丹江口水库早春真核浮游植物群落结构特征及其与环境因子的关系

Characteristics of eukaryotic phytoplankton community structure in early spring and its relationship with environmental factors in Danjiangkou Reservoir

采用高通量测序技术研究了2019年早春(2月)丹江口水库浮游植物群落结构特征及其与环境因子的关系.结果显示:(1)本次调查共检测到浮游植物6门57属,主要包括绿藻门、硅藻门、金藻门、甲藻门、隐藻门等,其中,绿藻种类(47种)>硅藻(24种)>金藻(17种),硅藻相对丰度(58.8%)>绿藻(27.2%)>金藻(11.8%),各采样点浮游植物群落结构总体相似;(2)浮游植物优势种为硅藻门的冠盘藻(Stephanodiscus suzukii)、变异直链藻(Melosira varians),绿藻门的葡萄藻(Botryococcus braunii)、索囊藻(Choricystis sp.),以及金藻类的近囊胞藻一种(Paraphysomonas sp.);(3)Shannon-Wiener多样性指数为1.76~2.52,Pielou均匀度为0.28~0.38,依据多样性指数水质评判标准判断水质整体处于β-中污带;水质符合Ⅱ类标准,但总氮(TN)除外,浓度为0.93~1.21 mg·L^(-1);(4)相关性分析表明,香农-威纳指数(H′)与Pielou均匀度指数(J)、Simpson多样性指数显著相关(p<0.01);冗余分析表明,pH、NH^(+)_(4)-N和NO^(-)_(2)-N是影响丹江口水库早春季节浮游植物群落结构最主要的环境因子.总体而言,丹江口水库水质较好,但早春季节冠盘藻(Stephanodiscus suzukii)的大量繁殖使丹江口水库发生水华的风险增加,因此,要加强对丹江口水库水质的检测和防范意识.

To understand the effects of environmental factors on phytoplankton community structure in Danjiangkou Reservoir,the species composition,cell abundance,and dominant species of phytoplankton in water samples from reservoir regions were investigated with high-throughput sequencing in 2019 spring.The results showed that:(1)A total 57 genera of phytoplankton were identified,which belonged to 6 phyla including Chlorophyta,Bacillariophyta,Chrysophyta,Dinoflagellate and Cryptophyta.Among the them,the most abundant species(47)belonged to Chlorophyta,followed by Bacillariophyta(24)and Chrysophyta(17).The higher relative abundance was found in Bacillariophyta(58.8%),Chlorophyta(27.2%),and Chrysophyta(11.8%).In addition,the similar phytoplankton community structure was detected in all sampled sites.(2)The dominant species of phytoplankton were Stephanodiscus suzukii,Melosira varians,Botryococcus braunii,Choricystis sp.,Paraphysomonas sp.(3)The Shannon-Wiener diversity index ranged from 1.76 to 2.52,while the evenness of Pielou varied in a range of 0.28 to 0.38.Based on the water quality evaluation standard of diversity index,the reservoir could be classified as theβ-middle pollution zone.The water quality conformed the classⅡstandard,except for high concentration of total nitrogen(0.93~1.21 mg·L^(-1)).(4)Shannon-Wiener index(H′)was significantly correlated with Pielou evenness index(J)and Simpson diversity index(p<0.01).Moreover,pH,NH^(+)_(4)-N and NO^(-)_(2)-N were the main environmental factors that affected phytoplankton community structure in Danjiangkou Reservoir in early spring.Overall,the water quality of Danjiangkou Reservoir was good,but the proliferation of Stephanodiscus suzukii in early spring probably increased the risk of algal-bloom in Danjiangkou Reservoir.Therefore,it is necessary to strengthen the water quality monitoring and environmental safety awareness in Danjiangkou Reservoir.