长江天鹅洲故道浮游动物群落结构及水质评价

于2011年4月~2012年1月按季度对长江天鹅洲故道浮游动物进行了采样调查。共检出浮游动物87种，其中原生动物22属38种，占总种类数的437%；轮虫25属36种，占总种类数的414%；枝角类8属9种，占总种类数的103%；桡足类4种，占总种类数的46%。浮游动物的年平均密度为25 7119 ind/L，以原生动物和轮虫为主，分别占总密度的937%和56%；年平均生物量为36 mg/L，以原生动物和枝角类为主，分别占总生物量的319%和281%。15种优势种中9种为富营养水体指示种。绿急游虫、双叉尾毛虫、长圆膜袋虫和小链巨头轮虫全年形成优势，而针簇多肢轮虫、缘板龟甲轮虫、角突臂尾轮虫在春、夏、秋季形成优势，螺形龟甲轮虫只在春秋形成优势。绿急游虫、双叉尾毛虫、长圆膜袋虫等富营养水体指示种在受污染较多的6和10号两处采样点数量较多。按现存量法和浮游动物优势种群法判定，天鹅洲故道属于富营养类型，与根据Shannon Weaver多样性指数和Pielou均匀度指数的评价为中污染水平的结果一致。同时对浮游动物种类组成小型化的形成原因进行了分析讨论

ZOOPLANKTON COMMUNITY STRUCTURE AND WATER QUALITY #br# ASSESSMENT IN TIAN E ZHOU OXBOW OF THE YANGTZE RIVER

Quarterly investigation of the zooplankton community in Tian E Zhou Oxbow in the middle reach of the Yangtze River was conducted during April 2011 to January 2012 A total of 87 zooplankton species were observed，among which，Protozoa （23 genera 38 species），Rotifer （25 genera 36 species），Cladocera （8 genera 9 species），Copepoda （4 species） accounted for 437%，414%，103%，46% of the total species，respectively The annual average density of zooplankton was 25 7119 ind./L with protozoa and rotifers accounting for 993% of total density The annual average biomass of zooplankton was 36mg/L，with protozoa and cladocera accounting for 60% of total biomass Among the 15 dominant species （7 species of protozoa and 8 species of rotifer），9 species were indicator species of eutrophic status Four species of protozoa，Strombidium viride，Urotricha furcated，Cyclidium oblongum， Tintinnidium fluviatile and one species of rotifer，Anuraeopsis fissa were predominant all year around Three species of rotifer，Polyarthra trigla，Keratella ticinensis，Brachionus angularis were dominant in spring，summer and autumn，and one species of rotifer，Keratella cochlearis was dominant only in spring and autumn Higher density of dominant species Strombidium viride，Urotricha furcated，Cyclidium oblongum occurred in the sampling sites of 6 and 10，with a large number of Polyarthra trigla in sampling site of 10 Analysis on the zooplankton community in Tian e zhou Oxbow demonstrated dominance of micro zooplankton because protozoa and rotifer，the small sized zooplankton，accounted for 993% in density，while cladocera and copepods，the large sized zooplankton，accounted for only 07% in density Intensive feeding by stocked filter feeding fish，silver carp and bighead carp and the selective predation on macro zooplankton by abundant small sized fish such as Taihu icefish，sharpbelly and shortjaw tapertail anchovy were the possible reasons for the changes in zooplankton community According to the standing crop and the dominant species，the trophic state of Tian e zhou Oxbow was classified into eutrophic level which were in agreement with the assessment results based on Shannons index and evenness of Pielou.