丝状绿藻腐烂过程对水质和沉水植物黑藻生长的影响实验研究

从野外采集沉水植物黑藻种植于120L的塑料桶内,然后采集丝状绿藻放在培养黑藻的桶内.设种植黑藻而不放入丝状绿藻的桶为对照.由于夏季高温和强光,丝状绿藻在数天内会逐渐腐烂.研究发现,在丝状绿藻腐烂过程中,水体的溶解氧(DO)、pH值、水下光强度与水面光强度的比值均比对照组大大降低,尤其是溶解氧,有时甚至下降为零.而水体的温度、总氮(TN)、总磷(TP)和高锰酸钾指数(CODMn)在丝状绿藻腐烂过程中则上升,后3个指标大大高于对照.有丝状绿藻处理的试验组,随着丝状绿藻的腐烂,沉水植物黑藻亦慢慢腐烂,最后消失.而对照组黑藻生长良好,生物量大大上升.因此,我们认为,丝状绿藻腐烂过程中引起的水质指标变化,尤其是降低溶解氧、降低水下光照强度、降低pH和使水体温度上升是沉水植物黑藻死亡的主要原因.这种现象在进行沉水植被恢复过程中值得注意,并应寻找对策.

Effect of Decomposed Filamentous green algae on water quality and the growth of submerged macrophyte Hydrilla verticillata

The collected filamentous green algae were added to the plastic buckets which were planted with the submerged macrophyte Hydrilla verticillata.For the high temperature and light intensity in summer,the filamentous algae decomposed in the following several days.As a result,in the process of algal decomposing,the diso1ved oxygen(DO) concentration,pH value and the ratios of light intensity under water to the light intensity on the surface of water were decreased greatly compared with the control.Other parameters such as temperature,total nitrogen(TN),total phosphorus(TP) and potassium permanganate index(COD_(Mn)) were increasing followed the decomposing process.The plants of Hydrilla verticillata decomposed and finally vanished with the treatment of filamentous green algae,while that biomass in control increased greatly.We concluded that the change! of water quality in the process of filamentous algae decomposing,especially the decreases of DO,light intensity under water and pH,and the increases of water temperature were the main reasons contribute to the death of Hydrilla verticillata.This phenomenon should be paid more attention in the practice of aquatic vegetation reconstruction,and countermeasures should be brought forward.