Preliminary investigation on phytoplankton and estimation to silver carp and bighead carp productivity of Taizi Lake
太子河浮游植物初步调查及鲢、鳙鱼产力评估

From June to October 2010,the investigation for phytoplankton species composition was carried out in Taizi River,which locates in Nanchang City,Jiangxi Province.The results showed there were 74 species belong to 5 phylums were found in the river.Chlorophyta was the mainly species(48.64% of the sum),followed by Cyanophyta(29.72% of the sum) and Bacillariophyta(14.86% of the sum).There was the most species of phytoplankton in October,followed by September and August,while the least was in July.The density of phytoplankton in July was the highest,for 313 × 105cells/L.The density of phytoplankton in other months differed little,ranged from(79-101) × 105 cells/L.Microcystis which belongs to Cyanophyta was the absolutely dominant species.The Shannon-Wiener diversity index(H′) and evenness index(J) were the lowest(0.10 and 0.03 respectively) in July.For the other months,the Shannon-Wiener diversity index ranged from 0.37 to 0.69,evenness index ranged from 0.10 to 0.18.Comprehesive of phytoplankton density,Shannon-Wiener diversity index and evenness index,indicating that water was at the level of eutrophication.The productivity of silver carp and bighead carp estimated on the basis of the productivity of phytoplankton was 12.675 kg/hm2.