Abstract: To explore the phytoplankton community structure and its relationship with environmental factors, a survey was conducted in the newly excavated landscape river (Port B, Lingang, Shanghai) from December 2011 to November 2012. The results showed that there were 223 phytoplankton species, which belong to seven Phyla. Phyla Chlorophyta had the most species, followed by Cyanophyta and Bacillariophyta. The phytoplankton abundance ranged from 7.52×10⁶ to 212×10⁶ cells·L^-1, with an average of 66.27×10⁶ cells·L^-1. The species abundance in the rainy period was significantly higher than in the drought period, while cell density was vice versa. The dominant species was simplex for each season, which mainly consisted of the Merismopedia spp. Canonical correspondence analysis (CCA) showed that the distribution of phytoplankton in the four quadrants was homogeneous, which reflected the typical characters of subtropical climate. PCA and CCA indicated that salinity and nutrients (TN and TP) were the main driving factors for the dynamic change of phytoplankton community. Chroococcus minor, Merismopedia glauca, Tetraedron tumidulum and Synedra sp. could be used as efficient indicators for salinity, while Fragilaria brevistriata, Synedra acus, Ntizschia closterium and Chroococcus tenax showed a potential value for indicating the organic pollution.

Key words: dominant species, generalized additive model., forest community, niche breadth, niche overlap