Kagoshima University · Division of Fisheries Sciences, School of Agriculture, Fisheries and Veterinary Medicine · 准教授

Research keywordsfish larvae ecology・DNA metabarcoding・Kuroshio ecosystem・mesozooplankton trophic pathways・jack mackerel larvae・stable isotope analysis・feeding ecology・coastal oceanography

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• 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 neigh2025 · 記述言語： 日本語 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
• 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 ichthyoplankton2024 · 記述言語： 日本語 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
• 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 neighbori2024 · 記述言語： 日本語 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
• 久米 元 . 奄美大島の役勝川におけるリュウキュウアユの食性 . 南太平洋海域調査研究報告64 58 - 59 2024年 詳細を見る CiNii Research2024 · CiNii Research

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