STUDIES ON THE CHANGES IN ABUNDANCE AND BIOMASS OF ZOOPLANKTON IN LAKE DONGHU WUHAN

This paper embodies the results of zooplankton survey made in 1974—1975 and 1979—1980, in lake Donghu, Hubei Province.Samples were collected monthly at two sampling stations. The species number of the zooplankton in 1974—1975 and 1979—1980 was smaller than in 1963; The difference of the zooplankton community between station Ⅰ and station Ⅱ diminished.In general, the standing crop of zooplankton was increased. In the pattern of seasonal fluctuation of zooplankton abundance the peaks were usually recorded in autumn and summer, with the former peak far exceeding the latter.The protozoan number was very high—about 85.5% on average in number of the total zooplankton.On the basis of biomass, the winter and spring peaks were usually observed. The annual averages of the standing crop (1974—1975, 1979—1980) for the four groups of zooplankton were as follows: station Ⅰ: Protozoa, 18.93% of total biomass; Rotatoria, 25.25%, Cladocera, 46.02%; Copepoda, 9.80%; Station Ⅱ: Protozoa, 13.92% of total biomass; Rotatoria, 15.24%, Cladocera, 58.93% Copepoda, 11.91%.The relationships between the seasonal changes and the ecological factors are discussed.