2017—2021年洞庭湖浮游植物变化趋势

Variation Tendency of Phytoplankton in Dongting Lake from 2017 to 2021

2017—2021年洞庭湖共记录浮游植物8门99属,其中蓝藻门20属,绿藻门39属,硅藻门24属,甲藻门3属,裸藻门6属,隐藻门4属,金藻门1属,黄藻门2属.出现的物种主要是绿藻门、硅藻门和蓝藻门,分别占全湖种类数的39.4%、24.2%和20.2%,其他门类占比为16.2%.与1988—2017年统计的数据相比,2017—2021年洞庭湖浮游植物绿藻门占比降低1.5%,硅藻门占比降低5.3%,蓝藻门占比增加2.4%.1988—2017年洞庭湖浮游植物藻密度为3.23×10^(5) cells/L,2017—2021年洞庭湖浮游植物藻密度为5.87×10^(6) cells/L.其中,东洞庭湖浮游植物藻密度为1.518×10^(7) cells/L,南洞庭湖浮游植物藻密度为1.187×10^(6) cells/L,西洞庭湖浮游植物为1.248×10^(6) cells/L.东洞庭湖浮游植物藻密度显著高于西洞庭湖和南洞庭湖.

From the investigation during 2017-2021,phytoplankton species belonging to 8 phyla and 99 genera were recorded in Dongting Lake,including 20 genera from Cyanophyta,39 genera from Chlorophyta,24 genera from Bacillariophyta,3 genera from Pyrrhophyta,6 genera from Euglenophyta,4 genrera fron Cryptophyta,1 genera from Chrysophyte and 2 genera from Xanthophyta.Within the phytoplankton assemblages in Dongting Lake,the dominat groups were Chlorophyta,Bacillariophyta and Cyanophyta,which accounted for 39.4%,24.2%and 20.2%of total numbers of species,respectively.Whereas others 5 phyla only accounted for 16.2%of total numbers of species richness.Compared with the data collected during 1988-2017,the proportion of Chlorophyta in the phytoplankton of Dongting Lake during 2017-2021 decreased by 1.5%,that of Bacillariophyta decreased by 5.3%,and that of Cyanophyta increased by 2.4%.From 3.23×10^(5) cells/L during 1988-2017 to 5.87×10^(6) cells/L at 2017-2021.The phytoplankton density of East Dongting Lake was 1.518×10^(7) cells/L,which was 1.187×10^(6) cells/L of South Dongting Lake,and 1.248×10^(6) cells/L of West Dongting Lake.The density of phytoplankton in East Dongting Lake was significantly higher than that in West and South Dongting Lake.