| Daqing River flows across four provinces and the cities of Shanxi, Hebei, Beijing and Tianjin. With a surface area of 45,131 km2, the river plays an important role in maintaining the ecological balance and climate regulation of northern China. In this study, we characterized the zooplankton community of Daqing River and evaluated the water quality based on the results. The objective was to provide a scientific basis for restoring the Daqing River ecosystem. Zooplankton investigations were carried out in May and August of 2018 at 25 sampling sites in the Daqing River basin, focusing on species composition, density, dominant species and community diversity. A total of 28 zooplankton species belonging to 18 genera were detected, with absolute dominance by rotifera (16 species, 10 genera, 57.14 % of the total species), followed by cladocera (6 species, 5 genera, 21.43 %) and copepoda (4 species, 3 genera,14.29%). There was not a significant difference in the average density of zooplankton between May (643.08 ind/L) and August (715.20 ind/L). Nine species were dominant during both investigations, with the dominant species in the order, rotifera＞cladocera＞copepoda, while the dominance degree was in the order, copepoda＞rotifera＞cladocera. The dominant species included Asplanvhna priodonta，Brachionus urceus，Brachionus calyciflorus, Polyarthra trigla, Moina rectirostris, Cyclops vicinus. The Shannon-Wiener diversity, Pielou evenness and Margalef richness indices of the zooplankton community in the Daqing River Basin were in the respective ranges of 0.35-1.83, 0.09-0.32, 0.30-1.39 in May and 0.23-2.18, 0.03-0.34, 0.12-1.44 in August. Water quality evaluation, based on community diversity, indicated that 2% of the sites were lightly polluted, 36% were moderately polluted and 62% were heavily polluted. To summarize, the pollution level in the Daqing River basin was at a medium to heavy level in 2018. |
