Water quality and quantity within the upper San Antonio River (Bexar County, Texas) were supported historically from spring flows of the Edwards Aquifer. Since the 1700s, water quality, quantity, physical aquatic habitats, and presumably fish communities have been altered in the upper San Antonio River, including loss of spring flow and replacement of base flow by treated wastewater. The upper San Antonio river fish community provides a unique opportunity to fill a gap in knowledge on spring-associated fish responses to spring flow loss. The purpose of our study was to describe temporal changes in the upper San Antonio River fish community in relation to increased anthropogenic alterations from reported fish collections and infer from reference conditions. Comparisons with reference conditions were necessary since anthropogenic alterations occurred before the first fish collections within the basin. We found the upper San Antonio River fish community changed through time with increases in native and introduced fishes and decreases in spring-associated fish richness and relative abundances. Decreases in spring-associated fish richness and relative abundances were attributed to decreases in spring flow and to changes in water quality; however, specific mechanisms between loss of spring flow and spring-associated fishes are unknown at this time. Quantifying historical fish community changes through time in systems with a long history of urbanization is difficult, but our assessment provides a greater understanding of how spring flow loss due to increasing water demand in highly urbanized areas can alter communities with spring-associated species.

历史上，爱德华兹含水层的泉水支持了圣安东尼奥河上游（得克萨斯州比克斯县）内的水质和水量。自1700年代以来，圣安东尼奥河上游的水质，数量，物理水生栖息地以及鱼类群落都发生了变化，包括泉水的流失和被处理后的废水替代了基流。圣安东尼奥河上游鱼类社区提供了一个独特的机会，可以填补有关春季相关鱼类对春季水流损失反应的知识空白。我们研究的目的是描述圣安东尼奥河上游鱼类群落的时间变化，这些变化与报告的鱼类收集物中人为改变的增加以及参考条件的推断有关。必须与参考条件进行比较，因为人为改变发生在流域内第一个鱼收集之前。我们发现圣安东尼奥河上游的鱼类群落随着时间的推移而变化，这是由于本地鱼类和引进鱼类的增加，以及春季相关鱼类的丰富度和相对丰度的降低。春季相关鱼类的丰富度和相对丰度的下降归因于春季流量的减少和水质的变化；但是，目前尚不清楚春季水流损失和春季相关鱼类之间的具体机制。很难量化具有悠久的城市化历史的系统中随着时间变化的历史鱼类群落变化，