东太湖不同水域浮游生物周年变化及鲢、鳙食性的研究

Annual variation of plankton in different water area of the East Taihu Lake and feeding habits of Hypophalmichthy molitrix and Aristichthys nobilis

2012年2-11月对东太湖不同水域浮游生物组成、数量、水质情况及水生植物密度进行了调查,并对9月份太湖鲢、鳙的食性进行了研究。结果表明：浮游动物和浮游植物多样性指数均为保护区＞余山＞老鼠山＞漫山岛。水体浮游生物数量和综合营养状态指数均为漫山岛＞老鼠山＞余山＞保护区。浮游植物总数量与蓝藻总数量、浮游动物总数量、富营养化因子呈正相关,与水生植物密度呈负相关。9月份太湖鲢、鳙的肠内含物中浮游植物和浮游动物分别占食物数量的89.1%、70.6%和10.9%、29.4%,其中蓝藻分别占74.5%、56%,枝角类和轮虫分别占3.7%、13.4%和1.5%、11.5%；鲢、鳙对蓝藻的选择性指数分别为1.42和1.07,对轮虫和原生动物的选择性指数分别为0.13、1.27和1.30、0.40。本研究结果对揭示影响太湖浮游生物周年变化的环境因素以及通过鲢、鳙控制蓝藻具有一定的理论价值和指导意义。

The composition, quantity of the plankton and the density of aquatic plant in different water area of the East Taihu Lake were investigated from February to November in 2012, and the feeding habits of Hypophalmichthy molitrix and Aristichthys nobilis in September in the Taihu Lake were studied. The results showed that the order of phytoplankton and zooplankton’s diversity index in four water areas was Protection Zone〉Yushan〉Mouse Moun-tain〉Manshandao. The order of quantity of plankton and trophic lever index in the four water areas was Manshan-dao〉Mouse Mountain〉Yushan〉Protection Zone. The total quantity of phytoplankton had a positive correlation with the total quantity of cyanobacteria. The total quantity of zooplankton and the eutrophication factors, however, has a negative correlation with the aquatic plant density. In September, the percentages of the phytoplankton and zoo-plankton in total fed quantity contained in the intestinal of H. molitrix or A. nobilis in the Taihu Lake were 89.1%or 70.6% and 10.9% or 29.4%, respectively, and the percentage of cyanobacteria was 74.5% or 56%, and that of cladocerans and rotifers were 3.7%or 13.4%and 1.5%or 11.5%, respectively. The selective index of cyanobacteria for H. molitrix or A. nobilis was 1.42 or 1.07, and that of cladocerans and rotifers was 0.13 or 1.27 and 1.3 or 0.4, respectively. The results of this study have theoretical value and great significance to reveal the effect of environ-mental factors on annual variation of plankton and to control cyanobacteria through H. molitrix and A.nobilis in the Taihu Lake.