不同环境胁迫因子耦合对凡纳滨对虾生长与摄食的影响

采用氨态氮与亚硝态氮耦合、亚硝态氮与盐度耦合和氨态氮与pH耦合三组环境胁迫因子对凡纳滨对虾生长及摄食的影响进行了亚慢性毒理实验。氨态氮梯度设置为0、5、10 mg/L三个水平,亚硝态氮水平梯度为0、5、10 mg/L,pH梯度设置为7.6、8.2、8.8,盐度的梯度设置为5、15、25三个水平。通过每天都给予恒定剂量的氮,连续培养7 d后,对虾的特定生长速率、摄食率和饲料转化率均随着氨态氮或亚硝态氮的增高而降低(P0.05)。最高浓度的氨态氮(10 mg/L)与亚硝态氮(10 mg/L)组与对照组相比较,特定生长率、摄食率和饲料转化率分别下降了18.31%、14.68%和17.49%。当氨态氮作为唯一氮添加的情况下,pH 7.6和pH8.8的参数均要低于pH 8.2(P0.05)。但高pH能进一步加剧氨态氮的毒性,pH 8.8的存活率显著低于pH7.6和8.2(P0.05),且pH 8.8和氨态氮为10 mg/L的对虾在实验第二天全部死亡。当亚硝态氮作为唯一氮添加时,盐度对摄食率并无显著影响(P0.05),但对特定生长率和饲料转化率影响显著(P0.05)。在亚硝态氮为10 mg/L时,盐度15和25的特定生长率、饲料转化率和存活率均高于盐度5。结果表明升高盐度能够缓解亚硝态氮对于对虾生长的抑制,高pH则会加剧氨态氮对于对虾的毒性。

Growth and feed intake of Litopenaeous vannemei under stress-environment interaction

In this study, sub-chronic toxicological experiments were carried out on the growth and feeding of Litopenaeus vannamei by three groups of two environment factors, including ammonia-nitrogen (0, 5, 10 mg/L) with nitrite-nitrogen (0, 5, 10 mg/L), nitrite-N (0, 5, 10 mg/L) with salinities (5, 15, 25), and ammonia-N (0, 5, 10 mg/L) with pH (7.6, 8.2, 8.8). After 7 days of continuous culture, the growth and feed intake parameters all decreased with nitrite-N and ammonia-N concentration (P<0.05). Compared with control treatment, the specific growth rate, feed intake and feed conversion rate decreased by 18.31%, 14.68% and 17.49% at highest concentration of ammonia-N and nitrite-N, respectively. In the culture with ammonia-N as exclusive N source addition, the parameters of pH 7.6 and pH 8.8 were significantly lower than those of pH 7.6 (P<0.05). Furthermore, the survival rate of pH 8.8 was lower than those of pH 7.6 and pH 8.2 (P<0.05), and all individuals died on the second day in the pH 8.8 and 10 mg/L ammonia-N treatment, suggesting that high pH value would enhance the negative effects induced by ammonia-N to L. vannamei. In the culture with nitrite-N as exclusive N source addition, the salinity had no influence on feed intake (P>0.05), but had significant effects on the specific growth rate and feed conversion (P<0.05). When concentration of nitrite-N reached 10 mg/L, the specific growth rate, feed conversion and survival rate of both salinity 15 and salinity 25 were higher than those of salinity 5 (P<0.05). The result showed that high salinity could alleviate the inhibition of nitrite-N on growth, while high pH value would exacerbate the toxicity of ammonia-N to L. vannamei.