密度胁迫对日本囊对虾生长和水环境的影响

为了探讨密度胁迫对日本囊对虾(Marsupenaeus japonicus)生长、存活及水质因子的影响, 作者设置了100尾/m²(DD)、200 尾/m²(GD)、400 尾/m²(GZ)、600 尾/m²(GG)4个养殖密度, 分析了不同养殖密度下日本囊对虾的生长量、存活率、肥满度及水质因子的差异。结果表明, 实验所监测的水质因子均在对虾生长的安全阈值内, 氨态氮、亚硝态氮、总氮和总磷含量表现出随养殖密度增加逐渐升高的趋势; 体长和体质量增长量、存活率与养殖密度呈负相关, 其中存活率处理间均达到极显著水平(P< 0.01), 且当养殖密度高于200尾/m²时存活率迅速降低; 低养殖密度(DD)处理的对虾肥满度与其他处理间差异均达到显著水平(P< 0.01)。因此, 在相似养殖条件下, 日本囊对虾的适宜养殖密度应该不高于200尾/m²。本实验过程中, 各处理间水质因子均在对虾生长的适宜范围内, 说明水质不是造成对虾死亡的主要原因。所以, 推测密度胁迫可能是造成日本囊对虾存活率低的主要原因。

Effects of density-stress on water quality and growth of Marsupenaeus japonicus

To examine the effects of density-stress on growth, survival rates and water quality during Marsupenaeus japonicus farming, four stocking densities (100 (DD), 200 (GD), 400 (GZ) and 600 (GG) individuals/m²) were set in this study. The body length, body weight, survival rate and water quality factors under different farming densities were determined. The results showed that the water quality factors were all within the safe range for shrimp growth. The concentrations of TAN, NO₂-N, TN and TP increased with the increase of stocking density. The gain of shrimp weight, and length and survival rate reduced with the increase of stocking density. The survival rate reduced significantly when the stocking density was more than 200 individuals/m². The relative fatness had significant difference between DD and other treatments (P< 0.01). This study suggests that the suitable stocking density for M. japonicus is less than 200 individuals/m². Furthermore, the density-stress, not the water quality might be the main cause resulting in low survival rate of shrimp.