| 摘要: |
| 为了探索褐毛鲿(Megalonibea fusca)胚胎孵化和早期仔鱼生长发育最适宜的盐度条件, 作者观察了其胚胎在6 个盐度(35、30、25、20、15、10)海水中沉浮性、发育、初孵仔鱼分布状态。结果表明: 胚胎在盐度35 时完全上浮, 盐度低于25 完全下沉, 在盐度30 时处于半悬浮状态; 不同盐度对胚胎发育有一定影响: 在盐度30~15 范围内, 胚胎发育较快, 孵化时间较为一致, 在盐度35 和10 发育变慢, 孵化时间延长2.5 h 以上; 初孵仔鱼在不同盐度海水中呈不同分布状态: 在盐度35 时完全上浮表层, 盐度25~30 分布于中下层至中上层, 盐度25 大部分仔鱼沉底, 盐度低于20, 初孵仔鱼全部沉底。观察了10 个盐度(35、32、29、26、23、20、17、14、11、8)海水中胚胎孵化率和早期仔鱼存活率, 结果表明:褐毛鲿胚胎在盐度35~8 范围内孵化率达(76±2)%~(98±2)%, 在较低盐度26~11 区间, 孵化率达(88±0)%~(98±2)%, 显示低盐区更高的孵化率, 而在较高盐度29~35 区间, 孵化率在(82±2)%~(84±2)%,并且具有明显趋向性, 即盐度大于29, 随盐度升高孵化率逐渐下降; 盐度对早期仔鱼存活率有明显影响: 孵化后40 h 正常仔鱼最高存活率在低盐度26~8 区, 为(89.4±2.2)%~(97.4±0.1)%, 盐度大于29,随着盐度上升仔鱼死亡率骤然升高, 在盐度29~35, 升至(31.7±0.7)%~(38.1±1.5)%, 畸形率升至(7.1±0.2)%~(10.7±0.5)%, 正常仔鱼存活率下降至(61.0±1.0)%~(61.9±1.5)%。低盐度区仔鱼有更高的存活率。褐毛鲿胚胎最适孵化盐度在29~32, 早期仔鱼最适培育盐度为26。 |
| 关键词: 褐毛鲿(Megalonibea fusca) 盐度 胚胎 孵化率 存活率 |
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| 基金项目:国家科技基础条件平台建设项目(水产种质资源平台); 福建省海洋与渔业厅项目(闽水科9803); 福建省发展计划委员会资助项目［闽计基(农)［2000］457］ |
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| Effects of salinity on embryonic development and early larval survival rate of Megalonibea fusca |
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| Abstract: |
| To investigate the most suitable salinity condition for the embryo hatching and larval growth of Megalonibea fusca, the embryonic development, ups and downs of embryo and newly hatched larvae distributions were observed in six salinities (35, 30, 25, 20, 15, and 10) seawater. The results showed that the embryo completely rose in the salinity 35, completely sank at the salinities less than 25, and in a suspended state at the salinity of 30. Different salinities had a certain influence on embryonic development. At the salinities ranged from 30 to15, embryonic developments were faster and incubation times were more consistent, and at the salinities of above 30 and less than 15, incubation times were prolonged longer than 2.5h. Newly hatched larvae showed a different distribution in seawaters with different salinities. At the salinity of 35, larvae fully floated on the surfaces; at salinities of 25-30, larvae was distributed in the lower-middle and upper-middle layer; at salinity of 25, most larvae sank to the bottom, and at salinities lower than 20, all newly hatched larvae sank. Embryonic hatching rates and early larvae survival rates were observed in ten salinities (35, 32, 29, 26, 23, 20, 17, 14, 11, 8) seawaters. The results showed that, at the salinities of 35 – 8, the embryonic hatching rates of Megalonibea fusca ranged from (76±2)% to (98±2)%. In low salinity zone from 26 to 11, hatching rates were from (88±0)% to (98±2)%, higher than those in low salt area. While in high salinity zone from 29 to 35, hatching rates were (82±2)%-(84±2)%, and had the obvious tendency that when the salinity was greater than 29, hatching rate gradually decreased with increasing salinity. Salinity had a significant effect on early larval survival rate. Normal larvae after hatching 40h had the highest survival rate of (89.4±2.2)％-(97.4±0.1)％ in the low salinity zones of 26-8. When salinity was greater than 29, larval mortality suddenly increased with the increasing salinity. In salinities of 29-35, larval mortality was up to (31.7±0.7)％-(38.1±1.5)％, malformation rate rose to (7.1±0.2)%-(10.7±0.5)%, normal larval survival rate dropped to (61.0±1.0)%-(61.9±1.5)%. Larvae had a higher survival rate in low salinity zone. The optimal hatch salinity of Megalonibea fusca was in 29-32 and the optimal cultivation salinity of early larva was 26. |
| Key words: Megalonibea fusca salinity embryo hatching rate survival rate |
