盐度对军曹鱼胚胎和仔鱼发育的影响

Effect of salinity on embryonic and larval development of cobia(Rachycentron canadum)

观察比较了不同盐度梯度(20、23、26、29、32、35、38、41和44)下军曹鱼受精卵的沉浮性、孵化率和畸形率以及测定了不同盐度梯度(10、14、18、22、26、30、34、38、42和44)下仔鱼不投饵存活系数SAI值。结果表明,受精卵在海水盐度32以上为完全浮性,26以下为完全沉性。军曹鱼受精卵孵化的最适盐度范围为29～38,适宜盐度范围为26～41,其中23～26和41～44分别视为受精卵孵化在低盐区和高盐区的两个临界区域,在此盐度上下,军曹鱼受精卵孵化率大幅度下降而仔鱼畸形率大幅度上升。试验盐度范围内军曹鱼仔鱼SAI值为2.32～16.24,仔鱼生长和存活的最适盐度范围为26～34,适宜盐度范围为22～38,而盐度18～22及38～42可分别视为军曹鱼仔鱼存活率在低盐区和高盐区的两个临界区域。

The sinking and floatation of fertilized eggs and the hatching rates and abnormal rates of eight broods of fertilized eggs under different salinities （20, 23, 26, 29, 32, 35, 38, 41 and 44） were observed and compared, and the SAt （survival activity index） values of larvae were evaluated under different salinities （10、 14、 18、 22、 26、 30、 34、 38、 42 和 44） for cobia. The results showed that the fertilized eggs entirely sank in the seawater with salinity lower than 26, and entirely floated in the seawater with salinity higher than 32. The suitable salinity for hatching was from 26 to 41 and the optimum was from 29 to 38. The ranges of 23-26 and 41-44 might be two critical salinity causing notable differences in hatching rate of fertilized eggs and abnormal rate of newly hatching larvae. The SAI values of cobia larvae in different salinities were 2.32-16.24. The suitable salinity range for larvae survival activity was 22 -38 and the optimum was 26-34 according to SAI values. The salinities from 18 to 22 and from 38 to 41 might be two critical ranges causing notabledifferences in SA1 values.