盐度对四指马鲅(Eleutheronema tetradactylum)幼鱼生长及其鳃丝Na+/K+-ATP酶的影响

The Effects of Salinity on the Growth of Juvenile Eleutheronema tetradactylum and Na+/K+-ATP Enzyme

关键词:  盐度  四指马鲅  幼鱼  生长  鳃丝Na+/K+-ATP酶

Key words:  Salinity  Eleutheronema tetradactylum  Juvenile fish  Growth  Gill Na+/K+-ATP enzyme

摘要:

采用盐度渐变的方法，研究了盐度2、10、18、26、34共5个梯度对四指马鲅幼鱼(7.82± 0.43 g)生长及其鳃丝Na+/K+-ATP酶的影响。结果表明，盐度对四指马鲅幼鱼的生长和存活均有不同程度的影响。在实验盐度范围内，随着盐度的升高，四指马鲅幼鱼的最终体重、特定增长率(SGR)、日增重(DWG)、增重率(GBW)和增长率(GBL)均出现逐渐降低的趋势，且部分盐度组间差异显著(P<0.05)，其中上述各项指标中，盐度2组均最高，与盐度10组差异不显著(P>0.05)，而与盐度18、26、34组存在显著性差异(P<0.05)，盐度34组显著低于其他盐度组(P<0.05)；幼鱼的饲料系数随盐度升高逐渐增大，且部分盐度组间差异显著(P<0.05)。在成活率方面，除盐度34组的成活率为72.2%，显著低于其他盐度组外(P<0.05)，其他各盐度组成活率均达到90%以上。盐度对四指马鲅幼鱼鳃丝Na+/K+-ATP酶也存在一定影响，经过3 d的盐度驯化后，实验第0天部分盐度组幼鱼鳃丝Na+/K+-ATP酶的活力有显著差异，其中盐度34组显著高于其他组(P<0.05)，盐度18、26组显著低于其他组(P<0.05)。实验开始后到第10天，盐度2、10、34组幼鱼鳃丝Na+/K+-ATP酶的活力有所降低，此后，各盐度组幼鱼鳃丝Na+/K+-ATP酶的活力趋于稳定。经过30d的养殖发现，盐度34组幼鱼鳃丝Na+/K+-ATP酶的活力最高，显著高于其他组(P<0.05)，而盐度2、10组幼鱼鳃丝Na+/K+-ATP酶的活力略低于盐度18、26组，但差异并不显著(P>0.05)。从以上结果可见，盐度对四指马鲅幼鱼的生长和鳃丝Na+/K+-ATP酶活力有一定影响。

Abstract:

Salinity has significant influences on the growth, metabolism and physiological changes in fish. In this study we explored the growth of juvenile Eleutheronema tetradactylum (7.82±0.43 g) and the Na+/K+-ATP enzyme under five graduated salinities, and found that salinities had impact on the growth and survival of the juvenile fish. We tested the growth performance under salinities of 2, 10, 18, 26 and 34. Along with the increase in the salinity, the final weights, SGR, DWG, GBW and GBL of the juvenile fish all decreased, and there were significant differences (P<0.05) between some salinity groups. Salinity 2 had the highest values of all measurements, and it was significantly different from salinity 18, 26 and 34 (P<0.05), but there was no difference between salinity 2 and salinity 10 (P>0.05). The measurements of salinity 34 were significantly lower than other groups (P<0.05). The feed coefficient of juvenile fish increased as the salinity rose, and some groups showed significant differences (P<0.05). The survival rate of salinity 34 is 72.2%, lower than other groups (P<0.05) of which the survival rates were above 90%. Salinity also affected the Na+/K+-ATP enzyme in the gill of juvenile fish. After 3-day salinity domestication, the activity of Na+/K+-ATP enzyme in some groups was remarkably increased. The enzyme activity at salinity 34 was significantly higher than other groups (P<0.05), and salinity 18 and salinity 26 exhibited lower enzyme activities (P<0.05). After 10 days the enzyme activities at salinity 2, 10 and 34 became slightly lower, and thereafter all salinity groups displayed stable enzyme activities. After a 30-day culture, we found that the optimal salinity for Na+/K+-ATP enzyme was 34 at which the enzyme activity was significantly higher (P<0.05). The enzyme activity at salinity 2 and 10 was insignificantly lower than that at salinity 18 and 26. These results demonstrated that salinity had effects on the growth of juvenile E. tetradactylum and its Na+/K+-ATP enzyme activity.