Zooplankton Community And The Relation To Environmental Factors In Lakes Connected To The Yangtze River In Anhui Province

There are numerous lakes on both sides of the Yangtze river in Anhui section,which are shallow,they generate a rich biodiversity,and keep connected with the Yangtze River state.Together with the Yangtze River,these lakes form unique riverd-lake compound wetlands.There mainly are Lake Longgan,Lake Huangda,Lake Bo,Lake Wuchang,Lake Shengjin.Lake Caizi,Lake Pogang,Lake Baidang and so on in Anhui section,these lakes are collectively referred to as river,with a total area of about 1498.97 km2.The lakes are affected by the monsoon and the Yangtze river for a long time,the unique fluctuation pattern of water level is formed:rising period,abundant period,retreating period and dry period.The fluctuation of lake level in the Yangtze River basin has also been significantly changed due to multiple influences such as water conservancy project and global climate change.Lake ecosystem is not only disturbed by human activities but also threatened by extreme climate due to increasing extreme climate and worse water environment.Therefore,protecting lake ecosystem is a hot issue in ecology and environmental science.Zooplankton is one of the water ecological system,has a unique form of life,not only because of its means of reproduction,but also because of its roles in the food chain.It makes the zooplankton in plasticity strong due to its sensitive to environmental changes.It can be as an important indicator to assess the water health according to the change of zooplankton community.Zooplankton is as the research object in the Yangtze river of Anhui Province in this study.Through zooplankton community function analysis,we identify driving the key factor of zooplankton community change in proven the community of zooplankton distribution pattern and function in lakes of the Yangtze River on the basis of discussion of extreme flood and purse seine to zooplankton community structure,the influence of and further discusses regional climate change and human activities on zooplankton community composition changes in lakes connected to the Yangtze River.To predict the response of the aquatic ecosystem of the lakes connected to the Yangtze River to the change of environmental factors and the change trend of the lake ecosystem in the future.The main research results are as follows:In this study,there were 64 species in 5 lakes in Anhui section of the Yangtze river,including 37 species of rotifers,16 species of cladocera and 11 species of copepods.The dominant species in the lakes conneceted to the Yangtze River were Diaphanosoma brachyurum,Bosmina spp.,copepoda larva,Mesocyclops leuckarti,Keratella cochlearis and Polyarthra trigla.The annual average density of zooplankton in lakes connected to the Yangtze River was 398.64 ind./L,among which the cladocera account for 7.0%,copepods for 9.0%,and rotifers for 83%.The average biomass of zooplankton was 2.58±1.74 mg/L,and that of copepods was the largest,1.01±0.61mg/L.The average biomass of zooplankton in the lakes connected to the Yangtze River in Anhui Province was 2.58 ± 1.74 mg/L,and that of copepods was the largest,1.01 ± 0.61 mg/L.In Lake Wuchang,the minimum average density was 5.21 ±4.08 ind./L,the maximum average density was 54.32 ± 57.69 ind./L in Lake Longgan,the maximum density was 59.74±31.86 ind./L in Lake Longgan,the minimum average density was 6.31 ± 4.57 ind./L in Lake Shengjin.The average density of rotifers was more than 2 times that of cladocera and copepods,and the maximum average density was 772.39±385.80 ind./L,which was the lowest in Lake Longgan and reached 34.67±27.47 ind./L in Lake Shengjin.The relative abundance of rotifers and the density of rotifers in different seasons had similar results,accounting for more than 50%in all seasons and 55.41%in summer.The maximum average density of rotifers reached 1139.2 ind./L in autumn and 89.36 ind./L in summer.The maximum relative abundance of cladocera and copepods was 24.71%and 19.87%respectively in summer.However,in spring,the maximum average density of cladocera reached 57.7 imd./L,while the maximum average density of copepods reached 39.85 ind./L in autumn.Copepods gradually increased from spring to summer,and then began to decrease until reaching the minimum average density(8.72 ind./L)in winter.In addition,the average density of rotifers in lakes connected to the Yangtze River in Anhui Province in each season was significantly higher than that of the other two crustacean zooplankton(p<0.05).The maximum zooplankton ? diversity was 25.81 in lakes connected to the Yangtze River in Anhui Province in spring,14.98 in winter,and 19.09 and 19.59 in summer and autumn,respectively.The closer the ? diversity value is to zero,the higher the similarity.The results showed that the zooplankton were not significantly different in the four seasons,but the similarity of zooplankton in each lake connected to the Yangtze River in Anhui Province was the highest in winter.According to the lake Seine characteristics of farmed fish in lakes connected to the Yangtze River in Anhui Province.On the basis of the functional division was divided into five in total groups:rotifers filter(RF),rotifers predators(RP),planktonic filter(PF),planktonic predators(PP),benthic filter(BF).68 species of zooplankton from 22 families were identified in the lakes connected to the Yangtze River in Anhui Province,and 5 functional groups were divided.The largest number of zooplankton species in the lakes was in spring and the smallest in winter.The species composition in each functional group decreased gradually with the change of seasons.There are 15 PF functional groups in spring and only 5 in winter.There were 5 PP functional groups in spring and summer,and only 3 in winter.BF functional group has 6,3,2 and 2 species from spring to winter,respectively.There are 31 species in spring,30 and 29 species in summer and autumn,and at least 12 species in winter.There are two kinds of RP in three seasons.The RP functional group of zooplankton in different lakes connected to the Yangtze River in Anhui Province was composed of the same two species.Among the PF functional group,the most species are found in Lake Bo,accounting for 12 species,and the least species are found in Lake Longgan.The largest number of species in PP functional group is Lake Longgan(9 species),and the smallest is Lake Shengjin(2 species).In BF functional group,there are 7 kinds of lakes in Lake Wuchang and Lake Longgan respectively,31 species at most in RF functional group,18 species at least in Lake Longgan,and in Lake Shengjin.Compared with the results of in Huayanghe lakes zooplankton dynamics in the normal water level fluctuation year,zooplankton dynamics and water environmental factors changed significantly in this study of extreme water level fluctuation in Huayanghe lakes,chlorophyll a and total nitrogen and total phosphorus was significantly higher than the normal water level fluctuation year(P<0.05).in the extreme water level fluctuation,we detected 23 species of crustacean zooplankton,rotifers in 39 species were higher than the normal water level fluctuations year.However,the biomass and density of crustacean zoopalnkton and rotifers in the year of conventional water level were significantly higher than those in the year of extreme water level fluctuation(P<0.05).Compared with the conventional water level fluctuation year,the zooplankton community in the extreme water level fluctuation year were only affected by temperature(WT)and water depth(WD),and total phosphorus(TP)(P<0.01)and pH(P<0.05)were also important factors affecting the zooplankton community in lakes connected to the Yangtze River in Anhui Province.There are 41 species of zooplankton in Lake Wuchang with fish farming in the whole lake,was less than that in Lake Longgan.Lake Huangda and Lake Bo with mooring lake Seine the 53 species of sampling area There were common species:Diaphanosoma brachyurum,copepods larva,Thermocyclops taihokuensis,Keratella cochlearis and Polyarthra trigla in Lake Wuchang,Within and outside the purse seine area,there are Bosmina spp.,Moina micrura,Schizocerca diversicornis,Polyarthra trigla.The density and biomass of Lake Wuchang were significantly lower than those within and outside the purse seine area(P<0.05).The results of zooplankton cluster analysis showed that the sampling sites in Lake Wuchang were clustered in the same branch,while the sampling sites within and outside of the lake purse seine were relatively scattered in Lake Bo,and the sampling sites outside Lake Longgan and Lake Huangda purse Seine with better connectivity were mostly clustered together.In addition,there was no significant change in the body length of zooplankton under different feeding pressures(P=0.881),and the maximum average body length was 0.73±0.18 mm,which appeared in sampling sites inside the purse seine,followed by the average body length of sampling points outside the purse seine was 0.70±0.20 mm,and the minimum average body length was 0.68±0.07 mm in Lake Wuchang.Daphnia galeata related to life cycle characteristics were recorded,in Lake Wuchang with the whole lake fish farming,D.galeata density was significantly less than that within the seine area(P<0.05),brood female body reached 1.4%outside the seine,slightly higher than that within the seine,D.galeata larva and immature female density within the seine was higher than that outside the seine,it may be that D.galeata mature time grew longer with fish predation pressure...