over the sill is studied through a fully nonlinear nonhydrostatic numerical model. The vertical fluid stratification and temporal change of the barotropic passage flow were adjusted to approximate our observation conditions. The results suggest that the wave packet is effectively amplified near the downstream side of the sill, where the Froude number becomes a critical point, because upstream propagating waves on the sill slope stagnate and overlap efficiently. In this dynamical process, however, even if the wave grows to large amplitude, it does not form a well-organized solitary wave, but is rather scattered due to the strong dispersion of waves.

• Isoprene production in seawater of Funka Bay, Hokkaido, Japan

  Atsushi Ooki, Ryuta Shida, Masashi Otsu, Hiroji Onishi, Naoto Kobayashi, Takahiro Iida, Daiki Nomura, Kota Suzuki, Hideyoshi Yamaoka, Tetsuya Takatsu

  Journal of Oceanography 75 (6) 485 - 501 0916-8370 2019/12 [Refereed][Not invited]
  
• Annual and seasonal changes in the assemblage of planktonic copepods and appendicularians in Funka Bay before and after intrusion of Coastal Oyashio Water

  Hideyoshi Yamaoka, Tetsuya Takatsu, Kota Suzuki, Naoto Kobayashi, Atsushi Ooki, Mitsuhiro Nakaya

  Fisheries Science 2019/09 [Refereed][Not invited]
  
• Numerical experiments of surface clockwise circulation in Funka Bay during early summer

  Kobayashi Naoto, Isoda Yutaka, Horio Kazuki

  Oceanography in Japan 日本海洋学会 28 (4) 51 - 74 0916-8362 2019 [Refereed]
   

  A current system consisting of surface clockwise circulation is the most remarkable feature observed in Funka Bay during early summer. The present study investigates its formation process using a numerical model driven by the following three factors during the typically strati fied season, i.e., (1) freshening of coastal water because of river discharge, (2) density inflow of Tsugaru Gyre water, and (3) surface heat flux. It was found that the "topographic heat accu mulation effect" resulting from surface heating is essential for the genesis of the surface clock wise circulation. Because of the surface offshore flow generated by the thermal contrast be tween the shallow coastal and deep central regions, a weak anti-clockwise geostrophic flow is initially formed. Nevertheless, with continuous thermal forcing, after a few months, this offshore flow gradually reinforces the upslope transport of cold dense water. When the cooling resulting from the dense water upslope dominates in comparison to the downward heating resulting from vertical diffusivity around the coastal sea bottom, the coastal water is relatively colder than the offshore surface water. Therefore, shallowing of the interface toward the coast drives the geos trophic flow proceeding along the coast to the left-handed side. In response to this change, an isolated clockwise circulation begins to establish from the surface layer of the northern bay head, while an initially formed anti-clockwise flow migrates to the deeper region.

• Observations and model experiments of the diurnal eddy of the Cold Water Belt along the offshore side of the Soya Warm Current

  Iida Hiroyuki, Isoda Yutaka, Kobayashi Naoto, Horio Kazuki

  Oceanography in Japan 日本海洋学会 27 (4) 155 - 174 0916-8362 2018 [Refereed]
   

  The detailed distributions of flow, temperature fields, and the temporal change of diurnal eddies accompanied with the Cold Water Belt (CWB) are observed by CTD and one-day repeated XBT/ADCP measurements across the Soya Warm Current (SWC) in the summer of 2016. Saline water originating from the Japan Sea Intermediate Water (JSIW) was found below the CWB. Tracer experiments using numerical models predict the offshore-side water of the SWC is supplied by onshore advection and upwelling of the deeper JSIW. The nearly homogeneous JSIW is taken into a counter-clockwise isolated eddy, which is periodically generated by the diurnal tidal current around the Soya Strait and is advected downstream along the offshore side of the SWC. Therefore, the majority of the water below the CWB, which is weakly stratified, is composed of this eddy street.

• Seasonal variation of volatile organic iodine compounds in the water column of Funka Bay, Hokkaido, Japan

  Yusaku Shimizu, Atsushi Ooki, Hiroji Onishi, Tetsuya Takatsu, Seiji Tanaka, Yuta Inagaki, Kota Suzuki, Naoto Kobayashi, Yoshihiko Kamei, Kenshi Kuma

  JOURNAL OF ATMOSPHERIC CHEMISTRY 74 (2) 205 - 225 0167-7764 2017/06 [Refereed][Not invited]
   

  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).
• Inflow process of low potential vorticity water originating from the intermediate waters of the Japan Sea into the Tsugaru Strait

  伊田 智喜, 山下 慎司, 磯田 豊, 小林 直人

  海の研究 日本海洋学会 25 (4) 101 - 122 0916-8362 2016/07 [Refereed]
  
• Regeneration dynamics of iron and nutrients from bay sediment into bottom water of Funka Bay, Japan

  Nanako Hioki, Kenshi Kuma, Yuichiroh Morita, Daichi Miura, Atsushi Ooki, Seiji Tanaka, Hiroji Onishi, Tetsuya Takatsu, Naoto Kobayashi, Yoshihiko Kamei

  JOURNAL OF OCEANOGRAPHY 71 (6) 703 - 714 0916-8370 2015/12 [Refereed][Not invited]
   

  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.
• Effects of hypoxia on the feeding intensity and somatic condition of the blackfin flounder Glyptocephalus stelleri in Funka Bay, Japan

  Yuta Inagaki, Tetsuya Takatsu, Takao Uenoyama, Noriko Yoneda, Shinichi Yokoyama, Yoshihiko Kamei, Naoto Kobayashi, Toyomi Takahashi

  FISHERIES SCIENCE 81 (4) 687 - 698 0919-9268 2015/07 [Refereed][Not invited]
   

  To clarify effects of hypoxia on feeding and somatic condition of blackfin flounder Glyptocephalus stelleri, we studied the temporal relationship between hypoxia and feeding intensity as well as the condition of this species in May and August 2006-2012. Hypoxia occurred near the seafloor in August between 2010 and 2012 but not in May. Population densities of gammarid amphipods Ampelisca brevicornis and Melita sp., the main prey items of blackfin flounder, were consistently low; however, the somatic condition and feeding intensity of blackfin flounder increased during hypoxia. Such an increase was not detected in May 2012 under non-hypoxic conditions. These facts imply that the hypoxia increased prey availability for blackfin flounder through the increased exposure of the gammarids over the sea floor, and, thus, resulted in improved body condition in August 2011 and 2012. Hypoxia positively would influence the somatic condition and feeding intensity of blackfin flounder in Funka Bay in August 2011 and 2012; however, the somatic condition during this period did not reach the levels recorded in 1983, suggesting that habitat quality for blackfin flounder in Funka Bay in 2011 and 2012 was worse than that in 1983.
• Production and sea-to-air flux of organic iodine gases associated with degradation of organic matter after diatom bloom in coastal sea area

  Shimizu Yusaku, Ooki Atsushi, Kuma Kenshi, Onishi Hiroji, Kamei Yoshihiko, Kobayashi Naoto

  Abstracts of Annual Meeting of the Geochemical Society of Japan 一般社団法人日本地球化学会 62 89 - 89 2015 

  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。
• Inverse Estuary Circulation in Mutsu Bay-(1) Hydrographic Observations during the Summer-time-

  河野航平, 磯田豊, 工藤勲, 藤原将平, 有田駿, 小林直人, 吉田達, 扇田いずみ, 高津哲也

  海と空 海洋気象学会 90 (1) 11 - 16 0503-1567 2014/08/31 [Refereed][Not invited]
  
• Improved growth of flathead flounder Hippoglossoides dubius in hypoxic waters in Funka Bay, Japan

  Yuta Inagaki, Tetsuya Takatsu, Masafumi Kimura, Yota Kano, Toyomi Takahashi, Yoshihiko Kamei, Naoto Kobayashi, Tatsuaki Maeda

  FISHERIES SCIENCE 80 (4) 725 - 734 0919-9268 2014/07 [Refereed][Not invited]
   

  To identify the factors that influence the growth rate of flathead flounder Hippoglossoides dubius in Funka Bay, Japan, we studied temporal changes in the growth of this species and its prey from 1989 to 2012. The lowest growth rate of H. dubius was recorded in the 1995 year-class, which had experienced severe hypoxia between 1995 and 1997. However, the highest growth rate was recorded in the 2007 year-class, which had experienced hypoxia between 2009 and 2011. In 2000 and 2001, small-sized flounder (< 200 mm TL) from the 1995 year-class were feeding on mysidaceans, whereas those from other year-classes fed on small Ophiura spp. (< 9 mm in disc diameter) in 2009, 2011, and 2012. Small Ophiura spp. were more abundant in 2007 and 2011 than in 2002 and 2003. Successful recruitment of Ophiura spp. took place between 2007 and 2011 and cohorts from these years could tolerate hypoxia. This suggests that food availability improved under hypoxic conditions, which led to improved growth in small flounders. Large flounders (a parts per thousand yen200 mm TL) from all year-classes fed on prickleback fishes (Stichaeidae) and walleye pollock Gadus chalcogrammus juveniles. The growth of large flounders was enhanced by an increase in the abundance of Stichaeidae fishes and G. chalcogrammus juveniles.
• Time series observation of volatile organoiodide compounds in Funka Bay, Hokkaido

  Shimizu Yusaku, Ooki Atsuhi, Kuma Kenshi, Oonishi Hiroji, Kamei Yoshihiko, Kobayashi Naoto

  Abstracts of Annual Meeting of the Geochemical Society of Japan 一般社団法人日本地球化学会 61 202 - 202 2014 

  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。
• Seasonal variations of bromoform distribution in the Funka Bay

  OOKI Atsushi, MIWA Kazuji, ONISHI Hiroji, KAMEI Yoshihiko, KOBAYASHI Naoto, KUMA Kenshi

  Bunseki Kagaku 62 (12) 1071 - 1078 0525-1931 2013/12 [Refereed][Not invited]
   

  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 bromofoun (15 pmol L-1) was found in December. The bromoform concentration in the basin area increased from 20 pmol L-1 to 25 pmol L-1 at a rate of 5 pmol L-1 month(-1) 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-1 month(-1), and the maximum concentration of 42 pmol L-1 in basin area was found in August. Much higher concentrations were found in the coastal area (125 pmol L-1) and the sea shore (up to 1800 pmol L-1). The late summer bromoform maximum found in the basin area would be derived from macro algal production near the sea shore.
• The Kyucho passing through the bay mouth of Funka Bay-(3) Numerical model experiment II-

  小林直人, 磯田豊, 高津哲也, 木村修, 亀井佳彦

  海と空 88 (3) 57 - 63 0503-1567 2013/03/22 [Refereed][Not invited]
  
• The Kyucho passing through the bay mouth of Funka Bay-(2) Numerical model experiment I-

  小林直人, 磯田豊, 高津哲也, 木村修, 亀井佳彦

  海と空 海洋気象学会 88 (2) 43 - 48 0503-1567 2012/11/30 [Refereed][Not invited]
  
• The Kyucho passing through the bay mouth of Funka Bay-(1) Data analysis-

  小林直人, 磯田豊, 小林雅行, 佐藤千鶴, 木村修, 山口秀一, 高津哲也, ROSA Ana Luisa

  海と空 海洋気象学会 88 (1) 9 - 20 0503-1567 2012/07 [Refereed][Not invited]
  
• Intrusion of the Oyashio water into the eastern mouth of Tsugaru Strait in early summer, 2003

  Hiroshi Kuroda, Yutaka Isoda, Hidetaka Takeoka, Kenshi Kuma, Satoshi Honda, Hiromi Matsuura, Yukiyo Saitoh, Hyoe Takata, Shoei Iwade, Taku Wagawa, Naoto Kobayashi

  CONTINENTAL SHELF RESEARCH 32 36 - 46 0278-4343 2012/01 [Refereed]
   

  Hydrographic observations based on XBT, XCTD, CTD, and ADCP were performed around the eastern mouth of the Tsugaru Strait in June 2003. This study aims to describe the hydrographic structure of the eastern mouth focusing on the subarctic Oyashio water occupying the northern part, and to discuss the intrusion pathway of this water and its modification after the intrusion. Residual and absolute geostrophic velocities show a nearly barotropic inflow (0-25 cm/s) and outflow (0-80 cm/s) structures in the northern and southern parts of the strait mouth, respectively. In the north, the Oyashio water, classified as the near-bottom and modified Oyashio waters in this study, inflows into the strait. It is inferred that the near-bottom water is changed to the modified Oyashio water after the intrusion by diapycnal mixing and outflow as the modified Oyashio water from underneath of the Tsugaru Warm Current (TWC) water in the deepest part of the strait mouth, together with the TWC water. Horizontal salinity distribution suggests that the near-bottom water is supplied along the isopycnal surface from the subsurface of Hidaka Bay deeper than the strait. (C) 2011 Elsevier Ltd. All rights reserved.
• The Kyucho occurred off Kameda Peninsula, Hokkaido, at the end of May, 2006

  小林直人, 磯田豊, 小林雅行, 佐藤千鶴, 木村修, 山口秀一, 高津哲也, ROSA Ana Luisa

  北海道大学水産科学研究彙報 北海道大学大学院水産科学研究院 = Research Faculty of Fisheries Sciences, Hokkaido University 58 (3) 29 - 41 1346-1842 2009/02 [Not refereed][Not invited]
   

  A large damage to fishing set-nets caused by the Kyucho occurred off Kameda peninsula on 30 May, 2006. Such Kyucho seldom occurs in this area and hence it is unusual phenomenon. Two current-meters setting off Usujiri located at Kameda peninsula and off Shiraoi faced the Hidaka Bay captured this sudden and swift current. The meteorological and oceanographical conditions in 2005 without the Kyucho and those in 2006 with the Kyucho were compared. The difference in both years was the oceanic stratification. That is, the surface halocline was thinly formed by a large quantity of rainfall water accompanied by the atmospheric disturbance on 28 May in 2006, before the Kyucho occurrence. In the case of such discontinuity subsurface thinner layer than usual, we will expect that the particle velocity of wind-induced internal Kelvin wave increases, but its phase propagation speed rather decreases. In fact, the observed surface current velocity (0.3-1.2 m/s) is almost as same as the estimated propagation speed (0.3-0.8 m/s).
• Processes Influencing Iron Distribution in the Coastal Waters of the Tsugaru Strait, Japan

  Yukiyo Saitoh, Kenshi Kuma, Yutaka Isoda, Hiroshi Kuroda, Hiromi Matsuura, Taku Wagawa, Hyoe Takata, Naoto Kobayashi, Seiya Nagao, Takeshi Nakatsuka

  JOURNAL OF OCEANOGRAPHY 64 (6) 815 - 830 0916-8370 2008/12 [Refereed]
   

  We report measurements of iron, nutrients, dissolved oxygen, humic-type fluorescence intensity and chlorophyll a concentrations in the coastal waters at the inflow (western) and outflow (eastern) ends of Tsugaru Strait (Japan) in June 2003 and 2004. Two different water masses (intensive eastward flow "subtropical Tsugaru Warm Current Water (TWCw)" and weak westward flow "subarctic Oyashio Water (OW)") were observed at the eastern end of the strait. TWCw at the southern part of the eastern strait was vertically homogeneous with a uniform concentrations of iron (0.7-1.1 nM for labile dissolved Fe and 14-20 nM for total dissolvable Fe in 2003) as well as other chemical, biological and physical components throughout the water column of 200 m due to strong vertical mixing in the strait. The degree of mixing in the Tsugaru Warm Current (TWC) is predominantly affected by diurnal tidal current, which is strong during the period of tropical tides and weak during the period of equinoctial ones. The especially strong vertical water mixing in 2003 is caused by large dissipation energy input due to the bottom friction of passage-flow through the strait and tidal current. At the northern part of the eastern strait, the fresh surface layer overlying the OW and the deep-bottom waters in 2003 contained large concentrations of dissolved iron, resulting from iron supplied from river runoff and shelf sediments, respectively. These results suggest that the most important mechanism for transporting iron in the strait is the strong vertical water mixing due to the tidal current, and that the iron sources in the coastal waters are the organic-associated, iron-rich freshwater input into the surface water.
• Tsushima Warm Current Water inflow to Tsugaru Strait

  中嶋與文, 磯田豊, 松浦宏美, 和川拓, 相木智一, 矢部いつか, 高田兵衛, 久万健志, 小林直人, 矢幅寛

  海と空 海洋気象学会 84 (1) 1 - 16 0503-1567 2008/06/30 [Refereed][Not invited]
  
• Transportation of pointhead flounder Cleisthenes pinetorum larvae in Funka Bay and its vicinity

  栗藤亜希子, 平岡優子, 高津哲也, 伊村一雄, 小林直人, 亀井佳彦

  水産海洋研究 69 (3) 145 - 155 0916-1562 2005/08 [Refereed][Not invited]
  

Works

• 北海道大学水産学部附属練習船による海洋漁業調査

  2001
• 北海道大学水産学部附属練習船による海洋漁業調査

  2000

MISC

• Vertical circulation induced by negative shear flow at the downside of Ooma-zaki in the Tsugaru Strait

  Asano Ryuta, Isoda Yutaka, Kobayashi Naoto, Nakamura Tomohiro, Itoh Kaoru  Bulletin of Fisheries Sciences, Hokkaido University  70-  (1)  63  -76  2020/08/24  [Not refereed]
  
• 陸奥湾における1989-2019年マダラ着底稚魚分布密度調査による加入量予測

  高津哲也, 中屋光裕, 神山晃汰, 亀井佳彦, 小林直人, 飯田高大, 野呂恭成  水産海洋研究  84-  (3)  2020
• The bifurcation of the Tsugaru Gyre over the Hidaka shelf slope

  小林 直人, 太田 紗生, 磯田 豊  海と空 = Sea and sky  90-  (1)  1  -10  2014/08
• 北海道西岸沖のホタテ貝種苗生産を支える産卵及び浮遊幼生の輸送過程

  磯貝 安洋, 磯田 豊, 下野 学, 小林 直人, 工藤 勲, 干場 康博  北海道大学水産科学研究彙報 = Bulletin of Fisheries Sciences, Hokkaido University  60-  (2)  23  -37  2010/12
• Seasonal Variations of Shelf Circulation in Hidaka Bay, Hokkaido, Japan, with an Interpretation of the Migration Route of Juvenile Walleye Pollock

  ROSA ANA LUISA, ISODA YUTAKA, KOBAYASHI NAOTO  Journal of oceanography  65-  (5)  615  -626  2009/10/01
• Tsushima Warm Current Water inflow to Tsugaru Strait

  NAKAJIMA Yobun, ISODA Yutaka, MATSUURA Hiromi, WAGAWA Taku, AIKI Tomokazu, YABE Itsuka, TAKATA Hyoue, KUMA Kenshi, KOBAYASHI Naoto, YAHABA Hiroshi  海と空  84-  (1)  1  -16  2008/06/30  [Refereed]
  
• 「津軽海峡通過流の海水変質過程

  松浦宏美, 磯田豊, 黒田寛, 久万健志, 斉藤雪美, 小林直人, 相木智一, 和川拓, 矢部いつか, 干場康博  海と空  83-  (1)  21  -35  2007  [Refereed][Not invited]
  
• Seasonal Variations of the Flow Pattern and Water Masses off Kameda Peninsula, Hokkaido

  Kobayashi Naoto, Isoda Yutaka, Kuroda Hiroshi, Kimura Osamu, Yamaguchi Hidekazu, Onishi Mitsuyo, Rosa Ana Luisa  Bulletin on coastal oceanography  44-  (1)  59  -67  2006  [Refereed][Not invited]
   

  Seasonally varying nearshore currents, which have not been described in the oceanographic literature, are believed to exist off Kameda Peninsula, Hokkaido; a northwestward current called the "Shikabe-jio", and a southeastward current called the "Esan-jio". The purpose of this study is to describe these currents quantitatively and to examine the relationship between seasonal variations in currents and water mass distribution by analyzing CTD and ADCP data. We have confirmed the seasonal variation of flow patterns with opposite current direction, i.e., the baroclinic southwestward flow (Esan-jio) from spring to summer and the barotropic weak northwestward flow (Shikabe-jio) in winter. Tsugaru Warm Current Water appears off the Peninsula with transitional changes of current in autumn, but rapidly replaces Oyashio Water in winter.
• Development of a Simultaneous Chemiluminescent Immunoassay for Bigeye Tuna, Thunnus obesus, Vitellogenin

  AMANO Haruna, FUKADA Haruhisa, FUJITA Toshiaki, KOBAYASHI Naoto, SAKAOKA Keiichirou, HARA Akihiko  水産増殖  52-  (3)  293  -300  2004  [Refereed][Not invited]
   

  ハイドロキシルアパタイトおよびゲル濾過カラムを用いて、Vgの構成成分である卵黄蛋白Lvをメバチマグロ卵巣から精製した。精製Lvはゲル濾過において300kDa、SDS-PAGEでは105kDaであった。Lvを抗原とした特異抗体は、Western blottingでは雄血清とは反応せず、雌血清とのみ特異的に反応した。雌血清で観察されたバンドは210kDaであり、Vgであると考えられた。精製Lvをスタンダードとしアクリジニウム標識抗体を用いて、simultaneous CLIAによるメバチマグロVg測定系を確立した。測定範囲は0.97－1000 ng／mlであり、卵抽出液と雌血清の希釈系列は精製Lvスタンダードカーブと平行性を示した。アッセイ内およびアッセイ間変動係数は10％未満であった。さらに、本測定系はクロマグロ、キハダマグロおよびブリと免疫交叉性を示した。ハワイ沖で捕獲したメバチマグロ雌魚では7個体中3個体からVgが検出され、雄個体からVgは検出されなかった。
• Quick-Offer of Current Information using T/V ADCP -Program for Quality Contral of ADCP Data-

  Kobayashi Naoto, Isoda Yutaka, Takatsu Tetsuya, Yamaguchi Shuichi, Kimura Osamu  Bulletin of Fisheries Sciences, Hokkaido University  55-  (2)  97  -103  2004  [Not refereed][Not invited]
  
• Wave Fluctuation with the Passage of a Depression

  YONETA Kunisaburo, MEGURO Toshimi, KAJIWARA Yoshiyuki, SAKAOKA Keiiciro  Bulletin of Fisheries Sciences, Hokkaido University  53-  (1)  51  -55  2002  [Not refereed][Not invited]
  
• Wave Fluctuation with the Passage of a Depression

  Bulletin of Fisheries ･ Sciences, Hokkaido University  53-  (1)  51  -55  2002  [Not refereed][Not invited]
  
• Results of the 2001 Salmon Research Cruise of the Hokusei Maru

  NPAFC Doc.  548-  2001  [Not refereed][Not invited]
  
• Results of 2000 Salmon Research Cruise of the Hokusei Maru

  NPAFC Doc.  486-  2000  [Not refereed][Not invited]
  
• Characteristics of standard methods of Norpac net towing in the high latitude sea area II. Overtowing under rough sea conditions and estimation of zooplankton abundance

  ODATE Tsuneo, SAKAOKA Keiitiro, KAJIWARA Yoshiyuki, IMAI Keiri, KOBAYASHI Naoto, MEGURO Toshimi, FUKUTI Mitsuo  Bulletin of the Plankton Society of Japan  46-  (2)  134  -142  1999  [Not refereed][Not invited]
  
• Characteristics of standard methods of Norpac net towing in the high latitude sea area (]G0002[). Over Towing under rough sea conditions and estimation of zooplahton abundance

  The Planhton Society of Japan  46-  (2)  134  -142  1999  [Not refereed][Not invited]
  
• Baroclinic Flow Referred to the 3000 m Reference Level across the 180゜ Transect in the Sabarctic North Pacific

  Ohtani Kiyotaka, Onishi Hiroji, Kobayashi Naoto, Anma Gen  Reprinted from Bulletin of the Faculty of Fishries Hokkaido University  48-  (3)  53  -64  1997  [Not refereed][Not invited]
  

Research Grants & Projects

• Verification of the turbulence and light-intensity hypotheses on larval survival of flathead flounder

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2008 -2011 

  Author : TAKATSU Tetsuya, ISODA Yutaka, KOBAYASHI Naoto

   

  Faster-growing larvae of flathead founder Hippoglossoides dubius in the initial feeding stage showed higher survival rate than slower-growing ones within cohort in Funka Bay, Hokkaido. The larvae of 2007 year-class that experienced warm-water-temperature condition showed the fastest growth in 2007-2011 year-classes. Contrary to expectations, the 2008 year-class that showed slowest-growing in larval stage became a strong year class in mature stage. Growth rate in the initial feeding stage was weakly correlated with wind speed as a turbulence indicator however did not with water temperature, global solar radiation, or density of copepod nauplii as principal prey for flathead founder larvae. Match-mismatch and growth-mortality hypotheses in initial feeding stage have some degree of validity but are insufficient to explain the variability seen in recruitment. The survival in later stage may determine the recruitment success.
• 北海道亀田半島東岸沖で発生した急潮現象

  Date (from‐to) : 2006 

  2006年5月29日から30日にかけて、北海道南西部に位置する亀田半島の鹿部から川汲に至る沿岸海域で、北側から順に漁業施設が破損する被害が発生した。このとき、亀田半島東岸沖では鹿部から恵山方向へ向かう非常に強い南東流であったことが漁業者から報告されている。しかし、このような急潮の発生報告は過去にはほとんどなく、この海域で急潮が発生することは非常に珍しい。この急潮が発生した初夏の平均的な海況は、主に雪解け水による表層付近の塩分躍層の発達が特徴であり、その表層の平均流は弱い南東流(0.2～0.5kt)である(小林ほか、2006)。本研究の目的は、2005年に限って、なぜ急潮が発生したのか、その原因および発生メカニズムを調べることにある。
• 北海道亀田半島沖の恵山潮と鹿部潮

  Date (from‐to) : 2005
• Study on the sampling properties of the plankton nets.

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2000 -2002 

  Author : SAKAOKA Keiichiro, YONETA Kunisaburo, SHIGA Naonobu, MEGURO Toshimi, BOWER John, YAMAMOTO Jun

   

  Plankton nets have been used for as a method for collecting the plankton. Especially, the NORPAC-NET is widely used in order to keep the compatibility of the data and there are many long-term data based on the NORPAC samples. NORPAC-NET sampling is easy to operate, the wire angles often exceed 40 degrees when sea condition is rough. These would suggest that these samples were estimated over or less than the normal condition. Then, this study investigates the collection characteristic of the NORPAC net and the property of the long-term data set. Furthermore, the present study examines other plankton net, MTD-Net, Bongo-Net and the retention on the survey-net mesh.
• 練習船ＡＤＣＰデータの品質管理処理と迅速な海流情報提供システムの開発
• 津軽暖流と親潮の係留観測
• 高緯度海域におけるノルパックネット標準採集の特性-その2 荒天下に起こる過剰曳網とプランクトン現存量評価
• Characteristics of standard methods of Norpac net Towing in the high latuliude sea area II.Overtowing under vough sea condirious and estimation of zooplankton abundance.