Annual Comparative Studies On Structure Of Zooplankton Community In The Three Area Of Lake Taihu

The study on annual variation of community structure of zooplankton (Copepoda, Cladocera, Rotifer) and the correlation between ecological factors and zooplankton was conducted in Lake Taihu in Jiangsu province from Oct. 2003 to Sep. 2004. Forty species of zooplankton was identified, among which there were 7 Copepoda species in 6 genera, 10 Cladocera species in 6 genera and 23 Rotifer species in 12 genera. The data indicated that the level of eutrophication was the highest in Lake Wulihu, high in Meiliang Bay and it was relatively low in Lake Taihu. The number of zooplankton species was 40 in Lake Wulihu, 37 in Meiliang Bay and 33 in Lake Taihu. And the annual average density of zooplankton was 384 ind./L in Lake Wulihu, 309 ind./L in Meiliang Bay and 218 ind./L in Lake Taihu, respectively. Also, the annual average biomass of zooplankton was 3.55mg/L in Meiliang Bay, 3.31mg/L in Lake Wulihu and 2.62mg/L in Lake Taihu, separately.The data indicated that the dominant species of zooplankton were Daphnia hyaline in spring, Microcyclops varicans, Limnoithona sinensis, Bosmina longirostris, C. cornuta in summer, Bosmina longirostris, C. cornuta in autumn, Brachionus calysiflorus, Brachionus angularism, Synchaeta pectinata in winter in Lake Taihu. The dominant species of zooplankton was the same as Lake Taihu in Meiliang Bay. The dominant species of zooplankton were Moina macrocopa, Brachionus calysiflorus, Brachionus angularis, Synchaeta pectinata in spring, and Mesocyclops leuckarti, Bosmina longirostris, Diaphanosoma brachyurum, Polyarthra trigla in summer, and Brachionus calysiflorus, Monostyla bulla in autumn and Brachionus calysiflorus, Brachionus angularis in the winter in Lake Wulihu.There were highly significant positive correlation between Copepoda and TP, and WT, greatly significant negative correlation between Copepoda and NH₄-N. There were highly significant positive correlation between Cladocera and TP, and WT, and greatlysignificant negative correlation between Cladocera and NH4-N. There were greatly significant positive correlation between Rotifer arid NH4-N, and significant positive correlation between Rotifer and TN, and Tansparence, and Chl-a.