Pushing the switch: functional responses and prey switching by invasive lionfish may mediate their ecological impact

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