云贵高原富营养化湖泊杞麓湖浮游生物群落的季节性演替及其驱动因子分析

Seasonal Succession of Plankton Community and Driving Factors in Hypereutrophic Qilu Lake(Yunnan-Guizhou Plateau)

杞麓湖是云贵高原典型的重富营养化湖泊,水生态系统已严重退化.为揭示杞麓湖浮游生物群落季节性演替规律,阐明浮游生物群落季节性演替的驱动因子,于2017—2018年对杞麓湖浮游生物及水质理化参数进行季节采样调查和浮游生物群落结构特征分析,并运用CCA(典范对应分析)方法分析浮游植物群落组成与环境因子的关系.结果表明:①杞麓湖夏季营养状态最高,达重度富营养水平,春秋冬三季均为中度富营养.水体SD(透明度)春季最高,夏季最低;ρ(Chla)、ρ(COD Mn)均为夏季最高,冬季最低;ρ(TN)冬季最高,秋季最低;ρ(TP)春夏最高,冬季最低.②杞麓湖浮游植物共6门163种(其中包括8个变种).浮游植物密度春季最低(0.66×10^8 L^-1)而秋季最高(16.08×10^8 L^-1),主要为蓝藻门、绿藻门和硅藻门.其中,春季优势种为微细转板藻(Mougeotia parvula);夏季优势种为孟氏浮丝藻(Planktothrix mougeotii);秋冬季的优势种均为阿氏浮丝藻(Planktothrix agardhii).③杞麓湖浮游动物32种,浮游动物密度冬季最低(13.2 ind.L)而夏季最高(3696.0 ind.L).其中,春季优势种为曲腿龟甲轮虫(Keratella valga),夏季优势种为前节晶囊轮虫(Asplanchna priodonta),秋季优势种为螺形龟甲轮虫(Keratella cochlearis),而冬季优势种为桡足类幼体.研究显示,杞麓湖浮游动植物群落季节性演替明显,ρ(DTP)(DTP为溶解态磷)、ρ(TP)、ρ(NH 3-N)、ρ(COD Mn)和WT(水温)是影响杞麓湖浮游植物群落季节性演替的主要驱动因子.

Qilu Lake is a typical hypereutrophic lake in Yunnan-Guizhou Plateau,and its aquatic ecosystem has been significantly degraded.In order to understand the seasonal dynamics of plankton community in Qilu Lake and to reveal the driving factors of seasonal succession,seasonal change of water quality and plankton community were investigated from April 2017 to January 2018,and canonical correspondence analysis was performed to analyze the relationship between phytoplankton community and environmental factors.The results showed that:(1)The seasonal variation of trophic status in Qilu Lake was characterized by the hypereutrophic status in summer and moderate eutrophication in spring,autumn and winter.The water transparency(SD)was highest in spring and lowest in summer,while chlorophyll a(Chla)and permanganate index(COD Mn)were highest in summer and lowest in winter.The total nitrogen(TN)was highest in winter and lowest in autumn,while total phosphorus(TP)was highest from spring to summer and at lowest in winter.(2)During the investigation period,163 species of phytoplankton(including 8 varieties)were observed,belonging to 6 phyla in Qilu Lake.Phytoplankton density was at the lowest level in spring and at the highest level in autumn(0.66×10^8-16.08×10^8 L^-1).Cyanophyta,Chlorophyta and Diatomaceae were the dominant phytoplankton groups.Mougeotia parvula and Planktothrix mougeotii were the dominant species in spring and summer,respectively,and Planktothrix agardhii was the dominant species in autumn and winter.(3)Thirty-two species of zooplankton were observed during the investigation.The dominant zooplankton species in spring,summer and autumn were rotifer Keratella valga,Asplanchna priodonta,and Keratella cochlearis,respectively.Copepod larvae mostly dominated in winter.The density of zooplankton was lowest in winter and highest in summer(13.2-3696.0 ind.L).The results showed the distinct seasonal succession of plankton community in Qilu Lake.The dissolved total phosphorus(DTP),TP,ammonia nitrogen(NH 3-N),COD Mn and water temperature(WT)were the main driving factors for the seasonal succession of phytoplankton communities in Qilu Lake.