【摘要】 沉水植物是维持浅水湖泊清水型生态系统的关键因子.沉水植物可以从水和沉积物中吸收营养盐,但具有不同根冠比的种类有明显的差异,因此对生态系统的影响可能存在差异.以根冠比不同的两种常见沉水植物——苦草(Vallisneria natans)和轮叶黑藻(简称黑藻)(Hydrilla verticillata)为研究对象,通过建立实验水体,比较不同磷负荷条件下沉水植物生物量、水和沉积物中磷含量的变化,以探讨具有不同沉水植物种群的水体对外源营养盐负荷的响应特征.结果显示:随着磷负荷增加,苦草生物量降低,而黑藻生物量上升;苦草的根冠比显著高于黑藻,且两种沉水植物的根冠比都随磷负荷增加而降低.与没有沉水植物的结果比较显示:苦草和黑藻在不同磷负荷条件下,都能显著降低水和沉积物中磷的含量;苦草对沉积物中磷含量的影响大于黑藻,而黑藻对水中磷含量的影响大于苦草.因此,在外源营养盐负荷较高时,黑藻比苦草能更有效地削减水中磷浓度,从而更有利于维持浅水湖泊清水型生态系统;但沉积物扰动较强时,苦草和黑藻对水体的影响尚需进一步研究.更多还原

【Abstract】 Owing to their capability to take nutrients from both water and sediments,submerged macrophytes play an important role in maintaining the clear-water ecosystems in shallow lakes.Species with different root to shoot ratios may have different effects on lake ecosystems.In order to explore the responses of aquatic ecosystems with different submerged macrophytes to external nutrient loadings,this study,we established experimental ecosystems inhabited with two submerged macrophyte species Vallisneria natans and Hydrilla verticillata,and compared their biomass,the phosphorus(P) concentrations in water and in sediments under different phosphorus loadings.The results showed that with the increase of P loadings the biomass of V.natans decreased and that of H.verticillata increased;the root to shoot ratio was higher in V.natans than in H.verti cillata,though both decreased during the experiment.Compared with the control without submerge macrophytes,t he water and sediments of both V.natans and H.verticillata had lower P contents.V.natans had more significant effects than H.verticillata on sediment P contents.In contrast,the effect on water P concentrations was more signi ficant in H.verticillata than in V.natans.Thus,our study suggests that in higher external nutrient loadings,H.verticillata is more sufficient to reduce P concentrations in waters than V.natans.However,the effect of V.natans and H.verticillata on aquatic ecosystems need further study when there is a strong sediment resuspensi on.更多还原