Study on the spatio-temporal distribution of cyanobacteria in the East Tiaoxi River and its relationship with environmental factors
东苕溪蓝藻时空分布及其与环境因子关系研究

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).