洞庭湖浮游植物时空变化特征及影响因素分析

The analysis of spatial and temporal variations characteristics and driving factors of phytoplankton in Dongting Lake

为了解洞庭湖浮游植物的时空分布特征及原因,在2016年对洞庭湖浮游植物开展了季度调查。结果表明洞庭湖浮游植物样品中共检出6门53属,其中蓝藻门4属、绿藻门19属、硅藻门21属、隐藻门2属、裸藻门4属、甲藻门3属。洞庭湖浮游植物的平均密度为28.6×104cells/L,其中硅藻门最为丰富,占总密度的43.1%,其次为蓝藻门占23.4%、绿藻门占18.9%、隐藻门占8.8%、裸藻门占3.9%、甲藻门占1.9%。空间分布上,东洞庭湖浮游植物密度最高,其次为南洞庭湖、洞庭湖出口、入湖口和西洞庭湖。时间分布上,6月份浮游植物密度最高,其次为9月、3月和12月份。洞庭湖全湖综合营养状态指数为49.9,为中营养水平,其中东洞庭湖出现了轻度富营养化,尤其是大小西湖在夏秋季节有水华爆发的风险。典范对应分析(CCA)分析表明总磷和透明度是影响洞庭湖藻类分布的主要影响因素。

The quarterly surveys were carried out in 2016 to investigate the spatial and temporal variations and their driving factors of phytoplankton in Dongting Lake.The results showed that the phytoplankton community belonged to 6 phyla and 53 genera,including 4 genera of Cyanophyta,19 genera of Chlorophyta,21 genera of Bacillariophyta,2 genera of Cryptophyta,4 genera of Euglenophyta and 3 genera of Pyrrophyta.The average density of phytoplankton was 28.6× 10^4 cells/L ,with Bacillariophyta as the most dominant class （ accounted for 43.1% of the total density）,followed by Cyanophyta （ 23.4%）,Chlorophyta （ 18.9%）,Cryptophyta （ 8.8%）,Euglenophyta （ 3.9%） and Pyrrophyta （ 1.9%）. On the spatial distribution,the density of phytoplankton was highest in East Dongting Lake,followed by South Dongting Lake,outlet,estuary and West Dongting Lake.On the temporal distribution,the highest density of phytoplankton was in June,followed by in September March and December.The eutrophication state index in Dongting Lake was 49.9,showing that this lake was mesotrophic.The light eutrophication was occurred in East Dongting Lake,especially in Daxiaoxi Lake,where existing the risk of algae bloom in summer and fall.Canonical correspondence analysis （ CCA） showed total phosphorus and transparency were the key factors controlling the community structure of phytoplankton.