盐度变化对军曹鱼稚鱼相关免疫因子及其生长的影响

研究了盐度(5、10、20、30及对照37)对军曹鱼(Rachycentron canadum)稚鱼生长及其血清溶菌酶、碱性磷酸酶(ALP)、旁路途径补体(ACP)溶血活性(ACH50)和总免疫球蛋白(T-Ig)含量等免疫因子的影响。实验周期为14 d。结果表明,在逐渐达到设定盐度后养殖14 d,盐度30组稚鱼特定生长率(SGR)最高(5.77%/d),而盐度5和10组的SGR(分别为4.24%/d和4.38%/d)显著低于其他组(P<0.05)。在低盐度环境中血清溶菌酶活性在第7天各组都有不同程度升高,其中以盐度20组升高最为显著,其次为盐度10和30组,但第14天各组溶菌酶活性又都回落至对照组水平;而稚鱼在低盐度环境中血清ALP活性受到明显抑制,且活性与盐度呈一定正相关;各组间ACP活性在第7天各盐度组间无明显差异,但实验结束时盐度5和10两组出现显著升高;而T-Ig含量在盐度10组中始终明显高于其他组。研究显示,军曹鱼稚鱼在盐度20~37范围内都可正常生长,尽管稚鱼有较强的低盐度耐受能力,但过低盐度明显影响其生长率并导致体色变黑、蛀鳍和应激增强等异常表现。此外,盐度变化还影响稚鱼多种免疫相关因子。中国水产科学,2007,14(1):120-125]

Effects of salinity on growth and several immune parameters of juvenile cobia,Rachycentron canadum

Cobia(Rachycentron canadum) is a new aquaculture candidate for offshore cage in Taiwan Province and southern coast of China due to its high growth rate.The effects of salinity(5,10,20,30 and 37 as control)] on growth,serum lysozyme activity,alkaline phosphatase(ALP),alternative complement pathway(ACP) activity and total immunoglobulin(T-Ig) in serum of cobia juvenile were determined on days 7 and 14 after adapting to the final treatment salinity.The results showed that the hightest SGR of 5.77%/d was obtained at salinity 30,and SGR was significantly lower(P<0.05) at salinities 5 and 10(4.24%/d and 4.38%/d,respectively).The lysozyme activity,in some extent,increased in low salinity treatments on day 7,with the activity at salinity 20 being significantly higher than those in other treatments.But no significant differences were found among treatments on day 14.Inversely,compared with the control,the ALP activities in low salinity treatments were evidently restrained with a positive correlation to salinity.Juvenile serum ACP activities among treatments were not distinctly different on day 7,but showed significant raise in salinities 5 and 10 treatments on day 14.The T-Ig content in treatment of salinity 10 was higher than those in other treatments throughout the experiment,moreover,significantly higher than those in salinity 30 and the control.The results indicate the cobia juvenile can obtain well-growth at salinity ranging from 20 to 37.Though the juvenile can tolerate hyoposalinity environments as low as 5 for a short period without mortality,such salinity clearly influences its growth rate and induces and results in poor health appearance such as fin erosion,discoloration,hyperirritability,etc..Salinity also effects some immune parameters of cobia juvenile,for instance,rearing at salinities 5 and 10 can increase the serum ACP activity and total Ig content,contrarily restrain the activity of ALP.Journal of Fishery Sciences of China,2007,14(1):120-125]