养殖密度对缢蛏养殖系统水质的影响

Effect of stocking density on water quality in Sinonovacula constricta culture system

依据辽宁丹东东港地区的实验池塘中缢蛏（Sinonovacula constricta）实际放养密度，设置了0、30、60、90和120ind·m-2 5个密度梯度，采用实验生态学方法室内模拟研究了放养密度对缢蛏单养系统水质的影响。结果表明：放养密度对溶解氧（DO）、硝态氮（NO3--N）、亚硝态氮（NO2--N）、活性磷（PO43--P）及总磷（TP）含量的影响极显著（P〈0．01），对铵态氮（NH4＋-N）含量的影响不显著（P〉0．05）；其中，DO、NO3--N及NO2--N含量随缢蛏放养密度的增加而减小，PO43-P及TP含量随缢蛏放养密度的增加而增大；缢蛏放养密度相对较高的实验组（90和120ind·m-2）明显促进了底泥沉积物中P的循环和再生，同时提高了水中营养物质N的利用率，有效控制NO2--N及NH4＋-N等有害物质的含量；在实际养殖中可以按照90～120ind·m。的密度放养，并且加强对池塘水质的管理。

According to the practical stocking density of Sinonovacula constricta from the experi- ment ponds in Donggang, Liaoning Province, stocking density was set up at 0, 30, 60, 90 or 120 ind . m-2. Effect of S. constricta stocking density on water quality in S. constricta culture sys- tem in the laboratory was studied by experimental ecology methods. The results indicated that the stocking density of S. constricta had significant effects on the concentrations of DO, NO3--N, NO2--N, PO43--P and TP （P〈0.01） but not NH4＋-N （P〉0.05）. The concentrations of DO, NO3--N and NO2--N decreased with the increase of the stocking density, while PO43--P and TP concentrations increased with the increase of the stocking density. The higher density of S. con- stricta （ 90 and 120 ind. m-2） improved the cycle and regeneration of P in sediment and the uti- lization of N in water, which could help to control the concentrations of NO2--N and NH4＋-N in the culture period. Based on this study, the stocking density of S. constricta ranging from 90 to 120 ind .m-2 is feasible in the culture ponds, but we need pay more attention on water quality management during the culture period.