Seasonal Succession And Its Driving Factors Of Phytoplankton Functional Groups In Yuqiao Reservoir

Phytoplankton occupies the primary producer status in the aquatic ecosystem.The community change of phytoplankton plays a very important role in monitoring water nutrient changes and indicating the quality of water body.The classification method of functional groups is the newest method of community research at home and abroad.In this paper,the phytoplankton and water bodies in Yuqiao Reservoir were sampled in 2016 and 2017 to study the effects of major environmental factors on the phytoplankton functional groups.RDA was used to analyze the correlation between the phytoplankton and the environmental factors.The main conclusion are as follows.(1)A total of 72 species of phytoplankton were identified in the studied area in 2016,which belonged to 6 phyla and 37 genera.Among these species,37 species belonging to Chlorophyta were identified,accounting for 51%of the total number of phytoplankton species;16 species of cyanobacteria,accounting for 22%of the total phytoplankton species species;the others were 12 species of diatoms,3 species of Cryptophyta,2 species of Dinoflagellate,2 species of Euglenophyta.In spring,the total phytoplankton abundance was 2.94 × 107 cells/L.In summer,the total phytoplankton abundance was 2.89 × 108 cells/L.In autumn,the total phytoplankton abundance was 8.281 x 106 cells/L.The overall trend of the spatial distribution of the three seasons is higher in the west than in the east.Diversity index on water quality evaluation,said the level of pollution in spring and summer is heavy pollution,good water quality in autumn.(2)A total of 73 species of phytoplankton were identified in the studied area in 2017,which belonged to 6 phyla and 38 genera.Among these species,40 species of Chlorophyta,accounting for 59%of total phytoplankton species,11 species of diatoms,accounting for 17%of the total phytoplankton species species;the rest were 8 species of cyanobacteria,3 species,3 species of dinoflagellate,2 species of Euglenophyta.In spring,the total phytoplankton abundance was 6.63 × 106 cells/L.In summer,the total phytoplankton abundance was 3.82 × 107 cells/L.In autumn,the total phytoplankton abundance was 1.98× 107 cells/L.Diversity index on water quality evaluation,said spring and summer water quality is good,slight pollution in autumn.Phytoplankton abundance in spring and summer 2017 was significantly higher than in 2016,with significant improvement in eutrophication and a slight increase in phytoplankton abundance in autumn 2017.(3)During the survey in 2016 and 2017,a total of 20 functional groups were found.In 2016,the seasonal variation of dominant functional groups were J,K,LO and TC in spring;the dominant functional groups in summer were M;and the dominant functional groups in autumn were G,J,K and M.In 2017,the seasonal variation of dominant functional groups were J,K and P in spring;the dominant functional groups in summer were H1,K and M;the dominant functional groups in autumn were J,K and M;According to the different adaptation environment of different functional groups,different dominant functional groups were formed in different seasons,and the functional group M represented by Cyanophyta became the dominant functional group in both 2016 and 2017 summer and autumn.(4)RDA analysis of dominant functional groups and environmental factors in 2016 and 2017.The main influencing factors in 2016 are transparency,total nitrogen,temperature and permanganate index.In 2017,temperature and nitrite nitrogen are the major influencing factors for phytoplankton functional group.Temperature and nitrogen content became the main driving factors of water quality in Yuqiao Reservoir.