研究者詳細 - 小針　統

論文 - 小針　統

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Kobari T., Manako Y., Hara A., Yamanoue K., Azuma T., Fukuda R., Wang Y.C., Kodama M., Kume G. . Community structure of fish larvae associated with advections of the Kuroshio and its neighboring waters . Progress in Oceanography231 103386 - 103386 2025年2月査読

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Progress in Oceanography

The Kuroshio has been long thought to be disadvantageous as nursery grounds for larval fishes due to the low plankton standing stocks under the oligotrophic conditions. Despite of the potential risk for survival and growth, early life stages of various fishes appear abundantly in the Kuroshio and its neighboring waters. Here, we report what kind of taxonomic groups establish community structure of larval fishes in the Continental shelf waters (CW) and the Kuroshio (KW). 16 orders and 78 families were classified in the present study. Mesopelagic fishes more abundantly appeared in the KW than in the CW, while larval fish abundance was not different between the two areas. Multivariate analysis demonstrated the regional difference of the taxonomic compositions, represented by Callionymidae, Bothidae, Labridae and Bregmacerotidae for the CW and Gonostomatidae, Myctophidae and Notosudidae for the KW. Abundance of fish larvae to ambient salinity exhibited significantly positive correlations for Gonostomatidae, Sigmops gracilis and Myctophum orientale predominated in the KW and negative correlations for Labridae appeared abundantly in the CW. These results suggest that mixture of advected specimens from the coastal and Kuroshio waters also contribute to larval fish community with high biodiversity and comparable abundance between the Kuroshio and its neighboring waters.

DOI： 10.1016/j.pocean.2024.103386

Scopus

Kume G., Oba H., Kodama M., Shigemura T., Shiozaki K., Ichinomiya M., Komorita T., Azuma T., Kobari T. . Growth, mortality, and predatory impact on mesozooplankton of chub mackerel Scomber japonicus larvae in an upwelling system, southern Japan . Continental Shelf Research285 105399 - 105399 2025年2月査読

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Continental Shelf Research

In the northern Satsunan area, southern Japan, upwellings generated by the intrusion of the Kuroshio branch current into Kagoshima Bay are observed at the bay's mouth once every two weeks in winter and spring, and the resulting nutrient supply promotes phytoplankton blooms. Currently, this is a key spawning and nursery habitat for chub mackerel Scomber japonicus in Japan. This study examined how water temperature and prey density influenced the growth, mortality, and predatory effects of S. japonicus larvae in the northern Satsunan area. Recent growth (measured as the average width of the last three otolith increments) of S. japonicus larvae was positively correlated with water temperature but not with prey density, indicating that prey abundance was adequate for larvae and that water temperature controlled their growth rate in the study area. The instantaneous daily mortality rate of S. japonicus larvae was 0.322 in 2021 and 0.252 in 2022 (equivalent to 27.5% mortality d−1 in 2021 and 22.3% in 2022). The food requirements of S. japonicus larvae and mesozooplankton production were 0.00427 ± 0.00334 and 6.37 ± 3.04 mg DW m−3 d−1, respectively. S. japonicus larvae had no significant predatory impact on mesozooplankton (0.0869 ± 0.0796%). The present study suggests that none of the plankton feeders have a significant top-down regulating effect on mesozooplankton biomass in the northern Satsunan area, which provides a good food environment for S. japonicus larvae.

DOI： 10.1016/j.csr.2024.105399

Scopus

Kodama M., Yamazaki R., Hayakawa J., Murata G., Tomikawa K., Kawamura T., Kume G., Kobari T. . Feeding ecology of the urchin symbiont Dactylopleustes yoshimurai (Amphipoda) revealed by DNA metabarcoding . Marine Biology171 ( 10 ) 2024年10月

担当区分：最終著者記述言語：日本語出版者・発行元：Marine Biology

The nature of symbiotic relationships between organisms can be difficult to assess and may range from commensalism, to mutualism, and parasitism. Trophic linkage and feeding ecology are essential to disentangle symbiont-host relationships/interactions. Amphipods of the genus Dactylopleustes are known as urchin symbionts. Though their ecology remains largely unknown, Dactylopleustes was recently reported to aggregate on diseased hosts, suggesting that Dactylopleustes feeds on diseased urchins’ tissues and uses urchins as both a habitat and prey. We investigated by DNA metabarcoding analyses, the feeding ecology of Dactylopleustes yoshimurai in relation to growth and disease status of the host (Strongylocentrotus intermedius). Contrary to our hypothesis, sequence reads from the gut contents were dominated by planktonic copepods regardless of body size or host disease status. These results suggest that they mainly feed on copepod fecal pellets deposited on sediments, and do not have a strong trophic linkage with their host. Large individuals on diseased urchins feed more on urchins than those on healthy urchins. However, their main prey still remains copepods, implying that host disease has a limited effect on the feeding behavior. In conclusion, our study indicates that this species is mainly commensal, but also may parasitize its host depending on the situation.

DOI： 10.1007/s00227-024-04507-1

Scopus

Kobari T., Taniguchi A., Hirata M., Kume G., Ichinomiya M., Komorita T., Kodama M., Makino F., Hirai J. . Comparison of the trophic sources and pathways of mesozooplankton and ichthyoplankton in the Kuroshio current and its neighboring waters . Progress in Oceanography229 103356 - 103356 2024年9月査読

担当区分：筆頭著者,　責任著者記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Progress in Oceanography

Commercially important fish spend their vulnerable early life stages in the Kuroshio Current, resulting in high fishery production even in the vicinity of poor prey availability under oligotrophic conditions. Nevertheless, little information is available on how ichthyoplankton are supported by trophodynamics in complicated food webs. Here, we have explored trophic sources and pathways toward ichthyoplankton in the Kuroshio and its neighboring waters based on metabarcoding analysis of gut DNA content for major taxonomic groups of mesozooplankton and ichthyoplankton. Calanoids were found to be the most predominant and frequently appearing prey, whereas non-crustaceans were the secondary prey for most mesozooplankton and ichthyoplankton groups. Trophic networks based on gut DNA content demonstrated that calanoids were the most important sector with multiple linkages among their prey and predators, and gelatinous and non-crustacean mesozooplankton were the secondary sectors. These findings suggest that calanoids are important hubs of trophic pathways toward ichthyoplankton, and that gelatinous and non-crustacean mesozooplankton groups strengthen trophic relationships with multiple components. Contrary to general thought, our metabarcoding analysis has revealed that trophodynamics toward ichthyoplankton are not strongly dependent on the grazing food chain, but are supported by multiple trophic pathways in the Kuroshio and its neighboring waters.

DOI： 10.1016/j.pocean.2024.103356

Scopus

髙﨑蒼, 志水勝好, 小針統, 幅野明正, 中村啓彦, 内海真生, 千村涼 . 高光合成植物ケナフを用いた二酸化炭素深海貯蔵 . 環境科学会誌37 ( 4 ) 131 - 137 2024年7月

記述言語：日本語出版者・発行元：社団法人環境科学会

温室効果ガスであるCO2排出量を減らす取り組みが世界各国で行われている。しかしこれらの取り組みで，CO2排出量は減少するが，これまで大量に空気中へ排出されてきたCO2の絶対量は低下せず，大気中CO2濃度も低下しない。すなわち空気中のCO2を除去しなければ，今後現在以上の地球温暖化の進行を招く。そのためネガティブエミッション技術（大気中のCO2を回収・吸収し，貯留または固定化等を組み合わせることにより，正味としてマイナスのCO2排出量を達成する技術）の利用が必要である。本研究の目的は光合成能力が高くCO2を固定量が多いと考えられるケナフ（Hibiscus cannabinus L.）を栽培し，深海に貯蔵することによりケナフによるネガティブエミッション技術の可能性を明らかにすることである。CO2回収・吸収の評価として2020年および2022年に供試品種にはEverglades 41を用い，2020年は株間が15 cmと30 cm, 2022年は株間10 cm, 20 cmで栽培し，効率的なCO2固定のための栽植密度を明らかにした。CO2貯留・固定化に関する実験として2018年にケナフの主茎を30 cm程度に切断し，それらを5本ずつ網袋に入れ，2019年6月に沖縄県近くの東シナ海（N27°02.634′ E125°56.632′）の水深606 mで貯留した。そして2020年9月に回収した。深海係留前の乾物重と比較して深海貯蔵による影響を調査した。その結果ケナフの茎は深海貯蔵前後で乾物重に差は見られなかった。また走査電子顕微鏡観察で，生物による食害の形跡は観察されなかったことから，生物による食害・分解は行われていないものと考えられた。以上のことから，ケナフによるCO2の深海貯蔵の可能性が明らかとなった。

DOI： 10.11353/sesj.37.131

Liu H., Gilmartin J., Sluis M.Z., Kobari T., Rooker J., Bi H., Quigg A. . Dynamic oceanographic influences on zooplankton communities over the northern Gulf of Mexico continental shelf . Journal of Sea Research199 102501 2024年6月査読国際共著

記述言語：英語出版者・発行元：Journal of Sea Research

Dynamic influences of ocean processes on distribution, abundance, and diversity of zooplankton communities were studied over the continental shelf in the northern Gulf of Mexico (GoM) from 2015 to 2017. Zooplankton sampling was conducted on four summer cruises in the northcentral GoM. Sampling was designed in waters potentially influenced by the Loop Current (LC) and/or Mississippi River discharge to assess the impacts of these two mesoscale features on the abundance and diversity of zooplankton. During the three-year study, the LC displayed distinct spatial-temporal variations in penetration and occurrence in the northern GoM. Environmental conditions (i.e., sea surface temperature, salinity, and dissolved oxygen) varied between months and years sampled, and were significantly different among cruises (ANOVA, p < 0.001). The majority of zooplankton consisted of calanoid copepods (65% ± 7.2%, mean ± SD), while non-copepod taxa were primarily chaetognaths, polychaetes, tunicates, and ostracods (23 ± 9.2%). Species abundance and diversity of zooplankton were significantly correlated with sea surface temperature, salinity, and dissolved oxygen (p < 0.05). Canonical correspondence analysis displayed significant associations between mesoscale features and dominant zooplankton groups among cruises and by taxa (Monte Carlo Permutation Test, p < 0.001). In addition, non-metric multidimensional scaling indicated that zooplankton assemblages were distinct, likely caused by Mississippi River plumes during the study period. As one of the few efforts to examine zooplankton dynamics at a low taxon level over the GoM continental shelf regarding the impact of mesoscale features, this study revealed seasonal (i.e. summer) and spatial patterns in distribution, abundance, and diversity of zooplankton communities subjected to the dynamic physicochemical conditions in the northern GoM, which will continue in a changing climate.

DOI： 10.1016/j.seares.2024.102501

Scopus

Komorita T., Kobari T., Kume G., Kako S., Habano A., Arita Y., Makino F., Ichinomiya M. . Temporal changes in the microplankton community due to Kuroshio branch current inflow . Regional Studies in Marine Science75 103576 - 103576 2024年5月査読

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Regional Studies in Marine Science

Inflow from the Kuroshio Current into coastal areas stimulates biological production. However, to date there are no detailed reports on its temporal changes. In the target area of this study, Kagoshima Bay, Japan, the time of inflow of the Kuroshio branch current can be identified a posteriori based on water temperature data. This study aimed to determine the relationship between the Kuroshio branch current inflow from the surface layer and phytoplankton bloom at the mouth of the bay during the mixing season. Therefore, we compiled data from ship observations in the Kagoshima Bay from 2016 to 2019 to examine changes in water quality (temperature, salinity, and nutrients), microphytoplankton, and microzooplankton versus time since current inflow. In this study, significant relationships were obtained for microplankton in terms of both biomass and cell abundance, and specific growth rates (0.060–0.079 d–1) comparable to that of chlorophyll a. In addition, the current inflow provided nutrients to the surface in the absence of strong wind and waves. Over time, phytoplankton, mostly athecate dinoflagellates, as well as microzooplankton, mainly naked ciliates, proliferated and were quickly preyed upon by mesozooplankton. Over the study period, such events could be observed once every two weeks in most years, suggesting that these frequent phytoplankton blooms support the high biomass of mesozooplankton and larval fish found in this area.

DOI： 10.1016/j.rsma.2024.103576

Scopus

Kobari T., Honma T., Kodama M., Kodama A., Watanabe T., Takikawa T. . Spatial and temporal variations in community structure, standing stock and productivity of mesozooplankton in the southwestern Japan Sea . Plankton and Benthos Research19 ( 1 ) 26 - 36 2024年2月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：日本プランクトン学会、日本ベントス学会

The Tsushima Strait and the neighboring waters has been known as major spawning and nursery grounds for migratory fishes due to the high standing stocks of the plankton community in spring to summer. In the present study, spatial and temporal variations in taxonomic composition, standing stocks and productivity of the mesozooplank-ton community were investigated in the southwestern Japan Sea to explore their variations during the productive sea-sons. Both spatial and temporal fluctuations were significant for mesozooplankton standing stocks while only temporal variability affected their productivity. The mesozooplankton community was split into one coastal group, represented by cladocerans and noctilucids throughout the seasons, and five pelagic groups, predominated by calanoids, cyclopoids and copepod nauplii, with temporal replacement during spring to summer. The coastal community group contained the additional standing stocks of cladocerans and noctilucids along with the predominant copepods from the other groups and thus resulted in the spatial difference in mesozooplankton standing stocks between coastal and pelagic sites. Three pelagic community groups were characterized by the abundant appearance of noctilucids and clustered toward the pelagic stations neighboring the coastal community group. Generalized linear models demonstrated that salinity was a significant explanatory variable for standing stocks of mesozooplankton and coastal taxonomic groups (i.e., cladocerans and noctilucids). These findings suggest that the spatial and temporal variations in mesozooplankton standing stocks are a mixture of the pelagic community groups with the coastal community group advected toward the pelagic sites.

DOI： 10.3800/pbr.19.26

Scopus

CiNii Research

小針統, 中谷颯人, 後藤慎之介, 津田周平, 牧野文洋, 東隆文, 小森田智大, 一宮睦雄, 小玉将史, 久米元 . 薩南海域に来遊するブリ稚魚の餌料源 . 水産海洋研究87 ( 4 ) 209 - 217 2023年11月査読

担当区分：筆頭著者,　責任著者記述言語：日本語出版者・発行元：一般社団法人水産海洋学会

ブリ稚魚は海面養殖の天然種苗として利用されてきたが，初期成長を支える餌料源に関する情報は少ない．本研究では，安定同位体比およびメタバーコーディング解析により，薩南海域に来遊するブリ稚魚の初期成長を支える餌生物および餌料源を明らかにした．ブリ稚魚の筋肉組織の炭素・窒素安定同位体比は，黒潮域の水柱内に分布する動物プランクトンおよびブリ稚魚以外の仔稚魚と近似した．ブリ稚魚の消化管内容物から検出された遺伝子では，カラヌス目カイアシ類が最も優占し頻出する餌生物であった．小型稚魚ではポエキロストム目カイアシ類，大型稚魚では尾虫類・毛顎類がこれに次ぐ餌生物であった．また，消化管内のカラヌス目カイアシ類が増加すると，ブリ稚魚の成長指数も増加する傾向を示した．これらの結果は，流れ藻に随伴して薩南海域に来遊するブリ稚魚が，流れ藻の葉上動物ではなく水柱内の動物プランクトンを餌料源として成長することを示唆する．

DOI： 10.34423/jsfo.87.4_209

CiNii Research

Tomiyasu T., Matsuki H., Oda M., Kodamatani H., Kanzaki R., Kobari T. . Impact of mercury discharged from submarine volcano on inner bay ecosystems . Chemosphere339 139748 - 139748 2023年10月査読国際誌

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Chemosphere

Organic mercury, inorganic mercury and total mercury concentrations in phytoplankton (<0.1 mm) and zooplankton (>0.1 mm) collected in Kagoshima Bay, Japan were measured from 2017 to 2019 to estimate the impact of mercury discharged from submarine volcanoes on ecosystems; submarine volcanic activity continues at a depth of 200 m in the inner part of Kagoshima Bay. The total mercury concentrations in phyto- and zooplankton collected by vertical hauling at 0–200 m at just above the submarine volcano were in the range of 0.11–2.0 mg kg−1 (avg. 0.67 mg kg−1) and 0.090–0.56 mg kg−1 (avg. 0.21 mg kg−1), respectively. These values were one order of magnitude higher than the values in plankton collected in the central part of Kagoshima Bay. Organic mercury concentrations in phyto- and zooplankton were <0.010–0.071 mg kg−1 (avg. 0.028 mg kg−1) and 0.012–0.25 mg kg−1 (avg. 0.10 mg kg−1), respectively, for the inner part, and <0.010–0.040 mg kg−1 (avg. 0.010 mg kg−1) and <0.010–0.025 mg kg−1 (avg. 0.012 mg kg−1), respectively, for the central part. The values obtained in the inner part of the bay increased in summer and decreased in winter, which was consistent with changes in seawater mercury concentrations affected by volcanic activity. The organic mercury concentration in zooplankton collected just above the submarine volcano showed a size dependency, and a higher value was observed in the larger size, which suggested that the discharged mercury from the volcano was absorbed and concentrated through the ecosystem.

DOI： 10.1016/j.chemosphere.2023.139748

Scopus

PubMed

Kume G., Nakaya K., Takeda T., Ichinomiya M., Komorita T., Habano A., Makino F., Kodama M., Kobari T. . Distribution and growth rates of Japanese jack mackerel Trachurus japonicus larvae relative to oceanographic conditions in the northern Satsunan area, southern Japan . Plankton and Benthos Research18 ( 3 ) 148 - 159 2023年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：日本プランクトン学会、日本ベントス学会

The northern Satsunan area, comprising the mouth of Kagoshima Bay and Osumi Strait, is an important spawning and nursery ground for Japanese jack mackerel Trachurus japonicus in Japan. Upwellings frequently occur at the mouth of the bay during winter and spring, and the consequent nutrient supply promotes phytoplankton blooms. This study examined how T. japonicus utilizes upwelling (Kagoshima Bay) and non-upwelling areas (Osumi Strait) as larval nursery grounds. Densities and growth rates (measured as the average width of the last three otolith increments) of T. japonicus larvae in both areas were compared to determine the upwelling influence on nursery ground formation. The mouth of the bay had lower temperature and salinity but higher chlorophyll-a concentrations and prey density than that of the strait. Densities of larvae were consistently higher in the bay than in the strait, indicating that the main nursery of T. japonicus is formed in Kagoshima Bay. No significant differences were observed in the growth rates of larvae among areas, suggesting that lower temperatures and prey availability are growth limiting factors in the mouth of the bay and the strait, respectively, and the Osumi Strait could also provide a favorable nursery area.

DOI： 10.3800/pbr.18.148

Scopus

CiNii Research

Masafumi Kodama, Ryoga Yamazaki, Jun Hayakawa, Gakuto Murata, Ko Tomikawa, Tomohiko Kawamura, Gen Kume, Toru Kobari . Feeding ecology of the obligate urchin symbiont Dactylopleustes yoshimurai (Crustacea: Amphipoda: Pleustidae) revealed by DNA metabarcoding analysis. . 2023年4月査読

担当区分：最終著者出版者・発行元：Research Square Platform LLC

Abstract

Symbiosis includes commensalism, mutualism, and parasitism, however in many symbiotic relationships, it is difficult to determine which type they are in. Since trophic-linkage is a necessary factor to determine this, data on feeding ecology of symbionts is essential to understand symbiont-host relationships. Amphipods of the genus Dactylopleustes are known as obligate urchin symbionts. Though their ecology remains largely unknown, Dactylopleustes was recently reported to aggregate on diseased hosts, suggesting that Dactylopleustes feeds on diseased urchins’ tissues and uses urchins as both a habitat and prey. We investigated by DNA metabarcoding analyses, the feeding ecology of Dactylopleustes yoshimurai in relation to growth and whether host is disease or not. Contrary to our hypothesis, sequence reads from the gut contents were dominated by planktonic copepods regardless of body size or host disease. These results suggest that they mainly feed on copepod fecal pellets deposited on sediments, and do not have a strong trophic-linkage with their host. Large individuals on diseased urchins feed more on urchins than those on healthy urchins. However, their main prey still remains copepods, implying that host disease has a limited effect on the feeding behavior. In conclusion, our study supports this species is not a strong parasite but more of a commensal of urchins.

DOI： 10.21203/rs.3.rs-2655652/v1

その他リンク： https://www.researchsquare.com/article/rs-2655652/v1.html

Chang F.H., Lin Y.C., Chiang K.P., Nien Y.H., Hsieh C.H., Chen W.J., Hung C.C., Kobari T., Saito H., Savidge W. . Editorial: Oceanographic processes linking nearshore, continental shelf, and shelf break . Frontiers in Marine Science10 2023年1月査読

Kobari T., Shinyashiki M., Saito K., Kume G., Ichinomiya M., Komorita T., Miyamoto H., Okazaki Y., Makino F., Fukuda R., Hyodo F., Noguchi-Aita M. . Trophic sources and pathways of mesozooplankton and fish larvae in the Kuroshio and its neighboring waters based on stable isotope ratios of carbon and nitrogen . Progress in Oceanography210 102952 - 102952 2022年12月査読

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Progress in Oceanography

Major forage fishes spend their vulnerable early life stages in the Kuroshio and its neighboring waters where phytoplankton standing stocks are much lower than in coastal areas. Nevertheless, little is known of how mesozooplankton and fish larvae with their high biodiversity are supported in the Kuroshio ecosystem. Here we report stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) for mesozooplankton and fish larvae from coastal to pelagic sites in the East China Sea to evaluate trophic sources and pathways at lower trophic levels in planktonic food webs under different environmental regimes. Although δ13C and δ15N in mesozooplankton and fish larvae varied among taxonomic groups and sites, mesozooplankton δ13C and δ15N tended to be lower for particle-feeders than carnivores and fish larvae and at more pelagic sites than in coastal waters. There were significant linear regressions between δ15N and δ13C of mesozooplankton communities, with the similar slopes among sites and lower intercepts at more pelagic sites. The δ15N and δ13C of small copepods, euphausiids, ostracods, appendicularians and fish larvae were aligned close to the regression line covering all regions, indicating that these were trophic sources and pathways to mesozooplankton and fish larvae. Our results suggest that trophic sources of mesozooplankton and fish larvae are supported through copepods and appendicularian-integrated microbial production and are more dependent on diazotrophic production in more pelagic waters.

DOI： 10.1016/j.pocean.2022.102952

Scopus

数野真, 加古真一郎, 中村啓彦, 山城徹, 仁科文子, 久米元, 小針統 . 高分解能沿岸海洋モデルの粒子追跡による黒潮への黒潮内側域水塊移流の評価 . 水産海洋研究86 ( 4 ) 153 - 165 2022年11月査読

担当区分：責任著者記述言語：日本語出版者・発行元：一般社団法人水産海洋学会

貧栄養である黒潮でも，黒潮内側域の水塊移流がプランクトン現存量や生産力を増大させる可能性が指摘されているが，情報が限られている．そこで本研究では，高分解能沿岸海洋モデルにおける粒子追跡実験により，黒潮へ移流する黒潮内側域の水塊の供給源および移流過程を再現した．黒潮フロントで頻発する蛇行や渦などの擾乱に遭遇することで，黒潮内側域から黒潮域への水塊移流が励起されていた．沿岸水の供給源としては，トカラ海域での定常的な移流が最も大きく，東シナ海での冬期から春期の移流も貢献した．黒潮内側域から黒潮域への動物プランクトン移流量は，黒潮内での動物プランクトン輸送量の2–44%に相当し，九州南方海域から九州東方海域での移流が貢献した．黒潮内側域から移流する動物プランクトンの生物量は，黒潮内の動物プランクトンの成長による増分に匹敵し，黒潮における魚類群集の餌要求を支えている可能性がある．

DOI： 10.34423/jsfo.86.4_153

CiNii Research

Mutsuo Ichinomiya, Takehito Nomiya, Tomohiro Komorita, Toru Kobari, Gen Kume, Akimasa Habano, Yoichi Arita, Fumihiro Makino . Seasonal variation in the environments, biomass and community structure of microplankton in the northern Satsunan area, the west Japan . Journal of Marine Systems234 103767 - 103767 2022年10月査読

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Marine Systems

Seasonal variations in hydrographic conditions, nutrients, and microplankton abundance and biomass were investigated inside and outside Kagoshima Bay in the northern Satsunan area. The area is a nursery ground for the migrating fish. During the mixing season from November to April, highly saline water (>34.5) originating from a branch of the Kuroshio Current, the western boundary current of the North Pacific Subtropical Gyre, intruded from the surface layer into the bay causing extrusion of coastal bottom water. This intrusion generated vertical mixing between surface water and nutrient-rich bottom water. Consequently, chlorophyll a concentrations increased (>1 μg l−1) around the bay mouth. During the stratified season from May to August, the coastal surface water was extruded due to intrusion of saline water from the bottom layer. High chlorophyll a concentrations (>1 μg l−1) were also observed in the surface layer in July during the rainy season. Such differences in hydrographic conditions between mixing and stratified seasons were due to vertical distribution of highly saline water from outside the bay, which seasonally migrated between surface and subsurface layers. Relatively distinct redundancy analysis plots and boxplots generated from a generalized linear model showed that microplankton community structure differed between mixing and stratified seasons. The mixing and stratified seasons were characterized by high diatom abundance and low microplankton abundance, respectively, suggesting that vertical mixing increases nutrient supply and consequently increases diatom abundance. Thus, microzooplankton (mainly naked ciliates and athecate dinoflagellates) abundance was related to the abundance of prey organisms, such as diatoms, thecate dinoflagellates and cryptophyte-like flagellates, rather than hydrographic conditions. Thus, saline water intrusion from a branch of the Kuroshio Current likely governs hydrographic conditions in Kagoshima Bay and consequently affects temporal variations in abundance and taxonomic composition of phytoplankton and microzooplankton communities.

DOI： 10.1016/j.jmarsys.2022.103767

Scopus

眞子裕友, 小針統, 一宮睦雄, 小森田智大, 幅野明正, 東隆文, 久米元 . 黒潮およびその周辺海域における仔稚魚の成長活性 . 日本プランクトン学会報69 ( 2 ) 93 - 101 2022年8月査読

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：日本プランクトン学会

It has been thought that food availability for fish larvae was poor in the Kuroshio because of the low standing stocks of plankton in the oligotrophic conditions under thermal stratification throughout the year. Despite a potential risk or disadvantage for larval survival and growth, Kuroshio and its neighbouring waters are nursery grounds for the early life stages of various fishes. Here, we compared the growth activity of fish larvae among 15 taxonomic groups, including 11 families in the Kuroshio and its neighbouring waters, based on protein synthetase activity and protein contents. Protein-specific (spAARS), individual-based aminoacyl tRNA synthetase activities (iAARS), and protein contents (PRO) of fish larvae ranged from 2 to 232 nmol PPi mg protein−1 h−1, from 1 to 21 μmol PPi ind−1 d−1, and from <1 to 26 mg ind−1, respectively. spAARS, iAARS and PRO were variable among the taxonomic groups and were not classified between mesopelagic groups and the others. Compiling these measurements among all taxonomic groups, a significant negative correlation was found for spAARS to PRO. The correlation showed no significant difference between the Kuroshio and its neighbouring coastal waters, indicating that growth activities to fish larvae body mass were comparable in the Kuroshio and its neighbouring waters. Based on nonmetric multidimensional scaling on spAARS, iAARS and PRO among 15 taxonomic groups, two different groups were classified for fish larvae, represented by the high iAARS under the high PRO but low spAARS (Group 1) and the low iAARS under the low PRO but high spAARS (Group 2), representing the different life strategies for larval growth among the taxonomic groups. The present findings suggest that these biochemical indices are useful for evaluating the growth activity of fish larvae among various taxonomic groups and that food availability is not poor enough to support larval growth in the Kuroshio and its neighbouring waters.

DOI： 10.24763/bpsj.69.2_93

Scopus

CiNii Research

眞子裕友, 小針統, 一宮睦雄, 小森田智大, 幅野明正, 東隆文, 久米元 . 黒潮およびその周辺海域における仔稚魚の成長活性 . 日本プランクトン学会報69 93 - 101 2022年8月査読

Kobari T. . Mesopelagic community supported by epipelagic production in the western North Pacific Ocean based on stable isotope ratios of carbon and nitrogen . Deep-Sea Research Part I: Oceanographic Research Papers182 103722 - 103722 2022年4月査読

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Deep-Sea Research Part I: Oceanographic Research Papers

We compared stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) of epi- and mesopelagic mesozooplankton communities at subarctic (K2) and subtropical (S1) sites in the North Pacific Ocean to evaluate the relationship between mesopelagic communities and epipelagic production. Although δ13C and δ15N varied among the taxonomic groups, ostracods, carnivorous copepods, and chaetognaths tended to exhibit higher δ13C and δ15N than omnivorous copepods within the same layers. Mesozooplankton δ13C and δ15N were higher in the upper (200–500 m) and lower (500–1000 m) mesopelagic layers than in the epipelagic layer (0–150 m). δ13C and δ15N of mesozooplankton were positively correlated at all three depth-ranges at both sites. Although the slopes of linear regressions of δ15N vs. δ13C exhibited no significant differences among layers or between sites, the intercept was lower for mesozooplankton at S1. We attributed the similarity of slopes to common isotopic fractionation during protein synthesis among the different taxonomic groups, and the lower intercept to primary producers supported by recycled nutrients and atmospheric nitrogen fixation under the high thermal regime at S1. Our results further confirm earlier evidence that metabolic requirements of mesopelagic communities are supported by epipelagic production through the biological pump.

DOI： 10.1016/j.dsr.2022.103722

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眞子裕友, 小針統, 久米元, 兵藤不二夫, 野口真希, 一宮睦雄, 小森田智大, 河邊玲, 中村乙水, 米山和良, 土田洋之 . 北部薩南海域に来遊したジンベエザメの餌生物 . 日本プランクトン学会報69 ( 1 ) 18 - 24 2022年2月査読

記述言語：日本語出版者・発行元：日本プランクトン学会

The prey of whale sharks (Rhincodon typus) visiting the northern Satsunan area (western North Pacific Ocean) was investigated using microscopic and metabarcoding analysis of their faecal pellets. The stable isotope ratios of the dorsal fin and faecal pellets from the whale sharks were compared with those of their potential prey (plankton and fish larvae). Microscopic analysis identified protozoans (foraminifera) and metazoans (copepods, ostracods, and amphipods) but unclassified material was predominant in their faecal pellets. Metabarcoding analysis detected metazoans in the faecal pellets, represented by copepods, ostracods, amphipods, hydrozoans, and tunicates. Comparison of stable isotope ratios (δ13C and δ15N) from their dorsal fin and faecal pellets with those of zooplankton in the northern Satsunan area showed different feeding histories for the whale sharks appearing in the northern Satsunan area.

DOI： 10.24763/bpsj.69.1_18

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CiNii Research

数野真, 加古真一郎, 中村啓彦, 山城徹, 仁科文子, 久米元, 小針統 . 高分解能沿岸海洋モデルの粒子追跡による黒潮への黒潮内側域水塊移流の評価 . 水産海洋研究86 135 - 165 2022年査読

Kobari T. . Metabarcoding analysis of trophic sources and linkages in the plankton community of the Kuroshio and neighboring waters . Scientific Reports11 ( 1 ) 23265 - 23265 2021年12月査読国際誌

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Scientific Reports

Trophic sources and pathways supporting early life stages are crucial for survival of forage fishes recruiting around the oligotrophic and unproductive Kuroshio. However, information is limited for the Kuroshio planktonic food web and its trophodynamics because of its high biodiversity. Here, we explore trophic sources and linkages in the Kuroshio plankton community using metabarcoding analysis of gut-content DNA for 22 mesozooplankton groups. The major prey was dinoflagellates and calanoids for omnivorous groups, and calanoids and gelatinous organisms for carnivorous groups. Larvaceans and hydrozoans were the most frequently appeared prey for both omnivores and carnivores, whereas they were minor constituents of the available prey in water samples. Although calanoids overlapped as major prey items for both omnivores and carnivores because they were the most available, contributions from phytoplankton and gelatinous prey differed among taxonomic groups. Further analysis of the metabarcoding data showed that in addition to omnivorous copepods like calanoids, gelatinous groups like larvaceans and hydrozoans were important hubs in the planktonic food web with their multiple trophic linkages to many components. These findings suggest that gelatinous organisms are important as supplementary prey and provide evidence of niche segregation on trophic sources among mesozooplankton groups in the Kuroshio.

DOI： 10.1038/s41598-021-02083-8

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PubMed

Kume G. . Distribution, Feeding Habits, and Growth of Chub Mackerel, Scomber japonicus, Larvae During a High-Stock Period in the Northern Satsunan Area, Southern Japan . Frontiers in Marine Science8 2021年10月査読

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Frontiers in Marine Science

To evaluate the importance of the northern Satsunan area in southern Japan as a spawning and nursery ground for chub mackerel (Scomber japonicus), we investigated the early life history characteristics (e.g., larval distribution, feeding habits, and growth) of S. japonicus over five successive years. This area is considered the main habitat and spawning ground of the congeneric species, S. australasicus. Using polymerase chain reaction-restriction fragment length polymorphism analysis, we first confirmed that S. japonicus larvae were abundant in the northern Satsunan area, potentially representing a major spawning and nursery ground in the Japanese Pacific coastal area. The number of recorded larvae started to increase in 2016, corresponding to the population dynamics of the Pacific stock of the species, which has shown increasing trends in recent years. Morphological and DNA metabarcoding analyses of gut contents and stable isotope analysis showed that, in addition to copepods, the larvae fed substantially on appendicularians. The trophic pathway involving appendicularians might support the feeding habits of S. japonicus, promoting its coexistence with other dominant species. Both the instantaneous growth rate and daily specific growth rate were comparable to those in the southern East China Sea, which is the main spawning and nursery ground of the species. Our data strongly suggest that the northern Satsunan area has favorable conditions for sustaining high larval population densities, even during phases with high population numbers. Our results provide insights for the fisheries management for S. japonicus in the Japanese Pacific coastal area, especially during high-stock periods.

DOI： 10.3389/fmars.2021.725227

Scopus

Komorita T. . Spring phytoplankton blooms in the Northern Satsunan region, Japan, stimulated by the intrusion of Kuroshio Branch water . Estuarine, Coastal and Shelf Science259 107472 - 107472 2021年9月査読

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Estuarine, Coastal and Shelf Science

The Kuroshio current greatly affects biological processes in coastal areas. The Kagoshima Bay has good spawning ground for major migratory fish, serves as an important feeding area for fish larvae, and is affected by the Kuroshio current; however, there is little information concerning the biological response to the Kuroshio intrusion in this location. During the mixing period, the Kuroshio current approaches the Kagoshima Bay and a density flow, consisting of surface inflow and bottom outflow, is generated. We hypothesize that the bottom water in the bay, having a high nutrient concentration, mixes with the surface layer when the water flows out of the bay and that this contributes to the high biological production at the bay mouth. In this study, we conducted a field survey of the water quality in March 2016 and, using a three-end member mixing model, examined whether the bottom water of the bay could be a nutrient source supporting the phytoplankton bloom in the bay mouth. We discuss the fate of the organic matter derived from the primary production promoted by a nutrient supply event. The results indicate that the N-based phytoplankton biomass represented less than 80% of the N uptake by the phytoplankton, as estimated by subtracting the measured nitrate concentration from the supplied nitrate concentration based on the mixing model, indicating that the phytoplankton bloom at the bay mouth was supported by the supply of bottom water from the bay. Based on the C/N molar ratio (6.4) calculated by C/chlorophyll a (Chl-a) and N/Chl-a in this study, the highest value of nitrogen uptake was 12 mg C m−3 d−1 in terms of the carbon assimilation. The feeding rate of the mesozooplankton was estimated to be 13.6 mg C m−3 d−1 using a physiological model. An analysis of the food web structure is required to assess the effects of feeding by mesozooplankton; however, most of the phytoplankton bloom caused by mixing could be efficiently transferred to mesozooplankton in this study area.

DOI： 10.1016/j.ecss.2021.107472

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Daisuke Hasegawa, Takeshi Matsuno, Eisuke Tsutsumi, Tomoharu Senjyu, Takahiro. Endoh, Takahiro Tanaka, Naoki Yoshie, Hirohiko Nakamura, Ayako Nishina, Toru Kobari, Takeyoshi Nagai, Xinｙu Guo . How a small reef in the Kuroshio cultivates the ocean . Geographical Research Letters48 ( 7 ) e2020GL092063 2021年6月査読

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Geophysical Research Letters

Vertical nitrate fluxes associated with turbulent mixing and upwelling around a small reef in the Kuroshio are quantified by continuously deploying a turbulence microstructure profiler with an attached submersible ultraviolet nitrate analyzer while drifting from the upstream to the downstream of the reef. Flow separations and trains of Kelvin-Helmholtz billows (thickness = 60 m) are identified using a shipboard ADCP and an echo-sounder. The turbulence diffusivity associated with the vigorous turbulent mixing reaches up to O(10−1 m2 s−1), resulting in strong nitrate fluxes of O(1–103 mmol m−2 day−1). In addition, large differences between the upstream and downstream density profiles suggest a strong upwelling velocity of O(10−3 m s−1), as well as an upwelling nitrate flux of O(102 mmol m−2 day−1) in the entire subsurface layer.

DOI： 10.1029/2020GL092063

Scopus

Hasegawa Daisuke, Matsuno Takeshi, Tsutsumi Eisuke, Senjyu Tomoharu, Endoh Takahiro, Tanaka Takahiro, Yoshie Naoki, Nakamura Hirohiko, Nishina Ayako, Kobari Toru, Nagai Takeyoshi, Guo Xinyu . How a Small Reef in the Kuroshio Cultivates the Ocean . Geophysical Research Letters48 ( 7 ) e2020GL092063 2021年3月

記述言語：英語

[Abstract] / Vertical nitrate fluxes associated with turbulent mixing and upwelling around a small reef in the Kuroshio are quantified by continuously deploying a turbulence microstructure profiler with an attached submersible ultraviolet nitrate analyzer while drifting from the upstream to the downstream of the reef. Flow separations and trains of Kelvin-Helmholtz billows (thickness = 60 m) are identified using a shipboard ADCP and an echo-sounder. The turbulence diffusivity associated with the vigorous turbulent mixing reaches up to O(10^−1 m^2 s^−1), resulting in strong nitrate fluxes of O(1–10^3 mmol m^−2 day^−1). In addition, large differences between the upstream and downstream density profiles suggest a strong upwelling velocity of O(10^−3 m s^−1), as well as an upwelling nitrate flux of O(10^2 mmol m^−2 day^−1) in the entire subsurface layer. / 　 / [Plain Language Summary] / Vertical nitrate fluxes associated with flow-topography interactions around a small reef in the Kuroshio Current are quantified using state-of-the-art oceanographic instruments. When the flow passes over a shallow sill on the flank of the reef, the velocity differences between layers intensify, resulting in a substantial vertical overturning and mixing of the water column. This turbulent mixing causes the observed nitrate flux from deep water to reach a value among the highest observed worldwide. / 　 / [Key Points] / • Flow separations and trains of Kelvin-Helmholtz billows mix the water column around a small reef in the Kuroshio / • Doming of isopycnals/nitraclines suggests strong upwelling in the lee of the reef / • Turbulent nitrate fluxes reach up to O(10^3 mmol m^−2 day^−1)

CiNii Research

Hideaki Matsui, Taku Sasaki, Toru Kobari, Viliame Waqalevu, Kazuma Kikuchi, Manabu Ishikawa, Tomonari Kotani . DHA Accumulation in the Polar Lipids of the Euryhaline Copepod Pseudodiaptomus inopinus and Its Transfer to Red Sea Bream Pagrus major Larvae . Frontiers in Marine Science8 632876 2021年2月査読

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Frontiers in Marine Science

The euryhaline copepod Pseudodiaptomus inopinus play important roles in coastal waters as vectors of docosahexanoic (DHA) and eicosapentaenoic (EPA) acids for larval fish. While DHA and EPA in polar lipids (PLs) are more effective for fish larval development than non-polar lipid forms (NLs), there is little knowledge how much these lipids are accumulated in copepods from microalgae and are effective for early development of fish larvae. We report PLs fatty acid profiles of P. inopinus fed DHA-poor microalgae and evaluate its significance as a food source for larvae development of Pagrus major, compared with DHA-enriched rotifers. Copepods and rotifers were fed a mixed diet of three algal species (Phaeodactylum tricornutum, Tisochrysis lutea, and Pavlova lutheri), in addition of DHA-supplemented Super Fresh Chlorella (SFC) for rotifers. Compared with SFC, the algal mixture had higher EPA but lower DHA. Copepods had higher DHA and EPA in total lipids than rotifers fed each diet. Copepod PLs were specifically enriched with DHA and their contents were higher than both rotifers. On the other hand, PLs EPA contents were comparable between preys, indicating that copepods selectively fortified the PLs. Fish culture experiment showed that larvae fed copepods had higher growth than those fed SFC-enriched rotifers. Principal component analysis for each organism fatty acid composition emphasized trophic modification of DHA by copepods toward larval fish. This study highlighted that P. inopinus contribute to enhanced growth of coastal larval fish by efficiently transferring DHA via copepod fatty acid metabolism.

DOI： 10.3389/fmars.2021.632876

Scopus

Akimasa Habano, Toru Kobari, Wataru Ohbayashi, Gen Kume . Feeding habits of the skinnycheek lanternfish Benthosema pterotum (Alcock, 1890) in Kagoshima Bay, southern Japan . Ichtyological Research68 164 - 170 2021年1月査読

en Kume, Toru Kobari, Junya Hirai, Hiroumi Kuroda, Tsutomu Takeda, Mutsuo Ichinomiya, Tomohiro Komorita, Maki Aita-Noguchi, Fujio Hyodo . Diet niche segregation of co-occurring larval stages of mesopelagic and commercially important fishes in the Osumi Strait assessed through morphological, DNA metabarcoding, and stable isotope analyses . Marine Biology168 ( 1 ) 2021年1月査読

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Marine Biology

The Osumi Strait and its neighboring waters are major spawning grounds for commercially important small pelagic and coastal fish in the Pacific coastal area of Japan. Mesopelagic fish larvae are also abundant here, co-occurring with the larvae of commercial species. However, it is unknown whether these fish groups compete for prey. We examined the diet of four commercial fish groups (Engraulis japonicus, Trachurus japonicus, Triglidae spp., and Sebastiscus spp.) and two mesopelagic species (Sigmops gracilis, Myctophum asperum) during their larval stages to determine whether they had the same prey source. Morphological analysis and DNA metabarcoding of gut contents showed that the main prey species of all six fish groups were calanoid copepods. However, results from metabarcoding differed greatly from morphological analysis, showing that appendicularians were abundant in the guts of S. gracilis, M. asperum, and Sebastiscus spp. This may be because the methods differ in how they determine prey composition, with morphological analysis relying on counts of identifiable prey parts and metabarcoding being only a semi-quantitative method. In addition, appendicularians might be underestimated by metabarcoding analysis due to variation in genome size, copy number of target genes, and primer mismatches. Stable isotope analysis supported the importance of appendicularians as prey for S. gracilis, M. asperum, and Sebastiscus spp. Our results indicate that the two mesopelagic species and Sebastiscus spp. may compete for prey, but E. japonicus, T. japonicus, and Triglidae spp. occupy niches different from those of the two mesopelagic species. Our results imply that the trophic pathway via appendicularians may support the feeding of dominant mesopelagic species and enable coexistence with commercial species in the study area.

DOI： 10.1007/s00227-020-03810-x

Scopus

その他リンク： http://link.springer.com/article/10.1007/s00227-020-03810-x/fulltext.html

Yoshinaga S., Kobari T., Tanonaka N., Yamanoue K., Kume G. . Feeding habits of the mesopelagic fish Sigmops gracilis larvae in the Kuroshio and its adjacent water, southern Japan . Ichthyological Research68 ( 1 ) 171 - 176 2021年1月招待査読

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Ichthyological Research

We examined the feeding habits of the dominant mesopelagic fish Sigmops gracilis larvae across the Kuroshio Current, southern Japan. The feeding incidence tended to decrease toward the offshore area. Copepods, amphipods, ostracods, and appendicularians were microscopically observed in the guts. Larvae fed substantially on copepods such as calanoids and appendicularians. Appendicularians were more frequently ingested toward the offshore area and were the most preferential prey item in all areas. The microbial production integrated by appendicularians would support mesopelagic fish larvae in addition to the ordinary trophic pathway through copepods.

DOI： 10.1007/s10228-020-00760-8

Scopus

Habano A., Kobari T., Ohbayashi W., Kume G. . Feeding habits of the skinnycheek lanternfish [Benthosema pterotum (Alcock, 1890)] in Kagoshima Bay, southern Japan . Ichthyological Research68 ( 1 ) 164 - 170 2021年1月

記述言語：日本語出版者・発行元：Ichthyological Research

We examined the feeding habits of Benthosema pterotum in Kagoshima Bay. Benthosema pterotum undertook diel vertical migration and preyed in shallow waters at night. The most frequently consumed prey were copepods, and B. pterotum selectively foraged on poecilostomatoids. Poecilostomatoids were more predominant in the Kagoshima Bay zooplankton community than in neighboring sites, which suggested that the B. pterotum preference for poecilostomatoids may be an adaptation by the local population to prey availability. Benthosema pterotum probably plays an important role as a biological pump contributor and as a mediator that links secondary production and higher trophic levels.

DOI： 10.1007/s10228-020-00758-2

Scopus

Takeru Kanayama, Toru Kobari, Koji Suzuki, Naoki Yoshie, Taiga Honma, Fukutaro Karu, Gen Kume . Impact of microzooplankton grazing on the phytoplankton community in the Kuroshio of the East China Sea: a major trophic pathway of the Kuroshio ecosystem . Deep-Sea Research I163 2021年査読

小針統, 久米元, 一宮睦雄, 小森田智大 . 北部薩南海域におけるジンベエザメの餌料源 . 日本プランクトン学会報－ 2021年査読

Fukutaro Karu, Toru Kobari, Taiga Honma, Takeru Kanayama, Koji Suzuki, Naoki Yoshie and Gen Kume . Trophic sources and linkages to support mesozooplankton community in the Kuroshio of the East China Sea . Fisheries Oceanography29 ( 5 ) 442 - 456 2020年9月査読

Shohei Yoshinaga, Toru Kobari, Norika Tanonaka, Kaori Yamanoue, Gen Kume . Feeding habits of the mesopelagic fish Sigmops gracilis larvae in the Kuroshio and its adjacent water, southern Japan . Ichtyological Research68 171 - 176 2020年6月査読

Toru Kobari, Taiga Honma, Daisuke Hasegawa, Naoki Yoshie, Eisuke Tsutsumi, Takeshi Matsuno, Takeyoshi Nagai, Takeru Kanayama, Fukutaro Karu, Koji Suzuki, Takahiro Tanaka, Xinyu Guo, Gen Kume, Ayako Nishina, Hirohiko Nakamura . Phytoplankton growth and consumption by microzooplankton stimulated by turbulent nitrate flux suggest rapid trophic transfer in the oligotrophic Kuroshio . Biogeosciences17 2441 - 2452 2020年5月査読

中野寛, 小針統, 山口敦子, 久米元 . 奄美大島におけるリュウキュウアユの食性 . 魚類学雑誌67 ( 2 ) 287 - 292 2020年査読

記述言語：日本語出版者・発行元：一般社団法人日本魚類学会

The diet of the critically endangered Ryukyu-ayu Plecoglossus altivelis ryukyuensis in the middle reaches of the Kawauchi, Sumiyo, and Yakugachi Rivers, Amami-oshima Island, southern Japan was examined by gut content analysis and inferred from stable isotope signatures. No clear differences in diet composition were apparent among the rivers. Microalgae, such as diatoms and cyanobacteria, generally considered as important food, were only rarely observed in gut contents, whereas detritus was almost exclusively found. However, stable isotope signatures indicated that detritus was not directly utilized as a nutritional source, indicating that food availability was an issue for P. a.ryukyuensis.

DOI： 10.11369/jji.20-030

CiNii Research

小針統, 山崎朱音, 遠藤有紀, 久米元, 小森田智大, 一宮睦雄, 幅野明正, 有田洋一, 牧野文洋 . 北部薩南海域におけるメソ動物プランクトン群集の時空間変動 . 海の研究29 ( 6 ) 217 - 232 2020年査読

担当区分：筆頭著者,　責任著者記述言語：日本語出版者・発行元：日本海洋学会

北部薩南海域におけるメソ動物プランクトン群集組成，現存量（個体数密度および生物量），タンパク質合成酵素活性の時空間変動を明らかにした。メソ動物プランクトン現存量では時間および空間変動の両方が，タンパク質合成酵素活性では時間変動が卓越した。メソ動物プランクトン群集中ではカラヌス目およびポエキロストム目カイアシ類が優占し，多変量解析では鹿児島湾口部で季節的に遷移する6系群，湾外の季節性に乏しい2系群に識別された。メソ動物プランクトン現存量は鹿児島湾外よりも湾口部で高かったが，タンパク質合成酵素活性は両海域で同等であった。タンパク質合成酵素活性は水柱平均クロロフィル a 濃度と明瞭な傾向を示さなかったが，個体あたりの体重が小さいほど高くなった。また，水柱平均塩分が低いほど個体あたりの体重が小さく，メソ動物プランクトン個体数密度は増加する傾向を示した。これらの結果から，北部薩南海域におけるメソ動物プランクトン現存量やタンパク質合成酵素活性の時空間変動は，低塩分水の移流もしくは伸展に伴う小型のカラヌス目およびポエキロストム目カイアシ類の流入の影響を受けていることが示唆された。

DOI： 10.5928/kaiyou.29.6_217

CiNii Research

Kanayama T. . Impact of microzooplankton grazing on the phytoplankton community in the Kuroshio of the East China sea: A major trophic pathway of the Kuroshio ecosystem . Deep-Sea Research Part I: Oceanographic Research Papers163 2020年査読

阿部美穂子, 小針統, 本間大賀, 金山健, 加留福太郎, 吉江直樹, 長谷川大介, 仁科文子, 内山正樹, 東隆文, 中村啓彦 . トカラ海峡上流域から下流域におけるプランクトン群集組成，現存量および生産力の変化 . 沿岸海洋研究57 65 - 72 2019年8月招待査読

長谷川大介, 田中雄大, 松野健, 千手智晴, 堤英輔, 中村啓彦, 仁科文子, 小針統, 吉江直樹, 郭新宇, 長井健容, 奥西武, 安田一郎 . センサーによる硝酸塩鉛直乱流拡散フラックスの計測 . 沿岸海洋研究57 59 - 64 2019年8月招待査読

Takeyoshi Nagai, Gloria Silvana Duráｎ, Diego André Otero, Yasutaka Mori, Naoki Yoshie, Kazuki Ohgi, Daisuke Hasegawa, Ayako Nishina, Toru Kobari . How the Kuroshio Current delivers nutrients to sunlit layers on the continental shelves with aid of near-internal waves and turbulence . Geophysical Research Letters46 6726 - 6735 2019年5月査読国際共著

Toru Kobari, Yurie Kobari, Hiroomi Miyamoto, Yuji Okazaki, Gen Kume, Reo Kondo, Akimasa Habano . Variability in taxonomic composition, standing stock and productivity of the plankton community in the Kuroshio and its neighboring waters . Geophysical Monograph243 223 - 350 2019年4月査読

Toru Kobari, Akash R, Sastri, Lidia Yebra, Hui Liu, Russell R. Hopcroft . Evaluation of trade-offs in traditional methodologies for measuring metazooplankton growth rates: Assumptions, advantages and disadvantages for field applications . Progress in Oceanography178 2019年査読国際共著

阿部美穂子, 小針統, 本間大賀, 金山健, 加留福太郎, 吉江直樹, 長谷川大介, 仁科文子, 内山正樹, 東隆文, 中村啓彦 . トカラ海峡上流域から下流域におけるプランクトン群集組成，現存量および生産力の変化 . 沿岸海洋研究57 ( 1 ) 65 - 72 2019年査読

記述言語：日本語出版者・発行元：日本海洋学会　沿岸海洋研究会

黒潮に沿ったラグランジュ的な海洋観測と標本採取を行い，トカラ海峡を通過する黒潮の上流域と下流域のプランクト
ン群集組成，現存量，生産力を比較した．トカラ海峡より黒潮下流域では表層の水温や塩分が低くなり，亜表層の栄養塩
濃度やクロロフィルa 濃度が増加した．動物プランクトン分類群組成には地点間差が見られず，いずれの地点でも微小
動物プランクトンでは無殻繊毛虫，ネット動物プランクトンではカイアシ類が優占した．ネット動物プランクトン群集の
タンパク質合成酵素活性はいずれの地点でも高く，中型～大型画分によってネット動物プランクトン生物量および生産速
度がトカラ海峡より黒潮下流域で高くなる傾向が見られた．これらの結果は，トカラ海域下流域では亜表層の栄養塩供給
や植物プランクトン増加だけでなく，ネット動物プランクトン生物量や生産速度の増加も起こることを示唆している．

DOI： 10.32142/engankaiyo.2019.8.009

CiNii Research

江幡恵吾, 佐藤鴻成, 小針統, 本間公也, 前田一巳, 税所誠一, 宮本秀樹, 神渡巧 . 海中に浸漬した焼酎粕混和マグネシア系モルタルの初期段階における微細藻類の付着特性 . 土木学会論文集B3（海洋開発）75 ( 2 ) I_522 - I_527 2019年査読

記述言語：日本語出版者・発行元：公益社団法人土木学会

海中に浸漬した焼酎粕混和マグネシア系モルタルの微細藻類付着特性を明らかにすることを目的とした．セメントモルタルCMとマグネシア系モルタルMM，それぞれに乳酸発酵させた甘藷焼酎粕を混和したCS，MSの4種類の供試体（円柱形：直径11mm，高さ20mm）を用いて夏季と冬季に実験を行った．浸漬期間と微細藻類付着密度の関係を求めるために，海中に設置した供試体を回収し，N, N-ジメチルホルムアミド溶液に浸漬して蛍光光度計を用いてクロロフィルa濃度を測定した．MSのクロロフィルa付着密度はCM，CS，MMよりも高い傾向にあり，夏季実験では3週間後に最大になり，1，3，6週間後でCMよりも有意に高く，冬季実験では1，2週間後にCMよりも有意に高かった．海中構造物に焼酎粕を利用する上でマグネシア系モルタルと混合することで微細藻類付着量が多くなると考えられた．

DOI： 10.2208/jscejoe.75.i_522

CiNii Research

Toru Kobari, Wataru Makihara, Takahiro Kawafuchi, Kie Sato, G. Kume . Geographic variability in taxonomic composition, standing stock, and productivity of the mesozooplankton community around the Kuroshio Current in the East China Sea . Fisheries Oceanography27 336 - 350 2018年7月査読

Makio C. Honda, Kazuhiko Matsumoto, Tethuichi Fujiki, E. Siswanto, K. Sasaoka, H. Kawakami, M. Wakita, Y. Mino, C. Sukigara, M. Kitamura, Y. Sasai, S. L. Smith, T. Hashioka, C. Yoshikawa, K. Kimoto, S. Watanabe, T. Kobari, T. Nagata, K. Hamasaki, R. Kaneko, M. Uchimiya, H. Fukuda, O. Abe, Toshiro Saino . Comparison of carbon cycle between the western Pacific subarctic and subtropical time-series stations: highlights of the K2S1 project . Journal of Oceanography73 647 - 667 2017年10月査読

梅澤有, 福田秀樹, 小針統 . 水産・海洋系学部・大学院の学生動向，教育の現状と連携の必要性 . 沿岸海洋研究55 3 - 10 2017年8月査読

Toru Kobari, Sachi Miyake, William T. Peterson, Jay Peterson and Tracy Shaw . Nucleic acid ratio as a proxy for starvation of coastal and pelagic copepods in the North Paciﬁc Ocean . Plankton and Benthos Research12 25 - 33 2017年2月査読国際共著

Lidia Yebra, Toru Kobari, Akash R. Sastri, Felipe Gusmão, Santiago Hernández-León . Advances in Biochemical Indices of Zooplankton Production . Advances in Marine Biology76 157 - 240 2017年1月査読国際共著

Masahide Wakita, Makio C. Honda, Kazuhiko Matsumoto, Tetsuichi Fujiki, Hajime Kawakami, Sayaka Yasunaka, Yoshikazu Sasai, Chiho Sukigara, Mario Uchimiya, Minoru Kitamura, Toru Kobari, Yoshihisa Mino, Akira Nagano, Shuichi Watanabe, Toshiro Saino . Biological organic carbon export estimated from the annual carbon budget observed in the surface waters of the western subarctic and subtropical North Pacific Ocean from 2004 to 2013 . Journal of Oceanography72 665 - 685 2016年10月査読

Makio C. Honda, Hajime Kawakami, Kazuhiko Matsumoto, Masahide Wakita, Tetsuichi Fujiki, Yoshihisa Mino, Chiho Sukigara, Toru Kobari, Mario Uchimiya, Ryo Kaneko, Toshiro Saino . Comparison of sinking particles in the upper 200 m between subarctic station K2 and subtropical station S1 based on drifting sediment trap experiments . Journal of Oceanography72 373 - 386 2016年6月査読

Minoru Kitamura, Toru Kobari, Makio C. Honda, Kazuhiko Matsumoto, Kosei Sasaoka, Rie Nakamura, Kazuyuki Tanabe . Seasonal changes in the mesozooplankton biomass and community structure in subarctic and subtropical time‑series stations in the western North Pacific . Journal of Oceanography72 387 - 402 2016年6月査読

Toru Kobari, Rie Nakamura, Keisuke Unno, Minoru Kitamura, Kazuyuki Tanabe, Haruka Nagafuku, Akiko Niibo, Hajime Kawakami, Kazuhiko Matsumoto and Makio C. Honda . Seasonal variability of carbon demands and flux by mesozooplankton community at subarctic and subtropical sites in the western North Pacific Ocean . Journal of Oceanography72 403 - 418 2016年6月査読

Toru Kobari, Shigeki Kori and Haruko Mori . Ontogenetic variations in dry mass and nucleic acids contents of Artemia salina . Plankton and Benthos Research1 1 - 8 2016年2月査読

Toru Kobari, Sota Hosouchi, Haruko Mori, Hidehisa Ota, Ryuji Fukuda and Masaki Uchiyama . Seasonal variations in the population structure and depth distribution of Calanus sinicus in northern Kagoshima Bay . La mer53 61 - 71 2015年12月査読

Kon-Kee Liu, Chang-Keun Kang, Toru Kobari, Hongbin Liu, Christophe Rabouille and Katja Fennel . Biogeochemistry and ecosystems of continental margins in the western North Pacific Ocean and their interactions and responses to external forcing - an overview and synthesis . Biogeoscience11 11293 - 11330 2014年12月査読国際共著

Jokim Kitolelei, Satoru Nishimura, Takashi Torii, Kei Kawai and Toru Kobari . Multilayer rules and governance in Fiji coastal communities: a case study of Veivatuloa village . Evolutionary and Institutional Economics Review11 53 - 66 2014年11月査読国際共著

Toru Kobari, Minoru Kitamura, Masato Minowa, Hiroshi Isami, Hiroyasu Akamatsu, Hajime Kawakami, Kazuhiko Matsumoto, Masahide Wakita and Makio C. Honda . Impacts of the wintertime mesozooplankton community to downward carbon flux in the subarctic and subtropical Pacific Oceans . Deep-Sea Research I81 78 - 88 2013年11月査読

Yousef A. E. S. M. Buhadi, Toru Kobari*, Kei Kawai, Tomoko Yamamoto, Hiroshi Suzuki, Satoru Nishimura, Takashi Torii and Joeli Vitayaki . Food availability for particle-feeding bivalves, Anadara spp., in Fiji . Pacific Science67 539 - 551 2013年10月査読

Toru Kobari, Haruko Mori and Hitomi Tokushige . Nucleic acids and protein content in ontogenetically migrating copepods in the Oyashio region as influenced by development stage and depth distribution. . Journal of Plankton Research35 105 - 120 2013年1月査読

Sanae Chiba, Hiroya Sugisaki, Akira Kuwata, Kazuaki Tadokoro, Toru Kobari, Atsushi Yamaguchi and David L. Mackas . Pan-North Pacific comparison of long-term variation in Neocalanus copepods based on stable isotope analysis . Progress in Oceanography97-100 63 - 75 2012年5月査読国際共著

蓑輪政人・小針統・赤松弘康・市川敏弘・福田隆二・東政能 . 鹿児島湾におけるメソ動物プランクトン群集の豊度、バイオマス、鉛直分布の季節変化 . 水産海洋研究75 ( 2 ) 71 - 81 2011年5月査読

Toru Kobari, Kayo Hijiya, Masato Minowa and Minoru Kitamura . Depth distribution, biomass and taxonomic composition of subtropical microbial community in southwestern Japan. . South Pacific Study32 31 - 43 2011年5月査読

小針統・杉本智・四宮明彦・河合渓・西村知 . 奄美大島役勝川におけるリュウキュウアユ仔魚の餌環境 . 水産増殖60 53 - 58 2011年査読

Toru Kobari, Tomo Fujii, Yurie Kobari and Akimasa Habano . Seasonal variations in abundance, growth and mortality of heterotrophic bacteria in Kagoshima Bay . Journal of Oceanography66 845 - 853 2010年12月査読

小針統 . 浮遊性カイアシ類の成長速度測定法 . 海の研究19 213 - 232 2010年12月査読

Anila Naz Soomro, Hiroshi Suzuki, Megumi Kitazaki and Tohru Kobari . Species composition of freshwater shrimp in Kikai-jima island . Journal of Crustacean Biology30 721 - 726 2010年11月査読

Yuichiro Nishibe, Toru Kobari and Takashi Ota . Feeding by the cyclopoid copepod Oithona similis on the microplankton assemblage in the Oyashio region during spring . Plankton and Benthos Research5 ( 2 ) 74 - 78 2010年10月査読

Toru Kobari, Hiroyasu Akamatsu, Masato Minowa, Toshihiro Ichikawa, Kazuo Iseki, Ryuji Fukuda and Masataka Higashi . Effects of the copepod community structure to fecal pellet flux in Kagoshima Bay, a deep, semi-enclosed embayment . Journal of Oceanography66 673 - 684 2010年10月査読

Mutsuo Ichinomiya, Yasushi Gomi, Miwa Nakamachi, Takashi Ota and Toru Kobari . Temporal patterns in silica deposition among siliceous plankton during the spring bloom in the Oyashio region . Deep-Sea Research II57 1665 - 1671 2010年9月査読

Toru Kobari, Ai Ueda and Yuichiro Nishibe (September 2010) . Development and growth of ontogenetically migrating copepods during the spring phytoplankton bloom in the Oyashio region . Deep-Sea Research II57 1715 - 1726 2010年9月査読

Toru Kobari, Yumi Inoue, Yosuke Nakamura, Hidemi Okamura, Takashi Ota, Yuichiro Nishibe and Mutsuo Ichinomiya . Feeding impacts of ontogenetically migrating copepods on the spring phytoplankton bloom in the Oyashio region . Deep-Sea Research II57 1703 - 1714 2010年9月査読

Toru Kobari, Kazuma Mitsui, Takshi Ota, Mutsuo Ichinomiya and Yashushi Gomi . Response of heterotrophic bacteria to the spring phytoplankton bloom in the Oyashio region . Deep-Sea Research II57 1671 - 1678 2010年9月査読

Hideyuki Doi, Toru Kobari, Kayoko Fukumori, Yuichiro Nishibe and Shin-ichi Nakano . Trophic niche breadth variability differs among three Neocalanus species in the subarctic Pacific Ocean . Journal of Plankton Research32 1733 - 1737 2010年7月査読

Takahiro Adachi, Naoko Kohashi and Toru Kobari . Water quality and plankton composition during blooming of harmful algae in Kagoshima Bay . Suikougaku Ronbunshu53 1507 - 1512 2009年2月査読

上田愛, 小針統, Deborah K. Steinberg . 北太平洋西部亜寒帯循環域における鉛直移動性カイアシ類の体長, 体重および化学組成 . Bulletin of Plankton Society of Japan55 ( 2 ) 107 - 114 2008年8月査読国際共著

Deborah K. Steinberg, Joseph S. Cope, Stephanie E. Wilson, and Toru Kobari . A comparison of mesopelagic mesozooplankton community structure in the subtropical and subarctic North Pacific Ocean . Deep-Sea Resarch II55 1615 - 1635 2008年7月査読国際共著

Toru Kobari, Deborah K. Steinberg, Ai Ueda, Atsushi Tsuda, Mary W. Silver and Minoru Kitamura . Impacts of ontogenetically migrating copepods on downward carbon flux in the western subarctic Pacific Ocean. . Deep-Sea Resarch II55 1648 - 1660 2008年7月査読国際共著

Toru Kobari, Masatoshi Moku, Kazutaka Takahashi . Seasonal appearance of expatriated boreal copepods in the Oyashio-Kuroshio mixed region. . ICES Journal of Marine Science65 469 - 476 2008年4月査読

河合渓, 小針統, 真鍋尚也, Leon Zann . マングローブ林とサンゴ礁が併存する島嶼沿岸域の漁業と海洋環境 - フィジー諸島共和国ビチレブ島の漁村を例に . 島嶼研究7 1 - 16 2008年3月査読国際共著

真鍋尚也, 小針統, 河合渓, Leon Zann . マングローブ林とサンゴ礁が併存するフィジー諸島共和国沿岸域の魚類相 . 島嶼研究7 17 - 26 2008年3月査読国際共著

Steinberg, Deborah K., Benjamin A. S. Van Mooy, Ken O. Buesseler, Philip W. Boyd, Toru Kobari, and David M. Karl. . Bacterial vs. zooplankton control of sinking particle flux in the ocean’s twilight zone. Limnology and Oceanography. . Limnolory and Oceanography53 1327 - 1338 2008年査読国際共著

Toru Kobari, Kazuaki Tadokoro, Hiroya Sugisaki and Hiroshi Ito . Response of Eucalanus bungii to oceanographic conditions in the western subarctic Pacific Ocean: Retrospective analysis of the Odate Collections. . Deep-Sea Resarch II54 2748 - 2759 2007年11月査読

Toru Kobari, Yurie Kobari and Shuichi Koga . Possible underestimation of chlorophyll a measurements for subtropical phytoplankton community by the pigment extraction and the fluorometric determination. . South Pacific Study28 1 - 8 2007年10月

Toru Kobari, Keiko Shimizu, Seiko Nishikawa, Akimasa Habano . Seasonal variation in abundance of Oithonidae copepods in the Kagoshima Bay . Memoirs of the Faculty of Fisheries, Kagoshima University55 61 - 68 2006年12月

T. Kobari, T. Nagaki, K. Takahashi . Seasonal changes in abundance and development of Calanus pacificus (Crustacea: Copepoda) in the Oyashio-Kuroshio Mixed Region. . Marine Biology144 ( 4 ) 713 - 721 2004年4月査読

Toru Kobari, Atushi Tsuda, Akiyoshi Shinada . Functional roles of interzonal migrating mesozooplankton in the western subarctic Pacific . Progress in Oceanography57 ( 42067 ) 279 - 298 2003年6月査読

Toru Kobari, Tsutomu Ikeda, Yasuji Kanno, Naonobu Shiga, Shogo Takagi, Tomonori Azumaya . Interannual variations in abundance and body size in Neocalanus copepods in the central North Pacific . Journal of Plankton Research25 ( 5 ) 483 - 494 2003年5月査読

Toru Kobari, Kazuaki Tadokoro, Akihiro Shiomoto, Shinji Hashimoto . Geographical variations in prosome length and body weight of Neocalanus copepods in the North Pacific . Journal of Oceanography59 3 - 10 2003年2月査読

小針統 . これからのプランクトン研究をどうするか - 動物プランクトン研究の変遷と今後の展開視点 . Bulletin of Plankton Society of Japan50 ( 1 ) 25 - 29 2003年2月査読

Toru Kobari, Tsutomu Ikeda . Ontogenetic vertical migration and life cycle of Neocalanus plumchrus (Crustacea: Copepoda) in the Oyashio region, with notes on regional variations in body size . Journal of Plankton Research23 ( 3 ) 287 - 302 2001年3月査読

Toru Kobari, Tsutomu Ikeda . Life cycle of Neocalanus flemingeri (Crustacea: Copepoda) in the Oyashio region, western subarctic Pacific, with notes on its regional variations. . Marine Ecology Progress Series209 243 - 255 2001年1月査読

小針統, 池田勉 . 親潮域におけるNeocalanus属カイアシ類の生活史 . 日本プランクトン学会報47 ( 2 ) 129 - 135 2000年8月査読

Toru Kobari, Tsutomu Ikeda . Vertical distribution, population structure and life cycle of Neocalanus cristatus (Crustacea: Copepoda) in the Oyashio region, with notes on its regional variations . Marine Biology134 683 - 696 1999年9月査読

Toru Kobari, Syuhei Ban . Life cycles of two limnetic cyclopoid copepods, Cyclops vicinus and Thermocyclops crassus, in two different habitats . Journal of Plankton Research20 1073 - 1086 1998年6月査読

伊藤穂香, 数野真, 吉江直樹, 久米元, 長井健容, 畑辺佳奈子, 小針統 . 黒潮域およびその近隣水域における動物プランクトン現存量，生産力および分類群組成の地理変化 . 日本プランクトン学会報73 ( 1 ) 1 - 13 2026年2月

記述言語：日本語出版者・発行元：日本プランクトン学会

Growing evidence highlights the diverse biogeochemical processes that stimulate biological productivity in the oligotrophic Kuroshio. Although biological productivity stimulated by upwelling nutrients has been proposed by experimental approaches and intensive oceanographic observations, subsequent increases in zooplankton standing stocks and productivity have not been observed in the downstream Kuroshio. Here, we report geographical variations in standing stocks, productivity, and taxonomic composition of zooplankton communities in the Kuroshio based on oceanographic observations. Less saline water in the surface layers extended toward the Kuroshio Current, corresponding to high nutrient and chlorophyll a concentrations. Zooplankton standing stocks and taxonomic compositions exhibited significant differences between the coastal and Kuroshio waters, but no clear pattern was observed from the upstream to the downstream Kuroshio. Based on multivariate analysis, copepod species compositions were segregated between the coastal and Kuroshio waters, but some coastal species appeared abundantly in the Kuroshio waters. Significant positive correlations were found between nutrients, chlorophyll a concentrations, and zooplankton standing stocks, and the mixed ratio of less saline waters. We suggest that the geographical distribution patterns of zooplankton standing stocks and community structure along the Kuroshio current are affected by the advection of coastal communities in less saline waters than by locally stimulated biological productivity.

DOI： 10.24763/bpsj.73.1_1

Scopus

CiNii Research

Tomiyasu T., Uwashitomi H., Wakimaru T., Kodamatani H., Kanzaki R., Kobari T. . Seasonal variations in mercury species and selenium in plankton from Kagoshima Bay, southern Kyushu, Japan: Impact of active submarine volcanoes on ecosystems . Marine Chemistry275 104610 - 104610 2026年1月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Marine Chemistry

Seawater and plankton sampling were conducted every two months from 2019 to 2022 in the inner and central parts of Kagoshima Bay, where submarine volcanic activity continues at a bottom of 200 m depth in the inner part. Plankton samples were collected using a plankton net, with vertical hauls at depths of 0–140 m and 140–200 m just above the submarine volcano, and at 0–200 m in the central part of the bay. The collected samples were separated into phytoplankton (< 100 mm) and zooplankton (> 100 mm) for analysis of organic mercury, inorganic mercury and total selenium. The inorganic mercury concentrations in phytoplankton and zooplankton collected at the 140–200 m depth just above the submarine volcano were 1.80 ± 0.61 mg kg−1 and 0.47 ± 0.34 mg kg−1, respectively, while organic mercury concentrations were 0.15 ± 0.11 mg kg−1 and 0.16 ± 0.09 mg kg−1, respectively. These values were an order of magnitude higher than those found in plankton samples from the central part of the bay. In the inner part of the bay, the concentrations of these substances increased in summer and decreased in winter, mirroring fluctuations in seawater mercury concentrations, which are influenced by volcanic activity. The selenium concentrations in phytoplankton and zooplankton at 140–200 m above the submarine volcano were 1.64 ± 0.80 mg kg−1 and 1.82 ± 0.86 mg kg−1, respectively, while in the central part, they were 1.17 ± 0.58 mg kg−1 and 1.84 ± 0.67 mg kg−1, respectively. The organic mercury and selenium concentrations were higher in zooplankton than in phytoplankton at the locations of central part and 0–140 m above the fumaroles, which may suggest migration of organic mercury and selenium to higher trophic levels. Conversely, at the location just above the submarine volcano, no significant differences were observed between phytoplankton and zooplankton, and a significant negative correlation ( r = −0.72, p < 0.05) was observed between selenium and organic mercury concentrations in zooplankton with high mercury levels. This negative correlation may indicate an antagonistic effect of selenium on the accumulation of organic mercury in zooplankton.

DOI： 10.1016/j.marchem.2026.104610

Scopus

Kobari T., Kominato N., Ishimaru R., Kodama M., Kume G., Hanai M., Nitta A., Kabeya N. . Fatty acid contents and its compositions of mesozooplankton community in the Kuroshio Current and neighboring waters . Progress in Oceanography240 103598 - 103598 2025年10月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Progress in Oceanography

The Kuroshio Current and its neighboring waters are nursery grounds for the early life stages of migratory fish, despite poor food availability under oligotrophic conditions. Although recent findings suggest that standing stocks of mesozooplankton are not low and provide good prey availability for fish larvae, no information is available at their prey quality. Here, we investigated the spatial and temporal variations in the fatty acid content of mesozooplankton communities from transect lines across the Kuroshio to evaluate the nutritional quality of mesozooplankton as prey for fish larvae. We identified 5 saturated fatty acids (SFAs), 4 mono-unsaturated fatty acids (MUFAs), and 13 poly-unsaturated fatty acids (PUFAs) in the mesozooplankton community. Multivariate analysis demonstrated that fatty acid contents in mesozooplankton dry mass were more variable between the seasons than at the sites, with increasing SFA in summer. Long-chain PUFA (LC-PUFA) content, represented by arachidonic, eicosapentaenoic, and docosahexaenoic acids, was comparable between the Kuroshio and its neighboring waters. These LC-PUFA contents exhibited significant positive correlations with the relative abundance of Eucalanidae copepods and molluscans determined with metabarcoding analysis. These contents were also positively correlated with the fatty acid content of the haptophyte biomarker. Beaked sandfish larvae had higher LC-PUFA contents than those of Anguilliformes leptocephali. Multivariate analysis demonstrated that the fatty acid composition of omnivorous crustaceans, such as decapods and Eucalanidae copepods, was synchronized with that of beaked sandfish larvae. These findings suggest that the LC-PUFA contents of mesozooplankton communities accumulate in omnivorous crustaceans feeding on nano- to micro-sized phytoplankton and are transferred to planktivorous fish larvae.

DOI： 10.1016/j.pocean.2025.103598

Scopus

Kume G., Takahira H., Kodama M., Anraku K., Kotani T., Hirai J., Kobari T. . Analyses of gut content and isotopic composition of Japanese eel Anguilla japonica glass eels and elvers from an estuary in southern Japan . Marine Biology172 ( 8 ) 2025年7月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Marine Biology

The Japanese eel, Anguilla japonica, is a commercially important fish species. Most eels intended for consumption are currently produced in aquaculture systems that rely exclusively on wild-caught glass eels. Studies on the diet of glass eels and elvers have been limited in the wild populations. In the present study, we evaluated the feeding habits of Japanese glass eels and elvers in the Sendai River estuary of southern Japan using morphological and DNA metabarcoding analyses of the gut contents as well as stable isotope analyses of glass eels and elvers. Among 80 glass eels, amorphous materials were observed in the guts of 11 glass eels using stereomicroscopy. The feeding intensity of glass eels increased with increasing water temperature. Various eukaryotes were detected by DNA metabarcoding analysis of the gut contents of glass eels. Planktonic and benthic organisms were identified in the guts of six of the 10 elvers. The carbon and nitrogen stable isotope values were significantly different between glass eels and elvers. Our results suggest that Japanese glass eels resume feeding mainly on detrital particulate organic matter after metamorphosis and start actively feeding on planktonic and benthic organisms after the elver stage.

DOI： 10.1007/s00227-025-04699-0

Scopus

その他リンク： https://link.springer.com/article/10.1007/s00227-025-04699-0/fulltext.html

Kobari T., Nakamura F., Kume G., Makino F., Habano A., Kodamatani H., Tomiyasu T. . Bioaccumulation of discharged mercury from submarine fumaroles due to copepod life history traits in northern Kagoshima Bay, Japan . Plankton and Benthos Research20 ( 2 ) 148 - 159 2025年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：日本プランクトン学会、日本ベントス学会

Kagoshima Bay is a deep and semi-enclosed embayment with submarine fumarolic activities. High mercury contents have occasionally been reported for some fishes and this was hypothesized to be due to a bioaccumulation of discharged mercury from the submarine fumaroles. However, there is still no information about how the discharged mercury is accumulated into fishes through the planktonic food web. Here, we demonstrate a bioaccumulation of discharged mercury through copepod life history adapted to the embayment. Calanus sinicus was a minor contribution to the numerical abundance of zooplankton communities in both surface and deep layers during summer. In the deepest basin in northern Kagoshima Bay, copepodite stage 5 of this copepod species concentrated occurred at high abundances below the thermocline throughout the day in summer. Zooplankton communities residing in the deep waters exhibited much lower protein synthetase activity than those in the surface waters, indicating low physiological activity. Metabar-coding analysis of their gut contents demonstrated that copepods, dinoflagellates and diatoms composed more than half of gut content DNA. Mercury contents were higher for all taxonomic groups of zooplankton in the deep layers compared with those in the surface layers. C. sinicus residing in the deep waters exhibited high mercury contents equivalent to carnivorous groups. These findings suggest that bioaccumulation of discharged mercury from submarine fumaroles is accelerated by aspects of this copepod’s life history such as lipid accumulation for dormancy after actively feeding on copepod fecal pellets and phytoplankton and dormant stock accumulation restricted to the deepest basin in northern Kagoshima Bay.

DOI： 10.3800/pbr.20.148

Scopus

CiNii Research

Matakiviti K.M., Harada Y., Kodama M., Kobari T., Komorita T., Kume G. . Feeding Habits of Blacktip Grouper Epinephelus Fasciatus Around Koshikishima Island, Southern Japan . Thalassas41 ( 2 ) 2025年5月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Thalassas

The blacktip grouper (Epinephelus fasciatus) is commercially important and serves as the top predator in reef ecosystems. Understanding its dietary habits is crucial for understanding its ecological role and informing conservation strategies. In this study, we investigated the dietary composition and feeding ecology of E. fasciatus to assess potential variation by size and season. From May 2022 to January 2024, 171 specimens were collected via line fishing around Koshikishima Island, Japan. We determined the key prey items through stomach content analysis and dietary contributions through stable isotope (δ15N and δ13C) analysis combined with a Bayesian mixing model (MixSIAR). Crabs, shrimp, and fish were the primary prey groups, with less contributions from polychaetes, starfish, and slipper lobsters. Shrimp was the primary food source for the latter and start of the year (October–December and January–March). Peak crab consumption occurred in the second (April–June) and third (July–September) quarters. The diet of the smaller class (≤ 300 mm) primarily comprised of crabs and shrimp, whereas that of the larger class (≥ 301 mm) was more diverse. However, permutational multivariate analysis of variance indicated no significant dietary variation by size or season. Stable isotopes indicated an increase in trophic levels with body size. Notably, crabs contributed approximately 95% of the diet in smaller individuals, whereas the contribution of shrimp and fish was slightly higher in larger individuals. These findings provide critical insights into the feeding ecology and role of E. fasciatus in reef ecosystems.

DOI： 10.1007/s41208-025-00866-8

Scopus

その他リンク： https://link.springer.com/article/10.1007/s41208-025-00866-8/fulltext.html

Kume G., Minagawa A., Shiozaki K., Jinno S., Hirai J., Ichinomiya M., Komorita T., Kodama M., Habano A., Kobari T. . Analyses of gut content and isotopic composition of Anguilliformes leptocephali near southern Japan . ICES Journal of Marine Science82 ( 5 ) 2025年5月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：ICES Journal of Marine Science

Unlike most fish larvae that prey exclusively on mesozooplankton, such as copepods, leptocephali feed on a type of particulate organic matter (POM) known as marine snow. However, the components of POM consumed and assimilated by leptocephali have not been clarified to date. To characterize POM components ingested in the form of marine snow by leptocephali found in the waters around Satsunan, southern Japan, we performed morphological and DNA metabarcoding analyses of their gut contents and stable carbon and nitrogen isotope analyses for leptocephali and their potential food items. The analyses were carried out on the Dysomma, Gnathophis, and Muraenosox leptocephali, which occur abundantly in this area. Our data supported that leptocephali feed on marine snow particles, which can contain faecal pellets of copepods. The gut contents varied greatly among taxonomic groups of leptocephali. Differences in feeding depth and the transport of larvae from other regions may lead to differences in the leptocephali gut contents. Our results showed that the leptocephali of the Satsunan area did not actively use gelatinous zooplankton (i.e. cnidarians) and appendicularian houses, whose presence was frequently confirmed in leptocephali guts by former studies, as nutrient sources or as substrates to aggregate small particles such as bacteria, protozoans, and zooplankton faecal pellets. These results suggest that leptocephali feed non-selectively on marine snow in the ambient water column.

DOI： 10.1093/icesjms/fsaf065

Scopus

山口篤, 小針統 . 日本プランクトン学会70周年記念シンポジウム「プランクトン学会の過去，現在，未来」開催報告 . 日本プランクトン学会報70 ( 2 ) 62 - 68 2023年8月

小針統 . 2021年日本プランクトン学会・ベントス学会合同大会報告 . 日本プランクトン学会報69 ( 1 ) 39 - 41 2022年2月

平井惇也, 小針統 . 「次世代プランクトン研究を開拓する新技術・方法論」プログラム . 日本プランクトン学会報69 ( 1 ) 45 - 46 2022年2月

小針統, 一宮睦雄, 小森田智大, 久米元 . Distribution and growth of jack mackerel Trachurus japonicus larvae in the north Satsunan area, southern Japan . Fisheries Science－ 2021年査読

久米元, 小針統, 一宮睦雄, 小森田智大 . Mesopelagic fish larvae do not compete with larvae of fishery-target species in the Osumi Strait according to morphological, DNA metabarcoding, and stable isotope analyses . Marine Biology－ 2021年査読

Toru Kobari, Yurie Kobari, Toshihiro Ichikawa, Yoshiyuki Kugita, Takumi Yoshida, Tomo Fujii, Satoshi Furuhashi, Takashi Yamamoto, Akimasa Habano, Ryuji Fukuda . Seasonal dynamics of microbial plankton community in Kagoshima Bay . Aquabiology31 37 - 44 2009年2月

小針統 . 聴覚障害を持つ学生に対する乗船実習の教育環境-現状における問題点とその改善-. . Memoirs of the Faculty of Fisheries, Kagoshima University56 99 - 102 2007年12月

Toru Kobari, Shiori Imamura, Ai Ueda, Akimasa Habano . Growth rate of predominant copepods in Kagoshima Bay - Estimation by artificial cohort method . Memoirs of the Faculty of Fisheries, Kagoshima University56 45 - 54 2007年12月

T. Ichikawa, T. Kobari, A. Habano, Y. Oyama and C. Soga . Seasonal variation of chlorophyll in Kagoshima Bay, Japan. . Bulletin of the Marine Biomedical Institute, Sapporo Medical University, School of Medicine6 15 - 19 2005年12月

Toru Kobari, Akimasa Habano, Toshihiro Ichikawa . Seasonal variations in phyto- and zooplankton biomass in Kagoshima Bay . Memoirs of the Faculty of Fisheries, Kagoshima University51 19 - 25 2002年12月

Toru Kobari, Tetsuhiro Aono, Naonobu Shiga . Relationship between observed and estimated chlorophyll a concentrations from the Secchi depth in the central subarctic Pacific . Bulletin of the Faculty of Fisheries, Hokkaido University50 171 - 174 1999年12月

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