太湖五里湖沿岸带浮游植物群落生态特征(2014~2015年)

2014年7月~2015年6月对五里湖浮游植物开展了逐月调查，以研究综合治理后五里湖沿岸带浮游植物群落变化特征。本次调查共检出浮游植物8门196种，绿藻门物种最多(74种)，硅藻门次之(57种)。优势种共6门30种，其中2014年7、8、9、10月和2015年6月的第一优势种均为蓝藻门的小颤藻，其优势度范围为0.567~0.879。时间上，浮游植物密度和生物量的月均值变幅分别为1.07×106~2.18×108 ind./L，0.32~50.52 mg/L，其中由于蓝藻的大量增殖，夏和秋初密度、生物量极显著高于其他月份；空间上，A区浮游植物密度和生物量显著低于其余3个湖区。Pearson相关性分析表明，藻类密度、生物量和物种数与水体浊度(Tur)、pH和水温(WT)呈显著或极显著相关关系；RDA分析表明，WT、DO和Tur是与浮游植物群落结构相关性较强的环境因子(p<0.01)，其中相关性最强的为WT(r=0.8982)。依据浮游植物物种数和生物多样性指数对水质的分析表明：五里湖沿岸带水体处于中度富营养化水平。

Ecological Characteristics of Phytoplankton Community Structure in the Littoral Zone of Lake Wuli,Lake Taihu in 2014-2015

The ecological characteristics of phytoplankton community in the littoral zone of Lake Wuli, Lake Taihu were investigate monthly from July 2014 to June 2015 after the comprehensive treatment. A total of 196 species belonging to 8 phyla were identified. 37.76% of the phytoplankton was Chlorophyta, which contained 74 species. 29.08% was Bacillariophyta, which contained 57 species. The dominant phytoplankton contains 30 species of 8 phyla. In July, August, September and October of 2014, and June of 2015, Oscillatoria tenuis has an absolute advantage in the phytoplankton community, the dominant index ranged from 0.567 to 0.879. The averages variations of a month of phytoplankton density and biomass were 1.07×106-2.18×108 ind./L and 0.32-50.52 mg/L, respectively. The density and biomass of phytoplankton were significantly higher in summer and early fall than the rest month of the year due to the large scale proliferation of cyanobacteria. The density and biomass of phytoplankton were notably lower in zone A than in the rest zones. Pearson correlation analysis shows that the density of algae, biomass and species number are significant or notably significant correlated with turbidity(Tur), pH and temperature(T). Redundancy analysis shows that strong correlation was found between water temperature, dissolved oxygen, turbidity and phytoplankton community structure(p<0.01). Moreover, water temperature had the strongest correlation with phytoplankton community structure(r=0.898 2). The index calculated from phytoplankton species and diversity suggests that the littoral ecozone of Lake Wuli, Lake Taihu is suffering from a moderate eutrophication.