Introductions and invasions of non-native species alter nutrient cycling and trophic dynamics resulting in significant ecological disturbance. Stable isotope data were used to test for evidence of invader-induced trophic niche differences in a north Norwegian lake system differentially dominated by native European whitefish (Coregonus lavaretus) morphotypes and invasive vendace (Coregonus albula). Aspects of both realised trophic niche position and trophic niche width were affected by the invader, with the effects varying by whitefish morphotype. Densely rakered pelagic whitefish demonstrated a relatively lower reliance on pelagic resources in the presence of the invader and the isotopic niche size was relatively larger in conjunction with the broadening of the prey base. Within the benthic-dwelling sparsely rakered whitefish morphotype, the trophic impacts of invading vendace were size-dependent, with larger individuals experiencing niche compression. Smaller sparsely rakered whitefish increased, contrary to our hypothesis, reliance on pelagic-based energy in the face of invasion. Our findings demonstrate that the trophic ecology of invaded systems can differ in multiple and subtle ways that have consequences for community- and ecosystem-level energy flows, which if persisting over time are likely to have implications for the recruitment, growth and reproductive rate of the native fishes.

中文翻译：

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挪威北部湖泊系统中本地白鲑和入侵白鲑的营养生态位分离

外来物种的引入和入侵改变了养分循环和营养动态，导致严重的生态干扰。稳定同位素数据用于测试挪威北部湖泊系统中入侵者诱导的营养生态位差异的证据，这些差异主要由欧洲本土白鲑 ( Coregonus lavaretus ) 形态类型和侵入性白鲑 ( Coregonus albula）。已实现的营养生态位位置和营养生态位宽度都受到入侵者的影响，影响因白鲑形态类型而异。密集耙状的中上层白鲑在入侵者存在的情况下表现出对中上层资源的相对较低的依赖，并且同位素生态位大小随着猎物基地的扩大而相对较大。在底栖居住的稀疏耙状白鲑形态类型中，入侵白鲑的营养影响取决于大小，较大的个体经历生态位压缩。与我们的假设相反，较小的稀疏耙状白鲑在面临入侵时增加了对远洋能源的依赖。