Community structure and diversity of phytoplankton in lake Chaiwopu

Investigation was conducted on the species of phytoplankton in the Chaiwopu Lake in Xinjiang during May to September,2007.Qualitative analysis and quantitative analysis methods were adopted to identify and compare these species on their composition,abundance and diversity including Margalef diversity index,Shannon-Weaver diversity index and Pielou index.The results showed that 92 species of phytoplankton were identified from the total 4 sorts of water samples.They belonged to 60 genera,31 families and 8 divisions.Bacillariophyta is the most diversified division,while Chlorophyta is the abundant one,Chlorophyta takes second place.There are 5 dominant species,they are Synedra ulna Ehr.,Synedra affinis Ehr.,Scenedesmus quadricauda Breb.and Acanthosphaera zachariasi Lemm.The structure of the community is Bacillariophyta-Chlorophyta-Cyanophyta composition.In addition,the growths of phytoplankton at entrance and bank spots are dominant in summer and autumn.It also found that Chaiwopu Lake have been polluted and it was assessed to be meso-trophic by comparing diversity indices.