IntroductionIn the Southern Ocean, myctophids are the most successful pelagic fish group in terms of diversity, biomass, and abundance. They play a crucial role in linking primary consumers and coupling carbon flux between surface and mesopelagic depths. Understanding their trophodynamics is key to assessing pelagic ecosystem resilience under environmental change. Conventional stomach content analyses indicate that myctophids predominantly feed on crustaceans, such as copepods and euphausiids, but are less effective at detecting easily digestible, soft-bodied organisms like gelatinous zooplankton (GZP) and pteropods.MethodsThis study used multimarker (COI Leray-XT and 18S v1-v2) DNA metabarcoding to analyze the diets of two abundant myctophids in the Scotia Sea, Electrona antarctica and Electrona carlsbergi.Results and discussionWe found a diverse diet dominated by copepods and euphausiids, followed by pteropods and GZP in terms of frequency of occurrence and relative read abundances. Within the GZP, salps and appendicularians were major components of the diet for E. carlsbergi, while hydrozoans were prominent in E. antarctica. With regards seasonal and spatial variability in the dietary contribution of GZP, E. carlsbergi consumed primarily appendicularians, chaetognaths, and hydrozoans during spring (2006) in the northern region, and more salps (predominantly Ilhea racovitzai) and other cnidarians in autumn (2009) in the southern region. Our study reveals the dietary diversity of myctophid fish as well as the importance GZP consumption as a key trophic pathway in the Southern Ocean.

中文翻译：

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多标记元条形码揭示的南极中上层鱼类（Myctophidae：Electrona）的秘密膳食


简介在南大洋，真菌蚜虫是生物多样性、生物量和丰度方面最成功的中上层鱼类群体。它们在连接初级消费者和耦合地表和中层深度之间的碳通量方面发挥着至关重要的作用。了解它们的营养动力学是评估环境变化下远洋生态系统恢复力的关键。传统的胃内容物分析表明，真菌蚜虫主要以甲壳类动物为食，例如桡足类和真足类动物，但在检测易于消化的软体生物（如凝胶状浮游动物 （GZP） 和翼足类动物）方面效果较差。方法本研究使用多标记 （COI Leray-XT 和 18S v1-v2） DNA 宏条形码分析了斯科舍海两种丰富的真菌蚜虫 Electrona antarctica 和 Electrona carlsbergi 的饮食。结果和讨论我们发现以桡足类和真足类为主的多样化饮食，其次是翼足类和 GZP，就出现频率和相对读取丰度而言。在 GZP 中，salps 和 appendicularians 是 E. carlsbergi 饮食的主要组成部分，而水生动物在 E. antarctica 中占主导地位。关于 GZP 膳食贡献的季节和空间变化，E. carlsbergi 在春季 （2006） 主要消耗阑尾动物、毛颌和水生动物，而在南部地区秋季 （2009） 则更多地食用 salps （主要是 Ilhea racovitzai） 和其他刺胞动物。我们的研究揭示了霉蚜鱼的饮食多样性以及 GZP 消费作为南大洋关键营养途径的重要性。