Seasonal variations of diversity of periphytic algae in macrophyte-type lake of middle reach of the Changjiang River

The present paper reports in the species composition, density seasonal variations of diversity indices of periphytic algae in four lakes which undergo different phases of secondary succession. The paper records 135 species and 88 genera of common periphytic algae. Among them, there are 85 species and 49 genera in Qiaodunhu lake, 68 species and 46 genera in Biandantang lake, 50 species and 34 genera in Huangjiahu lake, 92 species and 55 genera in south Qinglinghu lake. Species recorded form Chlorophyta, Bacillariophyta and Cyanophyta are more than the other periphytic algae. Among them there are 67 species of chlorophyta, 36 species of Bacillariophyta and 21 species of Cyanophyta. In Qlaodunhu lake, the maximum density of periphytic algae appears in winter (11385.98 times 10-4ind cntdot gB-M-1), the medium in spring (5046.69x10-4ind cntdot gB-M-1) and the minimum in summer (2058.32 times 10-4ind cntdot gB-M-1). In Biandantang take, the maximal density of periphytic algae appears in autumn (6546.52 times 10-4ind cntdot gB-M-1) and the minimum in summer (1559.15 times 10-4ind cntdot gB-M-1). In the south - Qinglinghu and Huangjiahu lakes, the maximum density appears in the spring and summer respectively. The average annual diversity indices of periphytic algae are arranged in from large to small order in different lakes as follows:the South - Qinglinghu (3. 241) gt Huangjiahu(2. 984) gt Biandantang(2.598) gt Qiaodunhu(2.458). The species numbers of periphytic algae are lower than those of the planktonic algae in different lakes. The relationship between similarity coefficient of planktonic algae - periphytic algae(S) and bimass of macrophyte(B-M, Kg cntdot m-2) can be expressed as follows: S=0.486+0.0164B-M (P lt 0.01)