铜绿微囊藻对萼花臂尾轮虫与大型溞竞争关系的影响

EFFECT OF MICROCYSTIS AERUGINOSA ON COMPETITION BETWEEN BRACHIONUS CALYCIFLORUS AND DAPHNIA MAGNA

为探究铜绿微囊藻(Microcystis aeruginosa)浓度变化对浮游动物竞争关系的影响,通过控制实验法,评估了在3个铜绿微囊藻浓度梯度下,萼花臂尾轮虫(Brachionus calyciflorus)和大型溞(Daphnia magna)之间的种间竞争关系。结果表明不同浓度铜绿微囊藻对萼花臂尾轮虫、大型溞的增长及二者种间竞争影响具有差异,并且在3种铜绿微囊藻浓度下均以大型溞为主要优势类群。低浓度(5×104 cells/mL)铜绿微囊藻仅促进大型溞种群增长(P<0.01),大型溞占据主要优势地位;中浓度(1×10^(5) cells/mL)铜绿微囊藻对萼花臂尾轮虫和大型溞增长均有显著影响(P<0.01),在此浓度下大型溞在种群竞争中依旧占优势地位,使得萼花臂尾轮虫种群衰亡;在高浓度铜绿微囊藻(5×10^(5) cells/mL)环境中种群生长均受到抑制(P<0.01),在共培养体系中仅大型溞种群存活。在无其他外在影响因素存在时,实验结果显示在不同浓度的铜绿微囊藻下,大型溞均占优势,说明铜绿微囊藻的浓度可能不是影响大型溞与萼花臂尾轮虫的竞争地位的主要因素。研究不同浓度铜绿微囊藻条件下浮游动物种间竞争关系对于理解蓝藻水华暴发的生态效应有重要意义。

To investigate the determinants of zooplankton community structure in aquatic ecosystems under cyanobac-terial bloom and the effects of Microcystis aeruginosa density on zooplankton competition relationship,the interspeci-fic competition between Brachionus calyciflorus and Daphnia magna was evaluated by conducting experiments at three concentration gradients of M.aeruginosa.Our results showed that the concentrations of M.aeruginosa had significant effects on the growth and competition between B.calyciflorus and D.magna,it did not change the dominance of D.magna.The results also showed that a low level of addition of M.aeruginosa(5×104 cells/mL)promoted D.magna population growth(P<0.01)and increased dominance in D.magna in the mixing culture.The growth of both D.magna and B.calyciflorus was significantly(P<0.01)affected by the medium concentration(1×10^(5) cells/mL)level of M.aeru-ginosa.However,population growth of both species was suppressed(P<0.01)by the high concentration of M.aeru-ginosa(5×10^(5) cells/mL)and only D.magna population survived in the co-exist system.Thus,in the absence of other external influences,our results suggested that D.magna dominated under various concentration levels of M.aeru-ginosa co-exist with B.calyciflorus,indicating that the concentration of M.aeruginosa may not be the main factor af-fecting the competitive position of D.magna and B.calyciflorus.The study on zooplankton community dynamics un-der different concentrations of M.aeruginosa will contribute our understanding the ecological consequences of cya-nobacterial bloom.