Predator encounters during early life can elicit behavioral and physiological responses that have fitness consequences during subsequent prey life stages. In threatened lake sturgeon (Acipenser fulvescens) and other lithophilic-spawning fishes, newly hatched larvae (free embryos) are exposed to abundant predators including aquatic insect larvae that co-occupy stream substrates. We investigated stress effects on lake sturgeon larvae after encounters with common aquatic insect predators by quantifying mortality, body size, cortisol levels, and swimming behavior. Free embryos were exposed to either Perlidae (stonefly obligate predators) or Isonychiidae (mayfly filterers and facultative predators) or to no predators (controls). Free embryos that encountered perlids experienced high mortality, elevated cortisol levels, and exhibited cortisol reactivity when subsequently exposed to an acute stressor. Free embryos that encountered isonychiids exhibited elevated mortality, and elevated cortisol and cortisol reactivity relative to controls. Findings indicate that lake sturgeon free embryos are stressed by exposure to members of benthic stream communities during early life stages (predation of nearby conspecifics), and that metrics of stress exhibited threat sensitivity. Data are consistent with predictions that individuals modulate antipredator behavior in response to the intensity of perceived predation threat in the environment. We determined that behavioral outcomes associated with encounters with aquatic insects altered future behavioral trajectories, potentially as an adaptive response that can affect predation rates in subsequent life stages. Results contribute to a broader understanding of how interspecies interactions among co-occurring predator and prey communities may impact individual fitness and fish population recruitment.

在生命早期与捕食者相遇会引发行为和生理反应，从而在随后的猎物生命阶段产生健康后果。在受威胁的湖鲟（Acipenser fulvescens) 和其他亲石产卵鱼类，新孵化的幼虫（游离胚胎）暴露于丰富的捕食者，包括共同占据河流基质的水生昆虫幼虫。我们通过量化死亡率、体型、皮质醇水平和游泳行为，研究了遇到常见水生昆虫捕食者后对湖鲟幼虫的压力影响。游离胚胎暴露于 Perlidae（石蝇专性捕食者）或 Isonychiidae（蜉蝣过滤器和兼性捕食者）或没有捕食者（对照）。遇到 perlid 的游离胚胎死亡率高，皮质醇水平升高，并在随后暴露于急性压力源时表现出皮质醇反应性。与对照相比，遇到异爪的游离胚胎表现出较高的死亡率，以及较高的皮质醇和皮质醇反应性。研究结果表明，湖鲟游离胚胎在生命早期阶段（捕食附近的同种动物）暴露于底栖溪流群落的成员而受到压力，并且压力指标表现出威胁敏感性。数据与预测一致，即个体会根据环境中感知到的捕食威胁的强度来调节反捕食者的行为。我们确定与水生昆虫相遇相关的行为结果改变了未来的行为轨迹，这可能是一种适应性反应，可以影响随后生命阶段的捕食率。结果有助于更广泛地了解共同发生的捕食者和猎物社区之间的种间相互作用如何影响个体健康和鱼类种群的补充。