Study On Seed Rearing And Toxic Effects Of Ammonia-nitrogen Stress On Juveniles And Fry Of Coilia Ectenes Jordan

This paper discussed under the condition of artificial control in the greenhouse,the breeding methods and processes of juvenile and fry of Coilia ectenes Jordan.Studied the suitable feed and culture methods of the Coilia ectenes Jordan in juvenile and fry stages.when the larvae of Coilia ectenes Jordan growth to the juvenile and fry stage,the acute toxicity of ammonia nitrogen in fry and juvenile of Coilia ectenes Jordan was studied.And the semi-lethal concentration and safe concentration of ammonia nitrogen corresponding to the fry and juvenile stage were determined.Then,the effect of ammonia nitrogen stress on its antioxidant enzyme activity was carried out with a 40%concentration index of 96h semi-lethal concentration.1.In order to study the suitable feed and cultivation methods of the fry and juvenile of Coilia ectenes Jordan,the artificial cultivation technology of the fry and larva was studied.The 60-mesh sieve mesh was used to collect the fertilized eggs of the Coilia ectenes Jordan,and the eggs were placed in the hatchery to hatch.On the 5th day after hatching,the food organisms filtered by the sieve mesh were started.During the periodic sampling microscopy,the bait organisms ingested by the larvae were observed.It was found that the bait organisms that were eaten by the early larvae were Brachionus plicatis,small cladocerans,phytoplankton and paramecium,and the bait organisms that were eaten by the later larvae were leeches and swords.During the feeding period,the micro-flow water cultivation method is adopted,and absorb the pollution in regular.At the condition of 24-26?of water temperature,the length of larvae of Coilia ectenes Jordan can reach to 2.5-3.5cm.Use this cultivation pattern,more than 200000 tails juvenile and fry of Coilia ectenes Jordan were finally cultivated.2.In order to make the aquaculture water easy to control,the bait is easier to obtain and it is easier to observe the feeding conditions of the larvae of Coilia ectenes Jordan.The fry of Coilia ectenes Jordan with an average body length of 4.0±0.3cm were used as the taming object,the domestication transformation test was carried out at night with timing designated methods.The result showed that,on the 7th day of the taming,60%of the test fish were fed with compound feed,the feeding time was up to30min,and survival rate of the fry was 98%.On the 15th day of the taming,the feed intake was90%,the survival rate is 95%.According to the experimental results,it was concluded that the good effect was obtained after 15 days of taming,which made the food type of the fry of Coilia ectenes Jordan has been gradually transitioned from the amphibians to the artificial compound feed,achieving the purpose of domestication.3.In order to study the toxic effects of acute ammonia nitrogen toxicity on juvenile and fry of Coilia ectene.Acute ammonia nitrogen toxicity test was carried out on fry and juvenil by conventional bioacute toxicity test method.The specification of juvenile fish was?overall length 2.33±0.25?cm and the size of fry fish was?overall length5.12±0.45?cm.The results showed that the semi-lethal concentrations of ammonia nitrogen on the 24h,48h,72h and 96h of the larvae were 57.78,53.45,38.67 and53.45mg/L,while,the safe concentration was 2.54mg/L,at the condition of water temperature is 28±1.5°C and the pH is 8.0±0.4.;the semi-lethal concentrations of ammonia nitrogen on the 24h,48h,72h and 96h of the fry were 106.83,94.26,76.74and 46.83mg/L,and the safe concentration was 4.68mg/L.The semi-lethal concentrations of non-ionic ammonia against fry at 24h,48h,72h and 96h were 0.61,0.57,0.41,0.27mg/L,respectively,and the safe concentration was 0.03mg/L;The semi-lethal concentrations at24h,48h,72h and 96h were 1.13,1.10,0.81 and 0.50 mg/L,respectively,and the safe concentration was 0.07 mg/L.The toxic effects of ammonia nitrogen on juvenile and fry were related to ammonia nitrogen concentration,effect time and process positive,and the tolerance of fry fish to ammonia nitrogen was stronger than that of juvenile fish.4.In order to study the mechanism of ammonia-nitrogen stress on juvenile and fry of Coilia ectene,the total antioxidant capacity?T-AOC?,catalase?CAT?and total superoxide dismutase?T-SOD?and glutathione peroxidase?GSH-Px?were studied under ammonia-nitrogen stress.The specification of juvenile fish was?overall length2.33±0.25?cm,the size of juvenile fish was?overall length 5.12±0.45?cm.Tthe concentration of ammonia nitrogen in stress is 40%96h semi-lethal concentration,is record as 40%96hLC₅₀.After 24h of stress,the whole fish was taken.The remaining test fish were placed in aerated tap water for 24h to take the whole fish for use.The results showed that the activity of T-AOC and T-SOD in juveniles of Coilia ectene was stronger than that of fry,while the activity of CAT and GSH-Px was lower than that of fry.After 24h of stress,the T-AOC activity of juvenile and fry fish were all decreased significantly?P<0.05?,while the activity of GSH-Px increased but not significant?P>0.05?,and the activities of T-SOD and CAT increased significantly?P<0.05?.After24h recovery,the T-AOC of juvenile fish had a significant increase?P<0.05?,and the T-AOC activity of fry fish was also increased significantly?P>0.05?.The CAT activity of juveniles and fry was significantly decreased?P<0.05?.The activity of T-SOD also decreased significantly?P<0.05?;the activity of GSH-Px was also decreased?P>0.05?.The above results indicate that ammonia-nitrogen stress causes oxidative stress,and the antioxidant capacity is enhanced after recovery,which alleviates oxidative stress,but does not return to the control level.