Abstract: In the ecological restoration engineering of eutrophic water body, high coverage or biomass of submerged vegetation is the key to shift water body from turbid to clear. Filter feeding bivalves are always used to improve the light condition of water body and to promote the expansion and restoration of submerged vegetation. We conducted a controlled experiment to investigate the effects of different densities (control, low, medium, and high) of Corbicula fluminea on the growth of the submerged macrophytes Vallisneria natans. Compared with the control, the relative growth rate of V. natans in the low, medium and high density treatments increased significantly by 29.1%, 41.5% and 69.3%, respectively, while the abundance of tubers increased by 53.0%, 88.3% and 141.0%. Moreover, the root:leaf ratios of V. natans in the medium and high density treatments were 43.9% and 71.6% higher than that in the control, but no significant difference between the low density and the control. C. fluminea can filter-feed on phytoplankton and suspended materials, promote the growth of benthic algae, improve light conditions, change plant biomass allocation, resulting in a higher root:leaf ratio. Moreover, by biodeposition, C. flumineacan increase N and P concentrations in sediments and leaves, decrease C∶N and C∶P in leaves, and consequently enhance plant growth. Thus, the presence of the bivalve C. fluminea could facilitate the restoration of submerged macrophytes in shallow eutrophic lakes.

Key words: eutrophic water, Corbicula fluminea, submerged macrophyte, ecological restoration.