| Nowadays,with the advancing development of the urbanization in China,the urban ecosystem has been under growing pressure.As one of the most important water resource of urban ecosystem,urban lakes are becoming one of the researching hotspots currently.Urban lakes are sensitive to the environmental change.The regulation of urban lake's water quality change and the pattern of urban lake phytoplankton succession are significant for the protection and management of ecosystem in urban lake.Thus,it is necessary to conduct a synthetic research on the temporal and spatial distribution of urban lake water quality and phytoplankton succession.Based on the background above,the research combined the remote sensing inversion technology and network analysis method to conduct the comprehensive evaluation of the water quality and the spatial and temporal succession of the phytoplankton in the typical small lake,Shahu Lake,Wuhan.Via the correlation analysis and factor analysis,the research established a preliminary simulation model to predict the density of phytoplankton,which proved that there is a certain possibility in the further simulation of the community structure.Through the quantitative analysis of the phytoplankton and the clustering analysis of the water quality,the key factors in the process of phytoplankton succession were studied.The results indicated that there existed a positive correlation between the abundance of cyanobacteria and the concentration of constant cation(Na?K?Mg?Ca).COD,TN,TP and DO concentrations were less correlated with the phytoplankton structure characteristics;yet,within certain concentration range,they were correlated with the phytoplankton density,which indicated the possibility of predicting the phytoplankton density via the water quality indexes.The main conclusions of this paper are as follows:(1)In this study,the monitor period was from March to December in 2015.312 species were identified.The water quality indexes showed the seasonal distribution pattern.Chl-a,COD and the constant cations had similar distribution in the monitor period,and the distribution of TP and TN was different from Chl-a.The dissolved oxygen concentration is mainly related to temperature.The Chl-a,TP,TN,COD were applied to evaluate the eutrophic status of Shahu Lake.The results showed that the lake was in the severe eutrophic status during the monitoring period.And the homogeneity of sampling points varied greatly at different season,which suggested that the lacustrine zone and human activities may have an impact on the eutrophication status.(2)The species composition and relative abundance of phytoplankton in Shahu Lake showed obvious seasonal characteristics.The change of the dominant species per month in Shahu Lake showed that the community status had a certain pattern.The stable period was the summer time.And the stability of the phytoplankton was related to the lacustrine zone.In the phytoplankton of Shahu Lake,some species had significant influence in its succession process.The community composition tendency was obvious in the phytoplankton.And the change of relative abundance and community structure may be affected by both the water quality and the change of the interspecific relationships.(3)The characteristics of phytoplankton and the water quality of Shahu Lake showed that there were differences among the sampling sites.The eastern part of the lake was relatively homogeneous,and the effect of phytoplankton was more significant on the north shore.Within a certain range,the concentration of water quality parameters and the phytoplankton density showed the similar succession pattern.Based on their relationship,2 different type of statistical models(multiple linear regression model and support vector regression model)were formed.The results showed that the statistical model can predict the algae density by using the water quality parameter as the input value and the algae density as the output value,but their stability and universality need to be optimized. |
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