牡蛎壳作为生物絮凝养殖系统缓释碱度源的效果

为优化生物絮凝系统碱度调控策略,实验研究了在生物絮凝—罗非鱼养殖系统中牡蛎壳补充碱度的可行性。在系统启动阶段评估了不同牡蛎壳添加量0 g/L(对照组,A组)、0.36 g/L(B组)和0.72 g/L(C组)补充碱度的可行性。结果显示,C组碱度、pH和钙离子水平显著高于A组,但B与C组组间的水质差异不显著,牡蛎壳补充碱度效果明显。在生物絮凝系统启动阶段的基础上,对比研究了两种形态的牡蛎壳(壳粉,E组)、(壳,F组)]为生物絮凝在罗非鱼养殖系统中补充碱度的效果。各组的水质指标、鱼体酶活免疫性能以及细菌群落组成均无显著差异,牡蛎壳及壳粉对罗非鱼生长没有明显的负面影响,可以被应用到生物絮凝养殖系统中,但补充碱度效果不明显。牡蛎壳补充碱度与形态无关。研究表明,在目前实验条件下,牡蛎壳在生物絮凝养殖系统中不能完全替代碳酸氢钠,还需进一步优化相关工艺。

Effects of oyster shell as slow-release alkalinity source in biofloc technology culture system

Oyster shell was used as alkalinity supplementary material to study the feasibility of supplement alkalinity with oyster shell in biofloc technology-tilapia(GIFT Oreochromis niloticus)culture system. At the start-up stage, the feasibility of supplement alkalinity with different oyster shell dosage of 0.00 g/L (control group, group A), 0.36 g/L (group B) and 0.72 g/L (group C) was evaluated. The results showed that the level of alkalinity, pH and calcium in group C were significantly higher than those in group A (P < 0.05), but there was no significant difference between groups B and C (P > 0.05), the effect of supplement alkalinity with oyster shell is obvious. Based on the results of the start-up, The effects of supplement alkalinity to tilapia culture system with two forms of oyster shell -(shell powder, group B) and (shell, group C)-were studied. There were no significant differences in water quality, digestive enzyme activity, immunity and bacterial community composition among the three groups. Oyster shell and shell powder had no significant negative effects on the growth of tilapia and could be applied to the biofloc aquaculture system, but it is no obvious that the effect of supplement alkalinity with oyster shell in culture stage. The supplementation of alkalinity had nothing to do with forms of oyster shell. Under the current experimental conditions, oyster shell can not completely replace sodium bicarbonate in the biofloc aquaculture system, and the related technology need to be further optimized.