Differences Of Morphological Phenotypes,dorsal Musculoskeletal Textures And Related Physiological Characteristics On Juvebile Sparus Macrocephalus With Different Anti-flowing Property

Under the condition of water temperature(30 ± 1.0)℃ and salinity 17,the water flow was used as the stress factor(1 min).The experimental object were the juvenile fish of sparus macrocephalus(body length 99.843±2.071 mm).Designing a anti-flow performance device,the total flow length was 540 cm,the bottom of the overflow as the starting point.The device was divided into five sections,A(0-90cm),B(90-180cm),C(180-270cm),D(270-360cm),and E(360-540cm).In the end of the experiment,the 5% of the total number of experimental juvenile fish,which still was in zone A as standard.It’s confirmed that the flow rate was 39.7 cm / s,Which was divided into five experimental groups A,B,C,D and E with different anti-flow characteristics.Then,28 morphological characters,dorsal muscle and gill,liver antioxidant enzymes,digestive enzyme activity and ATPase activity were measured in5 different groups.The results showed:(1)There were 6 significant differences among the 28 morphological characters in the five groups.C2(the distance between two Caudal fins/ nasal distance),C4(the length of dorsal fin / nasal distance),C5(tail length/nasal distance),C16(the length of dorsal fin/The distance between the anterior and posterior margin of the ventral fins),among these characters,group A is different from group B,C,D,E.C8(head breadth/nasal distance),C17(the length of pectoral fins/The distance between the anterior and posterior margin of the ventral fins),C18(length of the tail/The distance between the anterior and posterior margin of the ventral fins),C22(Dorsal fin height/The distance between the anterior and posterior margin of the ventral fin),among these characters,group A is different from group B,C,D,E.C1(body length/nasal distance),C3(the length of pectoral fins/nasal distance),C7(gill cover back to dorsal fin base distance/The distance between the anterior and posterior margin of the ventral fins),C9(body length / nose spacing),C12(tail handle height /nose spacing),those characters in the A have significant difference with those in B,C,E.C6(body height /nasal distance),C13(body width /nasal distance),C19(body width/The distance between the anterior and posterior margin of the ventralfin),C24(net body weight/liver and pancreas weight),C25(stomach weight/liver and pancreas weight),C27(bowel weight/body weight),C28(fatness),in these 8characters,there were significant differences between any two means.Among them,in C9,C20,C27,A and B have significant differences;in C24,C25,A and C have significant differences;in C6,C13,A and E have significant differences;A and D have significant difference only in C8.The principal component analysis of the morphological proportions was carried out,and five principal components were extracted,and its variance cumulative contribution rate was 81.87%.The first group is defined as the strongest resistance to flow,the fifth group is defined as the weakest resistance to flow,,and the other three groups are defined as the intermediate group with anti-flow performance.The Fisher classification function with independent variables C13,C16 and C26 was established by using stepwise discriminant analysis.It can distinguish clearly between the strongest,middle,and the weakest groups.The comprehensive discrimination accuracy rate was 88.76%.(2)There were significant differences in texture,hardness,elasticity,chewiness between group A and D,E(P <0.05).The stronger the resistance flow of juvenile sea bream,the greater the elasticity and hardness,and the elasticity and hardness of B and D,E were significantly different.Coagulation and recovery were no significant difference(P> 0.05).There was a significant difference in adhesive between A and B.(3)The difference of Oxygen consumption rate.Oxygen consumption rate in 6:00-18: 00,there were significant differences between A,B and D,only in 18: 00-22:00 period,there was no significant difference in,B and C,And the oxygen consumption rate of each group in this period is lower than any other periods.There was no significant difference in the asphyxia between five different groups.The results showed that there was significant difference in the ammonia excretion rate among the other five periods,except for 6: 00-10: 00.There was significant difference between B and C groups in 10: 00-22: 00(P <0.05).There was a significant difference between C and D at 02: 00-06: 00 and 14: 00-22: 00.Only in 6: 00-14: 00,there was no significant difference between D and E.(4)There were significant differences(P﹤0.05)in digestive enzyme activity,Pepsin activity between A and E.The activity of pepsin increased with the decrease of anti-flow ability.There were significant differences in trypsin activity between C,A,B,D and E(P <0.05),showing a tendency to increase first and then decrease.There were significant differences in lipase activity between A,D and E(P <0.05),while there was no significant difference between A,B and C(P> 0.05).The activity of amylase of A group which was the strongest resistance to flow was the strongest.There were significant differences between A,B,C,D and E(P <0.05).(5)The activity of SOD in different groups was decreased.There was no significant difference between A,B,C and D(P> 0.05).There was a significant decrease in the activity of Na + / K +-ATPase and Ca2 + / Mg2 +-ATPase in the liver of the larvae of the black sea bream,and there was a significant difference between A and E(P <0.05).