Identification of Seasonal Variation and Influencing Factors of Phytoplankton Communities in Changqiao Lake at Yunnan Province
A survey on the biomass and communities of phytoplankton was conducted in June,Septem-ber,December of 2017 and March of 2018 in order to uncover the seasonal pattern of phytoplankton and their relationship with environmental factors in Changqiao Lake.The results showed that the phy-toplankton biomass ranged from 17.9~60.5 mg/L,with the highest in September and the lowest in June.The phytoplankton community was composed of Cyanophyta,Chlorophyta,Bacillariophyta,Pyr-rophyta,Euglenophyta,Cryptophyta and Chrysophyta.Cyanophyta was absolutely dominant and main-ly consisted of Limnothrix spp.,Cylindrospermopsis raciborskii and Pseudanabaena spp..The results of analysis of variance and analysis of similarity displayed that phytoplankton biomass and community structure(phylum and genus levels)both exhibited a significant seasonal variation.The Pearson corre-lation analysis revealed that total phytoplankton biomass was significantly and positively correlated with TN,N∶P and NO3-N.The Redundancy analysis indicated that WT,TN,TP,N∶P and NO3-N were significant factors influencing the change of phytoplankton communities.Variation partitioning analyses further demonstrated that WT,TN and TP independently explained 12.6%,20.9%and 5.1%of community variation,and the interaction of TP with WT and TN accounted for 2.1%and 1.1%of the total variance,respectively.Our results will provide basis for the environmental protection,man-agement and ecological evaluation of Changqiao Lake.