Community Structure Of Zooplankton And Ecological Assessment Of Water Quality 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 prevent flood, exchange water with other water bodies surrounded, meanwhile it provides tour and it influences the local climate. The water quality of Dishui Lake is widely concerned.Zooplankton had been sampled from 2006 to 2007 in Dishui Lake. We study on the community structure and distribution of Zooplankton based on the monitor of physical and chemical index and biology index, analyze and discuss the water quality of Dishui Lake primarily. This paper offers the detail list of Zooplankton in Dishui Lake, biology proof to the water quality protection and development of tour.The main results of this paper are listed as follow:1. There are 45 species of zooplankton in Dishui Lake, which belongs to 22 genera of 16 families. There are 32 species of Rotifera, which belongs to 14 genera of 8 families. There are 9 species of Copepoda in Dishui Lake, which belongs to 5 genera of 5 families. There are 4 species of Cladocera, which belongs to 3 genera of 3 families.2. The maximum of species number of zooplankton occurs in autumn, and the minimum occurs in spring. The species number of Rotifer varies widely from month to month, the species number of Copeoda varies smoothly, Cladocera only occurs in several month. The variety of species number of Rotifera influences that of zooplankton greatly.3. The quantity biomass of zooplankton in Dishui Lake varies from 80 ind/L to 18161 ind/L, the average is 2679 ind/L. The quantity biomass of Rotifera in Dishui Lake varies from 0 ind/L to 17939 ind/L, the average is 2175 ind/L. The quantity biomass of Copepoda in Dishui Lake varies from 28 ind/L to 2266 ind/L, the average is 522 ind/L. The weight biomass of zooplankton in Dishui Lake varies from 0.06 to 14.09 mg/L, the average is 3.40 mg/L. The weight biomass of Rotifera in Dishui Lake varies from 0.27 to 10.98 mg/L, the average is 1.21 mg/L. The weight biomass of Copepoda in Dishui Lake varies from 0.06 to 6.08 mg/L, the average is 2.18 mg/L. The quantity biomass of Rotifera contributes greatly to the quantity biomass of zooplankton.4. The biomass of zooplankton in Dishui Lake varies widely from season to season, it is high in summer and autumn, and is low in spring and winter.5. There are seven dominant species in Dishui Lake: Brachionus rotundiformis complex, Hexarthra intermedia, Brachionus angularis, Synchaeta sp., Keraatella cruciformis, Limnoithona sinensis, Bosmina longirostris. Limnoithona sinensis is representative zooplankton in Dishui Lake.6. The variety of dominant species relates to physical and chemical index obviously.7. The variety trend of zooplankton in Dishui Lake is much like that in Port C and Port D.8. Water temperature is the main factor that influences the variety of zooplankton community structure in Dishui Lake, fish is the second one.9. The water quality of Dishui Lake is at semi-eutrophic level according to the physical and chemical index and biology index. It is better in 2007 than 2006.