三峡水库175m蓄水前后香溪河库湾浮游植物的群落结构

Phytoplankton Community Structure of Xiangxi Bay before and after the 175 m Impoundment of Three Gorges Reservoir

2011年9-11月三峡水库175 m蓄水期前后,在香溪河库湾沿程布点和采样,监测分析库湾浮游植物群落结构及水体环境的时空动态。结果表明,蓄水期前后香溪河库湾共鉴定浮游植物7门、42属,主要为绿藻和硅藻;浮游植物密度随时间变化呈降低趋势,浮游植物成分空间差异不显著,时间上则由绿藻向硅藻演替;营养物质、光热条件等环境因子时间差异明显,空间差异不显著。利用物种多样性指数评价香溪河库湾水质,蓄水期前后库湾水质较好,为中污染状态。利用冗余分析(redundancy analysis,RDA)浮游植物群落结构与环境因子之间的关系,水位、表底温差、溶解性硅酸盐浓度ρ(SiO2-3-Si)、真光层深度/混合层深度(Zeu/Zmix)、水位日变幅、硝酸盐氮浓度是浮游植物群落结构的主要影响因子。

From September to November 2011, the succession of phytoplankton community structure and temporal-spatial dynamic of water environment along the Xiangxi Bay （ XXB） were monitored before and after the 175 m impoundment of Three Gorges Reservoir .The results showed that total of 7 phyla, 42 genera of phytoplankton were identified with the main dominance of green algae and diatom .During the period of investigation , the density of phytoplankton exhibited a tendency of decline and the composition of phytoplankton was characterized by the succession of the phytoplankton community from green algae to diatom , however , the spatial difference of phytoplankton composition wasn′t significant .Environmental factors such as nutrients , light and heat conditions varied greatly with time, while no significant difference was observed in terms of spatial variations .Analysis on diversity index indicated that the water of XXB was moderately polluted .Redundancy Analysis （ RDA） was applied to analyze the relationship of phytoplankton structure and environmental factors and showed that water level , temperature difference , concentration of soluble silicates ρ（SiO2-3 -Si）, thickness of the euphotic layer and the mixed layer （Zeu/Zmix）, daily fluctuation of water level , nitrate nitrogen concentration were the main factors which affected the phytoplankton community structure .