Phosphorus removal potential of aquatic macrophytes in a shallow eutrophic system.

Aquatic macrophytes in inland lakes provide a wide range of ecosystem services. Management efforts to restore aquatic macrophytes for ecosystem recovery need comprehensive understanding of the interaction between growth and nutrient removal efficiency. In contrasting hydrodynamic environments, we examined the growth and phosphorus accrual of two common submerged (Vallisneria natans) and emergent (Acorus calamus) macrophytes. Both biomass and nutrient storage of two macrophytes were observed with significant increases during the incubation period, suggesting the great potential of selected macrophytes in suppressing eutrophication in shallow lakes. Experimental results showed very opposite impacts of flowing water on two macrophyte types. The flowing water was observed to restrain submerged macrophyte's growth and nutrient accrual, but oppositely to stimulate the emergent type. Specifically, our study demonstrated an average reduction of 33.7% in individual plant biomass and 11.4% in nutrient inventory of V. natans, but an overall increase of 27.2% in biomass and 50.0% in nutrient inventory for A. calamus in flowing-water environments. We estimated a total removal of 470-ton phosphorus assuming the complete comeback of aquatic macrophytes in Lake Taihu, as much as 22% of the annual external loading. The results from this study could inform management of aquatic macrophytes at local and lake-wide scales. [ABSTRACT FROM AUTHOR]