Community structures of phytoplankton and their relationships with environmental factors in the Jinshahe Reservoir,Hubei Province

In order to evaluate the water quality of drinking water resource in the middle reaches of the Changjiang River,phytoplankton community structures and their diversities were investigated seasonally from August,2013 to April,2014 in the Jinshahe Reservoir,Hubei Province. Meanwhile,multivariate statistics was used to analyze the relationships between phytoplankton assemblages and environmental variables. The results showed that there were total of 216 species of phytoplankton belonging to 8 phyla and 94 genera. Chlorophyta which made up of 51. 39% of the total numbers of the species was the dominant group,followed by Bacillariophyta and Cyanophyta. Dominant species varied in different seasons. In summer,the ecological dominance of Synedra acus was the highest( 0. 195),and in autumn,Phormidium tenus( 0. 180) and Raphidiopsis sinensia( 0. 171) had the highest ecological dominance. In winter,Cyclotella stelligera( 0. 220) and Dinobryon cylindricum( 0. 234) had the highest ecological dominance,and Achanthidum catenatum was the absolute dominant species with its ecological dominance of 0. 910. In general,Cyanophyta,Bacillariophyta and Chlorophyta were dominant groups in summer,and Cyanophyta,Bacillariophyta,Chlorophyta and Cryptophyta were dominant groups in autumn. Bacillariophyta and Chrysophyta were dominant groups in winter,and Bacillariophyta was the absolute dominant group in spring. Biodiversity indices showed that phytoplankton had higher values of the ShannonWiener diversity and the Pielou diversity in autumn,but the lowest values in spring because the absolute dominant species appeared in spring other than in autumn. In addition,the highest value of Margalef diversity occurred in autumn because of its larger numberof species. Redundancy analysis was used to analyze the relationships between the dominant species in each season and the environmental factors filtered by Pearson correlation analysis. The results showed that phosphate,total phosphorus and water temperature were the main environmental factors that have influenced phytoplankton assemblages. The reservoir had worse water quality in summer and autumn than in spring and winter which impacted on the variations of dominant groups of phytoplankton in different seasons,and had worse water quality in spring and summer than in autumn and winter which impacted on the cell abundance and biodiversity indices.