Studies on phytoplankton community structure and its environmental impact factors in the ponds stocked mainly Ctenopharyngodon idellus

During May to October,2010,the community structures phytoplankton and physico-chemical factors in the ponds where Ctenopharyngodon idellus were predominant stocking fish species were investigated and analyzed. The relationship between phytoplankton community structure and environmental factors in the ponds were conducted using canonical correspondence analysis(CCA). Present study showed that phytoplankton identified from the ponds belonging to 240 species, 102 genera and 8 phyla. Specifically,phytoplankton included Chlorophyta(114 species,44 genera),Cyanophyta(44 species,20 genera),Bacillariophyta(19 species,12 genera),Euglenophyta(38 species,10 genera),Chrysophyta(7species,5 genera),Xanthophyta(8 species,5 genera),Pyrrophyta(6 species,4 genera),and Cryptophyta(4 species,2 genera). The phytoplankton density ranged from 1. 77 × 107to 8. 83 × 107ind / L and the average was 4. 23 × 107ind / L. The phytoplankton biomass ranged from 12. 24 to 298. 58 mg / L and the average was 44. 13 mg / L. ShannonWiener diversity index was 1. 80 ~ 3. 69,Margalef diversity index was 3. 12 ~ 6. 74 and Pielou evenness index was 0. 31 ~ 0. 61. The CCA final results showed that WT,SD,DO,pH,NO2--N and SS were the main factors affecting the number of phytoplankton.