The landscape theory of food web architecture (LTFWA) describes relationships among body size, trophic position, mobility, and energy channels that serve to couple heterogenous habitats, which in turn promotes long‐term system stability. However, empirical tests of the LTFWA are rare and support differs among terrestrial, freshwater, and marine systems. Further, it is unclear whether the theory applies in highly altered ecosystems dominated by introduced species such as the Laurentian Great Lakes. Here, we provide an empirical test of the LTFWA by relating body size, trophic position, and the coupling of different energy channels using stable isotope data from species throughout the Lake Michigan food web. We found that body size was positively related to trophic position, but for a given trophic position, organisms predominately supported by pelagic energy had smaller body sizes than organisms predominately supported by nearshore benthic energy. We also found a hump‐shaped trophic relationship in the food web where there is a gradual increase in the coupling of pelagic and nearshore energy channels with larger body sizes as well as higher trophic positions. This highlights the important role of body size and connectivity among habitats in structuring food webs. However, important deviations from expectations are suggestive of how species introductions and other anthropogenic impacts can affect food web structure in large lakes. First, native top predators appear to be flexible couplers that may provide food web resilience, whereas introduced top predators may confer less stability when they specialize on a single energy pathway. Second, some smaller bodied prey fish and invertebrates, in addition to mobile predators, coupled energy from pelagic and nearshore energy channels, which suggests that some prey species may also be important integrators of energy pathways in the system. We conclude that patterns predicted by the LTFWA are present in the face of species introductions and other anthropogenic stressors to a degree, but time‐series evaluations are needed to fully understand the mechanisms that promote stability.

中文翻译：

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在大湖中测试食物网理论：身体大小在密歇根湖栖息地耦合中的作用


食物网建筑景观理论（LTFWA）描述了身体大小、营养位置、流动性和能量通道之间的关系，这些关系有助于耦合异质栖息地，从而促进长期系统稳定性。然而，LTFWA 的实证测试很少，而且陆地、淡水和海洋系统的支持也不同。此外，尚不清楚该理论是否适用于劳伦森五大湖等由引进物种主导的高度改变的生态系统。在这里，我们使用来自整个密歇根湖食物网物种的稳定同位素数据，通过关联体型、营养位置和不同能量通道的耦合，对 LTFWA 进行了实证测试。我们发现身体大小与营养位置呈正相关，但对于给定的营养位置，主要由远洋能量支持的生物体比主要由近岸底栖能量支持的生物体具有较小的身体尺寸。我们还发现食物网中存在驼峰状的营养关系，其中，体型较大且营养位置较高的远洋和近岸能量通道的耦合逐渐增加。这凸显了体型大小和栖息地之间的连通性在构建食物网中的重要作用。然而，与预期的重大偏差表明物种引入和其他人为影响如何影响大型湖泊的食物网结构。首先，本地顶部捕食者似乎是灵活的耦合器，可以提供食物网的弹性，而引入的顶部捕食者在专注于单一能量途径时可能会带来较低的稳定性。 其次，除了移动捕食者之外，一些体型较小的猎物鱼类和无脊椎动物也将来自远洋和近岸能量通道的能量耦合起来，这表明一些猎物物种也可能是系统中能量路径的重要整合者。我们的结论是，LTFWA 预测的模式在一定程度上在面对物种引入和其他人为压力源时是存在的，但需要进行时间序列评估才能充分理解促进稳定性的机制。