Abstract: By using random amplified polymorphic DNA (RAPD) technique, this paper studied the α-diversity of plankton communities and its relationships with water quality and fish diseases in 7 Siniperca chuatsi ponds, as well as the effects of stocking density and a new culture model on the diversity and water quality. The results showed that there was a significant negative correlation between the DNA sequence diversity of plankton communities and water quality index, and high stocking density decreased the DNA sequence diversity and increased the water quality index. The new culture model with short culture period, low stocking density and high feeding stuff input had a greater damage on the water environment. Hierarchical cluster analysis indicated that there existed similarities in the DNA sequences of plankton communities and the physicochemical properties of water bodies in the ponds with fish diseases, which provided a possibility to predict the diseases occurrence in Siniperca chuatsi ponds.

Key words: Nutrient leaching, Paddy field, Taihu Lake area