Environmental Simulation and Pollution Control State Key Joint Laboratory, Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084, PR China.
Water Res. 2009 Dec;43(20):5053-62. doi: 10.1016/j.watres.2009.08.022. Epub 2009 Aug 26.
The toxic effects of a mixotrophic golden alga (Poterioochromonas sp. strain ZX1) and a cyanobacterium Microcystis aeruginosa grazed by Poterioochromonas to a cladoceran were investigated through life history experiments using Daphnia magna. Poterioochromonas cultured in two ways (fed M. aeruginosa in an inorganic medium or grown in an organic medium) both induced starvation-like effects on D. magna, indicating that Poterioochromonas is neither acutely toxic nor a good food for D. magna. Despite a microcystin-LR content of 10(-8)microgcell(-1) in M. aeruginosa, no toxins were accumulated in Poterioochromonas fed the cyanobacterium. The toxic effect of M. aeruginosa to D. magna was significantly reduced in the presence of Poterioochromonas, which may be performed in two ways: decrease M. aeruginosa cells ingestion of D. magna by grazing on M. aeruginosa; and decrease the toxicity of the medium by degrading the toxins released by M. aeruginosa. This study provides new information on the interactions between a cyanobacterium and its grazer under laboratory conditions and may increase our understanding of the ecological significance of such interactions in the aquatic food webs.
采用大型溞（Daphnia magna）生活史实验，研究了混养金藻（Poterioochromonas sp. strain ZX1）和被金藻吞噬的铜绿微囊藻（Microcystis aeruginosa）对桡足类动物的毒性效应。金藻以两种方式培养（在无机培养基中喂养铜绿微囊藻或在有机培养基中生长）均对大型溞产生类似饥饿的影响，表明金藻既没有急性毒性，也不是大型溞的良好食物。尽管铜绿微囊藻中的微囊藻毒素-LR 含量为 10(-8)microgcell(-1)，但被吞噬的铜绿微囊藻的金藻中并未积累毒素。在金藻存在的情况下，铜绿微囊藻对大型溞的毒性作用显著降低，这可能通过两种方式实现：通过吞噬铜绿微囊藻来减少大型溞对铜绿微囊藻的摄取；以及通过降解铜绿微囊藻释放的毒素来降低培养基的毒性。本研究为实验室条件下蓝藻与其摄食者之间的相互作用提供了新信息，并可能增加我们对这种相互作用在水生食物网中生态意义的理解。
