Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print.
We combined fatty acid (FA) and stable isotope (SI) analyses to investigate the trophic ecology of different stages of European eels (Anguilla anguilla) across seawater (SW), brackish water (BW), and freshwater (FW) habitats. Salinity was the main driver of differences in the biochemical composition, and the greatest variation occurred between SW and FW eels. SW eels had a higher content of the FA indicator of carnivory, as well as the highest stable isotope ratios (C, N). In contrast, FW eels exhibited the highest lipid content and omega-6 polyunsaturated FA, but the lowest stable isotope ratios, suggesting major dietary differences between the eels in these two habitats. While the biochemical composition of BW eels was closer to those of SW eels, BW eels had the largest SI range, indicating higher dietary plasticity. FW individuals had better overall condition compared to SW eels. Independent of habitat, larger individuals were in the best condition, and had higher lipid content and monounsaturated FA. These findings suggest a biological advantage for eels to maintain a catadromous life history strategy.

中文翻译：

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从脂肪酸和稳定同位素分析推断的不同盐度栖息地的欧洲鳗鱼（Anguilla anguilla）的营养生态

加拿大渔业和水产科学杂志，提前印刷。
我们结合脂肪酸 (FA) 和稳定同位素 (SI) 分析来研究不同阶段的欧洲鳗鱼 (Anguilla anguilla) 在海水 (SW)、咸水 (BW) 和淡水 (FW) 栖息地的营养生态。盐度是生化成分差异的主要驱动因素，SW 和 FW 鳗鱼之间的差异最大。SW 鳗鱼的食肉性 FA 指标含量较高，稳定同位素比（C、N）最高。相比之下，FW 鳗鱼表现出最高的脂质含量和 omega-6 多不饱和脂肪酸，但稳定同位素比率最低，表明这两个栖息地的鳗鱼之间存在主要的饮食差异。虽然 BW 鳗鱼的生化成分更接近 SW 鳗鱼，但 BW 鳗鱼的 SI 范围最大，表明其膳食可塑性更高。与 SW 鳗鱼相比，FW 个体的整体状况更好。独立于栖息地，体型较大的个体处于最佳状态，并且具有更高的脂质含量和单不饱和脂肪酸。这些发现表明，鳗鱼具有生物优势，可以维持一种灾难性的生活史策略。