The stingrays Potamotrygon amandae and Potamotrygon falkneri are nonnative species established in the Upper Paraná basin. Although they are widely distributed, few studies on their diets or respective metabolic responses exist. Therefore, the aim was to evaluate the dietary composition, trophic niche breadth and lipid/protein concentrations in muscle and hepatic tissues of these two species, as well as the interrelationships between them. The individuals were collected in two areas on the Upper Paraná River. The stomachs and samples of muscle and liver tissues were taken for analysis. A broad dietary spectrum was observed for both species, along with differences in dietary composition, with a higher consumption of detritus by P. amandae and Baetidae by P. falkneri . No differences were observed in the trophic niche breadth. Regarding the metabolic variables, differences were only found in the hepatic protein, with a higher content observed in P. falkneri . A significant positive correlation was observed between items of animal origin and detritus with muscle protein for this species. This shows that such feeding habits, which are characteristic of a generalist, influenced the metabolism of the species and possibly contributed to the successful adjustment of the species to new habitats in the Upper Paraná River.

中文翻译：

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两种非本地淡水黄貂鱼（软骨鱼类：Potamotrygonidae）的营养生态和代谢

黄貂鱼 Potamotrygon amandae 和 Potamotrygon falkneri 是在上巴拉那盆地建立的非本地物种。尽管它们分布广泛，但很少有关于它们的饮食或各自代谢反应的研究。因此，目的是评估这两个物种的肌肉和肝脏组织中的膳食组成、营养生态位宽度和脂质/蛋白质浓度，以及它们之间的相互关系。这些个体被收集在巴拉那河上游的两个地区。取胃和肌肉和肝脏组织样本进行分析。观察到这两个物种的饮食范围很广，以及饮食组成的差异，其中 P. amandae 和 Baetidae 对 P. falkneri 的碎屑消耗量更高。在营养生态位宽度上没有观察到差异。关于代谢变量，差异仅在肝蛋白中发现，在 P. falkneri 中观察到的含量更高。在动物来源的物品和碎屑与该物种的肌肉蛋白质之间观察到显着的正相关。这表明这种具有通才特征的饮食习惯影响了物种的新陈代谢，并可能有助于该物种成功地适应巴拉那河上游的新栖息地。