水绵(Spirogyra)对蓝藻复苏及藻类群落结构的影响

Effects of Spirogyra on the cyanobacteria recruitment and phytoplankton community structure

通过采集富营养化水体中的底泥与上覆水,在自然光照条件下建立了模拟自然水体的实验装置,并设置了高(42mg.L-1)、低(21mg.L-1)、空白(0mg.L-1)3个水平的水绵添加量,研究了不同剂量的水绵对水华蓝藻(以微囊藻为主)复苏过程及藻类群落结构的影响,同时考察了充足的营养盐在实验中所起的作用.整个实验在藻类的复苏期(2010年3—5月)进行.结果表明,不同剂量的水绵设置显著改变了水体环境,高剂量水绵的遮光率达到了93%,低剂量水绵的遮光率也可达到84%.水绵的添加降低了底泥表面的温度,并大量吸附了水体中的氮磷营养盐.水绵的光遮蔽效应是抑制蓝藻复苏,影响藻类群落结构演替的主要原因,即使在充足的营养盐条件下,水绵的这种影响依然很明显.

An experimental appliance was designed to study the effect of Spirogyra on the recruitment of cyanobacteria（mainly Microcystis） in eutrophic water body and the effect of nutrients.Intact surface sediments from an open pool of eutrophic water were put onto the appliance bottom and the water was gently added on preset surface sediments.Three levels of Spirogyra biomass（high 42 mg.L-1,low 21 mg.L-1,control 0 mg.L-1） were adopted and the experiment was carried out under natural light from March to May 2010.The results showed clearly that Spirogyra could prominently alter the water environment.Shading rate could reach 93% at a high dose of Spirogyra,and even 84% at a low dose.Spirogyra could lower the temperature of sediment surface and greatly absorb nitrogen and phosphorus nutrients of the water.The shading effects of Spirogyra on the water environment might be the main reason that Spirogyra inhibited the recruitment of cyanobacteria and changed the algal community structure.Even with abundant nutrition,the effect of Spirogyra on cyanobacteria recruitment was still significant.The shading effects of Spirogyra played a key role in inhibiting the recruitment of cyanobacteria and changing the algal community structure.