臭氧对斜带石斑鱼胚胎发育和初孵仔鱼的毒性效应

为了评价臭氧消毒技术及其对石斑鱼(Epinephelus)潜在的毒性, 首先评价了两种质量浓度(0.05 mg/L和0.30 mg/L)臭氧对亚硝酸盐和弧菌的水处理效果, 并以斜带石斑鱼(E. coioide)受精卵为实验材料, 探讨臭氧对胚胎发育和初孵仔鱼的毒性作用。结果显示, 臭氧的水处理效果良好, 0.30 mg/L的臭氧在3 h内对水中亚硝酸盐的去除率可达72.29%; 0.05 mg/L的臭氧处理20 min后也能完全杀灭弧菌。但高浓度臭氧(0.30 mg/L)对胚胎发育具有一定的毒性, 会造成胚胎油球数目增多、萎缩、解体和死亡, 而低浓度组(0.05 mg/L)臭氧处理后22 h胚胎孵化率高达(87.14±7.20)%, 与对照组无显著差异。与胚胎相比, 初孵仔鱼对臭氧更加敏感, 0.05 mg/L的臭氧处理24 h也会导致初孵仔鱼的全部死亡。本研究结果旨在为石斑鱼育苗及养殖过程中正确使用臭氧消毒技术提供重要的数据参考和理论依据。

The toxic effects of ozone on the embryonic development and post- embryonic larvae of Epinephelus coioide

Epinephelus coioide is one of the most important seawater fish that cultured in China. In recent years, with the breakthrough of grouper artificial seedling rearing, the farming scale of grouper has expanded rapidly, and the gross of cultured grouper reached 59 534 tons in 2011. The effective prevention and control of virus, vibrio, and the effective treatment for harmful water quality factors is the key link in grouper artificial seedling rearing. In traditional pond farming mode, strong oxidizers, such as chloride, iodine and potassium permanganate, have played a significant role in disease prevention and water treatment. In recent years, flatfish industrial farming system, as a mature mode, has been driving the technology intergration of grouper recirculating aquiculture system. The solid oxidants mentioned above were greatly limited in the advanced farming mode, while ozone, a kind of gas disinfectant, not only can remove toxic substance such as nitrite, hydrogen sulfide, ammonia nitrogen and killed pathogenic bacteria effectively, but also will not cause secondary pollution, has been widely applied in water treatment of recirculating aquiculture system in the European Union, the United States, Japan and other developed countries. Although the efficiency and stability of ozone disinfection was widely recognized, its security, especially its toxic effects on the cultured livestock, cannot be ignored. In order to evaluate the ozone disinfection and the potential toxicity of ozone to E. coioide, the efficiency of ozone at two kind of concentration (0.05 mg/L and 0.30 mg/L) on water treatment, such as removing vibrio and nitrite, was assessed. Furthermore, using the zygote of E. coioide as material, the toxic effects of ozone on the embryonic development and post-embryonic larvae were discussed. Our results demonstrated that the efficiency of ozone on water treatment was favorable, when the concentration of ozone reached 0.30 mg/L, the removal rate of nitrite can be up to 72.29% within 3 h; at the applied ozone dose of 0.05 mg/L and a treatment time of 20min, the vibrio all can be killed, while the amount of vibrio in the hatching water that was not disinfected by ozone showed a trend of increase, which was fatal to the embryonic development and post-embryonic larvae. However, the higher concentration of ozone had toxic effects on the embryonic development to some extent, which can caused the number of oil globules increased and led to analosis, collapse and death of the embryo, while the hatching rate can be up to (87.14±7.20)% when the embryo treated with the lower concentration of ozone(0.05 mg/L), suggesting the lower concentration of ozone(0.05 mg/L) had no significant effects on the embryo. The post-embryonic larvae were more sensitive to ozone compared with the embryo, all the post-embryonic larvae died when they exposed to the lower concentration of ozone (0.05 mg/L) for 24 h. The results of this study provided some important reference data and theoretical basis for using the ozone disinfection technology properly in the process of seedling rearing and cultivating of E. coioide, and was significant to the sustainable and healthy development of grouper rearing.