Study On The Change Structure Of Phytoplankton Community And Water Quality Evaluation In Dishui Lake

Dishui Lake is the biggest man-made freshwater lake in China, founded in 2003,locates in Nanhui District of Shanghai. The function of the lake is to precent flood, exchange water with other water bodies surrounded, meanwhile it provides tour and it influences the local climate. The water quality is wisely concerned.Phytoplankton had been sampled from 2006 to 2008 in Dishui Lake. We study on the community structure and distribution of Phytoplankton based on the monitor of physical and chemical index and biology index, analyze and discuss the water quality of Dishi Lake primarily. This paper offers the detail list of Phytoplankton in Dishui Lake, biology proof to the water quality protection a development of tour. The main results of this paper are listed as followed:1. Based on the results of all kinds of chemical and physical indexes, the average water temperature is above 5.16 degrees and the yearly one is 18.58 degrees and the water quality is linked to alkaline.2. There are 91 species of phytoplankton, which belonged to 60fenera of 8 phyla. Most of them are freshwater species; dominant species ascribing to chlorophyta accounted for 47.3 percent and the quality is 43 species belonging to 25 Genera; secondly the percentage of cyanophyta is 22.0 percent.3. On the issue of phytoplankton biomass, it appears that Chrysophyta is the dominant kind. Bacillariophyta, Chlorophyta, Cyanophyta are also important to the construction of biomass, the rest of the phytoplankton biomass is rare.4. There are 11 kinds of dominant species, including Oscillatoria tenuis Ag. , Microcystis sp., Merismopedia minima G. Beck., Aphanothece sp., Aphanocapsa sp.,Chromulina pygmaea Nygaard,Cocconeis placentula,Cyclotella meneghiniana, Oocystis lacustris Chodat., Chlamydomonas sp., Ankistrodesmus falcatus.5. The correlation analysis on the physiochemical index ande biological index of Dishui Lake: There is extremely positive correlation between biomass of phytoplankton and water temperature and chla; on the converse, biomass of phytoplankton have the reverse bonding with salinity and Zooplankton .6. Utilizing all kinds of methods of evaculations, the water of Dishui Lake lies in the status of semi-eutrophication.