密度胁迫对中国对虾幼虾生长、抗氧化系统功能及水质指标的影响

通过室内40 d养殖实验,研究了4个养殖密度G0(250尾/m^3)、G1(500尾/m^3)、G2(1000尾/m^3)、G3(2000尾/m^3)对体重为0.08 g的中国对虾(Fenneropenaeus chinensis)幼虾生长、抗氧化系统功能及水质指标的影响。研究表明,密度胁迫20 d时,G1、G2生长和成活率与G0差异不显著(P>0.05),G3显著低于G0(P<0.05);胁迫40 d时,G1生长和成活率显著低于G0(P<0.05),G2生长显著低于G0(P<0.05),G2成活率与G0差异极显著(P<0.01),G3生长和成活率均与G0差异极显著(P<0.01)。通过检测血淋巴、肝胰腺、鳃和肌肉组织中抗氧化系统指标发现,中国对虾的总抗氧化能力(T-AOC)、超氧化歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GPx)随密度增加呈先升高后降低的趋势:20 d时,4种酶的活性在G1和G2中显著高于G0(P<0.05);40 d时,则显著降低(P<0.05)。中国对虾中丙二醛(MDA)含量随密度的增加呈上升趋势,G3的MDA含量始终显著高于G0(P<0.05);G1、G2的MDA含量仅在40 d肝胰腺中显著高于G0(P<0.05),其他组织内均差异不显著(P>0.05)。不同养殖密度对主要水质指标pH、DO、NO2-N、NO3-N、NH3-N和COD无显著影响(P>0.05),均在中国对虾生长的适宜范围内。本研究表明,密度胁迫显著影响中国对虾的生长及抗氧化能力,养殖20 d时的适宜密度为1000尾/m^3,40 d时的适宜密度为250尾/m^3。

Effects of Stocking Density on Growth, Water Quality, and Antioxidant System of Juvenile Fenneropenaeus chinensis

This study analyzed the effective growth, non-specific immune function, and water quality required for juvenile shrimps of Fenneropenaeus chinensis (initial weight, 0.08 g) at four stocking densities of G0 (250 ind./m3), G1 (500 ind./m3), G2 (1000 ind./m3), and G3 (2000 ind./m3) during a 40-d indoor culture experiment. The results showed that the survival rate and growth index of G1 and G2 at 20 d were not significantly different from those of G0 (P>0.05), while the survival rate and growth index of G3 was significantly lower than those of G0 (P<0.05). At 40 d, the growth index and survival rate of G1 was significantly lower than G0 (P<0.05) The growth index of G2 was significantly lower than G0 (P<0.05), while G2 the survival rate was extremely significant different from G0 (P<0.01). And the growth index and survival rate of G3 was extremely significant different from G0 (P<0.01). Measurement of the antioxidant status in the serum, hepatopancreas, gill, and muscle tissue showed that the total antioxidative capacity, superoxide dismutase, hydrogen peroxide, and glutathione peroxidase first increased and then decreased with increase in density. At 20 d, the four oxidation indices were significantly higher in G1 and G2 than in G0 (P<0.05), and at 40 d, the indices were significantly lower than those in G0 (P<0.05). The content of malondialdehyde (MDA) increased gradually with increase in density; the MDA of G3 was always significantly higher than that of G0 (P<0.05). The MDA of G1 and G2 was significantly higher than that of G0 in hepatopancreatic tissue at 40 d (P<0.05), and was not significantly different from that in the other tissues (P>0.05). The pH, DO, NO2-N, NO3-N, NH3-N, and COD had no significant effect on the main water quality indices (P>0.05) at different densities, which were all within the suitable range for the growth of F. chinensis. The results showed that density stress significantly affects the growth and antioxidant capacity of F. chinensis, and the suitable densities were 1000 ind./m3 for 20 d and 250 ind./m3 for 40 d.