了解水生和陆地初级生产燃料热带水生食物网的程度仍然知之甚少，量化本地和异地投入的相对贡献在方法论上具有挑战性。碳和氮稳定同位素比(δ13C，δ15N)可以提供有关陆地资源和营养位置的贡献的有价值的见解，分别,但是这种方法在应用于典型的复杂天然食物网时存在警告。这里,我们使用了C的组合，N,和H（δ2H）稳定同位素测量和贝叶斯混合模型，以估计陆地（异源）和水生（自生）输入对刚果河（和一些支流）中鱼类和无脊椎动物群落的贡献。总的来说,我们的结果表明，我们通过使用多重示踪剂方法获得了区分来源的能力，并且我们能够区分水生来源和陆生来源（esp。包括氢同位素)。鱼的δ2H值与他们的食物偏好明显相关，并显示出这些热带水生群落中的同种异体程度变化很大。在社区层面,很明显，陆地C3植物是刚果河食物网的重要来源。然而,为了更好地限制这些复杂环境中的源贡献，将需要对藻类和甲烷衍生的C源的稳定同位素值进行更强大的约束。
Understanding the degree to which aquatic and terrestrial primary production fuel tropical aquatic food webs remains poorly understood, and quantifying the relative contributions of autochthonous and allochthonous inputs is methodologically challenging. Carbon and nitrogen stable isotope ratios (δ 13C, δ 15N) can provide valuable insights about contributions of terrestrial resources and trophic position, respectively, but this approach has caveats when applied in typical complex natural food webs.Here, we used a combination of C, N, and H (δ 2H) stable isotope measurements and Bayesian mixing models to estimate the contribution of terrestrial (allochthonous) and aquatic (autochthonous) inputs to fish and invertebrate communities in the Congo River (and some tributaries).Overall, our results show that we gained power to distinguish sources by using a multiple tracer approach and we were able to discriminate aquatic versus terrestrial sources (esp. including hydrogen isotopes). Fish δ 2H values were clearly correlated with their food preferences and revealed a high level of variation in the degree of allochthony in these tropical aquatic communities.At the community level, it is clear that terrestrial C3 plants are an important source fueling the Congo River food web. However, in order to better constrain source contribution in these complex environments will require more robust constraints on stable isotope values of algal and methane-derived C sources.
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