To investigate the role of aquatic plants in controlling alga] populations in eutrophic water, the number, structure and biomass of alga populations influenced by floating plants of Eichhornia, crassipe and Alternanthera philoxeroides, and filter-feeder Hypophthalmichthys molitrix, and the combination of above three were studied. The result showed that Eichhornia crassipe, Alternanthera philoxeroides, or Hypophthalmichthys molitrix could reduce the total biomass of algae in water, and Eichhornia crassipe + Hypophthalmichthys molitrix had the best effect. Hypophlhalmichthys molitrix decreased the total biomass of algae while increased the total number of algae. By the end of the experiment, the total biomass of alga treated with Eichhornia crassipe, Alternanthera philoxeroides, Hypophthalmichthys molitrix, Eichhornia crassipe+Hypophthalmichthys or Alternanthera philoxeroides + Hypophthalmichthys were respectively 20. 1% , 21. 1% , 94. 5% , 16. 8% and 20. 7% of the control. Eichhornia crassipe and Alternanthera philoxeroides could absorb nitrogen and phosphorus in the water. At the end of the experiment, the treatment of Eichhornia crassipe+ Hypophthalmichthys showed the highest total nitrogen removal efficiency of 41. 52% , and Alternanthera philoxeroides + Hypophthalmichthys molitrix displayed rnthe highest total phosphorus removal efficiency of 41. 94%. Total nitrogen and total phosphorus of the control group had significantly positive correlation with the total biomass of alga, but the correlations were not significant in other treatments. Various treatments changed the structure and proportion of alga. Bacillariophyta, Euglenophyta and Pyrrophyta with bigger volume in the treatment with Hypaphthalmichthys alone were inhibited, while Cyonophyta and Chlorophyta with smaller volume were poorly inhibited.%为了探讨水生植物对富营养化水体中藻类种群的控制作用,研究了飘浮植物凤眼莲和水花生、滤食性鲢鱼及其组合对水体中藻种群结构、生物量和数量等的影响.结果表明:凤眼莲、水花生和鲢鱼均可减少水体中藻类总生物量,其中水葫芦+鲢鱼组合的效果最好;单独放养鲢鱼的处理虽然藻类总生物量下降,但藻类总数量增加;试验结束时,水葫芦、水花生、鲢鱼、水葫芦+鲢鱼、水花生+鲢鱼处理水体藻类总生物量分别是对照的20.1％、21.1％、94.5％、16.8％、20.7％.水葫芦、水花生都可以吸收水体中的氮、磷,试验结束时,水葫芦+鲢鱼处理对总氮的去除效果最好,去除率达到41.52％,水花生+鲢鱼处理对总磷的去除效果最佳,去除率达到41.94％;对照组的总氮、总磷与水体藻类总生物量呈显著正相关.不同处理对藻类种群结构产生影响并且改变各藻类的比例,单独放养鲢鱼水体中平均体积大的硅藻、裸藻、甲藻受到了抑制,但对平均体积较小的蓝藻、绿藻的抑制效果不佳.
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