| The community structure and biodiversity of phytoplankton of Zhangweinan Canal were investigated at19sampling stations. A total of395species belonging to131genera, eight phyla were identified. The Chlorophyta had the highest species number (159) and the Bacillariophyta had the second (110), and the Euglenophyta and the Cyanophyta ranked the third and the fourth, respectively. The average cell density of phytoplankton was21.672×106cells/L, with a maximum of33.5×106cells/L in summer and a minimum of12.21×106cells/L in autumn; the Chlorophyta had the maximum cell density (11.67×106cells/L) among all the eight phyla. The average biomass density of phytoplankton was25.96mg/L, with a maximum of54.43mg/L in summer and a minimum of6.33mg/L in autumn; similarly a maximum of11.09mg/L occurred in the Chlorophyta. Biodiversity calculations included Shannon index, Margalef index and Pielou index. Shannon index changed from3.05to3.93with an average of3.49, Margalef index ranged from2.14to3.47with an average of3.01, and Pielou index varied from0.50to0.62with an average of0.55. The result shows that the biodiversity of phytoplankton was the highest in the summer, followed by in the spring.A Total of127species belonging to71genera of protozoan were identified;105species belonging to rotifers29genera were identified;21species belonging to Cladocera10genera were identified; three species belonging to Copepods were identified; the average cell density of zooplankton was116.536×103cells/L, with the largest number of protozoa of116.536×103cells/L, the percentage was96.66%, the number of Rotifers was the second with a average cell density of3.798×103cells/L, the percentage was3.26%; the number of Copepods was the third with a average cell density of0.0567×103cells/L, the percentage was0.0487%; the number of Cladocera was the least with a average cell density of0.0395x103cells/L, the percentage was0.03%; Zooplankton community constitutes a major protozoa, followed by Rotifers, Cladocerans and Copepods appeared less, mainly micro Moina, Cyclops and Nauplii. Zooplankton was relatively large, than less of its kind, which was a representation of the body of water contaminated. The average biomass density of zooplankton was13.187mg/L, with a maximum of17.159mg/L in spring and a minimum of5.805mg/L in autumn. The average annual biomasses of protozoa, rotifer, Cladocera and Copepoda were3.379,2.667,6.458and0.683mg/L,respectively. A total of48species belonging to benthic fauna were identified. Oligochaetes was9species, accounting for18.75%of the entire species; Aquatic insects was21species, accounting for18.75%; Molluscs insects was16species, accounting for33.33%; others was2species, accounting for4.17%. The seasonal changes of species composition of benthic was as below, Oligochaetes had the same species in the summer and autumn, with7species, spring had the second with6species; Aquatic insects had the species up to16in the summer, spring had the second with11species, spring had the least wih7species; Molluscs had the species up to7in the summer, autumu had the second with6species, spring had the least wih5species; the average density of Benthic fauna was186.24ind./m2, with a largest percentage of Oligochaetes of51.84%and a second percentage of Aquatic insects of44.92%; the average biomass density of Benthic fauna was2.79g/m2, with a percentage of Oligochaetes of59.88%, Mollusks20.80%, Aquatic insects17.21%and others2.12%. The average density of Benthic fauna of Zhangweinan canal was in spring (220.82ind./m2)> summer (181.16ind./m2)> autumn (153.39ind./m2), the average biomass density of Benthic fauna of Zhangweinan canal was in spring (6.61g/m2)> summer (1.48g/m2)> autumn (1.46g/m2). Viewing from the composition of the annual benthic fauna density, Oligochaetes had the largest percentage of51.9%, viewing from the composition of the biomass of the benthic animals, Oligochaetes had the largest percentage of47.4%. |
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