山仔水库沉积物蓝藻复苏试验研究

Recruitment of cyanobacteria from sediment of the Shanzai Reservoir

采用正交试验考察了温度、光照、营养盐和物理扰动4个因素对山仔水库冬季沉积物中蓝藻复苏的影响,每个因素设置两个水平,培养周期为6d,并以蓝藻复苏量为考察指标.结果表明,温度和光照为蓝藻复苏的主要影响因子,上覆水体的营养盐、物理扰动对沉积物中蓝藻门复苏的影响作用不显著,不同的蓝藻种属对温度和光照条件的响应程度不完全一致,蓝藻门微囊藻属(Microcystis)对温度和光照的复苏响应显著,颤藻属(Oscillatoria)仅对温度的复苏响应显著.同时,通过设置6.0～16.0℃之间6个温度梯度及50和2000lx两个光照梯度,进行了沉积物柱状样复苏模拟实验.结果显示,山仔水库冬季沉积物微囊藻属和颤藻属在10℃左右开始复苏,微囊藻属对光的敏感性使其更容易处于优势地位.

The effects of four environmental factors,including temperature,light,nutrient and physical disturbance,on the cyanobacteria recruitment from the winter sediment in the eutrophic Shanzai Reservoir were investigated using an orthogonal experiment.Two levels were designed for each factor and the experiments lasted for six days.The results showed that temperature and light were the most important for the recruitment of Microcystis and Oscillatoria.Increasing temperature would promote the recruitment of Microcystis and Oscillatoria which would make the cyanobacteria to dominate.The effects of the overlying water nutrient status and the physical disturbance on the recruitment of Microcystis and Oscillatoria from sediments were not obvious.Based on the results,different temperatures and light intensities were designed in the simulation experiment.The incubation temperatures were increased from 6.0 to 16.0 ℃ with six levels while each temperature level was kept for four days under 2000 and 50 lx light intensities,respectively.Recruitment was calculated by the diminution of benthic cyanobacteria abundance,and moreover,by the increase of cyanobacteria abundance in the water column.It is shown that the recruitment of Microcystis and Oscillatoria started at about 10 ℃.It was also demonstrated that the migration of Microcystis from the sediments was more pronounced at higher light intensity（2000 lx） than in dark（50 lx） treatments.