The spread of non-native species results in novel and often unexpected assemblages. Using stable isotopes, we disentangled the trophic relationships between three invasive crayfish species at two sites of a small thermal tributary of the Barát stream, Hungary. We studied Procambarus virginalis and Faxonius limosus living in sympatry in the upper section of this thermal tributary, and then an assemblage in a lower section also containing P. clarkii . The two species in the upper section largely shared trophic niches, although P. virginalis was more carnivorous than F. limosus , which fed more on detritus and aquatic plants. In the lower section, P. clarkii had a distinctive trophic niche, being more carnivorous than the other species and also preying on other crayfish and fish. The trophic niches of the other two species shifted slightly, being narrower and more overlapping in the presence of P. clarkii . It seems that the presence of P. clarkii affects the feeding habits and trophic niches of the other two crayfish. Our results also indicate that the species have somewhat distinctive feeding niches, which suggests that the ecosystem effects of these species are likely to be at least partially additive in the shared localities.

中文翻译：

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欧盟关注的三种同域入侵小龙虾的营养生态位

非本地物种的传播导致了新的且通常出乎意料的组合。使用稳定同位素，我们解开了匈牙利 Barát 溪一条小型热支流的两个地点的三种入侵小龙虾物种之间的营养关系。我们研究了生活在这条热支流上部的 Procambarus virginalis 和 Faxonius limosus，然后研究了在下部也含有 P. clarkii 的组合。上部的两个物种在很大程度上共享营养生态位，尽管 P. virginalis 比 F. limosus 更食肉，后者更多地以碎屑和水生植物为食。在下部，P. clarkii 具有独特的营养生态位，比其他物种更食肉，也捕食其他小龙虾和鱼类。其他两个物种的营养生态位略有变化，在 P. clarkii 的存在下变得更窄和更多重叠。似乎 P. clarkii 的存在影响了其他两种小龙虾的摄食习性和营养生态位。我们的研究结果还表明，该物种具有一些独特的觅食生态位，这表明这些物种的生态系统影响可能至少在共享地点具有部分累加性。