Biodiversity is declining on a global scale and the spread of invasive alien species (IAS) is a major driver, particularly through predatory impacts. Thus, effective means of assessing and predicting the consequences of IAS predation on native prey population stability remains a vital goal for conservation. Here, we applied two classic ecological concepts, consumer functional response (FR) and prey switching, to predict and understand the ecological impacts of juveniles of the lionfish (Pterois volitans), a notorious and widespread marine invader. Functional responses and prey switching propensities were quantified towards three representative prey species: Artemia salina, Palaemonetes varians, and Gammarus oceanicus. Lionfish exhibited potentially destabilising Type II FRs towards individual prey species, owing to high consumption rates at low prey densities, whilst FR magnitudes differed among prey species. Functional response attack rates (a) were highest, and handling times (h) lowest, towards A. salina, followed by P. varians and then G. oceanicus. Maximum feeding rates (1/h) and functional response ratios (FRR; a/h) also followed this impact gradient for the three prey species. Lionfish, however, displayed a potentially population stabilising prey switching propensity (i.e. frequency-dependent predation) when multiple prey species were presented simultaneously, where disproportionately less of rare prey, and more of abundant prey, were consumed. Whilst FR and FRR magnitudes indicate marked per capita lionfish predatory impacts towards prey species, a strong prey switching propensity may reduce in-field impacts by offering low density prey refuge in biodiverse communities. Our results thus corroborate field patterns documenting variable impacts of lionfish, with prey extirpations less likely in diverse communities owing to frequency-dependent predation.

生物多样性在全球范围内正在下降，外来入侵物种（IAS）的扩散是主要驱动力，尤其是通过掠夺性影响。因此，评估和预测IAS捕食对本地猎物种群稳定性的影响的有效手段仍然是保护的重要目标。在这里，我们应用了两个经典的生态学概念，即消费者功能响应（FR）和猎物转换，来预测和理解fish鱼（Pterois volitans）少年的生态影响，,鱼是一个臭名昭著且广泛传播的海洋入侵者。：功能反应和猎物切换倾向正朝三个有代表性的猎物量化卤虫，Palaemonetes varians和钩虾oceanicus。at鱼由于在低猎物密度下的高消耗率而表现出潜在的破坏II型FR对单个猎物种类的稳定性，而FR量在猎物种类中有所不同。功能性攻击率（a）最高，处理时间（h）最低，朝向盐沼曲霉（A. salina），其次是P. varians和G. oceanic us。最大进料速度（1 / h）和功能响应比（FRR; a / h）也遵循了这三种猎物物种的影响梯度。然而，当同时存在多种猎物时，鱼显示出稳定种群的猎物转换倾向（即依赖频率的捕食）的潜在可能性，其中稀有猎物消耗较少，而大量猎物消耗更多。尽管FR和FRR幅度表明人均l鱼对猎物种类有明显的掠食性影响，但强大的猎物转换倾向可能会通过在生物多样性群落中提供低密度的避难所来减少野外影响。因此，我们的结果证实了记录patterns鱼各种影响的田间模式，由于频率依赖性的捕食，猎物在不同社区灭绝的可能性较小。