Canonical Correspondence Analysis on Phytoplankton Community and Its Environmental Factors in Poyang Lake

Aimed at identifying the key influencing environmental factors of phytoplankton community, we investigated phytoplankton in June 2010 and February 2011 in Poyang Lake. Species from 58 genuses, 32 families and 7 phyla had been found in the investigations, and the major phyla were Chlorophyta, Bacillariophyta and Cyanophyta. The average abundance of phytoplankton in summer and winter were 35.92x10(5) cell/L and 6.63x10(5) cell/L, respectively. Even though the unique hydrodynamic conditions of such a water passing lake (during flood seasons Poyang Lake forming a vast lake, but in dry seasons, lake recedes into a channel) make the water environment unstably, Chlorophyta are able to adapt to the conditions and grow well, therefore, the lake was dominated by Chlorophyta, especially Chlorella and Cosmarium, respectively accounting for 56.38 % and 52.10 % of the total abundance in summer and winter. CCA ordination on 12 sampling sites, 58 genuses of phytoplankton and 10 environmental factors demonstrated that there were great geographic differences of water environmental physicochemical conditions in winter, while in summer, it's not significant, besides, DO, water temperatufe and nutrients (nitrogen and phosphate) were the most important environmental factors that regulated the distribution of phytoplankton community.