| The community structure and seasonal succession of phytoplankton were investigated from April 2011 to March 2012 in Erhai Lake. A total of 115 phytoplanktonic algal species belonging to 7 phyla were identified, including 24 species of Cyanophyta , 16 species of Bacillariophyta , 65 species of Chlorophyta, 3 species each of Pyrrophyta and Euglenophyta, and 2 species each of Cryptophyta and Chrysophyta. In Spring, Fragilaria capucina Desm,Chroomonas acuta Uterm and Melosira sp. were the dominant species. In Summer, Chroomonas acuta Uterm, Cyclotella sp., Melosira sp., Mougeotia sp., Microcystis wesenbergii and Woronichinia were the dominant species. In Autumn, Woronichinia sp. and Planctonema lauterbornii were the dominant species. In Winter, Planctonema lauterbornii , Aphanizonmenon flos-aquae and Fragilaria capucina Desm were the dominant species. The biomass of phytoplankton was lower in Spring and Winter than in Summer and Autumn. The peak cell density of algae was 5899.17×104 cells/L in November and the minimum value was 339.21×104 cells/L in February. The biomass of phytoplankton in Erhai Lake has been increasing, and the diversity index reducing. Microcystis wesenbergii and Woronichinia become the dominant species of phytoplankton in stead of Anabeana, the cell density of Chlorophyta has been growing. |
