长江中游宜昌至城陵矶江段浮游植物群落结构的周年变化特征

于2010年1、4、7和10月对三期蓄水后长江中游宜昌至城陵矶江段的浮游植物进行周年调查。结果显示：浮游植物共计8门74属147种，以硅藻、绿藻和蓝藻为主，分别占401%、265%和204%。优势种为颗粒直链藻（〖WTBX〗Melosira granulate）、颗粒直链藻最窄变种（M.granulata var. angustissima〖WTBZ〗 O.Müller）、美丽星杆藻(〖WTBX〗Asterione formosa〖WTBZ〗 Hass）、克洛脆杆藻（〖WTBX〗Fragilaria Crowe crisp bar〖WTBZ〗 sp.）、钝脆杆藻（〖WTBX〗Fragilaria capucina〖WTBZ〗 Desm）、普通等片藻（〖WTBX〗Ordinary film algae）、具星小环藻（Cyclotella stelligera〖WTBZ〗 Cl.et Grun.）、单角盘星藻具空变种（〖WTBX〗Pediastrum simplex var.duodenarium）、优美胶毛藻（Chaetophora elegans〖WTBZ〗 (Roth) Agardh）、小颤藻（〖WTBX〗O.tenuis）、飞燕角甲藻（Geratium hirundinella〖WTBZ〗）等11种。浮游植物种类组成的季节变化差异较明显，秋季种类数最多，为110种，夏季种类数最少，只有55种。全年浮游植物平均密度为1611×104 cells/L，平均生物量为226 mg/L，夏季生物量最大（497 mg/L），秋季最小（044 mg/L）。Shannon Wiener多样性指数均值为122，Pielou均匀度指数均值为027，Margalef丰富度指数均值为154，四季中春季的多样性指数、均匀度指数和丰富度指数均为最高。通过生物评价得出长江宜昌至城陵矶江段处于β 中污带，秋季部分江段出现富营养化

ANNUAL CHARACTERISTICS OF PHYTOPLANKTON COMMUNITIES AT YICHANG TO CHENGLINGJI SECTION IN THE MIDDLE REACH OF THE YANGTZE RIVER

Surveys on the phytoplankton communities were carried out at Yichang to Chenglingji section in the middle Reach of the Yangtze River in January,April,July,October,2010.A total of 147 plankton species belonging to 8 phyla and 74 genus were identified,among which Bacillariphyta(40.1%),Chlorophyta(26.5%) and Cyanophyta(20.4%) were dominant.The dominant species were Melosira granulate,M.granulata var.angustissima O.Müller,Asterione formosa Hass,Fragilaria Crowe crisp bar sp.,Fragilaria capucina Desm,Ordinary film algae,Cyclotella stelligera Cl.et Grun.,Pediastrum simplex var.duodenarium,Chaetophora elegans(Roth) Agardh,O.tenuis,Geratium hirundinella.As the seasons changed,the variation of phytoplankton was obvious.The quantity of species was the most in the autumn(110) and the least(55) in the spring.The mean density was 16.11×104 cell/L,and the mean biomass was 2.26 mg/L.The biomass was highest in the summer(4.97 mg/L),and lowest in the autumn(0.44 mg/L).The mean Shannon-Wiener diversitv was 1.22,the mean Pielou diversitv was 0.27,and the mean Margalef diversitv was 1.54.The Shannon-Wiener diversitv,Pielou diversitv and Margalef diversitv were highest in the spring.Obtained by biological evaluation,the section fromYichang to Chenglingji in the middle Reach of the Yangtze River was β-moderately polluted areas,and some section were eutrophication of the water body in the autumn.