Effects Of Salinity On Osmotic Pressure,growth,Nonspecific Immunity And Respiratory Metabolism Of Penaeus Monodon

In order to explore the effects of salinity on osmotic pressure,growth,nonspecific immunity and respiratory metabolism of Penaeus monodon,two experiments were carried out in this study.Experiment one:Taking Penaeus monodon young shrimp with initial weight(0.18±0.03)g as the research object,5 different salinity treatment groups of 10,15,20,25 and 30.Each group recorded as S10,S15,S20,S25 and S30.Three repeats for each group and each repeated 500 tail prawns,the size of the breeding experiment cement tank was 6m×4m×1.4m,and the experiment lasted 8 weeks.Experiment two:On the basis of experiment one,taking Penaeus monodon with a body weight of(2.74±0.50)g as the research object,five treatment groups with different salinity(10、15、20、25 and 30)and three treatment groups with sudden salinity(rom salinity 25 to 10,15,20 respectively)were set up.Three replicates in each group,each with 6 tails of Penaeus monodon,was performed in a sealed closed room of still water for 3 hours to study the effects of different salinity and sudden drop in salinity on respiratory metabolism.The results are as follows:1.Effect of salinity on osmotic pressure,Na~+-K~+-ATPase and gill tissue structure of Penaeus monodon.(1)Hemolymph osmotic pressure showed an upward trend with the increase of salinity.(2)The gill filament Na~+-K~+-ATPase and ultra-microscale total ATPase showed a downward trend with the increase of salinity.The gill filament Na~+-K~+-ATPase enzyme activity in the S20 group was significantly lower than that in the S10,S15 and S30 groups;the ultra-microscale total ATPase activity in the S10 and S30groups was significantly higher than that in the other three groups.2.The effect of salinity on the growth,body composition and muscle structure of Penaeus monodon(1)The final average weight,specific growth rate and weight gain rate all show a trend of rising first and then decreasing with the increase of salinity.The growth performance of Penaeus monodon in S25 group was the best;the survival rate of Penaeus monodon in S20,S25 and S30 group was the highest and there was no significant difference between the three groups;the feed coefficients of the S10 and S30 groups were significantly higher than those of the other three groups;salinity had no significant effect on the meat content of each group;the fullness of the S20 and S25groups was significantly higher than that of the S15 and S30 groups.(2)The water content of whole shrimp and muscle of Penaeus monodon in S10,S15 and S20 group was significantly higher than that in S25 and S30 group;the crude protein content of whole shrimp S25 and S30 group was significantly higher than that in S10 and S25group,the crude protein content of muscle was S20,The S25 and S30 groups were significantly higher than the other two groups;the crude fat content of the whole shrimps and muscles was not significantly different between the groups;the whole shrimp and muscle crude ash content of the S25 group was significantly higher than the other four groups;The calcium content of shrimp and muscle was significantly higher than that of the S10,S15 and S20 groups;the total phosphorus content of the shrimps of the S25 and S30 groups was significantly higher than that of the other three groups,but there was no significant difference in the total phosphorus content of the muscles among the groups.(3)The activity of intestinal lipase and trypsin increased first and then decreased with the increase of salinity.The activity of intestinal lipase and trypsin in S20 group was significantly higher than that of other groups;there was no difference between the treatment groups of intestinal amylase Significant;hepatopancreas lipase activity showed a decreasing trend with increasing salinity.S10 and S15 groups had significantly increased hepatopancreas lipase activity;salinity had no significant effect on hepatopancreas amylase activity;hepatopancreas in protease activity increased with salinity.The increase of serotonin showed an upward trend and then a declining trend.The hepatopancreas in activity of the S20 group was the highest and was significantly different from other groups.3.The effect of salinity on immune antioxidant activity and tissue structure of liver and pancreas in Penaeus monodon.(1)The activity of AKP and PO in serum showed a trend of increasing first and then decreasing with the increase of salinity,and reached the maximum value in the S25 group;the serum ACP activity in the S20 and S30 groups was significantly higher than that of the other three groups;hepatopancreas AKP and PO With the increase of salinity,the activity increased first and then decreased.The activity of AKP and PO reached the maximum in the S20 and S25 groups,respectively;the activity of ACP in hepatopancreas of S20 and S15 increased significantly.(2)Serum T-AOC showed an upward trend with increasing salinity.Serum T-AOC in the S25 and S30 groups was significantly higher than that of the other three groups;serum SOD and CAT activity showed a trend of increasing first and then decreasing with increasing salinity.The serum SOD activity of S15 group was significantly lower than that of other groups;the serum CAT activity of S20 group was significantly higher than other groups;the serum MDA content showed a trend of decreasing first and then increasing with the increase of salinity,and the serum MDA content of S25 group was significantly reduced;T-AOC increased significantly,T-AOC in S10 and S15 groups was significantly lower than other groups;hepatopancreas SOD activity increased with salinity,S30 group hepatopancreas SOD activity increased significantly;hepatopancreas CAT activity increased with salinity The increase showed a trend of first increasing and then decreasing.The hepatopancreas CAT activity in the S20 group increased significantly;the hepatopancreas MDA content decreased first and then increased with the increase of salinity.The MDA content between the S20 and S25 groups was significantly lower than that of the other three groups.4.The effect of salinity on the respiratory metabolism of Penaeus monodonAs the salinity increased,the oxygen consumption rate of Penaeus monodon showed a trend of decreasing first and then increasing.The oxygen consumption rate of the S20 group was the lowest,and the oxygen consumption rate of the S10 and S30groups increased significantly;the salinity dropped from 25 to 20,there was no significant change in the oxygen consumption rate of Penaeus monodon,and the oxygen consumption rate of Penaeus monodon increased significantly from 25 to 15and 10.The effects of different salinity and sudden drop in salinity on the suffocation point of Penaeus monodon were not significant.