Relationship between phytoplankton community in summer and environmental factors in Shanghai park lakes

In order to understand the phytoplankton community structure and the phytoplankton' s demands for environment in Shanghai park lakes, a field survey was conducted in 11 park lakes in Shanghai in July and September 2008 , with the relationships between the distribution of phytoplankton species and the environmental factors analyzed. A total of 384 species were identified, belonging to 8 phyla. The phytoplankton density ranged from 2. 01 × 10⁵-57. 60 × 10⁵ cells · L^-1. The phytoplankton community was mainly composed of Cyanophyceae, Euglenophyceae, Bacillariophyceae, and Chlorophyceae, and the dominant species were Oscillatoria subtillissima, Dactylococcopsis irregularis, Euglena caudata, Melosira granulata, Cyclotella meneghiniana, Chlorella vulgaris, and Scenedesmus quadricauda. The main environmental factors affecting the distribution of phytoplankton species in July were ammonium-nitrogen, dissolved oxygen, water temperature, and total phosphorus, while those in September were pH, water temperature, dissolved oxygen, transparency, and total nitrogen. Water transparency and zooplankton were the main factors affecting the biomass of Cryptophyceae, Pyrrophyceae, and Bacillariophyceae; while nitrogen, phosphorous, and dissolved oxygen were the main factors affecting the biomass of Cyanophyceae, Euglenophyceae, and Chlorophyceae.