Top‐predators can suppress mesopredator behaviour through risk effects. However, there is limited understanding of whether such behavioural suppression can dampen the lethal and sub‐lethal effects of mesopredators on bottom level prey. Here, we document a field experiment that examines whether the presence of top‐predator cues (visual and chemical stimuli from a coral trout) can cascade to indirectly influence the behaviour and survival of juvenile fish prey of different species (Pomacentrus amboinensis and P. chrysurus) and size (small = 1.18 cm SL versus large = 1.32 cm SL). Results showed that habitat patches exposed to top‐predator cues received fewer visits and foraging attacks from mesopredators, leading to higher space use (~ 46%), feeding rate (~ 95%) and survival (~ 67%) from juvenile fish prey. Survival was always higher for individuals of P. amboinensis and of large‐size, independent of the presence or absence of top‐predator cues. Our data indicate that predation risk from the top‐predator indirectly favoured the persistence and behaviour of juvenile fishes by promoting risk‐averse behavioural responses in mesopredators. This study underscores the behavioural mechanisms by which risk effects can cascade through the food web and highlights the consequences that harvesting top‐predators may have on the replenishment of bottom prey populations.

中文翻译：

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顶级捕食者对幼鱼行为和生存的积极间接影响

顶级掠食者可以通过风险影响来抑制中指行为。但是，对于这种行为抑制是否能够抑制中粒繁殖者对底层猎物的致死和亚致死作用，人们知之甚少。在这里，我们记录了一个野外实验，该实验检查顶级捕食者线索（珊瑚鳟鱼的视觉和化学刺激）的存在是否可以级联从而间接影响不同物种（波马森布鲁桑和P. chrysurus）的幼鱼猎物的行为和生存）和尺寸（小= 1.18厘米SL与大= 1.32厘米SL）。结果表明，暴露于顶级捕食者线索的栖息地斑块受到中捕食者的较少访问和觅食攻击，从而导致幼鱼猎物的空间利用率更高（〜46％），摄食率（〜95％）和生存率（〜67％）。P. amboinensis个体的存活率总是更高和大型的，与是否存在顶级捕食者线索无关。我们的数据表明，顶级捕食者的捕食风险通过促进中捕食者的厌恶行为而间接地支持了幼鱼的持久性和行为。这项研究强调了风险机制可通过食物网络级联的行为机制，并强调了收获顶级捕食者可能对底层捕食者的补给产生影响。