| The building of Three Gorges Project have a huge economic benefit to the comprehensive exploitation of water resources,but at the same time it also have an influence on the ecological environment of the Three Gorges reservoir area to some degree. After water stored into the reservoir, the attributes of Yangtse natural watercourse have changed. Due to supporting of the main branch, the tributaries flow slowly and the reservoir really becomes an artificial lake.Life sewage from cities and towns, industrial waste water and non-point source contamination have a long-term affect on the reservoir. And most tributaries and backwater of the Bay are polluted seriously, having high level of nutrient concentration, such as nitrogen and phosphorus. After storage, water flowing slowly results in much deposited silt from water. As a result, the water gets clearer and more beneficial for sunlight spreading in water. Above provide advantageous conditions for algae growth, emergence and development of eutrophication. Therefor, after water storeged in the Three Gorges Reservoir, some areas have different levels of eutrophication because of centralized sunshine and high water temperature.This paper studied a combined restoration technique for the eutrophic reservoir using aquatic flora and fauna. It had a simple man-made ecological system with nature water and with different aquatic flora and fauna. The test included two parts. Part one had six groups, and each group had one species of aquatic plants and one species of fish. Part two has four groups, with one species of fish and several species of aquatic flora in each group. Water quality indicators and biological indicators in each group were monitored, in this way, the effect of the ten groups with different combinations on the eutrophic water was analyzed. The results demonstrated that the group with Pistia stratiote Linn whose coverage was 70% had high values of TP and TN removal. At the end of trial,the removal rate of TN,TP has reached 85%,95% in each group with Pistia stratiotes Linn.The group also controlled COD content and Chla concentration effectively, increasing SD in water and decreasing the temperature of surficial water. But the large coverage of Pistia stratiote Linn reduced the dissolved oxygen dramatically, deteriorating the environment in which aquatic organisms live. During the entire experiment, DO daily average concentration is less than 2 mg/L in in each group with Pistia stratiotes Linn.The results also showed that the Vallisneria asiatica had poor effection in this study, but it can raise dissolved oxygen and improve organism environment in bottom water when combinated with other aquatic flora and fauna. The Chub had a contribution to controlling the COD content, Chla concentration and improving water transparency. But the Crucian had no contribution to the restoration, and worsen it to some extent, damaging reconstruction of the bottom plants. Furthermore, the combination of Myriophyllum spicatum, Pontederia cordata L and fish had high values of TN and TP removal. The combination of Vallisneria asiatica, Pontederia cordata L, Nymphaea tetragona, Pistia stratiote Linn and fish with coverage of 30% also had good removal of TN and TP. At the end of the second trial,the removal rate of TN,TP has reached 85%,95% in each group with Pistia stratiotes Linn.They controled the COD and Chla concentrations effectively, as well as raising the SD, ensuring dissolved oxygen that aquatic organisms need, improving the environment aquatic organisms live in and stabilizing aquatic ecosystem.
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