Structural Analysis Of Algae Functional Groups And Influence Of Environmental Factors In Dongping Lake

Dongping Lake is the main storage lake for the east route of the South-to-North Water Transfer Project.Fully understanding its structural succession characteristics of phytoplankton functional groups and its correlation with environmental factors can provide water supply security and water bloom prevention and control within the east route of the South-to-North Water Transfer Project effective theoretical basis.This study analyzed the water quality and algae data of Dongping Lake from May 2010 to December 2018.Based on the analysis of phytoplankton structure,the algae in Dongping Lake were divided according to the classification characteristics of phytoplankton functional groups.The interannual succession rules of the functional groups before and after water transfer and the dominant functional groups were analyzed.The growth characteristics of the dominant functional groups before and after water transfer were analyzed.The main environmental factors that promoted the evolution of Dongping Lake functional groups before and after water transfer were explored through redundant analysis The main conclusions are as follows:(1)A total of 300 species(including variants)of 8 phylum 123 genus of planktonic algae were detected in Dongping Lake,divided into 30 functional groups A,B,C,D,E,F,G,H1,J,K,LM,Lo,M,MP,N,P,S1,S2,SN,T,TB,TC,W1,W2,Ws,X1,X2,X3,XPh,Y.After the water diversion,the density and functional biomass of phytoplankton in Dongping Lake decreased drastically compared with that before water diversion,which is related to the improvement of water quality after water diversion in Dongping Lake.(2)Cluster analysis shows that the similarity of functional groups before water transfer to Dongping Lake is close to 70%,and the similarity of functional groups after water transfer is higher than 70%;NMDS analysis shows that the structural changes of functional groups before and after water transfer to Dongping Lake are quite different.The predominant functional groups before water transfer are P,D,S1,H1,B,X1,MP,Y,W1,Lo,C,and the predominant functional groups after water transfer are P,C,X1,MP,S1,D,W1,Y,A,J,B,F.The change of the functional group before and after water transfer is mainly manifested as the transformation of the functional group adapted to eutrophication and layered water to the functional group adapted to the higher mobility of the water and clean water.(3)Before water transfer,the main environmental driving factors affecting the structural changes of phytoplankton algae are T,TN and TP.The response of functional group H1 to T is obvious.Most functional groups have a positive correlation with TN and TP,indicating that the nutrient concentration of the water body before water transfer is the main factor affecting the structural changes of algae functional groups.After water transfer,the main environmental driving factors affecting the structural changes of phytoplankton algae were SD,T,CODMn,and TP.Except for functional group D,the other dominant functional groups are positively correlated with T,CODMn,and TP,and functional group P is negatively correlated with SD.Before the water transfer,the nutrient concentration in Dongping Lake is the main variable affecting the structure of the functional group.After the water transfer,the diversity of environmental driving factors reveals that the water body of Dongping Lake has improved to a certain extent after the water transfer.The fluidity of water also makes SD a major environmental driver.