| Studies of the effects of salinity on osmoregulation of juvenile T.ovates in short and long term and effects of salinity on digestive enzyme activities and weight loss for hunger , and acute hypoxic stress on serum biochemical ions. Designed for providing reference materials in breeding T.ovate in different environmental conditions breeding, riching the aspects of basic data of osmotic adjustment mechanism, digestive physiology, and blood of T.ovates.1,Effects of salinity stress on osmoregulation of juvenile Trachinotus ovatusStudies the effects of salinity changes on gill NKA activities,survival rates, and serum, gill, kideney osmolality of juvenile T. ovatus were measured at 1h,6 h ,12h, 1d, 2d, 4d, 6d, 9d and 12d after transfer to salinity level of 30(control) and salinity levels of 5,15,25,35. The results show that: the survival rate of salinity group 5,25,35 was 87.14%, 95.71%, 88.86%, no mortality occurred in the other salinity groups salinity at the end of experiment. Gill NKA activity salinity were tested the trend that is first decreased and then increased outside the salinity of 15 with salinity change, after the 2d the gill NKA was "U"-type distribution at other time. Plasma osmolality increased and then decreased and stabilized with the increase of time at the same salinity group,the plasma osmotic pressure in the 2d with the increase of salinity, salinity group 35,30 significantly higher than the other salinity groups (P <0.05) .The gills and kidney osmotic of T .ovatus larvae together complete the regulation of its osmotic pressure in low salinity (5,15), the kidney play a leading role in regulation of osmotic pressure of their body in the other salinity group.2,Effects of abrupt salinity stress on osmoregulation of juvenile Trachinotus ovatusEffects of abrupt salinity changes on gill Na~+-K+-ATPase(NKA) activities,survival rates, and serum, gill, kideney osmolality of juvenile Trachinotus ovatus were measured at 24 h, 48 h and 96 h after transfer to salinity level of 30(control) and salinity levels of 5,10,15,20,25,35. No mortality occurred in all the salinity groups and control group at the 96 h. In all treatments, the gill NKA activity and serum osmolality fluctuated in first 72 h, and then changed smoothly. The NKA activity varied with salinity changes grade in U shape, being higher in salinity 35 and the lowest in salinity 20 at 96h. With salinity changes, the serum osmolality ( ranged 222.5– 311.5 mOsmol·kg- 1 )to salinity of 15, 20 center showed symmetrical change, and it was the first post rise after a downward trend after salinity of 20.At the same salinity, the gills osmolality change showed the trend that was the first rise after a downward then gradually stabilized . Except the salinity of 5, 10, kideney osmolality had no significant change over time, maintain certain stability in other salinity group. It was concluded that Trachinotus ovatus could be characterized physiologically as a"higher NKA-in-hyperosmotic media"marine euryhaline teleost with the capability of rapid and effective balance and osmoregulation.3,Effects of salinity on digestive enzyme activities and weight loss for hunger of juvenile Trachinotus ovatusThe effects of salinity on three digestive enzyme activities of large-sized juvenile Trachinotus ovatus were investigated at salinity of 5, 15, 25, 30, 35 groups, with total length10.53±1.41 cm and body weight (15.01±2.46) g. Protease, amylase and lipase activities were measured and compared in four digestive organs, including intestine, pyloric caeca, stomach and liver. The results showed that under different salinities, the same distribution was in different digestive organs of protease, amylase and lipase activities, and activities in order were intestine, pyloric caeca, stomach, liver. With increasing salinity, in the stomach and liver protease activity increased first and then decreased, which at salinity of 25 group was significantly higher than at the other salinity groups (P﹤0.05); in the intestine and pyloric caeca protease activity decreased, which at salinity of 5,15 and 25 groups were obviously higher than at the salinity of 30 and 35 groups (P﹥0.05). In the stomach and liver the same trend existed in the amylase and protease activity, salinity of 25 group having the maximum activity was significantly higher than salinity of 5,30 and 35 groups (P﹤0.05); in the intestine and pyloric caeca decreased first and then began to rise in the salinity of 30.In the stomach, liver, pyloric caeca lipase activity increased first and then decreased, furthermore, the maximum activity at salinity of 30 groups and the minimum activity at salinity of 5 groups; in the intestine the activity had been increasing, furthermore, the maximum activity at salinity of 35groups (P< 0.05) and the minimum activity at salinity of 5 groups(P﹤0.05). .Salinity affected the weight loss rate for hunger of T.ovatus significantly. (F = 6.52> 5.99, df1 = 4, df2 = 10, P <0. 01).4,Acute hypoxia stress on ovatus serum biochemical indexesThe present study deal with the influence of acute hypoxia stress on serum biochemical indices of Trachinotus ovatus in the environment. The results showed: after acute hypoxia stress for T.ovatus, ions content in serum compared with the control group increased to varying degrees, including potassium, phosphorus, urea nitrogen concentration compared with the control group, no significant differences (P> 0.05), sodium and chloride , calcium concentration were significantly different (P < 0.05) from the control group, and iron was greatly higher than control group(P< 0.01). There was great significant differences on serum protein, uric acid, creatinine(P< 0.01), and significant differences on total protein and total cholesterol, and no significant differences on glucose, triglyceride, albumin, globulin (P> 0.05) between control group and test group. Serum creatine kinase, lactate dehydrogenase, isoenzyme, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase levels were not significantly different (P> 0.05) compared with the control group. Creatine kinase levels were greatly significantly higher (P< 0.01). Creatine kinase isoenzyme levels were significantly higher (P< 0.05). GGT was significantly lower than the control group (P< 0.05). |
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