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为比较投喂不同密度卤虫对灰海马幼体生长和存活的影响,共设3个卤虫无节幼体密度组[5(A)、10(B)和20(C)个/mL],用初始密度为2尾/L的灰海马幼体进行为期50 d的养殖研究.结果显示,总体而言,3个饵料密度对灰海马幼体的存活、生长有显著影响(P<0.05).在前10 d,3组海马间的成活率和生长速度差异均不显著(P>0.05);d20～50,B、C两组海马的成活率均显著高于A组(P<0.05),而B、C两组之间无显著差异(P>0.05).d 20时,B、C两组的生长速度显著快于A组(P<0.05);d 30往后,A、C两组的生长速度开始加快,随后3组海马生长速度间的差距进一步缩小,直至A组的体质量和体高超过B组和C组(P<0.05),而B、C两组间的差异显著性消失(P>0.05).随着投放卤虫密度的增加,各时间点水体的pH和溶氧含量呈显著下降的趋势(P<0.05);C组氨态氮含量显著高于A组和B组(P<0.05);除第24 h外,3组间亚硝态氮的含量差异不显著.综合结果表明,卤虫的最适投喂密度应随着灰海马的生长进行适时调整.从初孵至d 10,饵料密度以10个/mL最佳;从d 10起,将饵料密度上调至20个/mL;d 30后当海马密度降至0.5～1尾/L时,卤虫密度可降至10个/mL左右.图2表1参21
In order to compare the effects of different density Artemia on the growth and survival of the gray hippocampus, three Artemia nauplii density groups [5 (A), 10 (B) and 20 (C) / mL] The results showed that all three feeding densities had a significant effect on the survival and growth of the gray hippocampus larvae (P <0.05) .In the first 10 days (P> 0.05). The survival rates of hippocampus of d20 ~ 50, B and C groups were significantly higher than that of group A (P <0.05), while the survival rates of B, There was no significant difference between the two groups (P> 0.05). At day 20, the growth rate of group B and C were significantly faster than that of group A (P <0.05) Then began to speed up, then the gap between the three groups of hippocampal growth further narrowed until the body weight and height of group A exceeded that of group B and group C (P <0.05), but the differences of group B and C disappeared significantly (P> 0.05) .At the same time, the pH and dissolved oxygen content of water body decreased significantly with the increase of Artemia population (P <0.05), while the ammonia nitrogen content of group C was significantly higher than that of A and B groups (P < 0.05). There was no significant difference in the content of nitrite after three hours except 24th hour The results showed that the optimal feeding density of Artemia should be adjusted with the growth of the gray hippocampus.From the initial hatching to d 10, the optimum feeding density was 10 / mL; from d 10, the feed density was increased to 20 / ML; Artemia density can be reduced to about 10 / mL when the density of the hippocampus is reduced to 0.5-1 tail / L after d30.