Abstract:We measured nutrient release by the freshwater snail Bellamya sp. under different environmental conditions. In addition, we examined the effects of Bellamya sp. on water transparency, nutrient concentrations, growth of naturally-occurring phytoplankton, and its interactions with Hydrilla verticillata Royle, Elodea nuttalli ST John of Lake Taihu, China. Results showed that the rate of nutrient release by snails was affected by water temperature and the food they stored. The release rates increased with temperature increases. Nutrient release rates by snails were higher after they fed than when they were starved at the constant temperature. Bellamya sp. increased the transparency of water column on a short term, while the release of nutrients led to measurable increases in concentrations of nitrogen and phosphorus. The nutrients released by Bellamya sp., combined with adequate temperature and illumination, allowed phytoplankton growth to exceed remove by snail feeding. At the same time,nutrient release by Bellamya sp. promoted the growth of Hydrilla verticillata Royle and of Elodea nuttalli ST John. A survey of Bellamya sp. in Lake Taihu showed that snail biomass in the submerged macrophyte-dominated areas was higher than that in areas dominated by phytoplankton, and the submerged macrophytes played an important role in the distribution of snails. Collectively, the combination of biomanipulation of snails and restoration of submerged macrophytes shows promise in countering eutrophication, and improvement of water quality.