Department of Ecology and Institute of Hydrobiology of Jinan University, Guangzhou, 510632, China.
Cornell Biological Field Station, Department of Natural Resources, Cornell University, Bridgeport, New York, USA.
Environ Sci Pollut Res Int. 2017 Nov;24(31):24698-24707. doi: 10.1007/s11356-017-0108-x. Epub 2017 Sep 15.
Eutrophication in shallow lakes is characterized by a switch from benthic to pelagic dominance of primary productivity that leads to turbid water, while benthification is characterized by a shift in primary production from the pelagic zone to the benthos associated with clear water. A 12-week mesocosm experiment tested the hypothesis that the herbivorous snail Bellamya aeruginosa stimulates the growth of pelagic algae through grazing on benthic algae and through accelerating nutrient release from sediment. A tube-microcosm experiment using P-PO as a tracer tested the effects of the snails on the release of sediment phosphorus (P). The mesocosm experiment recorded greater total nitrogen (TN) concentrations and a higher ratio of TN:TP in the overlying water, and a higher light intensity and biomass of benthic algae as measured by chlorophyll a (Chl a) in the snail treatment than in the control. Concentrations of total phosphorus (TP), total suspended solids (TSSs), and inorganic suspended solids (ISSs) in the overlying water were lower in the snail treatment than in the control, though no significant difference in Chl a of pelagic algae between the snail treatment and control was observed. In the microcosm experiment, P activity in the overlying water was higher in the snail treatment than in the control, indicating that snails accelerated P release from the sediment. Our interpretation of these results is that snails enhanced growth of benthic algae and thereby improved water clarity despite grazing on the benthic algae and enhancing P release from the sediment. The rehabilitation of native snail populations may therefore enhance the recovery of eutrophic shallow lakes to a clear water state by stimulating growth of benthic algae.
富营养化浅水湖泊的特征是从底栖到浮游初级生产力的主导地位的转变，导致水浑浊，而底栖化的特征是初级生产力从浮游区向与清水相关的底栖区的转移。一项为期 12 周的中观实验测试了以下假设：草食性田螺（Bellamya aeruginosa）通过摄食底栖藻类和加速沉积物中养分释放来刺激浮游藻类的生长。使用 P-PO 作为示踪剂的管微宇宙实验测试了田螺对沉积物磷（P）释放的影响。中观实验记录到，在有螺处理中，上覆水中的总氮（TN）浓度更高，TN:TP 比值更高，光照强度更高，底栖藻类的生物量也更高，用叶绿素 a（Chl a）来衡量。与对照相比，上覆水中的总磷（TP）、总悬浮固体（TSSs）和无机悬浮固体（ISSs）浓度较低，尽管在有螺处理和对照之间没有观察到浮游藻类的 Chl a 有显著差异。在微宇宙实验中，上覆水中的 P 活性在有螺处理中高于对照，表明螺类加速了沉积物中 P 的释放。我们对这些结果的解释是，尽管田螺摄食底栖藻类并促进了沉积物中 P 的释放，但它们仍能促进底栖藻类的生长，从而改善水质。因此，恢复本地田螺种群可能通过刺激底栖藻类的生长，促进富营养化浅水湖泊恢复到清水状态。
