Along the Gulf ofAlaska, rapid glacier retreat has driven changes in transport of freshwater, sediments, and nutrients to estuary habitats. Over the coming decades, deglaciation will lead to a temporary increase, followed by a long-term decline of glacial influence on estuaries. Therefore, quantifying the current variability in estuarine fish community structure in regions predicted to be most affected by glacier loss is necessary to anticipate future impacts. We analyzed fish community data collected monthly (April through September) over 7 years (2013–2019) from glacially influenced estuaries along the southeastern Gulf of Alaska. River delta sites within estuaries were sampled along a natural gradient of glacial to non-glacial watersheds to characterize variation in fish communities exposed to varying degrees of glacial influence. Differences in seasonal patterns of taxa richness and abundance between the most and least glacially influenced sites suggest that hydrological drivers influence the structure of delta fish communities. The most glacially influenced sites had lower richness but higher abundance overall compared to those with least glacial influence; however, differences among sites were small compared to differences across months. Two dominant species—Pacific staghorn sculpin and starry flounder—contributed most to spatial and temporal variation in community composition; however, given only small interannual differences in richness and abundance over the period of the study, we conclude that year-to-year variation at these sites is relatively low at present. Our study provides an important benchmark against which to compare shifts in fish communities as watersheds and downstream estuaries continue to transform in the coming decades.

沿着阿拉斯加湾，快速的冰川退缩导致淡水、沉积物和营养物质向河口栖息地的运输发生变化。在接下来的几十年里，冰川消退将导致暂时的增加，随后冰川对河口的影响将长期下降。因此，量化预计受冰川损失影响最大的地区河口鱼类群落结构的当前变异性对于预测未来的影响是必要的。我们分析了 7 年来（2013-2019 年）每月（4 月至 9 月）从阿拉斯加湾东南部受冰川影响的河口收集的鱼类群落数据。沿冰川到非冰川流域的自然梯度对河口内的河流三角洲地点进行采样，以表征暴露于不同程度冰川影响的鱼类群落的变化。受冰川影响最大和最小的地点之间分类群丰富度和丰度的季节性模式差异表明水文驱动因素影响三角洲鱼类群落的结构。与受冰川影响最小的地点相比，受冰川影响最严重的地点的丰富度较低，但总体上丰度较高；但是，与几个月之间的差异相比，站点之间的差异很小。两种优势物种——太平洋鹿角杜鹃和星比目鱼——对群落组成的时空变化贡献最大；然而，鉴于研究期间丰富度和丰度的年际差异很小，我们得出结论，目前这些地点的年际变化相对较低。