鳑鲏鱼对河蚌-沉水植物关系的影响及其机理研究

Submerged macrophytes restoration has been considered to be one of the most powerful techniques to restore shallow eutrophic lakes. In order to enhance the water clarity for macrophytes community recovery, benthic filter-feeding mussel stocking is commonly used to maintain a relatively suitable light climate in the water. However, the mussels may also promote the population development of bitterling fish relying on mussel for reproduction. Little is known about how the bitterling fish affect the growth of submerged macrophytes. Here, we hypothesize that 1) a higher water clarity maintained by mussels will enhance the growth of submerged macrophytes, and the increase the biomass of periphyton, and 2) bitterling as a small omnivorous fish will prey more on periphyton rather than macrophytes which will eliminate the shadding effects by periphyton and promote the growth of macrophytes. In the present study, fish gut contents analysis and stable isotopes analysis techniques are combined to quantify the diet of bitterling fish in the natural lakes. While in the mesocosm experiments, we will investigate the effects of mussel, bitterling fish and mussel-bitterling fish system on the growth of submerged macrophytes, the biomass of periphyton, and physical and chemical parameters of water, repectively. Base on the field investigation and mesocosm experiment results, we will try to assess the effects of mussel on the growth of submerged macrophytes, and the role of bitterling fish.

沉水植物恢复是富营养化浅水湖泊生态修复的关键；河蚌通过滤食作用减少浮游植物、改善透明度，促进沉水植物生长，因此广泛应用于湖泊生态修复实践。然而，河蚌的增加会促进依赖河蚌繁殖的鳑鲏鱼种群发展（带来鳑鲏的卵和增加产卵基质），其对沉水植物的影响尚待研究。与传统的“杂食性鱼类增加会破坏沉水植物发育”观点不同，本研究认为：河蚌可促进沉水植物生长，同时附着藻类也会增加；而小型杂食性鱼类鳑鲏，优先利用营养更丰富的附着藻，对沉水植物的牧食较少，将削弱附着藻对沉水植物的遮光效应，进一步促进沉水植物生长。为验证以上假说，该项目通过野外调查，结合肠道内含物分析和稳定同位素技术，定量分析鳑鲏的食性；通过受控实验，分别设置河蚌、鳑鲏和河蚌–鰟鮍处理组，研究不同处理对附着藻类、沉水植物等的影响，并通过分析受控实验系统的营养盐、浮游生物群落变化特征以及河蚌、鰟鮍的稳定同位素特征，探讨鳑鲏对河蚌–沉水植物关系影响的机理。