Spatial And Temporal Distribution Of Zooplankton Communities In Fuxian Lake

Lakes are important natural complexes in the surface systems,which are an important part of the hydrological cycle and biogeographic distribution.They provide natural resources and environment for regional socio-economic development.Environmental changes such as global warming and water pollution will affect the distribution of aquatic biota and patterns of biodiversity.For now,the eutrophication of lakes,the irrational utilization of water resources and the degradation of aquatic ecosystems have become one of the major environmental problems in the highlands of Yunnan.Fuxian Lake is the largest deep-water lake in Yunnan.The development of industry,agriculture and tourism,make its comprehensive nutrition level rise.The distribution pattern of lake ecosystem structure and biodiversity also changes.In order to protect and treat Fuxian Lake effectively,a comprehensive study on the spatial and temporal scales of lake ecosystem structure and biodiversity is needed.Which will provide basic data and scientific basis for the regulation and restoration of Yunnan plateau lakes and the rational use of fish resources.In this paper,we conducted a space-time survey of the zooplankton community in Fuxian Lake through the monthly changes of 3 sampling points and the seasonal changes of 16 sampling points.We found the temporal and spatial characteristics of the zooplankton community structure in Fuxian Lake.We further identified the main environmental factors affecting the abundance of zooplankton community in Fuxian Lake through RDA and CCA.According to the survey of zooplankton community structure in Fuxian Lake from January to December in 2015,there are 28 species of zooplankton in Fuxian Lake: There are 21 species of Rotifera,belong to 11 genera of 8 families,accounting for 75% of total species.There are 4 species of cladocera,belong to 4 genera of 3 families,accounting for 18% of total species.There are 2 species of copepods,belong to 2 genera of 2 families,accounting for 7% of total species.There are several predominant species of zooplankton in Fuxian Lake: The rotifers appeared in Keratella cochlearis,Ployarthra dolichoptera and Ployarthra leleki for more than three months and belonged to the oligo-intermediate fouling species.In addition,Bosminea longirostris was the dominant species in the remaining months,except for August.The dominant species of copepods were Phyllodiaptomus tunguidus and Nauplii.Phyllodiaptomus tunguidus mainly exists in the form of Calanoida copepodites.The community structure of zooplankton in Fuxian Lake displayed insignificant differences among the sites,reflecting a high degree of spatial homogeneity in zooplankton distribution.The abundance of zooplankton zooplankton in Fuxian Lake has not changed significantly compared with the existing study,but the abundance of copepods shows a decreasing trend.The monthly zooplankton abundance and biomass varied in the range of 1.32-53.18 ind./L and 3.05-306.12 ?g/L,respectively.The highest zooplankton abundance was found at the site T8 in August and the highest zooplankton biomass occurred in July.While,the lowest value occurred in February for both zooplankton abundance and biomass.Furthermore,the Shannon-Wiener diversity index(H)varied in the range of 1.02-2.19 for zooplankton across month.The body size of plankton crustaceans has obvious seasonal variation.There are little differences among the plankton crustaceans in space.In the spring and summer(March and June),planktonic crustaceans are small(about 300 ?m).In autumn(September),the body size of planktonic crustaceans in the northern lake area is bigger than that in the southern lake area.In winter(December),the body size of planktonic crustaceans in the southern lake area is bigger than that in the northern lake area.The redundancy analysis and typical correspondence analysis results further indicate that zooplankton community structure changes month by month and spatial differences are small.Water temperature,concentration of calcium ion and phosphate have a strong driving effect on the spatio-temporal changes of zooplankton community structure.At the same time,the monthly variation of the abundance and individual size of planktonic crustacean is significant,and it is strongly influenced by fish predation pressure.The abundance and biomass of zooplankton in Fuxian Lake varied significantly with the seasons,and its community structure had a good correlation with environmental factors such as water temperature,calcium ion,and phosphate concentration.But Its community in space is not significantly different.Compared with the survey results of Fuxian Lake,the overall abundance of planktonic crustaceans has not changed significantly but there is a long-term downward trend in copepods.The monthly changes of the community of planktonic crustacean reflect the continuing role of predation pressure and selective dietary characteristics of the new whitebait in Taihu Lake.In this study,a one-year survey of the zooplankton community in Fuxian Lake was conducted to investigate the spatial-temporal patterns of zooplankton community structure in Fuxian Lake.We identified the main driving factors that affecting zooplankton community changes in Fuxian Lake.This research can provide important data foundation and scientific basis for ecological assessment and lake protection in Fuxian Lake.