调水后东平湖浮游植物群落结构及水质生物评价

Phytoplankton Community Structure and Bioassessment of Water Quality in Dongping Lake After Water Diversion

东平湖是南水北调东线工程的重要调蓄湖泊,在防洪、灌溉、休闲旅游、水产养殖及水资源供应等方面发挥着至关重要的作用。为了解南水北调东线调水后的东平湖浮游植物群落结构及水体健康状态,于2016年4月(春季)、7月(夏季)、10月(秋季)及2017年1月(冬季)对东平湖不同空间区域(根据调水路线划分为进水区、湖中区和出水区)的浮游植物进行了调查研究,共检出浮游植物8门143种(属),其中,绿藻门种类数最多,蓝藻门次之,硅藻门位居第三。东平湖浮游植物密度呈现出显著的季节差异,秋季(1.65×10^(8)cells/L)、夏季(3.06×10^(7)cells/L)浮游植物密度明显高于春季(1.68×10^(6)cells/L)和冬季(1.27×10^(6)cells/L),而出水区、湖中区及进水区之间未呈现出显著的区域差异,年均密度为4.96×10^(7)cells/L。浮游植物优势种群共计14种(属),以蓝藻门的伪鱼腥藻(Pseudoanabaena sp.)、拟浮丝藻(Planktothricoides sp.)为主。采用Shannon-Wiener多样性指数、Pielou均匀度指数、Marglef丰富度指数及优势种评价法对东平湖进行的水质生物评价表明,东平湖水质总体处于中污染水平。与历史数据相比,调水后的东平湖浮游植物群落密度、物种多样性均高于调水前,且主要优势种以β-中污染指示种居多,说明东平湖整体水质情况较调水前有所改善。

Dongping Lake is an important regulating lake for the Eastern Route of China's South-to-North Water Diversion Project,which plays a vital role in floods control,irrigation,tourism and recreation,aquaculture and supply of water resources.To understand the community structure of phytoplankton and the water quality status of Dongping Lake(the lake was divided into inflow,center,and outflow areas based on the water diversion route)after the water diversion,seasonal samplings were conducted in April(spring),July(summer),October(autumn)2016,and January(winter)2017.A total of 143 phytoplankton species/genus in 8 phyla were identified,of which Chlorophyta was the most abundant taxa,followed by Cyanophyta and Diatomophyta.The abundance of phytoplankton in Dongping Lake showed significant seasonal differences,with significantly higher abundance in autumn(1.65×10^(8)cells/L)and summer(3.06×10^(7) cells/L)than in spring(1.68×10^(6)cells/L)and winter(1.27×10^(6)cells/L),while no significant regional difference were observed among lake inflow,center,and outflow areas.The annual average abundance of phytoplankton was 4.96×10^(7)cells/L.A total of 14 dominant taxa were mainly from Cyanophyta,which primarily consisted of Pseudoanabaena sp.and Oscillatoria sp..Shannon-Wiener diversity index,Pielou uniformity index,Marglef richness index,and dominant species evaluation were used to conduct bioassessment of water quality of Dongping Lake.Results showed that the overall water quality of Dongping Lake was at the level of mesosaprobic.Compared with the historical data,density and biodiversity of phytoplankton community in Dongping Lake have increased after the water diversion,and most of pollution indicator species wereβ-mesosaprobic among the main dominant species.These indicated that the overall water quality of Dongping Lake has improved after the operation of the water diversion.