大菱鲆胚胎和仔稚鱼的热刺激耐受能力

以培育大菱鲆Scophthalmus maximus耐高温品系为目的,研究了胚胎和仔稚鱼对热刺激的耐受力差别,为通过高温刺激选育大菱鲆耐高温品系提供指导和基础数据。实验分别对大菱鲆胚胎期(孵化前期)、卵黄囊期(初孵仔鱼,0dph)、前弯曲期(10dph)和弯曲期(25dph)的仔鱼、稚鱼(50dph)使用22～33℃范围内不同梯度的高温海水,进行突变热刺激,2h后转入原水体中培育,记录之后60～84h的死亡率、仔鱼孵化率、畸形率等数据。结果表明,上述5个发育期大菱鲆经受2h热刺激的亚致死温度为24、23、<22、28、28℃,半致死温度为26、28、22、29、29℃,致死温度为30、29、27、30、30℃。根据热刺激后24和48h死亡率,耐热能力由弱到强依次为10dph<胚胎<0dph<25dph<50dph,总体上呈现随生长发育逐渐增强的趋势。10dph左右可能为大菱鲆热刺激耐受力低谷,此时也是开鳔期,对外界环境反应灵敏,受到不良环境刺激易导致死亡。

Study on the thermal tolerance of embryos and larvae of turbot Scophthalmus maximus

To study the effect of high temperature stress on the early development of turbot Scophthalmus maximus, the thermal tolerance of five early developmental stages of S.maximus was studied. The hatching stage embryo, yolk-sac larvae (0 days post hatching,0 dph ), preflexion larvae (10 dph), flexion larvae (25 dph) and juvenile (50 dph) of turbot were subjected to various temperatures from 22～33℃ for 2-hour heat shock, and then transferred to seawater at initial temperature (17.5℃) for 60～84 h. The mortality, larvae hatching rate and abnormal rate were recorded continuously. The results showed the sub-lethal temperature of early developmental stages of turbot were 24℃, 23℃, <22℃, 28℃, 28℃, respectively; the 50% mortality (LT50) temperature were 26℃, 28℃, 22℃, 29℃ and 29℃, respectively; and lethal temperature were 30℃, 29℃, 27℃, 30℃ and 30℃, respectively. Based on the experimental mortalities of turbot by heat shock after 24 h and 48 h, the order of thermal tolerance of turbot at five stages was 10 dph