The biological indicators of planktonic algae have been widely utilized in the field of monitoring and evaluating eutrophic state of different waters.In this paper,seasonal changes of planktonic alga composition were investigated to explore the relationship between planktonic alga indicators and the eutrophication characteristics of artificial lakes on four campuses in Beijing.During the investigation,39 genera of planktonic algae belonging to Chlorophyceae,Cyanobacteria and Bacillanophyta were identified.Seasonal average phytoplanktonic densities in four lakes were over 500 cell·ml-1.The biodiversity indices of four lakes across seasons were mostly between two and three.The water quality indicators,TN,TP and COD reflected that four lakes were all in eurtrophic state. However,the evaluation results on eutrophic levels were variable according to different indices.Therefore,cluster analysis was applied to combine the biological indicators and water quality indicators.The results showed that all of the seasonal waters could be classified into three different eutrophic types,according to the phytoplanktonic composition.The characteristics of phytoplankton community were most similar between Hehuachi and Hetang,while the eutrophic levels in summer were close between Hetang and Weiminghu.
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