草街水库蓄水后嘉陵江浮游植物群落特征及水质评价

为了解草街水库蓄水后嘉陵江的水环境变化情况,对嘉陵江浮游植物群落结构及水质状况进行了研究.研究期间共检出浮游植物145种,隶属8门74属,其中硅藻门种类数最多,23属57种,其次为绿藻门,28属53种.浮游植物平均细胞密度1.82×105cell·L-1,细胞密度居于前3位的分别为硅藻门、甲藻门、隐藻门,所占总密度比例分别为39.2%、29.9%、24.5%,春季细胞密度显著高于其他季节(P0.05).优势度分析显示,优势种主要为颗粒沟链藻(Aulacoseria granulata)、变异直链藻(Melosira varians)、倪氏拟多甲藻(Peridiniopsis niei)、具尾逗隐藻(Komma caudate)、啮蚀隐藻(Cryptomonas erosa)等.聚类分析结果表明,草街水库蓄水后对浮游植物的影响作用已初步显现.嘉陵江草街水库区在纵向上已初步形成不同特征的生态区域,各区域浮游植物群落结构存在差异,同时,草街水库大坝上、下游间浮游植物和水体特征也产生了差异.嘉陵江浮游植物的Shannon-Wiener多样性指数、Margalef丰富度指数和Pielous均匀度指数分别介于2.06~3.55、0.76~1.90、0.50~0.78,表明嘉陵江水体处于轻-中度污染状态.根据浮游植物群落结构评价显示,研究期间的嘉陵江水体营养水平为中营养类型.

Phytoplankton Community Structure and Water Quality Assessment in Jialing River After the Impoundment of Caojie Reservoir

The variation of phytoplankton community and the water quality in Jialing River after the impoundment of Caojie Reservoir was studied in this paper. There were 145 species of phytoplankton under the membership of 8 divisions and 74 genera. Bacillariophyta was the first dominant division, with a total of 57 species of 23 genera, accounted for 39.3% of total phytoplankton species, followed by Chlorophyta, with 53 species of 28 genera and accounted for 36.6%. Only 35 species of 23 genera belonged to Euglenphyta, Cryptophyta, Pyrrophyta, Chrysophyta, and Cyanophyta. The average phytoplankton abundance was 1.82×10⁵ cell ·L^-1, and the top three taxon of most abundant were Bacillariophyta, Cryptophyta and Pyrrophyta, accounted for 39.2%, 29.9%, and 24.5% of total abundance, respectively. The cell abundance in spring was significantly higher than those in other seasons. The dominant species included Aulacoseria granulata, Melosira varians, Peridiniopsis niei, Komma caudata, Cryptomonas erosa etc., indicated by the dominant index. Excluded by cluster analysis, the influence on phytoplankton had initially emerged after the impoundment of Caojie Reservoir. The reservoir area could be divided into different ecological regions longitudinally after Caojie Reservoir impoundment, which had an important impact on the phytoplankton. Meanwhile, the phytoplankton and flow velocity between upstream and downstream of the dam significantly varied. Shannon-Wiener species diversity index, Margalef species richness index and Pielous evenness index ranged 2.06-3.55, 0.76-1.90 and 0.50-0.78, respectively. The evaluation results of phytoplankton community structure showed that the eutrophic state was at medium eutrophication level, while diversity analysis results indicated light to moderate pollution.