2020年春夏季青海湖浮游植物群落结构及其影响因子

Community structure of phytoplankton and environmental impact factors in Qinghai Lake during spring and summer in 2020

为了解青海湖浮游植物群落结构特征及环境驱动因子,分别于2020年5月(春季)和8月(夏季)对青海湖进行了系统调查。调查共鉴定出浮游植物5门29属50种,物种组成以硅藻(58.00%)、绿藻(30.00%)、蓝藻(8.00%)为主。在密度上,春季最具优势类群为硅藻门(占总密度的47.01%),而夏季为蓝藻门取代硅藻门成为最优势的类群(63.27%)。从春季到夏季,优势种的组成及其优势度指数也发生了明显的季节变化,小环藻(Cyclotella sp.)优势度显著下降,环离鞘丝藻(Lyngbya circumcreta)的优势度显著上升。配对样本t检验结果显示,夏季浮游植物密度和生物量(3.35×10^(6) ind/L、98.56μg/L)显著高于春季(3.55×10^(5) ind/L、9.72μg/L),而Shannon多样性、Pielou均匀度、Margalef指数和Simpson多样性指数却显著低于春季。与已有的调查结果相比,本研究发现青海湖浮游植物群落夏季的主要优势类群由硅藻门逐渐演变为蓝藻门。浮游植物群落结构与环境因子的Pearson相关性分析和多元回归分析结果表明,水温和COD Mn是影响浮游植物密度和多样性指数季节变化的关键环境因子。

This study conducted a systematic survey during May(spring),and August(summer)in 2020 to understand the current situation of the phytoplankton community structure in Qinghai Lake.A total of 51 species belonging to 29 genera and five phyla were identified,with Bacillariophyta(58.00%)being the species-richest class,followed by Chlorophyta(30.00%),and Cyanophyta(8.00%).Bacillariophyta(accounting for 47.01%of total abundance)was the most dominant group in spring,whereas Cyanophyta(63.27%)became the most dominant group in summer.From spring to summer,the dominant species and dominance index of Lyngbya circumcreta decreased significantly,while Spirulina increased significantly.The paired sample T-test showed that the density and biomass of phytoplankton in summer(98.56μg/L,3.35×10^(6) ind/L)were significantly higher than that in spring(9.72μg/L,3.55×10^(5) ind/L).Still,the diversity indices such as Shannon-Wiener,Pielou,Margalef,and Simpson were significantly lower than that in spring.Compared with the previous studies in the last century,we found a dominant class of phytoplankton communities shifted from Bacillariophyta to Cyanophyta in Qinghai Lake.In addition,Pearson correlation analysis and regression analysis of phytoplankton community structure and environmental factors showed that WT and COD Mn significantly impacted seasonal variation of phytoplankton density and diversity indices.