Study On ·OH Inactivation Of Crytocaryon Irritans And Effects On Intestinal Morphology Of Larimichthys Crocea

China has the largest marine aquaculture industry in the world,which is an important part of marine economy.In recent years,with the rapid development of our country’s marine aquaculture,the farming scale is expanding and the degree of intensive farming is deepening,resulting in parasitic diseases caused by parasites frequently occur,which seriously hinders the green development of marine aquaculture industry.Traditional chemical methods have problems such as high concentration,long reaction time,drug residues,and generation of disinfection by-products,which seriously affect the health of fish and endanger the safety of the marine environment.In view of those problems,at the Larimichthys crocea base of Sanduao area,Ningde City,Fujian Province,we studied the effect of ·OH inactivation on Cryptocaryon irritans,analyzed the behavior and intestinal morphology of Larimichthys crocea farming with ·OH-treated water.The main research contents and results were as follows:(1)The ·OH solution was injected into the sand-filtered seawater pipeline and 0.53 mg/L ·OH was discharged into the clean water tank for 6 s to quickly inactivated Cryptocaryon irritans without detecting pathogenic microorganisms such as the pathogenic bacteria Vibrio in the clean tank.No disinfection by-products such as carcinogenic bromate was produced,dissolved oxygen in the water increased by 12.6%,and the nitrite nitrogen decreased by 64.3%,the water quality met the second category requirements of the Sea Water Quality Standard,ensuring the safety of the marine ecological environment.The seawater with ·OH-treated was discharged into the clean tank for storage to breeding Larimichthys crocea.(2)We studied the dose-effect of ·OH inactivation on Cryptocaryon irritans and determined the threshold CT was 0.053 mg·min/L,which was 1/155 of ClO2 and 1/11000 of formaldehyde.Compared with conventional chemical agents,·OH could effectively and quickly inactivate Cryptocaryon irritans and block the occurrence of Cryptocaryon irritans in mariculture fish from the source.(3)Larimichthys crocea cultured in seawater by ·OH-treated had normal behavior,growth and metabolism.The intestinal tissue morphology was intact,the intestinal villi were long and dense,the epithelial cells were arranged neatly.The secretion of digestive enzymes of intestine was normal,the ability to digest and absorb nutrients was not affected,and the survival rate was 100%,which ensured the healthy of Larimichthys crocea.In summary,·OH(0.53 mg/L,6 s)efficiently generated by atmospheric pressure ionization discharge could effectively and safely prevent and control Cryptocaryon irritans and ensured the healthy breeding of Larimichthys crocea,which had broad application prospects.