单体牡蛎诱导变态的研究

为了得到壳型规则、大小均一的单体牡蛎,作者以葡萄牙牡蛎(Crassostrea angulata)和长牡蛎(Crassostrea gigas)眼点幼虫为材料,从肾上腺素(EPI)浓度梯度、处理时间梯度和眼点幼虫密度梯度3个因素诱导产生不固着变态的单体牡蛎。结果表明,葡萄牙牡蛎用EPI处理24 h的最适浓度为5×10–4 mol/L,不固着变态率为72.8%,在该最适浓度下,最佳处理时间为12 h,不固着变态率为82.7%。长牡蛎用EPI处理6 h的最适浓度为5×10–5 mol/L,不固着变态率为53.2%,在该最适浓度下,最佳处理时间为8h,不固着变态率为56.8%,眼点幼虫密度在80个/m L以下EPI处理效果没有显著性差异。对长牡蛎幼虫进行后续生长测定,结果显示EPI处理组幼虫的壳长、壳高和存活率要高于对照组,表明EPI可能促进牡蛎幼虫变态长出次生壳并提高其生存能力。

The induction of metamorphosis in cultchless oysters (Crassostrea angulata and Crassostrea gigas)

To obtain cultchless oysters with a regular shell shape and uniform size, epinephrine (EPI) was applied to Crassostrea angulata and Crassostrea gigas eye-larvae to induce cultchless metamorphosis. We examined the effect of larval density, concentration of EPI, and length of exposure to EPI to determine optimum levels for each species. For C. angulata, we found that the optimum concentration of EPI was 5×10^-4 mol/L for a 24 h treatment (metamorphic rate = 72.8%) and the optimum treatment time at this concentration was 12 h (metamorphic rate = 82.7%). In contrast, in C. gigas, the optimum concentration of EPI was 5×10^-5 mol/L over 6 h (metamorphic rate = 53.2%), and the optimum treatment time at this concentration was 8 h (maximum metamorphic rate = 56.8%). However, there was no significant difference between EPI treatments at larval densities < 80 individuals/mL. The growth of C. gigas was also determined over the following days, which showed that shell length, shell height, and larval survival rate was higher in the treated groups than those in the control groups. Therefore, EPI can facilitate larval metamorphosis and improve their survival ability.