Guo Nichun, Xie Ping
Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, Chinese Academy of Sciences, Donghu South Road 7, Wuhan 430072, PR China.
Environ Pollut. 2006 Oct;143(3):513-8. doi: 10.1016/j.envpol.2005.11.044. Epub 2006 Jan 30.
This is the first experimental study to compare difference in the development of tolerance against toxic Microcystis among multi-species of cladocerans (Daphnia, Moina and Ceriodaphnia) pre-exposed to two M. aeruginosa PCC7820 strains (MC-containing and MC-free). Zooplankton were divided into S population (fed Scenedesmus), M-F population (fed Scenedesmus+MC-free Microcystis), and M-C population (fed Scenedesmus+MC-containing Microcystis). M-F and M-C populations were pre-exposed to Microcystis strains for 4 weeks, and their newborns were collected for experiments. A pre-exposure to MC-containing or MC-free Microcystis increased tolerance against toxic Microcystis. The marked increases in survival rate and median lethal time (LT(50), 100-194% increase) in the M-C population of Ceriodaphnia suggest that small-sized cladocerans may develop stronger tolerance against Microcystis than large-sized ones when both groups are exposed to toxic Microcystis. This may explain why dominant Daphnia is usually replaced by small-sized cladocerans when cyanobacteria bloomed in summer in eutrophic lakes.
这是第一项实验研究，旨在比较预先暴露于两种铜绿微囊藻PCC7820菌株（含微囊藻毒素和不含微囊藻毒素）的多种枝角类动物（水蚤、裸腹溞和角突网纹溞）对有毒微囊藻耐受性发展的差异。浮游动物被分为S种群（投喂栅藻）、M-F种群（投喂栅藻+不含微囊藻毒素的微囊藻）和M-C种群（投喂栅藻+含微囊藻毒素的微囊藻）。M-F和M-C种群预先暴露于微囊藻菌株4周，然后收集它们的新生个体用于实验。预先暴露于含微囊藻毒素或不含微囊藻毒素的微囊藻可提高对有毒微囊藻的耐受性。角突网纹溞M-C种群的存活率和半数致死时间显著增加（LT(50)，增加100 - 194%），这表明当两组都暴露于有毒微囊藻时，小型枝角类动物可能比大型枝角类动物对微囊藻产生更强的耐受性。这可能解释了为什么在富营养化湖泊夏季蓝藻水华爆发时，占优势的水蚤通常会被小型枝角类动物取代。
