1. Freshwater mussels (Order Unionida) are highly threatened. Interspecific competition for food sources with invasive alien species is considered to be one of the factors responsible for their decline because successful invaders are expected to have wider trophic niches and more flexible feeding strategies than their native counterparts.
2. In this study, carbon (δ¹³C: ¹³C/¹²C) and nitrogen (δ¹⁵N: ¹⁵N/¹⁴N) stable isotopes were used to investigate the trophic niche overlap between the native freshwater mussel species, Anodonta anatina, Potomida littoralis, and Unio delphinus, and the invasive bivalve Corbicula fluminea living in sympatry in the Tua basin (south-west Europe).
3. The species presenting the widest trophic niches were C. fluminea and A. anatina, which indicate that they have broader diets than U. delphinus and P. littoralis. Nonetheless, all the species assimilated microphytobenthos, sediment organic matter, and detritus derived from vascular plants, although with interspecific variability in the assimilated proportions of each source. The trophic niche of the invasive species overlapped with the trophic niche of all the native species, with the extent varying between sites and according to the species.
4. From the three native species analysed, Potomida littoralis may be at a higher risk for competition for food with C. fluminea in the Tua basin, if food sources become limited, because this native mussel presented the narrowest trophic niche across sites and the highest probability of overlapping with the trophic niche of C. fluminea.
5. Given the global widespread distribution of C. fluminea, the implementation of management measures devoted to the control or even eradication of this invasive alien species should be a conservation priority given its potential for competition with highly threatened native freshwater mussels.

中文翻译：

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原生淡水贻贝（订单：Unionida）和入侵的 Corbicula fluminea 之间的营养生态位重叠

1. 淡水贻贝（Order Unionida）受到高度威胁。与入侵的外来物种对食物来源的种间竞争被认为是导致其数量下降的因素之一，因为成功的入侵者预计比本土物种拥有更广泛的营养生态位和更灵活的喂养策略。
2. 在这项研究中，碳 (δ ¹³ C: ¹³ C/ ¹² C) 和氮 (δ ¹⁵ N: ¹⁵ N/ ¹⁴ N) 稳定同位素被用于研究原生淡水贻贝物种Anodonta anatina、Potomida之间的营养生态位重叠littoralis和Unio delphinus，以及生活在图阿盆地（欧洲西南部）同区的入侵双壳类Corbicula fluminea。
3. 具有最广泛营养生态位的物种是C. fluminea和A. anatina，这表明它们的饮食比U更广泛。Delphinus和P. littoralis。尽管如此，所有物种都同化了来自维管植物的微型底栖植物、沉积物有机质和碎屑，尽管每种来源的同化比例存在种间差异。入侵物种的营养生态位与所有本地物种的营养生态位重叠，其程度因地点和物种而异。
4. 从这三个乡土树种分析，Potomida北沙参可能是在为食物竞争的高风险C.河蚬的图阿盆地，如果食物来源变得有限，因为这种原生贻贝呈现跨站点最窄的营养生态位和概率最高用的营养生态位重叠C.蚬。
5. 鉴于全球广泛分布C.河蚬，管理措施致力于控制或该外来入侵物种甚至消灭的实施应给予其高度威胁到了当地蚌竞争潜力优先保护。