Eutrophication in freshwater bodies has becoming a worldwide environmental problem in recent years. It becomes more and more urgent to control the eutrophication in lakes and reserviors.. However, prevention and treatment of eutrophication problems are not only intractable but also expensive during the remediation of water pollution.
In the water ecosystem, the growth of phytoplankton is not only influenced by environment factors, but also controlled by biotic factors. It is possible to mitigate the biomass of phytoplankton by biomanipulation , namely, to mitigate the damage of algae bloom and improve the water quality by. regulating the structure of biotic community.
Based on the principle of classical biomanipulation, effects of the density and age of Anodonta woodiana elliptica Heude on the decline of Chla and of nutrients were studied, which would provide a theoretical data for the application on the Control of Cyanobacterial Bloom by Using Anodonta woodiana elliptica Heude in Heavy Polluted Bay in Dianchi Lake. At the same time, Experiments on the effect of different exposure time, various polluted water on the enzyme activity of Anodonta woodiana elliptica were done to explore whether the antioxidant enzymes can be act as of biomarkers indicationg the polluted situation of Dianchi Lake.
The main results are as followed:
1）The relationship of Anodonta woodiana Heude between ingestion rate (IR) and wet weight of tissue(W) can be represented by the allometric equation IR=aWb; the IR of three-year-old anodonta is higher than the one-year-old anodonta. The 3-year-old anodonta was founded to eliminate ChlorophyII a in water more efficient than one-year-old anodonta. Results showed that the the highest elimination rate of Chl a was occurred after anodontas (20 ind./m3) worked 8 days later.
2）Hanging culture is better than launching culture, for mussels suspended in the water column can clean up water in a wide range and rise SD. Though it can reduce the TP and CODMn obviously, the decrease of TN is not remarkable. The results indicate that the effect of elimination was the best when the density of mussels in enclosure was 40ind./m3.
3) The relationship between Shell length(X,cm) and Body weight (y) of anodontas living in Fubao Bay can be represented by the allometric equation: y=aXb.The litter anodonta has the higher death rate, and the higher density the higher death rate. In a word, 3-year-old anodontas were adapted to living in heavy polluted water.
4) The activity of SOD might indicate the lever of pollution, for it correlated positively with the lever of polluted water quality. .And the content of H2O2 in the body would increase when the water quality turned worse. For simple operation, we can only choose blood tissue. ACP is suitable as biomarker in the light polluted water, and AKP can reflect the body’s physiological condition. The content of protein also indicate organisms’ growth and health conditions