THE DENSITY AND DIVERSITY OF ZOOPLANKTONS IN THE SUCCESSION OF FIVE LAKES

This paper embodies the results of species composition, density and diversity of zooplanktons in several lakes in the middle reaches of Changjing River.Quarterly zooplankton samples were collected from Qiaodun Lake and Biandantang of Baoan Lake, South Qinglinghu, North Qinglinghu and Huangjiahu Lakes from 1993 to 1994. 104 species of zooplankton were identified in Biandantang, of which 46 species were protozoa, 35 rotatoria, 17 cladocera, 6 copepoda. 107 species of zooplankton were identified in Qiaodun Lake, with 45 being protozoa,37 rotatoria, 19 cladocera,6 copepoda. 89 species of zooplanktons were identified in South Qinglinghu, 37 of which were protozoa, 34 rotatoria,13 cladocera, 5 copepoda. 73 species of zooplanktons were identified in North Qinglinghu Lake, (28 protozoa, 28 Rotatoria,13 Cladocera, 4 copepoda). 88 species of zooplanktons were identified in Huangjiahu Lake (31 protozoa, 39 rotatoria, 13 cladocera, 5 copepod).The number of species of zooplanktons were reduced with the decrease of macrophyte biomass.The annual average density of zooplanktons were 2696 ind./L, 2706 ind./L, 1835 ind. /L, 3360 ind./L, 3793ind. /L, respectively in Biandantang, Qiaodun Lake, South Qinglinghu, North Qinglinghu and Huangjiahu Lake. In the water body surveyed,small protozoa and rotatoria were predominant in species composition and density of zooplanktons. The zooplankton density increased with the decrease of macrophyte biomass.The annual average diversity indexes of zooplankton were 3.2981, 3.4404, 3.2094,2.7119, 2.3961, respectively in five water bodies (Biandantang, Qiaodun Lake South Qinglinghu, North Qinglinghu, Huangjiahu Lake). The diversity index of zooplankton increased with the increase of macrophyte biomass.