富藻养殖水体中金鱼藻和篦齿眼子菜的抑藻效果研究

夏季高温时，养殖水体水华现象频繁发生，给养殖业带来巨大的损失。常见水生植物释放的活性物质在低浓度下可以起到抑藻作用，对藻类调控具有重要意义。本研究采用实验室静态模拟方法，取养殖池塘暴发蓝藻水华的水体，与沉水植物金鱼藻(Ceratophyllum demersum)及篦齿眼子菜(Potamogeton pectinatus)进行共培养，研究这2种沉水植物对养殖水华水体营养水平、藻类生长、藻类结构及浮游藻类生物多样性的影响。结果显示，金鱼藻和篦齿眼子菜可显著降低水华水体氮、磷等营养水平(P<0.05)；金鱼藻和篦齿眼子菜可有效抑制水华蓝藻(Cyanobacteria)生长，尤其对颤藻和微囊藻(Microcystis sp.)效果显著(P<0.05)，且篦齿眼子菜对水华蓝藻抑制效果更为显著。实验结束时，篦齿眼子菜培养组藻密度下降93.6%，生物量下降98.9%，叶绿素a含量下降60.5%；金鱼藻培养组藻密度下降72.5%，生物量下降86.8%，叶绿素a含量下降54.3%；金鱼藻和篦齿眼子菜的存在可促进养殖水体浮游藻类生物多样性增加，且金鱼藻提高浮游藻类生物多样性效果更显著。金鱼藻培养组浮游藻类生物多样性升高98.4%，篦齿眼子菜培养组浮游藻类生物多样性升高50.3%。本研究结果可为未来生态养殖提供理论依据和参考。

Responses of Eutrophic Ponds to Ceratophyllum demersum and Potamogeton pectinatus

Cyanobacterial blooms occur frequently in aquaculture ponds during summer, which has brought great losses to the aquaculture industry. Physical salvage and chemical reagents were previously used to kill the harmful algae and improve the water quality. However, physical salvage is time-consuming, and chemical reagents easily cause more pollution. Thus, there is currently greater consideration to regulate the water quality by using ecological strategies, such as the inhibition of cyanobacteria by submerged macrophytes. Because of its ecological safety, this method is being increasingly applied in eutrophic water bodies. In the present study, coculture simulation experiments were used to observe the effects of submerged plants (Ceratophyllum demersum and Potamogeton pectinatus) on the phytoplankton composition and water quality of ponds (i.e., the concentrations of total nitrogen, total phosphorus, soluble nitrogen, soluble phosphorus, nitrate, and ammonia, and chemical oxygen demand) during cyanobacterial blooms. The results showed that when compared with the control, C. demersum and P. pectinatus could significantly reduce the concentrations of nitrogen and phosphorus in the water column, with significant differences detected between the control and P. pectinatus treatment; inhibit the growth of cyanobacteria, especially of Oscillatoria sp. and Microcystis sp., with the effects of P. pectinatus being greater than those of C. demersum (compared with the values in the control pond, the algal density, biomass, and Chl.a content decreased by 93.6%, 98.9%, and 60.5%, respectively, in the P. pectinatus-treated pond and by 72.5%, 86.8%, and 54.3%, respectively, in the C. demersum-treated pond); and promote the phytoplankton biodiversity of the ponds. At the end of the experimentation, the biodiversity in the ponds treated with C. demersum and P. pectinatus increased by 98.4% and 50.3%, respectively, relative to that in the control pond. The results of this study provide a theoretical basis for the future restoration and remediation of eutrophic waters.