State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China, Xi'an University of Technology, Xi'an 710048, China.
Shaanxi Provincial Academy of Environmental Science, Xi'an 710069, China.
Ying Yong Sheng Tai Xue Bao. 2023 Jun;34(6):1669-1679. doi: 10.13287/j.1001-9332.202306.030.
Yanhe River is one of the important tributaries of the Yellow River, with a vital role in the maintenance of biodiversity and ecological conservation in the middle reaches of the Yellow River. In this study, we conducted a systematic aquatic ecological survey of the Yanhe River Basin in spring (April-May) and autumn (September-October) of 2021, with phytoplankton as indicator organism. A total of 33 sampling sections were selected in the mainstem, five first-class tributaries, and impounded water bodies (reservoir and check dam water bodies) of the Yanhe River Basin. The results showed that a total of 253 phytoplankton species, belonging to 7 phyla and 91 genera, were detected in the two surveys. Diatoms and green algae prevailed in spring (168 species), while diatoms and cyanobacteria dominated in autumn (179 species). The mean phytoplankton density and biomass were 316.07×10 cells·L and 6.41 mg·L in spring, and 69.56×10 cells·L and 1.59 mg·L in autumn, respectively. At the temporal scale, phytoplankton abundance in spring was higher than that in autumn. At the spatial scale, the phytoplankton abundance in the middle and lower reaches of the mainstream was higher than that in the upper reaches. Phytoplankton biomass in the impounded water bodies formed by dam interception was maintained at a high level, which was significantly higher than that in the mainstem and tributary water bodies in autumn. The phytoplankton diversity, as indicated by Shannon diversity index, Margalef richness index, and Pielou evenness index, in spring was greater than that in autumn. Phytoplankton diversity was greater in the trunk and tributary waters than that in impounded waters. The results of redundancy analysis showed that the key factors driving the phytoplankton community structure in spring were flow velocity, dissolved oxygen, nitrite nitrogen, and water depth. In contrast, the key driving factors in autumn were nitrate nitrogen, water depth, and dissolved oxygen.
延河是黄河的重要支流之一，对黄河中游的生物多样性维护和生态保护具有重要作用。本研究于 2021 年春季（4-5 月）和秋季（9-10 月）对延河流域进行了系统的水生生态调查，以浮游植物为指示生物。在延河流域的干流、5 条一级支流和库坝水体（水库和淤地坝水体）共选择了 33 个采样断面。结果表明，在两次调查中，共检测到浮游植物 253 种，隶属于 7 门 91 属。春季以硅藻和绿藻为主（168 种），秋季以硅藻和蓝藻为主（179 种）。春季浮游植物密度和生物量分别为 316.07×10 cells·L 和 6.41 mg·L，秋季分别为 69.56×10 cells·L 和 1.59 mg·L。在时间尺度上，春季浮游植物丰度高于秋季。在空间尺度上，干流中下游浮游植物丰度高于上游。坝拦截形成的库坝水体中的浮游植物生物量保持在较高水平，秋季显著高于干流和支流水体。春季浮游植物多样性（Shannon 多样性指数、Margalef 丰富度指数和 Pielou 均匀度指数）大于秋季。浮游植物多样性在干流和支流水域大于在库坝水域。冗余分析结果表明，春季浮游植物群落结构的关键驱动因素是流速、溶解氧、亚硝酸盐氮和水深。相比之下，秋季的关键驱动因素是硝酸盐氮、水深和溶解氧。
