PDF(Pubmed)
Abstract：
Aquatic food webs are spatially complex, potentially contributing to intraspecific variability in production pathway reliance of intermediate trophic level consumers. Variation in trophic reliance may be described by well-established trophic indicators, like stable isotope ratios (δ13C, δ15N), along with emerging trophic indicators, such as fatty acid composition. We evaluated stable isotope ratios and fatty acid profiles of European smelt (Osmerus eperlanus) among and within distinct regions of three large Swedish lakes (Hjälmaren, Mälaren, Vättern) which differed in trophic status. We expected that smelts in more oligotrophic lakes and regions would be characterized by distinct stable isotope signatures and fatty acid profiles, with particularly high polyunsaturated fatty acid (PUFA) relative levels. However, we acknowledge that frequent movement of smelts among regions may serve to spatially integrate their diet and lead to limited within-lake variation in stable isotope ratios and fatty acid composition. As expected, in comparison with more productive lakes (i.e., Hjälmaren and Mälaren), smelts from ultra-oligotrophic Vättern were characterized by low δ15N, high δ13C and high percent of a dominant PUFA, docosahexaenoic acid (DHA). Smelts from different regions of the morphometrically complex Mälaren displayed differential stable isotope ratios and fatty acid relative concentrations, which were consistent with within-lake differences in productivity and water residence times, suggesting that smelts in this lake forage locally within distinct regions. Finally, at the individual smelt level there were particularly strong and consistent associations between a well-established trophic indicator (δ13C) and percent DHA, suggesting that the relative concentration of this fatty acid may be a useful additional trophic indicator for smelt.
摘要：
水生食物网空间复杂，可能导致中等营养水平消费者的生产途径依赖种内变异性。营养依赖的变化可以通过完善的营养指标来描述，像稳定同位素比率(δ13C，δ15N)，随着新出现的营养指标，如脂肪酸组成。我们评估了三个瑞典大型湖泊（Hjälmaren，Mälaren,Vättern）的营养状态不同。我们预计，在更多的贫营养湖泊和地区的熔炼将以不同的稳定同位素特征和脂肪酸谱为特征，具有特别高的多不饱和脂肪酸(PUFA)相对水平。然而,我们承认，熔炼在地区之间的频繁移动可能会在空间上整合其饮食，并导致稳定同位素比率和脂肪酸组成的湖内变化有限。不出所料,与生产力更高的湖泊相比(即，Hjälmaren和Mälaren)，来自超贫营养Vättern的熔炼具有低δ15N的特征，高δ13C和高百分比的显性PUFA，二十二碳六烯酸（DHA）。形态复杂的Mälaren不同区域的熔炼物显示出不同的稳定同位素比和脂肪酸相对浓度，这与湖内生产力和水停留时间的差异一致，这表明在这个湖中的熔炼在不同的地区本地觅食。最后,在个体冶炼水平上，已建立的营养指标（δ13C）和DHA百分比之间存在特别强烈和一致的关联，表明该脂肪酸的相对浓度可能是冶炼的有用的额外营养指标。
