三峡库区支流浮游植物群落稳定性及其驱动因子分析

浮游植物群落稳定性变化不仅带来一系列水体生态环境变化，而且也影响了水体生态系统的服务功能.为了揭示库区水体浮游植物群落稳定性变化，分别于春季、夏季、秋季和冬季对三峡库区支流花溪河的11个样点进行浮游植物采集，并对资源利用效率（RUE_PP）、物种丰富度（S）、物种均匀度（J）和群落更替值（BC）进行研究.结果表明，花溪河全年共检测出藻类8门103属380种，春季、夏季、秋季和冬季分别采集到264、181、197和183种，绿藻种类最多，其次是硅藻、裸藻和蓝藻；S0样点物种数量和细胞密度最小，S2样点物种数量和细胞密度最大；夏季RUE_PP最大，秋季RUE_PP最小；BC与RUE_PP、物种均匀度、总磷（TP）、正磷酸盐（PO₄^3--P）、总氮（TN）、硝氮（NO₃^--N）、高锰酸盐指数和电导率（Spc）呈显著负相关，而与物种丰富度和溶氧（DO）呈显著正相关系，表明蓄水对花溪河浮游植物群落结构具有显著的影响，导致浮游植物群落不稳定，易发生更替，其更替程度受生物因子和非生物因子共同作用.

Analysis of Phytoplankton Community Stability and Influencing Factors in a Tributary of the Three Gorges Reservoir

Changes in the community stability of freshwater phytoplankton not only induce a series of ecological environment problems but also influence freshwater ecosystem service functions. To understand the changes in community stability and its driving factors, phytoplankton and environmental parameters were analyzed at 11 sample sites in Huaxi River, a tributary of the Three Gorges Reservoir, in spring, summer, autumn, and winter. Moreover, the resource use efficiency (RUE_PP), phytoplankton richness (S), phytoplankton evenness (J), and community turnover (BC) were also determined. Results showed that a total of 8 phyla, including 103 genera and 380 species, were identified in Huaxi River throughout the year. Among them, 264 species were collected in spring, 181 in summer, 197 in autumn, and 183 in winter. The number of Chlorophyta was the largest, followed by Bacillariophyta, Euglenophyta, and Cyanophyta. The number of species and cell density in S0 site were the smallest, while those in S2 site were the largest. The RUE_PP was fluctuated in four seasons, with the maximum in summer and the minimum in autumn. BC was significantly negatively correlated with RUE_PP, phytoplankton richness, total phosphorus (TP), orthophosphate (PO₄^3--P), total nitrogen (TN), nitrate (NO₃^--N), permanganate index, and conductivity (Spc); however, it was significantly positively correlated with phytoplankton evenness and dissolved oxygen (DO). These results suggest that water level regulation in the Three Gorges Reservoir has a significant impact on the structure of phytoplankton community in Huaxi River, which leads to the instability of phytoplankton community and easy replacement, and the degree of community turnover is affected by the combined effect of biological and abiotic factors.