Phytoplankton Community Structure and Diversity in Xiaoxingkai Lake

As a part of Xingkai Lake, Xiaoxingkai Lake has a hydraulic connection with Daxingkai Lake. The phytoplankton community structure and the nutrition status of Xiaoxingkai Lake will affect the water environment of Daxingkai Lake. In order to understand the phytoplankton community structure and the nutrition status of Xiaoxingkai Lake, phytoplankton survey was performed in 12 sampling sites to evaluate characteristics of phytoplankton species composition, abundance, biomass and distribution and their changes in Xingkai Lake from May to September, 2011. The results showed that, there were 121 species of phytoplankton which belong to 7 phyla during the five months in Xiaoxingkai Lake. Bacillariophyceae, Chlorophyta and Cyanophyta were the majorityes, which were 44%, 26% and 22% of the whole species. Melosira granulata var.angustissima, Chlorella vulgaris and Anabaena azotica were the dominant species. Abundance ranged from 0.11 mg/L to 1.73 mg/L. The diversity indexes of Shannon-Wiener, Margalef and Pielou ranged 2.64-4.64, 1.46-5.17, 0.35-0.86, respectively. Comprehensive assessment was conducted by composition, biomass and diversity index of phytoplankton in Xingkai lake, which showed that, the dominant species of Xiaoxingkai Lake were cyanobacteria and diatoms aunual, the most phytoplankton species was in July, and the least was in September. The highest ShannonWiener diversity index and Margalef species richness index was in May, the lowest was in September; the highest Pielou evenness index was in September, the lowest was in July. The phytoplankton diversity index of the undisturbed area in Xiaoxingkai Lake was significantly higher than the area where human activities effected.