太湖环棱螺(Bellamya sp.)及其与沉水植物的相互作用

选用太湖常见的环棱螺及沉水植物,研究了不同状态下环棱螺营养盐的释放特征,探讨了环棱螺对水体营养盐、透明度和浮游藻类的影响,及其与沉水植物的相互作用.结果表明:在一定温度范围内,环棱螺营养盐的释放速率随温度升高而增加,且进食状态下释放速率高于饥饿状态;环棱螺能在短时间内提高水体透明度,但其营养盐释放又引起局部水体溶解态氮磷含量的增加;适宜的条件下,水体中藻类的再生能力超过环棱螺对其的抑制力;水体营养盐含量增加,促进与环棱螺共存的伊乐藻和轮叶黑藻的生长.在太湖的不同湖区,草型湖区螺类的生物量远高于藻型湖区,这表明沉水植物可能是影响螺类分布的重要生态因子之一.

Bellamya sp. and its interaction with submerged macrophytes in Lake Taihu

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.