Community Structure And Functional Groups Of Plankton And Water Quality Evalution In Hanjiang River

As the largest tributary of the Yangtze River,the Hanjiang River is of great economic and ecological value.In recent years,affected by the human activities and hydraulic engineering,the water environment of the Hanjiang River has changed significantly.According to the actual situation of Hanjiang river,9 sampling points were set up to investigate the plankton and water environmental factors from July2018 to May 2019.The community structure and functional groups characteristics of plankton in Hanjiang River was studied.The correlation between the functional groups of plankton and water environmental factors was analyzed,and the water quality of Hanjiang River was evaluted by biological indexes and water environmental factors which provided theoretical basis for water resource utilization and water ecological protection in Hanjiang River..The survey results were as follows:1?During the investigation,a total of 116 species of 7 phyla and 71 genera of phytoplanton were collected in the Hanjiang River.The number of species of Chlorophyta and Bacillariophyta was higher than others,respectively 46 and 43 species.There were 15 species of Cyanophyta,6 species of Euglenophyta,3 species of Cryptophyta,2 species of Pyrroptata,and 1 species of Chrysophyta.The number of phytoplankton species was the highest in summer,followed by autumn,spring and winter.The dominant species of phytoplankton were species of Bacillariophyta,among which Cyclotella catenata,Cyclotella catenata,Synedra ulna and Pseudoanabaena sp.were the dominant species throughout the yeas.The abundance of phytoplankton was between 3.3×10~4 and 1.62×10~7 ind./L,the annual average abundance was 1.9×10~6 ind./L,and the biomass was between 0.0382 and 8.4800 mg/L,the annual average was 1.5332 mg/L.A total of 86 species of 55 genera of zooplankton were collected from Hanjiang River.The number of Rotifer was the highest,there were 48 species of Rotifers,21 species of Protozoa,6 species of Cladocerans and 11 species of Copepods.The seasonal variation of species numbers is consistent with zooplankton and phytoplankton.The dominant species of zooplankton were species of Protozoa,among which Strombidium viride Muller was the dominant species in the whole year.The abundance of zooplankton was between 10.5 and 2000.2 ind./L,the annual average abundance was 447.77 ind./L,and the biomass was between 0.0061 and1.9764 mg/L,the annual average was 0.2507 mg/L.2 ? There were 23 phytoplanton functional groups in Hanjiang River,among which B,D,MP and P functional groups appear at all sampling points throught the year.The important functional groups were B,P,D,MP,TB,and Lo.The dominant functional groups composition of phytoplankton demonstrated obviously seasonal dynamics of D+MP+B+P?D+MP?D+MP+P+TB?D+MP+P+B+Lo.The water temperature,transparency,nitrogen and phosphorus nutrients were the main water environmental impact factors of phytoplankton functional groups.There were 9 zooplanton functional groups in Hanjiang River.The important functional groups were Protozoa filter feeders(PF)and Rotifers filter feeders(RF).The dominant functional groups composition of zooplankton demonstrated obviously seasonal dynamics of LCF+RF?PF+RF+MCC?PF+MCC?PF+RF+SCF.The nitrogen nutrients,water temperature,electrical conductivity and transparency were the main water environmental impact factors of zooplankton functional groups.3?Water quality evaluation was carried out by Chemical Comprehensive Pollution Index(Pb/n),plankton Biodiversity Inder and phytoplankton functional group Qr Inder.The results showed that Hanjiang Rriver was belong to slightly to moderately polluted.