Effects of the phytoplanktivorous silver carp (Hypophthalmichthys molitrixon) on plankton and the hepatotoxic microcystins in an enclosure experiment in a eutrophic lake, Lake Shichahai in Beijing
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- 作者：Xia Zhang ; Ping Xie ; Le Hao ; Nichun Guo ; Yingan Gong ; Xiulin Hu ; Jun Chen and Gaodao Liang
- 关键词：Biomanipulation ; Silver carp ; Plankton ; Algal biomass ; Microcystins
- 刊名：Aquaculture
- 出版年：2006
- 出版时间：30 June 2006
- 年：2006
- 卷：257
- 期：1-4
- 页码：173-186
- 全文大小：398 K
文摘
The responses of nutrients, water transparency, zooplankton, phytoplankton and microcystins to a gradient of silver carp biomass (0, 18, 55, 110 g/m3) were assessed using enclosures in Lake Shichahai (Beijing). Picophytoplankton biomass increased with increasing fish stocking density (r = 0.64, p = 0.09). Silver carp significantly depressed zooplankton biomass, and thus, zooplankton grazing was too low to control phytoplankton. Intracellular microcystin (MC) content in the enclosures was correlated only to Microcystis biomass in the present study. Microcystis spp. biomass and intracellular microcystins content were much higher in lake water than those of enclosures with and without stocking fish. Stocking of silver carp could be an appropriate in highly productive Lake Shichahai, which naturally lacks of large cladoceran zooplankton. A fish stocking density of 55 g/m3 was most efficient at controlling Microcystis blooms and increasing water clarity. Mean extracellular MC concentration in the lake water was almost the same with that of the enclosures with fish.