Omnivorous shrimp

Lake eutrophication often causes declines and even losses of submerged macrophytes through the shading effects of increased periphyton and phytoplankton. The Chinese swamp shrimp Neocaridina denticulata sinensis Kemp (Decapoda, Atyidae) is a common omnivore in Chinese lakes, where its presence may impact both periphyton and phytoplankton, with previously unstudied consequences for submerged macrophytes. Here, using a mesocosm experiment, we studied the effect of N. d. sinensis on periphyton, phytoplankton and the submerged macrophyte Vallisneria denseserrulata. Results showed that in the presence of N. d. sinensis, the biomass of periphyton on the leaves of V. denseserrulata was significantly reduced, and that growth rate of V. denseserrulata increased. The presence of N. d. sinensis also significantly increased the total phosphorus concentrations in the water column and phytoplankton biomass (chlorophyll-a). The enhanced growth of V. denseserrulata is likely to be linked to improved light harvesting due to the reduced periphyton attached to their leaf surface. The results suggest that stocking with Chinese swamp shrimps may enhance the development of macrophytes in eutrophic shallow lakes.