孟氏浮游蓝丝藻在模拟水体中的垂直分布与浮力规律研究

采用大型室内湖泊模拟装置对孟氏浮游蓝丝藻在富营养化湖泊中的垂直分布与迁移特征进行了模拟,并通过10 L玻璃瓶实验对孟氏浮游蓝丝藻浮力对光的响应进行了分析.湖泊模拟实验结果表明,光照后,表层孟氏浮游蓝丝藻开始向下层迁移,光照8h后,藻丝在深2～3m左右水层形成稳定聚集层;藻丝容易集聚层在光照度为10μmol·(m2·s)-1左右水层,处于该水层上部的藻丝漂浮百分率<50%趋向于沉降,处于该水层下部的藻丝漂浮百分率>50%趋向于漂浮;无光照后,藻丝开始往水体表层聚集,无光照12h后,约20%的藻丝聚集在水体表层,无光照48h后,约50%的藻丝聚集在水体表层;说明浮游蓝丝藻白天主要分布在水体2～3m处,在早晨或连续的阴天后,可能在水体表层形成水华.10 L玻璃瓶实验结果表明,强光照[100μmol·(m2·s)-1]/无光照周期下藻丝漂浮百分率在30%-70%间变化,弱光照[25μmol·(m2·s)-1]/无光照周期下藻丝漂浮百分率在30%-50%间变化,说明强光照[100μmol·(m2·s)-1]/无光照周期下藻丝具有明显的沉降与漂浮特征.1昼夜内,藻细胞蛋白质和伪空胞的变化不明显,糖含量在14%-35%间变化,藻丝的浮力对光照的响应可能通过藻细胞的糖含量变化实现.

Buoyancy Regulation and Vertical Distribution of Planktothrix mougeoti in the Simulator Experiments

The dominance of gas-vacuolated cyanobacteria is often attributed to their buoyancy and buoyancy in response to environmental conditions. Lake simulator experiments (4 m high and 1 m diameter) and pyrex bottle experiments (10 L) were applied to investigate the buoyancy regulation and vertical distribution of Planktothrix mougeotii in eutrophic lakes at 28 degrees C. During light phase, the filaments stratify in the 2-3 m after 8 h light exposure and the biomass at the layer attach maximum after 12 h light exposure. During dark phase, the filaments are tent to migrate to the surface. 20% of filaments migrate to the surface after 12 h and 50% of filaments migrate to the surface after 48 h. The buoyancy regulation under light condition is that filaments stratify in 10 micromol x (m2 x s)(-1) layers, and the filaments above the layer sink down, while those suspended below the layer float up. The amplitude of diel changes in buoyancy is related to photon irradiance, and the change of buoyancy in light [100 micromol x (m2 x s)(-1)]/ dark is higher than its in light [25 micromol x (m2 x s)(-1)]/ dark. Carbohydrate ballasting may be the only mechanism for buoyancy changes in Planktothrix mougeotii filaments during the period.