鱼蚌混养对池塘水质、藻相结构及三角帆蚌生长的影响

2012年4月26日—2012年12月12日通过在鲢鳙鱼养殖池塘中放养不同密度的三角帆蚌,研究不同三角帆蚌放养比例对鲢鳙鱼养殖池塘中水质、藻相结构及三角帆蚌生长的影响。实验中,鲢鳙放养比例统一为3∶7,总密度为1.5尾/m3。三角帆蚌放养密度则设置4个水平,分别为单养鲢鳙鱼池塘(0只/m3),低密度三角帆蚌混养池塘(0.8只/m3),中密度三角帆蚌混养池塘(1.0只/m3)和高密度三角帆蚌混养池塘(1.2只/m3)。结果显示,混养三角帆蚌池塘的水化指标(TP、PO4-P、NH3-N、NO2-N和NO3-N)均显著低于单养鱼池塘。中密度三角帆蚌混养池塘除NH3-N和化学需氧量(COD)与低密度三角帆蚌混养池塘无显著差异外,其他各项水化指标均显著低于其他3个池塘,并且极显著低于单养鲢鳙鱼池塘。单养鲢鳙鱼池塘藻类平均密度均极显著高于鱼蚌混养池塘,其中在鱼蚌混养池塘中浮游植物密度与三角帆蚌密度成负相关关系。单养鲢鳙鱼池塘的浮游植物生物量均极显著低于中、高密度鱼蚌混养池塘,并且显著低于低密度混养池塘。浮游植物生物量与三角帆蚌密度成正相关关系,鱼蚌池塘中绿藻和裸藻的生物量在养殖过程中上升显著。低、中密度三角帆蚌混养池塘三角帆蚌存活率均显著高于高密度三角帆蚌混养池塘;低密度混养池塘中蚌湿重、壳长及壳宽相对增长率均为最大,显著高于中、高密度三角帆蚌混养池塘。研究表明,养鱼池塘混养三角帆蚌不仅能改善养殖池塘的水质,还能控制藻类数量,促使绿藻和裸藻等大型藻类的生长,提高养殖水体浮游植物的生物量总量,最终还能有效提高三角帆蚌的存活率及生长率。从改善水质,藻相结构,蚌成活率及生长等指标角度考虑,在鲢鳙鱼养殖池塘中,三角帆蚌最佳放养密度为1.0只/m3。

The impact of polyculture of freshwater mussel on water quality, plankton community and mussel growth performance in ponds of silver carp and bighead carp

A pond-based experiment was conducted from 26 April to 12 December 2012,in order to evaluate the effects of polyculture of freshwater mussel Hyriopsis cumingii in the ponds of silver carp Hypophthalmichthys molitrix and bighead carp Aristichthys nobilis,on water quality,plankton community and mussel growth performance.During the experiment period,four mussel densities were set up:fish monoculture pond(0/m³),low density mussel polyculture pond(0.8/m³),medium density mussel polyculture pond(1.0/m³)and high-density mussel polyculture pond(1.2/m³).The results revealed that water quality parameters(TP,PO₄-P,NH₃-N,NO₂-N and NO₃-N)of the ponds with mussels were significantly lower than the fish monoculture ponds.All water quality parameters of medium density mussel polyculture ponds were significantly lower than those of the other three ponds,except that its chemical oxygen demand(COD)and NH₃-N showed no significant difference with that of low density mussel polyculture ponds.The plankton densities in fish monoculture ponds were significantly higher than those of mussel polyculture pond.In mussel polyculture ponds,negative correlation was found between phytoplankton density and mussel culture density.Phytoplankton biomass of fish monoculture pond was significantly lower than that of mussel polyculture pond,while significantly lower than that of the low density museel polyculture pond.Phytoplankton biomass positively correlated with mussel density.The biomass of green algae and bare algae significantly increased in the polyculture mussel pond.the mussel survival rates were significantly higher in low density and medium density mussel polyculture ponds than that of high-density polyculture pond,but the values of mussel wet weight,shell length and shell width were the highest in the low density mussel polyculture pond.This study indicated that polyculture with freshwater mussel can effectively improve the water quality,control excess growth of harmful algae,accelerate the growth of chlorella and euglenophyta,increase the biomass of plankton,and improve survival and growth performance of the mussels.Finally,this study demonstrated that the optimal culture density of freshwater mussel in the ponds of silver and bighead carps was 1.0/m³.