Ghia Daniela, Fea Gianluca, Murtas Annagiulia, Ventimiglia Martina, Bo Tiziano, Basso Andrea, Pretto Tobia, Sacchi Roberto, Ercoli Fabio
Dipartimento di Scienze Della Terra e Dell'Ambiente Università Degli Studi di Pavia Pavia Italy.
Chair of Hydrobiology and Fishery Estonian University of Life Sciences, Institute of Agricultural and Environmental Sciences Tartu Estonia.
Ecol Evol. 2025 May 14;15(5):e71385. doi: 10.1002/ece3.71385. eCollection 2025 May.
The North American signal crayfish, , is one of the most successful invasive crayfish species in Europe. Its broad trophic niche and ability to exploit various food sources across different trophic levels, coupled with the spread of lethal crayfish disease, pose significant threats to native crayfish populations. However, documentation of co-occurrence between invasive signal crayfish and native crayfish in invaded freshwater ecosystems remains rare, and research on their coexistence remains limited. In an Italian stream, signal crayfish coexist with native, white-clawed crayfish, . This study investigated the trophic ecology of signal crayfish and white-clawed crayfish at sites where they co-occurred versus those where they occurred alone. We evaluated whether ecological traits, such as trophic niche, the presence of crayfish plague (), and body condition of signal crayfish at the invasion front, facilitated the invasion progress of signal crayfish and replacement of native white-clawed crayfish. The research employed stable isotope analyses of carbon and nitrogen, using SIBER and MixSIAR mixing models, along with stomach content analyses and Fulton and hepatopancreas indices. When the two species occurred alone, they exhibited trophic niche partitioning. When they coexisted, their trophic niches significantly overlapped. Specifically, signal crayfish shifted their trophic niche to that of white-clawed crayfish, changing from a predatory-omnivorous diet to a primary consumer. A greater occurrence of crayfish was found in the stomachs of signal crayfish compared to white-clawed crayfish, indicating higher cannibalistic behaviour, while both species consumed substantial proportions of macroinvertebrates, detritus, and periphyton when co-occurring. In general, signal crayfish exhibited better conditions when co-occurring with native species compared to allopatric individuals, suggesting higher strength in individuals at the invasion front. This study highlights the complex dynamics of invasive and native crayfish interactions, emphasising the greater trophic plasticity and improved biological conditions exhibited by invasive signal crayfish during co-occurrence.
北美信号小龙虾（Pacifastacus leniusculus）是欧洲最成功的入侵小龙虾物种之一。其广泛的营养生态位以及利用不同营养级各种食物来源的能力，再加上致命小龙虾疾病的传播，对本地小龙虾种群构成了重大威胁。然而，在入侵的淡水生态系统中，关于入侵信号小龙虾与本地小龙虾共存的记录仍然很少，对它们共存的研究也很有限。在意大利的一条溪流中，信号小龙虾与本地的白爪小龙虾（Austropotamobius pallipes）共存。本研究调查了信号小龙虾和白爪小龙虾在共存地点与单独出现地点的营养生态学。我们评估了诸如营养生态位、小龙虾瘟疫（Aphanomyces astaci）的存在以及入侵前沿信号小龙虾的身体状况等生态特征，是否促进了信号小龙虾的入侵进程以及本地白爪小龙虾的替代。该研究采用了碳和氮的稳定同位素分析，使用SIBER和MixSIAR混合模型，以及胃内容物分析和富尔顿指数与肝胰腺指数。当这两个物种单独出现时，它们表现出营养生态位划分。当它们共存时，它们的营养生态位有显著重叠。具体而言，信号小龙虾将其营养生态位移向白爪小龙虾的生态位，从捕食性杂食性饮食转变为初级消费者。与白爪小龙虾相比，在信号小龙虾的胃中发现更多的小龙虾，这表明其同类相食行为更频繁，而当两者共存时，两个物种都消耗了大量的大型无脊椎动物、碎屑和附生植物。总体而言，与异域个体相比，信号小龙虾与本地物种共存时表现出更好的状况，这表明入侵前沿的个体更强壮。本研究强调了入侵小龙虾与本地小龙虾相互作用的复杂动态，强调了入侵信号小龙虾在共存期间表现出的更大营养可塑性和更好的生物学状况。
