青海湖入湖河流浮游植物群落时空格局及其影响因子

Spatio-temporal patterns and influencing factors of phytoplankton communities in the main inflow rivers of Qinghai Lake

为了探究青海湖入湖河流浮游藻类的群落结构、时空分布特征及其影响因素,于2020年8月(夏)和10月(秋)对青海湖4条主要入湖河流(布哈河、泉吉河、沙柳河和哈尔盖河)进行了系统调查.两次调查共检出浮游植物7门26科48属76种,其中,硅藻门为主要优势类群.秋季浮游植物的密度和生物量高于夏季,但各多样性指数却低于夏季.泉吉河和哈尔盖河的物种数较多,生物多样性指数也较高.置换多元方差分析(PERMANOVA)和主坐标分析(PCoA)显示,浮游植物群落结构在4条入湖河流和2个季节间具有显著差异.基于距离的冗余分析(dbRDA)结果表明,入湖河流浮游植物群落分布主要受NH_(3)-N、pH、水温、海拔和总磷(TP)等环境因子及PCNM1、PCNM2和PCNM9等不同尺度空间因子的影响.变差分解结果显示,环境因子对浮游植物群落变化的单独解释率为9.4%,空间因子的单独解释率仅为0.3%,二者共同解释了5.4%的群落变化,表明环境因子起到了更重要的作用.本研究可为青海湖流域河流的浮游植物群落分布特征及水生生态系统保护提供基础资料和理论依据.

To understand the spatio-temporal patterns of phytoplankton communities and driving factors in the inflow rivers of Qinghai Lake,we conducted a systematic survey on four main inflow rivers of Qinghai Lake basin(Buha River,Quanji River,Shaliu River and Haergai River)during August(Summer)and October(Autumn)of 2020.A total of 76 species belonging to 7 phyla,26 families and 48 genera were identified,with Bacillariophyta being the dominant phylum.During the two seasons,the density and biomass in autumn were higher than those in summer,but four biodiversity indices were lower than those in summer.Among different rivers,taxon richness and biodiversity indices were all higher in the Quanji River and Haergai River than in the other two rivers.Permutational multivariate analysis of variance(PERMANOVA)and principal coordinates analysis(PCoA)both indicated that the structure of phytoplankton communities varied significantly among different rivers and seasons.In addition,the distance-based redundancy analysis(dbRDA)results showed that five environmental factors(NH_(3)-N,pH,water temperature,altitude and total phosphorus)and three spatial factors(PCNM1,PCNM2 and PCNM9)were the key drivers structuring the phytoplankton communities.The variation partitioning analysis indicated that the pure effect of environmental factors(accounting for 9.4%variance)was more important in controlling phytoplankton communities than the pure effect of spatial factors(0.3%).This study provides basic data and theoretical basis for the conservation of aquatic ecosystems in the Qinghai Lake basin.