Data from: Direct effects of microalgae and protists on herring (Clupea harengus) yolk sac larvae

This study investigated effects of microalgae (Rhodomonas baltica) and heterotrophic protists (Oxyrrhis marina) on the daily growth, activity, condition and feeding success of Atlantic herring (Clupea harengus) larvae from hatch, through the end of the endogenous (yolk sac) period. Yolk sac larvae were reared in the presence and absence of microplankton and, each day, groups of larvae were provided access to copepods. Larvae reared with microalgae and protists exhibited precocious (2 days earlier) and ≥ 60% increased feeding incidence on copepods compared to larvae reared in only seawater (SW). In the absence and presence of microalgae and protists, survival and growth trajectories of yolk sac larvae were similar and digestive enzyme activity (trypsin) and nutritional condition (RNA-DNA ratio) markedly declined in all larvae directly after yolk sac depletion. Thus, microplankton promoted early feeding but was not sufficient to alter survival and growth during the yolk sac phase. Given the importance of early feeding, field programs should place greater emphasis on the protozooplankton-ichthyoplankton link to better understand match-mismatch dynamics and bottom-up drivers of year class success in marine fish.本研究探究了微藻（microalgae）波罗的海红胞藻（Rhodomonas baltica）与异养原生生物（heterotrophic protists）海洋尖尾藻（Oxyrrhis marina）对大西洋鲱（Atlantic herring，Clupea harengus）仔鱼从孵化直至内源性（卵黄囊）发育阶段结束期间的每日生长、活动状态、营养状况与摄食成功率的影响。研究将卵黄囊期仔鱼分别置于添加与不添加微型浮游生物（microplankton）的环境中培育，且每日为部分仔鱼提供桡足类（copepods）作为摄食对象。与仅在海水（seawater，SW）中培育的仔鱼相比，共育有微藻与原生生物的仔鱼，其摄食桡足类的启动时间提前了2天，且摄食发生率提升60%及以上。无论是否添加微藻与原生生物，卵黄囊期仔鱼的存活与生长轨迹均无显著差异；且在卵黄囊完全耗尽后即刻，所有仔鱼的消化酶活性（胰蛋白酶（trypsin））与营养状况（RNA-DNA比值）均显著下降。由此可见，微型浮游生物可促进仔鱼提前启动摄食，但无法在卵黄囊发育阶段改变仔鱼的存活与生长情况。鉴于早期摄食的重要性，野外生态学研究应更加重视原生浮游动物与仔鱼浮游动物的营养关联（protozooplankton-ichthyoplankton link），以此更深入地理解海洋鱼类年群成功的匹配-失配动态与上行驱动机制。