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.

中文翻译：

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黑潮洋流及其邻近水域中浮游动物和浮游鱼的营养源和途径比较


具有重要商业价值的鱼类在黑潮洋流中度过其脆弱的早期生命阶段，即使在寡营养条件下猎物供应不足的地方，渔业产量也很高。然而，关于鱼浮游生物如何在复杂的食物网中得到滋养动力学的支持的信息很少。在这里，我们基于对中浮游动物和鱼浮游生物主要分类群的肠道 DNA 含量的元条形码分析，探索了黑潮及其邻近水域中浮游鱼的营养来源和途径。发现 Calanoids 是最主要和最常出现的猎物，而非甲壳类动物是大多数中浮游动物和鱼浮游动物群的次要猎物。基于肠道 DNA 含量的营养网络表明，蝈螨是最重要的部门，其猎物和捕食者之间存在多重联系，而凝胶状和非甲壳类中浮游动物是次要部门。这些发现表明，类鱼是向鱼浮游生物营养途径的重要枢纽，凝胶状和非甲壳类中浮游动物类群加强了与多个成分的营养关系。与一般想法相反，我们的元条形码分析表明，浮游鱼的营养动力学并不强烈依赖于放牧食物链，而是受到黑潮及其邻近水域的多种营养途径的支持。