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首页> 外文期刊>Estuarine Coastal and Shelf Science >River damming leads to decreased phytoplankton biomass and disappearance of cyanobacteria blooms
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River damming leads to decreased phytoplankton biomass and disappearance of cyanobacteria blooms

机译：河流堰塞导致浮游植物生物量减少，蓝藻水华消失

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The large Alqueva dam was built in the early 2000s in the Guadiana River (southern Portugal) and has highly controlled the freshwater flowing into the Guadiana estuary, leading to significant changes in the natural hydrological regime. To evaluate the impacts of water restriction and flow regularization on estuarine phytoplankton and their environmental variables, sampling campaigns were conducted in the Guadiana estuary throughout a 14-year period, covering different phases related to the Alqueva dam construction. Significant alterations in phytoplankton and their environmental drivers were observed. In the post-filling period, river flow became more constant throughout the year and its natural seasonal variability, with maxima in the winter and minima in the summer, was greatly reduced, leading to higher river flows in the summer and lower in the winter, in relation to the pre-filling phase. Nutrient and light availability and, hence, phytoplankton dynamics, were greatly affected. Phytoplankton abundance and biomass decreased in the post-filling phase related to a decrease in diatoms and cyanobacteria. Since cyanobacteria blooms in the Guadiana are frequently dominated by toxic species, this constitutes an improvement in water quality. However, the overall decrease in phytoplankton biomass and, specifically, the decline in diatom biomass, will have major consequences for the higher trophic levels that depend on planktonic food.
机译：大型的Alqueva大坝建于2000年代初，位于瓜迪亚纳河（葡萄牙南部），对进入瓜迪亚纳河口的淡水进行了严格控制，导致自然水文状况发生了重大变化。为了评估水限制和流量规则化对河口浮游植物及其环境变量的影响，在瓜迪亚纳河口开展了长达14年的采样活动，涵盖了与阿尔奎瓦大坝建设有关的不同阶段。观察到浮游植物及其环境驱动因素发生了重大变化。在充水期之后，全年的河流量变得更加恒定，其自然季节变化（冬季的最大值和夏季的最小值）大大减少，导致夏季的河流流量增加，而冬季的流量减少。关于预填充阶段。营养和光的利用率以及浮游植物的动力学受到很大影响。充填后阶段的浮游植物丰度和生物量减少与硅藻和蓝细菌的减少有关。由于瓜迪亚纳州的蓝细菌开花经常被有毒物种所控制，因此这构成了水质的改善。然而，浮游植物生物量的总体下降，特别是硅藻生物量的下降，将对依赖浮游食物的较高营养水平产生重大影响。

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