1. Understanding of trophic structure and flow of energy within river systems is essential for informed management of these ecosystems and conservation of native fish fauna and fisheries resources. Food resources used by riverine fish depend on productivity within the main stem and adjacent floodplains, terrestrial inputs, and longitudinal and lateral hydrologic connectivity.
2. Trophic ecology of puye (Galaxias maculatus Jenyns, 1842) in Chilean river systems remains poorly understood and studies that combine short‐term (stomach content) and long‐term (stable isotope analyses) analyses have not been performed to date. In this study, we assessed spatial variability in diet of puye based on both stomach content and analyses of stable isotopes of carbon and nitrogen in 10 river systems of southern Chile (including main stem, headwater lakes, and estuaries). Fish in the main stems of more northern rivers, with predictable flow regimes, were characterised by the most diverse diets, broad niche space, and high proportion of terrestrial prey items and zooplankton in diet. Fish collected in lakes were characterised by narrow isotopic niche space and diet dominated by zooplankton.
3. Diet of G. maculatus in Chilean river systems is associated with characteristics of riverine habitats within each river system (lentic, lotic, and estuarine) and hydrologic connectivity among them. Indeed, connectivity with floodplain habitats and direct supply from headwater lakes appeared to be primary drivers of fish diet in systems where these are present. These supplies maintain fish populations of good condition and allow freshwater recruitment. Therefore, maintaining seasonal flow dynamics and connectivity is essential to preserve the natural function of these river systems and conserve native fish populations.

中文翻译：

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智利南部大河系统中Puye Galaxias maculatus（Jenyns，1842）的胃含量和同位素生态位的变化

1. 了解河流系统的营养结构和能量流对于对这些生态系统进行知情管理以及保护本地鱼类动植物和渔业资源至关重要。河边鱼类使用的粮食资源取决于主干和邻近洪泛区的生产力，陆地投入以及纵向和横向的水文连通性。
2. 智利河流系统中的puye（Galaxias maculatus Jenyns ，1842）的营养生态学仍然知之甚少，迄今为止，尚未进行结合短期（胃内容物）和长期（稳定同位素分析）分析的研究。在这项研究中，我们基于胃的含量以及智利南部10条河流系统（包括主干，源头湖泊和河口）的碳氮稳定同位素分析，对普耶饮食的空间变异性进行了评估。北部河流干流中的鱼类具有可预测的水流方式，其特点是饮食种类最丰富，生态位空间广阔，并且陆栖猎物和浮游动物在饮食中所占比例很高。在湖泊中收集的鱼类的特征是狭窄的同位素生态位空间和以浮游动物为主的饮食。
3. 智利河流系统中的斑节对虾的饮食与每个河流系统中的河流栖息地（透镜，水和河口）的特征以及它们之间的水文联系有关。确实，与洪泛区栖息地的连通性和源头湖泊的直接供应似乎是存在这些系统的鱼类饮食的主要驱动力。这些补给维持了鱼类的良好状况，并允许淡水补充。因此，保持季节性流量动态和连通性对于维护这些河流系统的自然功能和保护本地鱼类种群至关重要。