Relationship between phytoplankton community and environmental factors in landscape water with high salinity in a coastal city of China

Relationship between phytoplankton community and environmental variables was explored in three landscape water bodies (namely Jiyun River Oxbow (JRO), Qingjing Lake (QL), and Jiyun River (JR)) with high salinity, located in Sino-Singapore Tianjin Eco-city of China, using redundancy analysis (RDA). A total of 48 species of phytoplankton were identified during the study period, in which Chlorophyta and Bacillariophyta accounted for 35.42 and 31.25%, respectively. The most dominant species of the studied water bodies were Cyclotella meneghiniana (Bacillariophyta) and Aphanocapsa elachista (Cyanophyta). The diversity index ranged from 0.56 to 1.42, with an average of 1.11, reflecting low biodiversity in the phytoplankton community. Moreover, the average density of phytoplankton was 42.39x10(6)cells/L, indicating that those landscape water bodies belonged to moderate eutrophication. The results of RDA revealed that the most significant environmental factors influencing phytoplankton community were water temperature (WT), dissolved total phosphorus (DTP), salinity, and total nitrogen (TN) (p<0.05, Monte Carlo permutation test). Meanwhile, Aphanocapsa elachista was positively correlated with WT, TN, and salinity, while Cyclotella meneghiniana was positively related to salinity and negatively related to TP. The results suggested that salinity was a non-negligible key factor affecting the phytoplankton community of the water body with high salinity.