Abstract Trait mediated indirect effects are integral to many multiple-level predator-prey interactions. They arise routinely when, in response to predators, prey decrease their foraging on a basal resource, often due to fear. Less examined is a common assumption about trait-mediated indirect effects: that reductions in prey foraging track the instantaneous presence or absence of predators. In particular, although it is recognized that behavioral, physiological, and morphological changes in prey can persist after a predator departs, whether those changes ultimately affect trophic levels below remains an open question. Here, we tested whether legacy effects of predators lead to trait-mediated indirect effects that persist beyond when predators are present, using a model intertidal system that included a crab predator (Cancer productus), a carnivorous snail prey (Nucella ostrina), and a basal suspension feeder (the mussel, Mytilus californianus). We found that previous conditioning of snails to predator cue instilled a sustained behavioral fear response that depressed foraging by snails for at least two weeks beyond when the predator cue was present. Indeed, snails conditioned previously to predator cue consumed similar numbers of mussels as snails currently subjected to cue. Because such durations are long enough to allow new mobile predators to enter prey detection domains previously vacated by other predators, these findings suggest that neglecting the time course of persistence of trait-mediated indirect effects could appreciably underestimate their strengths. Our study supports the notion that prey use prior experience in addition to their body state to inform their anti-predatory decision making, which results in a persistent trophic cascade.

中文翻译：

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捕食者的遗产：性状介导的间接影响在潮间带食物链中持续存在

摘要 性状介导的间接效应是许多多层次捕食者-猎物相互作用的组成部分。当猎物为了回应捕食者而减少对基本资源的觅食时，它们通常会出现，这通常是由于恐惧。较少研究的是关于特征介导的间接影响的一个常见假设：猎物觅食的减少跟踪捕食者的瞬时存在或不存在。特别是，虽然人们认识到捕食者离开后猎物的行为、生理和形态变化可以持续存在，但这些变化是否最终影响以下营养水平仍然是一个悬而未决的问题。在这里，我们测试了捕食者的遗留影响是否会导致性状介导的间接影响在捕食者存在后持续存在，使用包括螃蟹捕食者（癌症产品）的潮间带模型，肉食性蜗牛猎物（Nucella ostrina）和基础悬浮饲养者（贻贝，Mytilus californianus）。我们发现，先前将蜗牛适应捕食者线索会灌输持续的行为恐惧反应，在捕食者线索出现后至少两周内抑制蜗牛的觅食。事实上，先前接受捕食者暗示的蜗牛消耗的贻贝数量与目前受捕食暗示的蜗牛相似。因为这样的持续时间足够长，允许新的移动捕食者进入先前被其他捕食者腾出的猎物检测领域，这些发现表明，忽视性状介导的间接影响持续时间过程可能会明显低估它们的优势。