STUDY ON PLANKTON OF DIFFERENT CATEGORIES OF LAKES IN SUMMER BY MEANS OF PRINCIPAL COMPONENT ANALYSIS,FACTOR ANALYSIS AND CLUSTER ANALYSIS

In order to understand the change regularity of the lake ecosystem deeply and provide basic data for lake fishery and management,the author measured the plankton in five aquaculture lakes,Liangzi Lake,Futou Lake,Chaipo Lake,Nanhu Lake and Yezhi Lake respectively,in Wuhan in summer 2007.SPSS was used for principal component analysis and factor analysis of quantity and biomass of six phyla of phytoplankton and four species of zooplankton of five lakes.Two analysis results were different,which was attributed to the difference between two methods.The combination of the above methods would effectively improve the accuracy of analysis result.The result indicated that the first principal component of planktons of the 5 lakes was cladocera and copepod quantitative and gravimetric factors;the second was rotifer quantitative and gravimetric factors and chlorophyta quantitative factor;the third was cryptophyta quantitative and gravimetric factors;the fourth was protozoan quantitative and gravimetric factors;the fifth was cyanophyta quantitative factor;and the sixth was euglenophyta quantitative and chlorophyta gravimetric factors.In addition,SPSS was also used for hierarchical clustering of quantity and biomass of each phylum and species of plankton of the five lakes,and 13 points were divided into five categories,that is,Points 3 and 5 of open water zones of Liangzi Lake and Futou Lake belonged to one category;Points 1 and 4 of enclosed aquaculture zones of Liangzi Lake and Futou Lake and Point 2 near Liangzi Island belonged to one;Points 6,7 and 8 of Chaipo Lake belonged to one;Point 10 near the sewage drainage outlet of Nanhu Lake belonged to one;and Points 9,11,12 and 13 of Nanhu Lake and Yezhi Lake belonged to one.According to the analysis,the above results are caused by urban wastewater,domestic wastewater and aquaculture production.