碱度调节对凡纳滨对虾室内高密度养殖固定化微生物处理效果的影响

在凡纳滨对虾(Litopenaeus vannamei)零换水室内水泥池高密度养殖系统中, 使用生物填料进行微生物固定化, 并通过泼洒碳酸氢钠(NaHCO₃), 将养殖池的碱度分别控制在: T1处理组130 mg (CaCO₃)/L; T2处理组100 mg (CaCO₃)/L; T3处理组70 mg (CaCO₃)/L; T4处理组不调节, 每处理组设置3个重复。在养殖周期内定期检测各水层和各生物填料层微生物的数量变化, 以及水质参数和对虾生长性状参数, 结果表明, T1和T2处理组在各水层和填料层的细菌总数和氮循环细菌数量, 显著高于T3和T4处理组(P＜0.05), 总氮浓度、无机氮浓度、对虾体质量增长速度、饵料转化率等参数亦显著优于T3和T4处理组(P＜0.05)。将碱度提高到100 mg (CaCO₃)/L以上, 可有效提高高密度养殖系统中固定化微生物的处理效果, 从而提高养殖效益。

Alkalinity-regulating effect of immobilized microorganisms on indoor high-density culture of Litopenaeus vannamei

Alkalinity control in an indoor, concrete pond, zero water exchange high-density culture system for Litope­naeus vannamei, using bio-filler microbial immobilization and addition of sodium bicarbonate (NaHCO₃), was tested at various levels. Level T1 involved treatment with 130 mg(CaCO₃)/L, T2 was treated with 100 mg(CaCO₃)/L, T3 was treated with 70 mg(CaCO₃)/L, and the T4 treatment group was not adjusted and acted as the control. There were three replicates for each treatment group. The number of microorganisms in the water and biological filler layers were recorded regularly during the breeding cycle, and water quality parameters and shrimp growth traits parameters were monitored. The results show that the T1 and T2 treatments had a significantly better effect on the total number of bacteria in the water and biological filler layers plus the nitrogen cycle. In T1 and T2, the number of bacteria was significantly higher than in the T3 and T4 treatment groups (P<0.05), while the concentration of total nitrogen and inorganic nitrogen, shrimp weight gain, feed conversion rate, and other parameters were also significantly better than in the T3 and T4 treatment group (P<0.05). The higher the alkalinity was maintained, the shorter the time interval of adjustment in adding sodium bicarbonate. In the late breeding period, the high alkalinity of the water and filler layer and thus total number of bacteria and nitrogen cycle bacteria were significantly higher than the number in low-alkalinity water. This trend was more obvious with increasing water depth. The mechanism of the ecological impact of alkalinity in shrimp farming mainly affects the number of microbes and microbial decomposition efficiency. The growth of microorganisms and increase in decomposition efficiency reduces ammonia nitrogen and inorganic nitrogen concentrations, and thereby maintains a better growth environment for shrimp and thus the growth of shrimp. In conclusion, in a high-density shrimp farming system, raising the alkalinity to 100 mg(CaCO₃)/L or more can effectively increase the number of immobilized microorganisms, thereby improving breeding efficiency. As regards reducing the amount of alkalinity-adjusting agent and ease of management, maintaining water alkalinity at 100 mg(CaCO₃)/L is appropriate.