The increasing number of taxa being translocated across the globe is leading to many non-native species encountering indigenous taxa as well as other non-native species. Environmental heterogeneity may strongly influence the spatial distribution, habitat use and refuge availability for these taxa. Using a series of 24-h mesocosm experiments we examined the predator–prey interactions between an invasive crayfish (Pacifastacus leniusculus) and four amphipod taxa, one indigenous (Gammarus pulex) and three non-native species (Crangonyx pseudogracilis, Dikerogammarus villosus and Gammarus tigrinus) to Great Britain. The potential mediating effect of physical habitat on predator–prey interactions was examined via the use of different substrate particle sizes; cobbles, gravels and, sand. Survivorship of amphipods in response to crayfish predation varied significantly with the highest rates recorded for the non-native species D. villosus, followed by G. tigrinus, and C. pseudogracilis, with the lowest survivorship recorded for the indigenous species G. pulex for all substrates except cobble. However, total biomass consumption of the indigenous G. pulex and the non-native D. villosus by P. leniusculus were similar suggesting that crayfish may have been satiated by larger D. villosus individuals. Substrate size had a significant influence on the predation success of P. leniusculus, with larger substrate clasts typically resulting in increased survivorship rates for all species except C. pseudogracilis, which displayed lower predation rates for sand substrates. The findings of this study highlight the risks that naïve indigenous taxa may face from new invasive species and the importance of characterising physical habitat (complexity and refugia potential) when considering the potential ecological effects of invaders on predation success.

越来越多的分类单元在全球范围内转移，导致许多非本地物种遇到本地分类单元以及其他非本地物种。环境异质性可能强烈影响这些类群的空间分布，栖息地使用和避难所可用性。通过一系列的24小时内观试验，我们研究了侵入性小龙虾（Pacifastacus leniusculus）与四个两栖类群，一个土著（Gammarus pulex）和三个非本地物种（Crangonyx pseudogracilis，Dikerogammarus villosus和Gammarus tigrinus）之间的捕食者与猎物之间的相互作用。）去英国。通过使用不同的底物粒径，研究了物理栖息地对捕食者与猎物相互作用的潜在中介作用；卵石，砾石和沙子。应对小龙虾捕食的两栖动物的存活率差异显着，其中非本地物种D. villosus的记录率最高，其次是tigrinus和C. pseudogracilis，所有物种的土著物种G. pulex记录的生存率最低。除卵石外的所有底材。然而，P。leniusculus对本地G. pulex和非本地D. villosus的总生物量消耗量相似，这表明小龙虾可能已经满足了更大的需求。D.绒毛个体。基板尺寸对的捕食成功显著影响P. leniusculus，与更大的衬底碎屑通常导致增加的存活率除了所有物种C. pseudogracilis，其显示砂基板下捕食率。这项研究的结果突显了新的入侵物种可能会给幼稚的土著分类群带来的风险，以及在考虑入侵者对捕捞成功的潜在生态影响时表征物理栖息地（复杂性和避难所潜力）的重要性。