关键词: 浮游动物, 分布特征, 综合营养状态指数, 冗余分析, 恰甫其海

Abstract:

To study the community structure of zooplankton and aquatic environment at Qapchy Lake, Xinjiang, China, a survey was conducted in July (abundant water period), September (level water period), and December (dry water period) in 2019. Biodiversity indices and comprehensive trophic level index method were used to analyze the aquatic environment state during different months. The redundancy analysis method was used to analyze the relationship between the structures of the zooplankton community and environmental factors. The results showed that: (1) Thirty-seven species of zooplankton were detected, including 17 species of protozoa, 10 species of rotifer, 4 species of Cladocera, and 6 species of Copepods. The community structure of zooplankton was dominated by Strobilidium sp., Centropyxis sp., Tintinnopsis wangi, Synchaeta sp., Polyarthra vulgaris, and Centropyxis sp. The abundance of zooplankton was 580.40 ind·L ^-1 during the abundant water period, 152.68 ind·L^-1 during the level water period, and 137.01 ind·L^-1 during the dry warer period. Zooplankton biomass was 0.550 mg·L^-1, 0.018 mg·L^-1, and 0.007 mg·L^-1 during the abundant water period, level water period, and dry water period, respectively. The maximum values of zooplankton abundance and biomass values appeared in the abundant water period. (2) The spatial and temporal distribution of the diversity index differed in each water period. In the abundant water period, H \mathrm{\text{'}} and D values showed an increasing trend from reservoir head to the dam. Conversely, in the level water and dry water periods, H \mathrm{\text{'}} and D values of zooplankton in the middle position of the reservoir showed the lowest values. H \mathrm{\text{'}} and D mean values of zooplankton in Qapchy Lake of three water periods were 1.19 and 0.82. (3) As the results of redundancy analysis showed, water temperature, chemical oxygen demand, and nutrient salt (including the concentration of TN, TP, $NO_{3}^{-}-N$, $NO_{2}^{-}-N$, $NO_{4}^{+}-N$, $PO_{4}^{3-}-P$) were environmental factors influencing the change in zooplankton community. Water temperature was the main factor affecting the community structure of zooplankton in different water periods. Based on the results from the biodiversity and trophic state indices, the water environment of Qapchy Lake was oligotrophy or mild moderately eutrophication, meaning that the water environment in the reservoir of the upper Ili River was less disturbed by herding, cropping, and human activities. The relatively healthy water environment made a good habitat for freshwater fishes, which was suitable for them as wintering, swamping, and feeding ground.

Key words: zooplankton, distribution tendency, comprehensive trophic level index, redundancy analysis, Qapchy Lake