调水背景下南亚热带水库蓝藻水华前后优势种变化特征及其驱动因子分析

Characteristics of Dominant Species Changes Before and After Cyanobacterial Blooms and Its Driving Factors in a South Subtropical Diversion Reservoir

为探究蓝藻水华前后优势种的动态变化及其驱动因子,于2022年1—4月对我国南方某水库进行浮游植物采集调查.该水库根据调水供水特点设置3个采样点进行水环境监测.运用主坐标分析(PCoA)探究水华前后蓝藻优势种的差异性,并采用变差分解(VPA)和线性拟合分析蓝藻优势种与驱动因子之间的关系.结果表明:(1)研究期间共鉴定出3个优势种属,分别为伪鱼腥藻、拟柱孢藻和小尖头藻.(2)水华前伪鱼腥藻占绝对优势(72.17%),水华期间3种优势蓝藻均快速繁殖且三者占比分别为33.06%、30.71%和28.65%.(3)VPA结果和线性拟合共同表明,水体稳定性指数(RWCS)、水温(WT)和总磷(TP)是该水库蓝藻水华的主要驱动因子.研究显示,该水库调水过程对蓝藻产生了显著影响,后续应当深入揭示动态调水对蓝藻水华的响应特征与机制.

A phytoplankton collection survey was conducted in a southern Chinese reservoir from January 2022 to April 2022 to investigate the dynamics of dominant cyanobacterial species and their drivers before and after cyanobacterial blooms.To facilitate water environment monitoring,three sampling sites were set up based on the water diversion and supply characteristics of the reservoir.The principal coordinates analysis(PCoA)was used to explore the dissimilarity of dominant cyanobacterial species before and after the bloom.Furthermore,the relationship between dominant cyanobacterial species and driving factors was analyzed using variation partitioning analysis(VPA)and linear fitting.The results showed that:(1)Three dominant genera were identified,namely Pseudanabaena,Cylindrospermopsis raciborskii,and Raphidiopsis curvata.(2)Pseudanabaena were the most dominant genus before the water bloom,accounting for 72.17% of the total phytoplankton.During the water bloom,all three dominant cyanobacteria reproduced rapidly,and their relative content was 33.06%,30.71%,and 28.65%,respectively.(3)The VPA results and linear fits indicated that the relative water column stability(RWCS),water temperature(WT),and total phosphorus(TP)were the main factors affecting the cyanobacterial blooms in the reservoir.This study showed that the water diversion process of the reservoir had a significant impact on cyanobacteria,and the response characteristics and mechanism of dynamic water diversion on cyanobacterial blooms should be further studied.