The bleak Alburnus alburnus is native to most of Europe. This cyprinid fish is a successful invader in the Iberian Peninsula. No studies exist on its foraging strategies on a large scale for this ecoregion. The aim of the present study was to compare dietary traits of invasive bleak among the main Iberian rivers and a ‘reference’ native bleak population from France. Bleak were sampled during May–June 2019 from the Iberian Rivers Ebro, Tagus, Guadiana, Segura and Guadalquivir and the River Saone (France). Diptera larvae and zooplankton were common food categories in the River Saone. Insect nymphs were more important in the River Ebro. The intake of plant material was higher in the River Tagus. Flying insects were more consumed in the River Guadiana. Nektonic insects were important in the River Guadalquivir. Detritus was a frequent food category for all populations, in terms of occurrence and mass. Dietary parameters followed a unimodal response in relation to the latitudinal gradient, with the maximum values for the Tagus and Guadiana populations. Overall, results suggest that this wide interpopulation variability will contribute to the species’ successful establishment throughout Mediterranean Europe, which poses a serious risk to its highly valuable native fish fauna.

中文翻译：

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跨越伊比利亚半岛的入侵性苍白白鳍金枪鱼（Actinopterygii，Cyprinidae）饮食特征的种群间变异性

暗淡的 Alburnus alburnus 原产于欧洲大部分地区。这种鲤科鱼类是伊比利亚半岛的成功入侵者。没有关于该生态区大规模觅食策略的研究。本研究的目的是比较伊比利亚主要河流中侵入性荒凉的饮食特征和来自法国的“参考”本地荒凉人群。2019 年 5 月至 6 月期间，从伊比利亚河埃布罗河、塔霍河、瓜迪亚纳河、塞古拉河和瓜达尔基维尔河以及索恩河（法国）采集了暗淡的样本。双翅目幼虫和浮游动物是索恩河常见的食物种类。昆虫若虫在埃布罗河中更为重要。塔霍河的植物材料摄入量较高。飞虫在瓜迪亚纳河被消耗得更多。游动昆虫在瓜达尔基维尔河中很重要。就发生率和质量而言，碎屑是所有人群常见的食物类别。饮食参数遵循与纬度梯度相关的单峰响应，其中塔霍和瓜迪亚纳种群的最大值。总体而言，结果表明，这种广泛的种群间变异将有助于该物种在整个地中海欧洲的成功建立，这对其高价值的本地鱼类群构成严重威胁。