| Xinxiang Yellow River Wetland Bird National Nature Reserve is the main route forthe migration of birds from north to south in China and one of the wintering grounds for waterfowl in North China.It has crucial ecological value.Chenqiao east lake and Qinglong lake are located in the central experimental area of Xinxiang Yellow River Wetland,they are the perennial catchment areas on the north side of the Yellow River embankment and the main water bird settlements.Water quality is closely related to the survival of wetland birds,the current severely degraded of wetland water environment has caused strong effect with waterfowls.Plankton,as an important component of the water ecosystem and the starting point of the aquatic food chain,is often used as an indicator of water pollution because of its sensitivity to water environmental changes.In order to correctly evaluate the water quality of the two lakes and provide scientific and rational basis for the ecological restoration of their water eutrophication,we conducted periodic sampling surveys of plankton and water environmental factors in Chenqiao east lake and Qinglong lake from December 2016 to November 2017,and analyzed the relationship between the characteristics of plankton community structure and water environment factors.The results are as follows:(1)We have identified phytoplankton 67 genera 118 species during the survey.Among them,there were 47 species of Chlorophyta,which account for the total number of kinds of 40%,followed by Diatoms 35 species,15 species of Cyanobacteria,9 species of Euglenophyta,and fewer other species.The seasonal variation trend of the number of phytoplankton species is summer>autumn>spring>winter.The spatial distribution showed Chenqiao east lake(112)>Qinglong lake(68).The variation range of phytoplankton abundance is 2.13×10~6 cells/L~3.97×10~7 cells/L,and the annual average value is 8.38x10~6 cells/L.The annual average abundance of Cyanobacteria was the highest,accounting for 44.15%of the annual abundance of phytoplankton,followed by 29.25%of Chlorophyta,and the seasonal variation trend of phytoplankton abundance was summer>autumn>spring>winter.The spatial distribution showed Chenqiao east lake(8.54×10~6 cells/L)>Qinglong lake(8.07×10~6cells/L).A total of 16 phytoplankton dominant species were found,accounting for 13%of phytoplankton species.Among them,4 species of Diatoms,4 species of Chlorophyta,5 species of Cyanobacteria,1 species of Euglenophyta,1 species of Cryptophyta and 1 species of Chrysophyceae.Both lakes are belonging to Cyanobacteria-Chlorophyta-Diatom lake.(2)There were 20 genera 34 species of zooplankton,of which 21 species of rotifer,accounting for 62%of the total;8 species of Cladocera,accounting for 23%;5 species of Copepods,accounting for 15%.The seasonal variation trend of the number of zooplankton was the same as the phytoplankton.The spatial distribution showed Chen East Lake(31)>Qinglong Lake(20).The range of zooplankton abundance is 41~1342 ind/L,with an annual average value of 216 ind/L.The abundances of Rotifer occupied the dominant position throughout the year,and the Cladocera was the lowest.The seasonal variation trend of zooplankton abundance is autumn>summer>spring>winter.The spatial distribution showed Chen East Lake(282ind/L)>Qinglong(84 ind/L).There are 9 dominant species of zooplankton,accounting for 24%of the total species.Among them,6 species of Rotifer,2 species of Copepoda and 1 species of Cladocera.B.calyciflorus and copepods larvae were the dominant species in four seasons.The functional groups of zooplankton were divided into 6 categories,which was mainly Rotifer filter eaters(RF).(3)The results of water environment factors showed obvious seasonal trends and spatial differences.The annual mean value of pH is 8.24(variation range is 7.50~8.78);Annual mean water temperature is 18.25°C(3.9~34.2°C);The annual average dissolved oxygen is8.85 mg/L(3.43~12.7 mg/L);The average annual value of transparency is 45.8 cm(12~110cm);The average annual value of oxidation-reduction potentia is 140.62 mv(62.8~255.2 mv).As a whole,physical indicators showed Qinglong lake is greater than Chenqiao east lake.The annual mean value of total nitrogen is 1.499 mg/L(0.784~2.524 mg/L);The temporal and spatial changes of ammonia nitrogen and total phosphorus were basically the same as total nitrogen.The annual average value of total phosphorus was 0.113 mg/L(0.021~0.261 mg/L);The annual average value of ammonia nitrogen was 0.913 mg/L(0.372~1.802 mg/L).61%of total nitrogen;The annual average value of chemical oxygen demand was 52.9 mg/L(17.0~126.4 mg/L);The seasonal variation of chlorophyll-a was consistent with the phytoplankton abundance,with an annual average of 23.29?g/L(1.90~99.98?g/L).The chemical indicators showed that Chenqiao east lake is greater than Qinglong lake.Chenqiao east lake presented relatively heavy pollution.(4)The results of the assessment of water quality based on the indices of plankton diversity and the modified Carlson Nutrition Index showed that the results were consistent.The status of eutrophication in Chenqiao east lake and Qinglong lake is relatively serious and the overall performance is moderate pollution.(5)The results of CCA analysis showed that the correlation coefficient of environmental factors and phytoplankton dominant species ranked as WT,DO,ORP,TN,SD and pH in descending order,and the correlation with dominant species of zooplankton was in descending order ORP,WT,SD,pH,Chl-a and DO.(6)The eutrophication of Chenqiao East Lake and Qinglong Lake is relatively serious. so that appropriate measures should be taken for ecological restoration.meanwhile,the scientific model of ecotourism development should be paid attention to and the awareness of the local residents on environmental protection should be enhanced so as to promote the sustainable and healthy development of the wetland ecological environment. |
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