Department of Ecology and Genetics, Limnology, Uppsala University, Uppsala, Sweden.
Plant Ecology and Nature Conservation, University of Potsdam, Potsdam, Germany.
Oecologia. 2021 May;196(1):53-63. doi: 10.1007/s00442-021-04913-y. Epub 2021 Apr 25.
Fatty acids are widely used to study trophic interactions in food web assemblages. Generally, it is assumed that there is a very small modification of fatty acids from one trophic step to another, making them suitable as trophic biomarkers. However, recent literature provides evidence that many fishes possess genes encoding enzymes with a role in bioconversion, thus the capability for bioconversion might be more widespread than previously assumed. Nonetheless, empirical evidence for biosynthesis occurring in natural populations remains scarce. In this study, we investigated different feeding types of perch (Perca fluviatilis) that are specialized on specific resources with different levels of highly unsaturated fatty acids (HUFAs), and analyzed the change between HUFA proportions in perch muscle tissue compared to their resources. Perch showed matching levels to their resources for EPA, but ARA and especially DHA were accumulated. Compound-specific stable isotope analyses helped us to identify the origin of HUFA carbon. Our results suggest that perch obtain a substantial amount of DHA via bioconversion when feeding on DHA-poor benthic resources. Thus, our data indicate the capability of bioconversion of HUFAs in a natural freshwater fish population.
脂肪酸被广泛用于研究食物网组合中的营养相互作用。通常认为，从一个营养级到另一个营养级，脂肪酸的变化非常小，因此它们适合作为营养生物标志物。然而，最近的文献提供的证据表明，许多鱼类具有编码具有生物转化作用的酶的基因，因此生物转化的能力可能比以前认为的更为广泛。尽管如此，在自然种群中发生生物合成的实证证据仍然很少。在这项研究中，我们调查了专门以具有不同高度不饱和脂肪酸（HUFAs）水平的特定资源为食的鲈鱼（Perca fluviatilis）的不同摄食类型，并分析了鲈鱼肌肉组织中与资源相比 HUFAs 比例的变化。鲈鱼的 EPA 比例与资源相匹配，但 ARA 特别是 DHA 会积累。特定化合物的稳定同位素分析有助于我们确定 HUFAs 碳的来源。我们的结果表明，当鲈鱼以富含 DHA 的底栖资源为食时，它们通过生物转化获得了大量的 DHA。因此，我们的数据表明，在自然淡水鱼类种群中，HUFAs 具有生物转化的能力。
