Research On Plankton Functional Groups And Water Quality Evaluation In Qixinghe Nature Reserve

Qixinghe Nature Reserve,located at the south shore of the middle and lower reaches of the Qixing River,it is one of the most typical and representative wetlands in the Three-River Plain.In recent years,affected by the urban expansion and human activities,wetlands were reclaimed into farmland and the area was reduced.According to the actual situation of Qixinghe Nature Reserve,10 sampling points were set up to investigate the plankton and physi-chemical factors of water environment in spring(May),summer(July)and autumn(September)of 2017.The correlation between plankton and water environmental factors was analyzed and discussed,and the water quality of Qixinghe Nature Reserve was evaluated by physi-chemical indicators and biological indexes.The survey results were as follows:During the investigation,a total of 130 species of 8 phyla and 73 genera of phytoplankton were collected in the Qixinghe Nature Reserve.The number of species of Chlorella and Diatoms was higher than others.There were 59 species of Chlorella,40 species of Diatoms,12 species of Euglenophyta,7 species of Cyanophyta,5 species of Jinzaomen,3 species of Dinoflagellate,and 2 species of Cryptophyta and Xanthophyta.The number of phytoplankton species was the highest in spring(97 species),followed by summer(73 species)and autumn(53 species).The abundance of phytoplankton was between 0.6×104ind./L?506.4xl04ind./L,the annual average abundance was 44.81×104ind./L,and the biomass was between 0.018mg/L and 8.057mg/L,the annual average biomass was 1,24 mg/L.There were 25 phytoplankton functional groups in Qixinghe Nature Reserve,10 dominant functional groups were identified.The dominant functional groups composition of phytoplankton sdemonstrated obviously seasonal dynamics of D/MP/P/Y?D/P?X2/Y.The results of Canonical Correspondence Analysis(CCA)showed that water temperature,turbidity,pH,nitrogen and phosphorus nutrients were the main water environmental impact factors of phytoplankton functional groups.A total of 46 species of 29 genera of metazoan zooplankton were collected from Qixinghe Nature Reserve.The number of rotifer species was the highest,there were 37 species of Rotifers,5 species of Cladocerans and 4 species of Copepods.The number of zooplankton species was summer>spring>autumn,which were 38,29,and 21 species.The abundance of metazoan zooplankton was between 43.00ind./L-5495.00ind./L,the annual average abundance was 564.49ind./L,and the biomass was between 0.028 mg/L and 4.655mg/L,the annual average biomass was 0.69 mg/L.There were 5 metazoan zooplankton functional groups in Qixinghe Nature Reserve:Rotifers filter feeders(RF),Rotifers carnivora(RC),Small copepods and claocera filter feeders(SCF),Middle copepods and claocera filter feeders(MCF)and Middle copepods and claocera carnivora(MCC).The composition of metazoan zooplankton functional groups demonstrated obviously seasonal dynamics of RC/MCC?RF/RC/SCF/MCC?RF/MCC.The results of Redundancy Analysis(RDA)showed that water temperature,conductivity,turbidity,chloride ion,nitrogen and phosphorus nutrients were the main water environmental impact factors of metazoan zooplankton functional groups.The seasonal differences of water temperature(WT),chloride(Cl-)and ammonium ion(NH4+)in Qixinghe Nature Reserve were significant.Water quality evaluation was carried out by Trophic State Index,phytoplakton Biodiversity Index and phytoplankton functional group Q Index.The results showed that Qixinghe Nature Reserve was in the light pollution state with medium nutrient level.