Abstract: The six stations of Zhangye National Wetland Park in drought and cold area were selected for surveying phytoplankton community structure and water environmental quality from 2014a to 2015a. The results showed that in the park there were 257 species belonging to 8 divisions, 91 genera and including variants. The average density of phytoplankton in the spring, summer, autumn and winter were 1.02×106, 1.04×107, 7.12×106 and 9.28×105 cells/L, respectively. The dominant species ecological succession was remarkable in each season. Bacillariophyta was dominated in spring and winter. However, blue-green algae was dominated in summer and autumn. The phytoplankton communities were varied with the Shannon-Weaver diversity index of 1.02-3.45, the Margalef richness index of 2.35-4.18 and Pielou evenness of 0.27-0.89, respectively. Through the comprehensive evaluation to diversity and density of algae, the water was moderately polluted in summer due to a large number of visitors to the park while the remaining seasons had high water quality.

Key words: Zhangye National Wetland Park, phytoplankton, community, diversity, water quality