Estuaries are influenced by seasonal and inter-annual variability in marine and freshwater intrusion. This variability affects the abundance and distribution of resources and consumers and may drive estuarine food web dynamics. This study tests for relationships among environmental variables and estuarine consumer δ¹³C, and assesses whether freshwater-derived sources increase in relative contribution to estuarine consumers during high freshwater inflow events. Data were collected seasonally from 2010 through 2016 for Patos Lagoon, Brazil, and included rainfall and river discharge in the drainage basin, and salinity, chlorophyll-α, and phytoplankton abundance in the estuarine zone of the lagoon. Similarly, stable isotope data (δ¹³C, δ¹⁵N) were collected seasonally for autochthonous sources and consumers (detritivorous and zooplanktivorous fishes) in the estuarine zone, and allochthonous sources of freshwater and marine origin. Mixed-effect models assessed relationships among consumer δ¹³C and environmental variables, and Bayesian mixing models (MixSIAR) estimated the relative importance of autochthonous and allochthonous sources for estuarine consumers. Hydrology affected estuarine consumer δ¹³C, corresponding to greater contributions of marine-derived organic material during periods with high freshwater inflow, especially for detritivorous juvenile mullet. This unexpected finding is likely due to high freshwater inflows delaying recruitment of juvenile mullet from coastal areas into the estuarine zone such that data from seasonal sampling reflected marine rather than local feeding and active transport of marine-derived sources into the estuarine zone. In addition to transporting freshwater-derived organic material, high freshwater inflow events may have other important indirect effects on the dynamics of trophic subsidies to estuarine food webs which require further study.

中文翻译：

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淡水流入量变化影响河口鱼类异源来源的相对重要性

河口受海洋和淡水入侵的季节和年际变化的影响。这种变化会影响资源和消费者的数量和分布，并可能推动河口食物网的发展。这项研究试验环境变量和河口消费者δ之间的关系¹³ ℃，并评估是否淡水来源的来源增加在高的淡水流入事件河口消费者相对贡献。收集了2010年至2016年巴西Patos泻湖的季节性数据，包括流域的降雨和河流流量，以及泻湖河口区的盐度，叶绿素-α和浮游植物的丰度。类似地，稳定同位素数据（δ ¹³ C，δ ¹⁵N）是季节性收集的，用于河口地区的本地水源和消费者（有害的和浮游鱼类）以及淡水和海洋来源的异源。混合效应模型评估消费者δ之间的关系¹³ ℃，环境变量，贝叶斯模型混合（MixSIAR）估计的河口消费者原地和异地来源的相对重要性。水文影响河口消费者δ ¹³C，对应于淡水大量流入期间海洋来源的有机物质的更大贡献，尤其是对于de鱼幼鱼。出乎意料的发现可能是由于大量的淡水流入推迟了从海岸地区到河口区域的幼鱼的招募，因此季节性采样的数据反映的是海洋生物，而不是本地饲料和海洋来源的主动运输到河口区域。除了运输源自淡水的有机物质外，大量的淡水流入事件还可能对营养补贴向河口食物网的动态产生其他重要的间接影响，需要进一步研究。