【作者】 亓磊；

【导师】 乔振国；

【作者基本信息】 上海海洋大学 ， 水产养殖， 2011， 硕士

【摘要】 以不同地理种群拟穴青蟹幼体、C1和C5期仔蟹为研究对象,从形态特征、养殖性能等方面进行了较为系统的研究,旨在为拟穴青蟹良种选育提供必要的理论基础和技术支持。本研究主要结果如下:1 3个地理种群拟穴青蟹幼体对低盐的生态适应性与形态差异的初步研究为了解不同地理种群拟穴青蟹幼体的生态习性及形态差异,本研究对采自越南北部、我国广西北海和海南文昌3个地理种群拟穴青蟹人工繁育所获Z1期幼体在实验条件下进行了不同盐度的适应性培育实验。比较了不同地理种群拟穴青蟹幼体在不同盐度条件下的存活率、发育历期及大眼幼体形态性状的差异。结果表明:(1)在同一盐度条件下,3个地理种群拟穴青蟹初孵幼体发育至大眼幼体的存活率呈显著差异(P<0.05)。3个地理种群拟穴青蟹初孵幼体发育至大眼幼体的存活率在盐度为32和29时均较高(20.0%和26.7%、23.3%和23.3%、20.0%和26.7%),但在盐度低于29时,3个地理种群则有较大差异,其中盐度为26时的海南种群发育至大眼幼体的存活率(26.7%)显著高于相同盐度下培育的北海和越南种群(P<0.05)。(2)在盐度为20～32下,越南种群初孵幼体发育至大眼幼体的历期显著短于相同盐度下的海南和北海种群(P<0.05),而海南和北海种群的无显著差异(P≥0.05)。(3)3个地理种群拟穴青蟹大眼幼体的形态性状指标(头胸甲宽、头胸甲长、额缘宽)存在明显差异(P<0.05),其中越南拟穴青蟹大眼幼体各形态性状指标值表现为最大,而北海和海南拟穴青蟹大眼幼体形态指标值较小。2中国5个地理种群拟穴青蟹仔蟹形态差异分析选取不同地理种群拟穴青蟹C5期仔蟹作为研究对象,应用可量性状数据,以多元统计分析方法对不同地理种群拟穴青蟹仔蟹进行综合分析,比较不同种群间的形态变异特点。据聚类分析结果来看,厦门种群最先和三门种群聚在一起,随后与饶平种群、海南种群聚集,最后才和北海种群聚集。据判别分析结果来看,三门、厦门、饶平、北海及海南种群的判别准确率分别为80.0%、63.3%、70.8%、81.3%和78.1%,平均拟合概率为75.0%,判别准确率较低,各个种群间的错判率较高。这说明5个地理种群间形态出现了一定程度的差异,但这种差异程度较小,而形态差异可能是由于不同种群的遗传差异所致。3 5个地理种群拟穴青蟹仔蟹对低盐环境的生态适应性为比较不同地理种群拟穴青蟹的生长特性和对环境盐度的适应性,作者将三门、厦门、饶平、北海和海南种群拟穴青蟹仔蟹分别在不同环境盐度条件下养殖,对5个种群的生长发育情况进行了比较。研究结果为:就蜕壳间期而言,5个地理种群拟穴青蟹C2和C3期仔蟹蜕壳间期均无差异显著(P≥0.05),而盐度仅对C3期仔蟹蜕壳间期有显著影响(P<0.05),其中盐度为12时的海南种群C3期仔蟹蜕壳间期最短,为3.6 d。就特定生长率上而言,5个地理种群拟穴青蟹仔蟹在盐度为12时的甲宽和体重特定生长率均高于其它盐度。盐度为12时的海南种群甲宽和体重特定生长率最高,而盐度为6时的北海种群甲宽特定生长率和厦门种群体重特定生长率均是最低。在盐度为6、12和32时,海南种群甲宽和体重特定生长率分别比相同盐度下的北海种群高出20%、10%、5%和19%、10%、11%;分别比相同盐度下的饶平种群高出13%、27%、5%和10%、19%、8%;分别比相同盐度下的厦门种群高出10%、16%、1%和20%、16%、13%;分别比相同盐度下的三门种群高出5%、8%、5%和8%、5%、15%。5个地理种群拟穴青蟹仔蟹的生长随着环境盐度的升高有降低的趋势。就甲宽增量而言,5个地理种群3次蜕壳甲宽增量均存在显著差异(P<0.05),盐度为18时的海南种群C1至C2期仔蟹甲宽增量最大,盐度为6时的最小。在盐度为6、12、24和32时,海南种群的C1至C2期仔蟹甲宽增量分别比相同盐度下的北海种群小11%、6%、13%和12%;分别比相同盐度下的饶平种群小20%、25%、31%和14%;分别比相同盐度下的厦门种群小27%、11%、9%和0%;分别比相同盐度下的三门种群小4%、6%、13%和4%。盐度为12时的海南种群C2至C3期仔蟹甲宽增量最大,盐度为6时的北海种群最小。在盐度为12、18和32时,海南种群C2至C3期仔蟹甲宽增量分别比相同盐度下的北海种群大66%、16%和7%;分别比相同盐度下的饶平种群大28%、22%和4%;分别比相同盐度下的厦门种群大20%、14%和10%;分别比相同盐度下的三门种群大30%、14%和21%。盐度为12时的海南、北海和三门种群C3至C4期仔蟹甲宽平均增量最高,分别为2.77、2.71和2.71 mm;盐度6时的饶平种群最低。在盐度为6和12时,海南种群C3至C4期仔蟹甲宽增量分别比相同盐度下的北海种群大27%和2%;分别比相同盐度下的饶平种群大34%和31%;分别比相同盐度下的厦门种群大20%和7%;分别比相同盐度下的三门种群大13%和2%。更多还原

【Abstract】 In this study, we take larvae, C1 and C5 juveniles of Scylla paramamosain as main materials, and do study on culture performance and morphometeric difference. Results of this present study will be an important contribution to the biology of this species and will be valuable in the breeding of new variety for the commercial production of the crab juveniles. The major results are as following:1 Morphological variations of mud crab, S. paramamosain, larvae collected from different zones and their ecological adaptability to low salinityThis crab is capable to survive under different salinity conditions due to its wider adaptability. The effects of low-salinity water on larval survival and development of three mud crab populations were investigated in a 3×5 factorial designed experiment in the laboratory. S. paramamosain broodstock were collected from Beihai region (Guangxi province, China), Hainan region (China) and Vietnam in 2009 and these broodstock populations were named as BH, HN and YN respectively. Five different levels of salinity conditions, 20, 23, 26, 29 and 32 were used in the experiment. We transferred newly hatched larvae from seawater (32) in the stock tank directly to 1 L beakers filled with 900 mL seawater, and maintained under the respective salinity conditions throughout the experiment. Seawater was pumped from the Hainan coast. The diluted SW was prepared by mixing the seawater with municipal water. These experimental media were also treated with disinfection by use of chloric disinfectant solution which had been dechlorinated with sodium thiosulfate and were well aerated before use, and contained florfenicol (1 - 2mg/L) or enrofloxacin (1 - 2mg/L). The experiment was conducted under a light-dark cycle of 12L: 12D with a light intensity of 5000-6000 lx using the incandescent bulb as light source. Each treatment was conducted in triplicate with each beaker containing 30 larvae. Every morning during the experiment, larvae were transferred with a large pipette to new beakers filled with freshly prepared feed and water with the desired salinity. Larval mortality and development were recorded daily during the transfer and identifying the stage of the larvae (zoea 2, 3, 4, 5 and megalopa). Differences in morphology at megalopa stage were obtained by measurements of the carapace size.The results showed that: the survival rates to megalopa in salinity 29 and 32 from BH and YN were signi?cantly higher, while within salinity 26 - 32 no significant effects on survival of zoeal larvae from HN were detected. The survival rates in salinity 26 from HN were higher than those of the other two populations. A low salinity of 20 led to the lowest larval survival for different populations among the salinities tested. The mean larval development time to megalopa from HN and BH under different salinity conditions ranged from 15.5 to 16.3 days. The shortest average development time to megalopa was observed in YN. Larvae reared at salinity 20 among different populations showed longer intermoult durations. It is worth noting that unusual cases of prolonged development duration and low survival rate were recorded for larvae reared at salinity 20. In summary, S. paramamosain larvae tolerate a broad range of salinity conditions. All these results showed that S. paramamosain collected from different zones had the different ecological adaptabilities to salinity, and local populations were considered as the basic populations to breed new strains.2 Analysis on morphological variations among five populations of S. paramamos- ainMultivariation analysis methods were used to investigate the morphological variations among the five geographical populations from China Sea areas (Hainan, Beihai, Raoping, Xiamen and Sanmen) according to 14 morphological characters of crab instar 5 (C5) juveniles. The results of cluster analysis showed that the populations from Xiamen and Sanmen formed a common cluster firstly, after that Raoping, Hainan and Beihai joined to the cluster in turn. Accuracy rate of discrimination on five S. paramamosain populations from Hainan, Beihai, Raoping, Xiamen and Sanmen is 78.1%, 81.3%, 70.8%, 63.3% and 80.0%, respectively. The synthetic identification discriminant analysis accuracy was 70.5%. Base on the above, it is suggested that there exist certain differences between different populations, and morphological differences appear to result from genetic differences.3 Effect of low-salinity stress on growth, development among five populations of early juvenile mud crabs, S. paramamosainEffect of acute low-salinity stress on growth, development of early juvenile mud crabs among five populations of S. paramamosain was conducted. S. paramamosain broodstock were collected from Beihai region, Hainan region, Raoping region, Xiamen region and Sanmen region in 2010. Five different levels of salinity conditions, 6, 12, 18, 24 and 32 were used in the experiment. We transferred crab instar 1 (C1) juveniles from seawater (32) in the stock tank directly to 2.5 L plastic casks filled with 1.5 L seawater, and maintained under the respective salinity conditions throughout the experiment. Each plastic cask contained 1 stage 1 juveniles. Each population consisted of 150 plastic casks. The day of transfer was designated as day 1 in this study. Carapace width and wet weight were measured during each molt, while juvenile mortality and moults were recorded daily. Results demonstrate that salinity significantly affects the specific growth rates (SGR) for carapace length or weight, C3 intermolt duration and carapace width increase at C1 to C2, C2 to C3 or C3 to C4 stages of early juvenile mud crabs (P<0.05). There was significant difference in SGR and carapace width increase between different populations (P<0.05). There was no significant difference in C2 intermolt duration. In each population, the C3 intermolt duration is shorter than other salinities under salinity 12 and the specific growth rates in experiment were the highest under salinity 12. But Hainan population shows the best performance. All populations show the lowest under salinity 6. Under salinity 6, 12 and 32, CWSGR of Hainan population are faster by 20%, 10% and 5% than Beihai population, respectively; by 13%, 27% and 5% than Raoping population, respectively; by 10%, 16% and 1% than Xiamen population, respectively; by 5%, 8% and 5% than Sanmen population, respectively. Under salinity 6, 12 and32, WSGR of Hainan population are faster by 19%, 10% and 11% than Beihai population, respectively; by 10%, 19% and 8% than Raoping population, respectively; by 20%, 16% and 13% than Xiamen population, respectively; by 8%, 5% and 15% than Sanmen population, respectively. At the first molt, the carapace width increase of Hainan population is highest at 18. Under salinity 6, 12, 24 and 32, the carapace width increases of Hainan population are lower by 11%, 6%, 13% and 12% than Beihai population, respectively; by 20%, 25%, 31% and 14% than Raoping population, respectively; by 27%, 11%, 9% and 0% than Xiamen population, respectively; by 4%, 6%, 13% and 4% than Sanmen population, respectively. At C2 to C3 stage, the carapace width increase of Hainan population is highest at 12. Under salinity 12, 18 and 32, the carapace width increase of Hainan are higher by 66%, 16% and 7% than Beihai population, respectively; by 28%, 22% and 4% than Raoping, population respectively; by 20%, 14% and 10% than Xiamen population, respectively; by 30%, 14% and 21% than Sanmen population, respectively. At C3 to C4 stage, the carapace width increase of Hainan, Beihai and Sanmen population, which are best than other treatments, is 2.77, 2.71 and 2.71 mm. Under salinity 6 and 12, the carapace width increase of Hainan are higher by 27% and 2% than Beihai population, respectively; by 34% and 31% than Raoping population, respectively; by 20% and 7% than Xiamen population, respectively; by 13% and 2% population, respectively. In each population, the carapace width increase at C2 to C3 or C3 to C4 stages are lowest at 6. Base on the above, it is suggested that the growth of Hainan is best of all, which indicated that it is a super candidate for further selection. However, from an aquaculture point of view, a salinity range of 12 - 24 was recommended at C1 to C3 stages for early juvenile S. paramamosain, which widened in the later stages for the culture, but different salinity ranges were flexibly applied according to different population and conditions, which should be taken into account.更多还原