Community characteristics of phytoplankton in Yangcheng Lake and relationships with water environmental factors

An investigation was conducted in Yangcheng Lake from July to November,2014,Pearson correlation analysis and redundancy analysis( RDA) were applied to analyze the relationship between the phytoplankton community structure and water parameters. 142 species, 68 genera and 8 phyla were identified,including Chlorophyta( 63 species,accounting for 44. 37%),Bacillariophyta( 27 species),Cyanophyta( 22 species). The number of Chlorophyta was the highest in dominant species,while Cyanophyta was with the highest density. 61. 11% of the dominant species were indicating algae of rich nutritional water.Abundance and biomass of phytoplankton during summer [averaging( 3. 99 ± 4. 00) × 106 cell / L and( 1. 41 ± 1. 05) mg /L,respectively] were considerably higher than those during autumn. Besides,algal density was mainly composed of Cyanophyta,while biomass was mainly composed of diatoms. The results showed that the water quality in Yangcheng Lake was moderately-polluted and the water during autumn was better than summer. The results of Pearson correlation analysis showed that the primary factors affecting the structure of phytoplankton community were identified to be p H,Tem and NO-2-N content during summer.Contents of NO-2-N,CODMn,DTN and DTP were the main factors affecting the structure of phytoplankton community during autumn. RDA results indicated that the key environmental factors influencing the phytoplankton assemblages were Tem,TN and DTP,whereas p H,Tem,DO and DTN were the key factors during autumn.