Species Composition Of Zooplankton Resting Eggs In Urban Lakes

Zooplankton is an important part of aquatic ecosystem and plays an important role in material circulation,energy flow and information transmission.Resting eggs are produced when zooplankton suffers from environmental stress,like lacking of food,sharp increase in population density.The formation and hatching of resting eggs is an important life history strategy for zooplankton.In surface sediments,resting eggs hatch under suitable conditions to supplement active population,which regulate zooplankton community structure and population dynamics,in turn to maintain zooplankton diversity in water body and its stability of active population of zooplankton.By studying species diversity of resting eggs in sediments,zooplankton species diversity and the effects of environmental changes on zooplankton community structure in water bodies can be reflected.In order to understand the species composition of zooplankton resting eggs in urban lakes,we selected Liuyehu Lake in Changde,Donghu Lake in Wuhan and Baiyangdian Lake in Xiong'an as our study sites.We used CO??Cytochrome c oxidase subunit I?gene as DNA barcode to identifiy the zooplankton resting eggs in order to obtain community structure information of resting eggs in sediments.We then analyzed the relationship between community structure of zooplankton eggs and environmental factors in the water,as well as the coupling relationship between zooplankton population in the water and resting eggs in sediments.Main results are as follows:?1?Fifty-four species of zooplankton resting eggs were successfully identified from the three lakes by DNA barcode technology,including 38 species of cladocerans,2 species of copepods,and 14 species of rotifers.The dominant species of resting eggs in the three Lakes were indicator species of pollution,such as Brachionus sp.and Moina sp.,indicating that the three lakes could be eutrophication.?2?The abundance of zooplankton resting eggs in surface sediments of the three lakes was between 0.2-4.5×10⁶eggs/m³.?3?The results showed that there was a significantly positive correlation between the abundance of resting egg and COD_Mn content in the Liuyehu Lake?P<0.05?.There was a significantly positive correlation between the Shannon-Wenner index and DO concentration in the Donghu Lake?P<0.01?.The Simpson index was significantly negatively correlated with total nitrogen?P<0.01?.There was a significantly negatively correlation between the density of cladoceran resting eggs and p H in Baiyangdian Lake?P<0.05?,and the total abundance of resting eggs was significantly positivily correlated with the concentration of chlorophyll??P<0.05?.Environmental factors could influence zooplankton community structure,which in turn affected the species diversity and density of resting eggs.The results showed that DNA barcoding technique could rapidly and accurately identify the species of resting eggs in lake sediments,so as to obtain the community structure information of zooplankton resting eggs in sediments,and provided a powerful tool for further understanding the diversity and community structure of zooplankton in lakes.However,the incomplete information of DNA database of zooplankton hinders the wide application of DNA barcoding technology.With the further development of molecular biology of zooplankton,DNA barcoding technology will play an increasingly important role in molecular ecology of zooplankton.