摘要
为探究大型水库浮游植物优势属演替的驱动因子和丝状蓝藻增殖机制,研究了千岛湖2017—2021年浮游植物群落结构变化及其与环境因子之间的关系。研究发现,千岛湖浮游植物密度和生物量均呈逐年上升趋势,其中蓝藻密度显著上升。2021年,浮游植物年均密度和生物量分别达到1.54×10^(7)cells/L和2.23 mg/L,比2017年分别上升了161.02%和52.74%。2017—2021年千岛湖浮游植物蓝藻门优势属由微囊藻属(Microcystis)和长孢藻属(Dolichospermum)占优势,演替为假鱼腥藻属(Pseudanabaena)、细鞘丝藻属(Leptolyngbya)、尖头藻属(Raphidiopsis)和Dolichospermum等多种丝状蓝藻共同占优势。浮游植物功能群分析表明,由功能群M和有异形胞的丝状蓝藻H1功能群占绝对优势向功能群H1、S1和S_(N)等多种丝状蓝藻共同占优势转变。在监测期间,千岛湖全湖平均TN和TN/TP显著下降,而TP呈上升趋势。曼特尔检验(Mantel Test)和结构方程模型(SEM)分析结果表明,降雨形成的地表径流输入对TP升高贡献较大,浮游植物总生物量主要与TP、WT、DO、pH、SD和Temp显著相关,浮游植物总密度则受TN、WT、pH、SD和Temp驱动。其中,蓝藻密度和生物量的变化均受TN、WT、pH、SD、Pre和Temp共同驱动。通过冗余分析(RDA)表明浮游植物优势属和优势功能群变化由TN、TP和WT等共同驱动。丝状蓝藻Pseudanabaena、Raphidiopsis、Leptolyngbya与TN负相关,而Dolichospermu与TN正相关、Microcystis与TP正相关,研究表明,TN的降低是导致丝状蓝藻种类增加的主要原因之一。在营养盐较低的水库中,浮游植物群落结构较易受极端气候(暴雨、高温等)、营养输入和水体扰动等因素的影响。较强降雨导致水体混合增加和营养脉冲补给,可能诱发水库浮游植物生物量增加及丝状蓝藻增殖问题。研究结果对于贫-中营养水库蓝藻水华预测和防控具有重要的意义。
As the primary producers of aquatic ecosystems,phytoplankton communities play important roles in shaping ecosystem stability and function.In recent years,the excessive proliferation and algal bloom of filamentous cyanobacteria in many oligo-mesotrophic reservoirs have been reported more and more frequently.In order to explore the driving forces of dominant genus succession of phytoplankton and the mechanism of excessive proliferation of filamentous cyanobacteria in large reservoirs,the Qiandaohu Reservoir was chosen as the case study.The relationships between the variation of phytoplankton community structure and environmental factors during the period from 2017 to 2021 were studied.A total of 92 genera which belong to 8 phyla were identified in Qiandaohu Reservoir,which were mainly composed of Bacillariophyta,Chlorophyta and Cyanophyta.The results found that both the density and biomass of phytoplankton in Qiandaohu Reservoir showed a yearly increasing trend,especially with regards to cyanobacterial density which increased significantly.In 2021,the annual average density and biomass of phytoplankton reached 1.54×10^(7) cells/L and 2.23 mg/L,respectively,which increased by 161.02%and 52.74%compared with 2017.During the period from 2017 to 2021,the dominant genus of cyanobacteria shifted from being dominated by Microcystis and Dolichospermum to various filamentous cyanobacteria including Pseudanabaena,Leptolyngbya,Raphidiopsis,and Dolichospermum.The phytoplankton functional group(FG)analysis also showed similar result,with the main dominant functional group being various filamentous cyanobacteria H1,S1 and SN instead of M and heterocystous filamentous cyanobacteria H1.During the monitoring period,the mean annual values of TN and TN/TP ratio in Qiandaohu Reservoir decreased significantly,while TP showed an increasing trend.The Mantel Test and SEM analysis indicated that the surface runoff input from rainfall contributed significantly to the increase in TP,and the increase in total biomass of phytoplankton was significantly correlated with TP,WT,DO,pH,SD and Temp.The total density of phytoplankton was mainly by TN,WT,pH,SD,Pre and Temp.Moreover,the changes in density and biomass of cyanobacteria were both driven by TN,WT,pH,SD and Pre.The redundancy analysis(RDA)showed that the changes of dominant genera and dominant functional groups were jointly driven by TN,TP and WT.The responses of filamentous cyanobacteria to nutrition differed among genera.The dominant genera Pseudanabaena,Raphidiopsis and Leptolyngbya which belong to FGs S1 and SN were all negatively related to TN but Dolichospermum which belong to FGs H1 were positively correlated with TN and TP.The decrease of TN concentration might be one of the main reasons for the increase of the number of dominant filamentous cyanobacteria species in Qiandaohu Reservoir.The results of this study suggest that algal community composition in oligo-mesotrophic reservoirs are more susceptible to change caused by extreme climates(rainstorm,elevated temperature,etc.),nutrient inputs and water disturbances.Intense rainfall could increase water mixing and nutrient pulse supply,which might trigger excessive proliferation of filamentous cyanobacteria in reservoirs.The response of filamentous cyanobacteria to environmental factors are complex,which need to be further studied in different genera.Our study can provide important implications for the prediction,prevention and control of cyanobacterial blooms in oligo-mesotrophic reservoirs.
作者
陈玉茹
刘佳睿
郑文婷
岳智颖
沈宏
程新良
吴志旭
谢平
CHEN Yu-Ru;LIU Jia-Rui;ZHENG Wen-Ting;YUE Zhi-Ying;SHEN Hong;CHENG Xin-Liang;WU Zhi-Xuand XIE Ping(Dalian Ocean University,Dalian 116023,China;Donghu Experimental Station of Lake Ecosystems,State Key Laboratory of Freshwater Ecology and Biotechnology of China,Institute of Hydrobiology,Chinese Academy of Sciences,Wuhan 430072,China;Zhejiang Environmental Monitoring Center,Hangzhou 310000,China;University of Chinese Academy of Sciences,Beijing 100049,China;Hangzhou Bureau of Ecology and Environment Chun’an Branch,Hangzhou 311700,China)
出处
《水生生物学报》
CAS
CSCD
北大核心
2023年第12期1877-1888,共12页
Acta Hydrobiologica Sinica
基金
国家科技基础资源调查专项(2021FY100704)
杭州生态环境局淳安分局科研项目(ZF2022049)资助。
关键词
千岛湖
浮游植物
优势属
丝状蓝藻
驱动因子
Qiandaohu Reservoir
Phytoplankton
Dominant genus
Filamentous cyanobacteria
Driving factor
