Study On ·OH Inactivation Of Cryptocaryon Irritans And Effects On Intestinal Structure Of Epinephelus Coioides

Cryptocaryon irritans is one of the most serious diseases threatening fish aquaculture.It has the characteristics of extremely high incidence and mortality,extremely fast propagation and no specific host.So far,no effective prevention and control measures have been taken.Traditional methods for the prevention and control of the stimulation of Cryptocaryon irritans,such as formaldehyde method and copper sulfate method,have drug residues,are harmful to fish health,and pollute the water quality of coastal waters.Therefore,a new efficient,safe,green and pollution-free method is urgently needed to solve the international difficulty of the stimulation of Cryptocaryon irritans.Generated by using atmospheric pressure ionization discharge active gas particles,high concentration of oxygen in gas and liquid immiscible in mixed with water,the water jet cavitation,generates a high concentration of ·OH solution,injection to the volume of 500 L,the breeding for quick kill aquaculture water body in stimulating hidden nuclear insect larvae,guarantee the farmed fish body health,specific work content is as follows:（1）the ·OH killing Cryptocaryon irritans experiment,construct the ·OH experiment device,the preparation of ·OH solution injected into the beaker containing theront solution,the bright field microscope and FDA/PI fluorescence microscopy judgment theront anyway,determine the ·OH to 1000 cells·mL^-1 theront kill threshold is 0.50 mg/L,killing time is 30 s,CT threshold is 0.25 mg min/L.（2）An experimental system was constructed for the prevention and control of Cryptocaryon irritans under the influence of the grouper,and the pilot experiment was conducted on the scale of 500 L,and the comparative experiment was conducted with the conventional chemical agents ClO₂ and formaldehyde.In the prevention and control experiment of ·OH,·OH solution was injected into the breeding pool,and TRO concentration reached 0.5 mg/L in the breeding pool was maintained for 10 min.The TRO was treated three times a day for four consecutive days,and the water culture was conducted for five days.In the ·OH treatment,the theront killing rate was 100%.·OH can effectively kill the theront,block the transmission of Cryptocaryon irritans,improve the survival rate of grouper,and effectively prevent and control Cryptocaryon irritans in practical application.In the comparison experiment of 1.0 mg/L ClO₂,the killing rate of ClO₂ treated theront was 100%.But grouper survival was only 36.1 percent.It indicated that ClO₂ could block the transmission of cryptosporidium,but caused acute toxic effect on grouper health,leading to a large number of grouper deaths.In the formaldehyde control experiment,in the formaldehyde treatment,the killing rate of theront was 100%.Grouper survival rate is 100%.The results showed that formaldehyde could block the transmission of Cryptocaryon irritans,but the high dosage resulted in drug residues and polluted the coastal waters.（3）The intestinal structure of grouper was studied in the prevention and control experiment.In the prevention and control experiment of ·OH,there was no damage to the intestinal tissue structure of grouper.The intestinal mucosal villi remained intact and healthy,with no obvious intestinal pathological features.In the ClO₂ comparison experiment,the intestinal tissue structure of groupers was irreversibly damaged,which was not conducive to the healthy and safe breeding of groupers in oblique zones.In the formaldehyde contrast experiment,the intestinal tissue of grouper was slightly diseased,which was not conducive to long-term healthy breeding of grouper.To sum up,this paper uses atmospheric pressure ionization discharge to prepare high concentration of ·OH,to achieve rapid and efficient killing the Cryptocaryon irritans theront,and is conducive to the healthy breeding of grouper,pro viding a new method for the prevention and control of the Cryptocaryon irritans.