东苕溪蓝藻时空分布及其与环境因子关系研究

研究了东苕溪(太湖主要入湖河流)秋季和春季浮游植物的空间分布格局,监测了东苕溪18个采样点的浮游植物叶绿素a含量、细胞密度及种类组成等指标,分析了影响蓝藻时空分布差异的环境因子.结果表明:调查期间,共观察到浮游植物8门60属132种,其中,蓝藻门9属14种,蓝藻细胞密度占浮游植物细胞密度的平均比例为60.3%,蓝藻细胞密度自东苕溪下游至上游呈减小趋势,最高值出现在东苕溪下游距南太湖湖口3km以内.在秋季,东苕溪下游以铜绿微囊藻(Microcystis aeruginosa)为优势种,春季为水华鱼腥藻(Anabaena flos-aquae);丝状蓝藻(小席藻)是上游的优势代表种.东苕溪下游蓝藻的绝对优势与特殊的水动力条件、高浓度的营养盐有关.相关性分析表明,蓝藻细胞密度与水深(p<0.01)、总氮(p<0.01)和溶解性总碳(p<0.05)呈显著正相关.

Study on the spatio-temporal distribution of cyanobacteria in the East Tiaoxi River and its relationship with environmental factors

An investigation of the spatio-temporal distribution of phytoplankton community was carried out in the autumn and spring seasons in the East Tiaoxi River. Chlorophyll a concentration, density and composition of phytoplankton were measured. Furthermore, environmental factors influencing the spatio-temporal distribution of cyanobacteria were also investigated. The obtained results showed that a total of 132 taxa in 60 genera of eight phyla was observed, including 14 taxa in nine genera belonged to cyanobacteria, accounting for 60.3% of the phytoplankton density. The highest values of cyanobacteria density were found three kilometers away from the mouth. Microcystis aeruginosa dominated downstream in autumn and Anabaena flos-aquae dominated in spring, while Phormidium tenue dominated upstream. The special hydrodynamic conditions and high concentration of nutrients led to a sustained high abundance of cyanobacteria downsteam the river. Correlation analysis showed that the density of cyanobacteria was significantly correlated with the water depth and total nitrogen concentration (p<0.01), and also positively correlated with dissolved total carbon (p<0.05).