于桥水库浮游植物群落时空动态及影响因素分析

Spatiotemporal dynamics of and influencing factors on the phytoplankton community in the Yuqiao Reservoir

为探究于桥水库浮游植物群落结构时间与空间变化及其与环境因子的相关性,本研究于2020年5—12月,对于桥水库5个采样点浮游植物群落结构及水体理化因子进行调查分析,运用浮游植物种类多样性指数及综合营养状态指数(TLI)对水体营养状态进行评价,同时应用Pearson相关性分析探究影响浮游植物群落结构的主要环境因子。结果表明:于桥水库浮游植物共隶属于7门86属194种,以绿藻门、蓝藻门及硅藻门为主,7月种类数最多,12月最少。优势种共有17种,蓝藻门最多。于桥水库全年浮游植物平均丰度为1.35×10^(8)cells·L^(-1),年均生物量为67.73 mg·L^(-1),从浮游植物群落组成时间差异来看,蓝藻门丰度始终最高,占比为78.75%~95.17%。甲藻门、金藻门及裸藻门占比均较小,合计占比在0.10%~1.48%之间。空间分布上,库中心浮游植物丰度最高,水库入口三岔口最低。TLI评价结果表明,于桥水库2020年处于轻度富营养状态,且夏季评价结果较好。在空间上,库区北部东马坊评价结果较差,水库入口三岔口较好。Pearson相关性分析结果表明,水温、pH、总氮浓度、高锰酸盐指数及叶绿素a浓度是影响于桥水库浮游植物群落结构的重要因子。

To explore the temporal and spatial changes in phytoplankton community structure and its correlation with environmental factors in the Yuqiao Reservoir,the phytoplankton and physio-chemical factors at 5 sampling sites were investigated from May to December 2020.The evaluation was based on diversity indices and a comprehensive trophic level index(TLI).Pearson correlation analysis was used to analyze the main environmental factors affecting phytoplankton community structure.In total,194 species of phytoplankton belonging to 86 genera and 7 phyla were identified.The number of species identified was largest in July and smallest in December.The main phytoplankton species belonged to Chlorophyta,Cyanophyta,and Bacillariophyta.The dominant taxa were a total of 17 species,most belonging to Cyanophyta.The annual average abundance and biomass of phytoplankton were 1.35×10^(8) cells·L^(-1) and 67.73 mg·L^(-1),respectively.In terms of the seasonal composition of the community,Cyanophyta was dominant,accounting for 78.75%–95.17%of observed taxa.Pyrrophyta,Chrysophyta,and Euglenophyta were minor,totally accounting for only 0.10%–1.48%.In terms of spatial distribution,phytoplankton abundance was highest at the reservoir center and lowest at the reservoir entrance.The TLI showed that the reservoir was at a light eutrophic state in 2020,while evaluation results were better in the summer.Diversity was worse in the northern part of the reservoir than near the entrance to the reservoir.Pearson analysis showed that temperature,pH,total nitrogen,permanganate index,and the concentration of chlorophyll a played key roles in affecting the structure and dynamics of the phytoplankton community in the Yuqiao Reservoir.