长江中游江段浮游生物群落结构及其与环境因子的关系

Plankton community structure and its relationship with environmental factors in the middle reaches of the Yangtze River

为了解长江中游江段浮游生物群落结构及其与环境因子之间的关系,于2019年7、10月,2020年1、5月进行4次采样调查。结果显示:共鉴定出浮游植物6门76属117种,其中硅藻门种类数最多(43.59%),其次是绿藻门(29.91%);浮游动物44属74种,以轮虫(48.65%)和原生动物(20.27%)为主。浮游生物优势种主要包括假鱼腥藻(Pseudanabaena sp.)、变异直链藻(Melosira varians)、小环藻(Cyclotella sp.)、长额象鼻溞(Bosmina longirostris)等。浮游植物年平均密度及生物量分别为5.3×10^(5)cells/L、1.54 mg/L;浮游动物年平均密度及生物量分别为69.61 ind./L、0.61 mg/L。根据生物多样性评价,初步得出长江中游江段浮游生物群落结构较稳定,且水质状况呈轻度污染-中度污染型。冗余分析表明,TP、TN和NH_(3)-N是浮游植物群落分布的主要影响因子;TP、NH_(3)-N、COD_(Mn)是浮游动物群落分布的主要影响因子。

A total of four sampling surveys were conducted in July and October 2019,and January and May 2020 to understand the status of plankton community structure and its relationship with environmental factors in the middle reaches of the Yangtze River.The results showed that a total of 117 species of phytoplankton in 6 phyla and 76 genera were identified,with the most abundant species of Bacillariophyta(43.59%),followed by Chlorophyta(29.91%).A total of the zooplankton had 44 genera and 74 species,the species composition was dominated by rotifers(48.65%)and protozoa(20.27%).During the study period,the dominant species of plankton mainly include Pseudanabaena sp.,Melosira varians,Cyclotella sp.,and Bosmina longirostris.The mean density and biomass of phytoplankton were 5.3×10^(5) cells/L and 1.54 mg/L.The mean density and biomass of zooplankton were 69.61 ind./L and 0.61 mg/L.Diversity index was used to analyze the water quality of the middle reaches of the Yangtze River,it was preliminarily concluded that the structure of the plankton community in the middle reaches of the Yangtze River was relatively stable,and the water quality was slightly polluted to moderately polluted.Redundancy analysis indicated that total phosphorus(TP),total nitrogen(TN),and ammonia nitrogen(NH_(3)-N)were the key factors affecting the distribution of phytoplankton community.the total phosphorus(TP),ammonia nitrogen(NH_(3)-N)and permanganate index(COD_(Mn))were the significant factors affecting the distribution of the zooplankton community.