西枝江流域浮游植物群落结构特征与主要环境因子的关系研究

于2012年枯水期、丰水期与平水期(2、8、11月)在西枝江全流域开展浮游植物群落的种类组成、密度和生物多样性指数研究,并分析环境因子与浮游植物群落之间的关系.结果表明,西枝江流域共检出浮游植物6门98种,其中卵形隐藻(Cryptomonas ovata)为流域全年常见种,西枝江流域浮游植物种类数由上游至下游逐渐增加,且支流淡水河浮游植物种类和数量高于干流;西枝江流域水体浮游植物群落密度变化范围为2.2×104~6.72×106cell·L~(-1);Shannon-Weaver多样性指数、Pielou均匀度指数、Margalef丰富度指数评价结果表明,西枝江流域部分点位浮游植物群落生物多样性受到一定程度的损害.西枝江流域平水期总氮浓度显著高于枯水期、丰水期(p0.05);西枝江干流总磷全年差异不明显(p0.05),支流淡水河总磷在枯水期显著高于丰水期、平水期(p0.05).氮磷含量空间分布特征为淡水河高于西枝江下游高于西枝江中游,西枝江上游水质最优,且浮游植物指示种的演替与流域内水质变化情况相吻合;RDA分析结果表明,氮磷营养盐、T以及CODMn是西枝江流域浮游植物群落结构的重要影响因子.

The community structure of phytoplankton and its relationship with environmental factors in Xizhijiang River

In this study, phytoplankton community structure, cell density, and biodiversity of Xizhijiang River and their relationship to various environmental factors were investigated in dry season (February), wet season (August) and normal season (November) in 2012. The results show that a total of 98 species were identified and belonged to 6 phyla, in which Cryptomonas ovata was the dominant species during the whole year. The number of phytoplankton species increased gradually from upstream to downstream, and the species number and cell density were both higher in the Danshui River (branch) than those in mainstream. Phytoplankton cell density of Xizhijiang River basin was in the range of 2.2×10⁴~6.72×10⁶ cell·L^-1, and the results of Shannon-Wiener diversity index, Pielou index and Margalef index analysis show that phytoplankton biodiversity in Xizhijiang River basin had been damaged. TN concentration of Xizhijiang River basin in normal season was obviously higher than that in dry season and wet season (p<0.05). The temporal difference of TP concentration in mainstream was not obvious (p>0.05), however, TP concentration in Danshui River (branch) was obviously higher in dry season than in wet and normal season. TN and TP concentrations in Danshui River were higher than those in Xizhijiang River, meanwhile, in the mainstream of Xizhijiang River, TN and TP concentrations were higher in downstream than in midstream, butwere the lowest in upstream. also, the succession of the indicator species was corresponding to the change of water quality in the river basin. The result of redundancy analysis (RDA) shows that nitrogen, phosphorus, temperature (T) and permanganate index (COD_Mn) were the most important factors influencing the structure of phytoplankton communities in Xizhijiang River.