鮸（Miichthys miiuy）早期生长存活过程和消化生理机制的研究

IOCAS-IR > 海洋环流与波动重点实验室

	鮸（Miichthys miiuy）早期生长存活过程和消化生理机制的研究
其他题名	Survival and Growth and Mechanism of Physiological Digestion in Miiuy Croaker（Miichthys miiuy）during Early Development
	单秀娟
学位类型	博士
	2008-05-31
学位授予单位	中国科学院海洋研究所
学位授予地点	海洋研究所
关键词	鮸异速增长延迟投饵组织学消化酶
摘要	鮸Miichthys miiuy是中国南方重要的经济养殖种类，早期发育阶段的高死亡率和高畸形率严重制约着鮸养殖的工业化和商品化进程。为了更好的了解鮸早期发育规律，提高其人工养殖技术和管理策略，本论文在实验条件下对鮸早期生长和存活过程、消化生理发生机制及其在胁迫条件下的生态对策进行了研究。鮸早期发育阶段分为仔鱼期和稚鱼期。个体发育的形态学变化和组织器官分化主要集中在仔鱼期，胚胎期所具有的特征在仔鱼期被具体的功能系统所代替，如呼吸、摄食、运动和消化系统。鮸个体的头、尾部快于躯干部的生长，表明其早期发育过程中摄食和运动器官发育的优先性。鱼类早期是优先发育对其生存起首要作用的器官，然后是对其生存作用次之的器官。在24℃，鮸仔鱼在3日龄开口摄食，4日龄卵黄囊吸收完毕，6日龄仔鱼如不能建立外源性营养即进入饥饿死亡不可逆点(PNR)，而延迟投饵3天（6日龄）以上的仔鱼在8日龄全部死亡。在7日龄时，正常投喂仔鱼的SGR明显高于延迟投饵仔鱼。延迟3天和饥饿的仔鱼在6日龄后出现明显的负增长。在36日龄时，正常投喂仔鱼与延迟投饵1天仔鱼之间的生长差异消失，与延迟投饵2天的仔鱼之间的生长差异显著。饥饿显著影响开口仔鱼的生长存活，但对后期存活仔鱼的生长存活及体成分的影响不显著。仔鱼在12L条件下存活率（9-16%）要小于其他的各组（12-39%），仔鱼的存活率随着密度的增加逐渐减小。SGR与存活率具有相同的变化趋势，在18L条件下仔鱼的生长（3-10%）要大于12L（2-7%）和24L（2.8-8.7%）条件下仔鱼的生长。鮸消化系统发育分为三个阶段：从孵化到初次摄食之前，消化道为一细长管道；从外源营养开始到胃腺出现，在此阶段，液泡、杯状细胞开始出现在消化道中，在6日龄胃出现，消化道明显分为口咽腔、食管、胃、前肠和后肠；从20日龄胃腺出现开始，胃在25日龄分为贲门胃、胃体和幽门胃三个部分，幽门盲囊出现，消化系统趋于完善。饥饿严重影响鮸消化器官及消化腺的正常发育过程。饥饿使其组织学的结构和功能明显衰退，肝组织变得疏松，细胞缩小，细胞核解体，稚鱼肝组织内没有脂质积累，细胞质中液泡减少；胰脏组织变得致密，腺泡萎缩，分泌物减少；胃腺细胞收缩，结构不完整，肠微绒毛退化，肠粘膜褶减少，肠上皮细胞遭到破坏。鮸主要消化酶分为三个发育时期：从初孵到外源营养开始的迅速增长期；继而是从3日龄到25日龄波动期；25日龄后处于相对稳定期。各种消化酶总活性随着个体的发育逐渐增加，30日龄后总活性显著增加。延迟1天投饵的仔鱼和正常摄食的仔鱼其消化酶的活性没有显著差异（P>0.05），但是延迟2天投饵的仔鱼和正常摄食及延迟1天投饵的仔鱼消化酶的活性存在显著差异(P<0.05)，无论是延迟1天还是延迟2天仔鱼消化酶与正常摄食的仔鱼具有相同的发育方式。延迟3天投饵的仔鱼和饥饿仔鱼发育方式类似，从3日龄开始，消化酶活性显著下降。饥饿对鮸仔稚鱼胰蛋白酶、淀粉酶和脂肪酶的活性有显著的影响。在初次摄食期，摄食仔鱼和饥饿2天的仔鱼各种消化酶活性均存在显著差异（P<0.05）；但是仔鱼后期，经过3天饥饿的仔鱼其消化酶的活性和摄食仔鱼之间存在显著差异（P<0.05），饥饿4天的仔鱼恢复摄食5天，即可恢复到和摄食仔鱼相同水平。饥饿6天的鮸稚鱼其消化酶与正常摄食的稚鱼之间存在显著差异（P<0.05），在恢复摄食5天后其消化酶活性可以恢复到和正常摄食仔鱼相同水平。光照和饲养密度显著影响了鮸消化酶的活性。胰蛋白酶、淀粉酶和脂肪酶在18L低密度饲养条件下其活性明显高于（P<0.05）其他各组；12L高密度饲养条件下各种消化酶活性明显低于（P<0.05）其他各组；在0L条件下，各种消化酶活性在开口摄食之前明显低于其他各组，开口摄食之后，各种消化酶活性迅速下降。延迟投饵、光照周期和饲养密度虽然对鮸消化酶的活性产生了重要影响，但是对消化酶的发育方式没有显著影响，因此，鮸消化酶的具体发育方式是由内部遗传机制来控制，但受外界环境因素（食物组成、光照和饲养密度）的调节。
其他摘要	Miiuy croaker Miichthys miiuy is an important commercial species in southern China. High mortality and deformity during early development have hindered the industrialization and commercialization of this species and the protection of natural resources. With an attempt to better understand the early life history of the miiuy croaker and also to provide useful information for improving their artificial reproduction technique, rearing management and recruiting natural stocks, the process of growth and survival, the mechanism of physiological digestion and ecological countermeasures under controlled conditions were studied. The early development of miiuy croaker was divided into two phases: larval and juvenile stages. Morphogenesis and differentiation were more intense during larval stage than juvenile stage. Larval stage was characterized by the replacement of embryonic adaptations and functions by definitive ones, such as respiration, exogenous feeding and active swimming. The results confirmed the hypothesis that growth patterns of fish at early life stages: developed the essential organs for survival in priority, and followed by the lower priority for survival. The larvae started to open mouth and feeding on 3 days after hatching (dah) at 24℃. Yolk absorption was completed on 4 dah and the larvae reached PNR (point of no return) on 6 dah. Larvae first fed on 3 and 4 dah (15%—16%) survived better than those fed on 5 dah (9%) at the end of the experiment (36dah). High larval mortality occurred from first feeding time to 7dah in all treatments, accounting for 40% (first fed prior to 5 dah larvae) to 90% (first fed on 6 dah and no fed larvae) of the total mortality throughout the experiment. No larvae first fed after 5dah could survive up to 8dah. Larvae first fed on 3 and 4dah had better growth performance (specific growth rate, SGR=5%) than those first fed on 5dah (4%). However, neither larval survival nor growth showed noticeable differences between the 3 and 4dah first feeding groups. Starvation had significant effects (p<0.05) on survival of miiuy croaker during early development, no starved larvae could survive up to 8dah; in postlarvae period, a starvation-feeding experiment was done with 4 and 6 days starved larvae, the survival rates were 27% and 15%, respectively; but the survival rate of starved 6 days larvae was 85% for juvenile. Photoperiod and density had no significant effects (p>0.05) on growth at early stages. Significant effects (p<0.05) of photoperiod and density on growth were detected after 20dah. Growth was significantly greater at 18L than at 12L and 24L, and at 10 ind l-1 than at 80 ind l-1. Larvae did not start feeding at 0L, and all larvae died within 7dah. Significant differences (P<0.05) were detected in SGR among all groups with the increasing size of miiuy croaker after 20dah. The digestive tract was undifferentiated at newly hatched larvae, and became functional with the development, gastric glands occurred on 20dah and pyloric caecum was formed on 25dah, which showed the complete function of digestive system. The effects of starvation on histological changes mainly embodied the degeneration of cell in digestive organs, such as cell shrinkage, separation and loss of intercellular substance in liver, pancreas, intestine and stomach, and became more severe with starvation elongated. In addition, the effects of starvation on fish were age-dependent. The specific activities of trypsin, amylase, lipase and alkaline phosphatase showed three distinct phases: a sharp increase in enzyme activity from hatching to the onset of exogenous feeding on 3dah; followed by a fluctuation period from 3dah to 25dah; and then a period of relative constant activity from 25 to 53dah. The total activities of these enzymes showed gradual increase from hatching to 30dah, followed by a sharp increase toward 53dah. In addition, delayed 1d first feeding had no effects on the activities of digestive enzymes, but delayed 2d first feeding larvae had significant effects (P<0.05) in activities of digestive enzymes when compared with those of delayed 1d first feeding larvae and normal fed larvae; the activities of digestive enzymes in delayed 3d first feeding larvae had the same developmental patterns with those in starved larvae, and their activities had a sharp decrease from first feeding to 7dah. As a general trend, enzymes activities were significantly lower (P <0.05) in starved fish. On 4 days starved–fed miiuy croaker postlarvae, digestive enzymes activities took 5 days to reach control group levels. On the other hand, 6 days starved–fed postlarvae showed significant differences (P<0.05) after 2 days feeding again; digestive enzymes activities of 6 days starved–fed juvenile took 5 days to reach control group levels. The results showed that the effects of starvation on digestive enzymes decreased with age. The countermeasures of miiuy croaker to starvation was that they firstly consumed the energy of muscle, then consumed the energy of functional organs; when food was available, they firstly recovered the functional organs, then met with the growth of fish body. Digestive enzymes activities also were affected by photoperiod and density, and the digestive enzymes activities in group with 18L and 10 ind l-1 were higher than those in the other groups. Photoperiod, density, starvation and delayed first feeding greatly affected the activities of digestive enzymes, but no effects on the developmental patterns of digestive enzymes, which might be modulated by internal adaptive mechanism.
页数	148
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/1361
专题	海洋环流与波动重点实验室
推荐引用方式 GB/T 7714	单秀娟. 鮸（Miichthys miiuy）早期生长存活过程和消化生理机制的研究[D]. 海洋研究所. 中国科学院海洋研究所,2008.

条目包含的文件
文件名称/大小	文献类型	版本类型	开放类型	使用许可
10001_20051800681205（6741KB）			限制开放	--	浏览