Plankton After The Ecological Restoration Of The Backshore Wetland Of Expo Garden In Shanghai

The Wetland of Expo Garden is the only natural wetlands of Shanghai along theHuangpu River, which havs attracted much attention because of its unique urban naturaland urban ecological security. It is the emphasis of the World Expo construction projectin Shanghai in2010, China programming district. It has a variety of functions such asinprovig the environment, controlling the pollution. It also plays a unique role inconserving biological diversity and maintaining ecological balance. As the developmentof industry and agriculture, the problem of eutrophication in water become increasinglyserious, and the ecological restoration technology is used to aolve the problem, whichhas become a worldwide research hotspot. Currently, they mainly focus on aquaticplants, physical and chemical factors, environmental effects, planktonic algaes andbenthic animals, but rarely reported on the plankton community structures. So far, theanniversary dynamics of plankton community structure has not been reported in theExpo Garden in Shanghai. The community structure of phytoplankton, rotifer, cladoceraand copepod in10sites were investigated from September2009to August2010.Through statistical analysis of a large number of original data to analyze thephytoplankton and metazoan zooplankton community structure, the spatial and temporalvariation and species diversity indexes, as well as the relationship between their speciescomposition, abudance, biomass and their correlations with ecological factors. In orderto provide the basic data and scientific basis for ecological restoration, utilizing andprotecting the resources of the Wetland.The main results as below:1.371species and varieties belonging to109genera of8phylums ofphytoplankton and119species in45genera of12families of rotifer and36speciesbelonging to5families and13genera of cladocera and23species in11genera of6 famlies of copepod were identified in the Backshore Wetland of Expo Garden inShanghai during September2009to August2010. Total number of plankton showed asignificant seasonal variation, the total species of phytoplankton was the peak insummer, the second highest in spring and autumn, and the lowest in winter; the totalspecies of rotifer was the peak in summer, the second highest in summer and winter, andthe lowest in spring; the cladocera with high species number in sammer and autumn andlow in winter and spring; species richness of copepod was, higest in spring and autumn,and lowest in winter.2. According to the quarterly average density, a total of18dominant speciesbelonging to Cyanophyta （6）, Bacillariophyta （5） and Chlorophyta （7）, Phormidiumtenus was the only dominant species during the four seasons. There were18dominantspecies of rotifer with the only dominant species of Polyarthra trigla. There were12dominant species of cladocera in the four seasons and Chydorus sphaericus, Chydorusovalis, Chydorus latus were dominant species of autumn, winter and spring.5dominantspecies of copepod rin the present study, there were Eucyclops serrulatus,Thermocyclops taihokuensis, Mesocyclops leuckarti, Thermocyclops. Brevifurcatus,Mesocyclops leuckarti, Microcyclops varicans.3. The average annual density of phytoplankton, rotifer, cladocera and copepodwere711.11×104cells·L^-1,815ind.L^-1,5.7ind.L^-1and8.6ind.L^-1,respectively; and thebiomass were5.6965mg·L^-1,0.3649mg·L^-1,0.3559mg.L^-1and0.0836mg.L^-1,respectively.4. The average value of H′, D and J of phytoplankton, rotifer, cladocera andcopepod were2.08,2.74,0.56；1.46,1.14,0.78；0.83,1.01,0.62. The average valueof D was2.31. The seasonal variation of H′, D and J for both phytoplankton andcladocera were higher in summer and autumn, lower in winter and spring. The seasonalvariation of H′, D and J showed the peak in the summer, the second highest in winterautumn, and the lowest in spring.5. The density of phytoplankton had significant positive correlation with nitratenitrogen. The density of rotifer had a significant negative correlation with pH andammonia nitrogen, but significant positive correlation with TP; the biomass had asignificant positive correlation with DO. The density of cladocera had a significantpositive correlation with TP, the biomass had a significant positive correlation withwater temperature, TP and nitrate nitrogen, and had a significant negative correlation with DO. The density and biomass of copepod both had a signification positivecorrelation with water temperature, ammonia nitrogen and TP, and the biomass had asignification negtive correlation with DO.6. Both the density and biomass of phytoplankton both had significant negativecorrelation with the density and biomass of rotifer. The standing crop of cladocera hadsignificant positive correlation with the standing crop of copepod.7. Of the species recorded,93were pollution indicator species of rotifer, witchOligosaprobity （32） and Oligo-β-mesosaprobity （30） species made up the largest share,the second largest were and β-mesosaprobity （23）；7species were β-α-mesosaprobity；and the lowest were α-mesosaprobity （1）, which account for34.41%、32.26%、24.73%、7.53%and1.08%, respectively.8. Site10is the outlet of the wetland water system. Under the condition of theecological restoration, the nutrition levels decreased along the flow direction from theheadwaters of the river system （Site1, TLI=57.29） to the minimum of the Site10, whichcalculated the trophic state index was the lowest one （TLI=36.56）. The lowest standingcrops of the phytoplankton, cladocera and copepod were at the10sites.