Effect Of Ammonia Nitrogen On The Tissue Structure And Nonspecific Immune Indexes Of Juvenile Crucians(Carassius Auratus)

High-density intensive aquaculture will have a serious impact on the water quality of the aquaculture,and the ammonia nitrogen produced by the excrement and bait is difficult to remove in time.The damage to the cultured fish is particularly serious.In order to understand the effects of chronic ammonia nitrogen toxicity on juvenile crucian carp,this experiment selected juveniles with a weight of 3.10±0.15 g to study the effects of chronic ammonia nitrogen toxicity on gill,liver and kidney of juvenile crucian carp,and the changes of non-specific immune indicators.Firstly,through acute toxicity experiment,we got the 96-hour lethal concentration was 289.29 mg/L,and the safe concentration was 28.9 mg/L.On this basis,the chronic ammonia nitrogen concentration was set as 6 mg/L,15mg/L and 24 mg/L respectively.The chronic ammonia toxicity experiment was during 60 days,tissue samples were taken every 15 days respectively,which was used for histology and non-specific immune indexes studying.1.With the increase of ammonia nitrogen concentration and the extension of stress period,the weight gain of young crucian carp became slower.The histological results showed that: the chlorine cells at the base of gill lamellae were hyperplastic.The columnar cells were deformed and the cell nuclei were not arranged neatly(P<0.05),the gill lamellae became short,thick,fused,overlapped and curved(P<0.05).There was edema in the liver cells,The cell nucleus has shifted,swelled and lysed,and the blood sinus in liver had expanded and hyperaemia.We found that necrosis of the glomeruli and glomeruli occurs,and the lumen of the tubules shrinks in kidney.It is confirmed the degree of damage in different tissues and organs under chronic ammonia nitrogen stress was different.The damage to the gill was more serious than the damage to the liver and kidney,while the kidney suffered less damage.The results of histological study showed that,the damage level of gill,liver and kidney tissues were increased gradually along with increase of ammonia nitrogen concentration and the increase of stress time.2.The results of non-specific immune indexes showed that: the activities of alkaline phosphatase and acid phosphatase in different tissues were increased significantly with the increase of ammonia concentration and the extension of stress time(P<0.05).The activities of the alanine aminotransferase and the aspertate aminotransferase as well as the superoxide dismutase and the catalase have showed different change trends in different tissues.It was indicated that different tissues had suffered different damage when exposed to high concentration or extension of ammonia nitrogen stress.Each of value in different group was significantly increased(P<0.01),and then there's a downward trend,however,the enzyme activity was significantly different from that of the control group(P<0.05).In this experiment,the gill was damaged at first,and damage to kidney was less than damage to liver and gills.As mentioned above,when the body was damaged,enzyme activity increased and non-specific immune functions were activated.However,with the prolonged period of chronic ammonia nitrogen stress and the increase of ammonia nitrogen concentration,gill liver and kidney's damage were aggravated,the body's metabolic regulation mechanism and detoxification mechanism and the function is inhibited,the enzyme activity in the tissue is reduced,and the body is seriously damaged.