九龙江华安段浮游植物群落特征

Characteristic of phytoplankton community in Hua'an reaches of Jiulongjiang River

2013年对九龙江华安段的浮游植物种类组成和细胞密度开展为期一年的调查。调查结果表明调查水域浮游植物种类共计57种,分属于硅藻门、绿藻门、蓝藻门、裸藻门、甲藻门和隐藻门等6个门类,以硅藻占相对优势,占总平均细胞密度的69.61%;其次为绿藻,占12.89%;隐藻和裸藻分别为7.22%和6.51%;而甲藻、蓝藻最少,分别为1.98%和1.80%。优势种主要有颗粒直链藻最窄变种（Melosira granulata var.angustissima）、菱形藻（Nitzschia sp.）、尖针杆藻（Synedra acus）、裸藻（Euglena sp.）、布纹藻（Gyrosigma sp.）、隐藻（Cryptomonas spp.）、多甲藻（Peridinium sp.）等。各调查站位的浮游植物细胞密度变动范围为3 700-12 500 cells/L,平均为28 232 cells/L。3个调查库区浮游植物细胞密度年平均值分别为西陂29 113 cells/L、绵良31 863 cells/L、城关23 721 cells/L。浮游植物多样性指数和均匀度指数的平均值分别是2.91和0.76,二者变动情况基本一致,存在一定的相关性。浮游植物细胞密度全年变化情况明显与水温和汛期有关,以1月、5月和7月最低,3月最高。多甲藻在3月部分站位形成优势种,存在水华的可能性。根据浮游植物细胞密度变化情况及控制冬春季水华的需要,认为秋季是增殖放流的适宜时间。

A one-year survey studying on species composition and cell density of phytoplankton in Hua＇an reaches of Jiulongjiang River was carried out in 2013.The result showed that there were 57 species of phytoplankton in the investigated waters,which belonged to 6 phyla of phytoplankton including Bacillariophyta,Chlorophyta,Euglenophyta,Cryptophyta,Pyrrophyta and Cyanophyta.The species of Bacillariophyta had the relative advantage,accounting for the total average cell density of 69.61%.Chlorophyta took the second place,accounting for 12.89%.Following by were Euglenophyta and Cryptophyta,accounting for 7.22% and 6.51% respectively.Pyrrophyta and Cyanophyta were the least,accounting for 1.98% and1.80% respectively.The main dominant species included Melosira granulata var.angustissima,Nitzschia sp.,Synedra acus,Euglena sp.,Gyrosigma sp.,Cryptomonas spp.and Peridinium sp.,etc.The average cell density of phytoplankton at all investigation stations was 28 232 cells /L,with a range of 3 700 - 12500 cells /L,29 113 cells /L in Xipi reservoir,31 863 cells /L in Mianliang reservoir,23 721 cells /L in Chengguan reservoir,respectively.Average diversity index and evenness were 2.91 and 0.76 respectively.The annual change of the two indices was similar at each same station,and there was a certain correlation between the two indices.The annual change of cell density of phytoplankton was related to water temperature and flood season obviously,it was the lowest in January,May and July,and the highest in March.Peridinium sp.became the dominant species in some stations in March,and had the possibility of dinoflagellate bloom.According to the variation of cell density of phytoplankton and the need of controlling bloom in spring and winter,we thought autumn was suitable for the release and enhancement.