【作者】 韦柳枝；

【导师】 张秀梅；

【作者基本信息】 中国海洋大学 ， 增殖养殖工程， 2010， 博士

【摘要】 本文综述了国内外关于缺氧对水生甲壳动物生理生态学影响的研究进展,并以中国明对虾为研究对象,采用实验生态学、生物能量学及生理学等方法,开展了低溶解氧(DO)对其生长、补偿生长、能量收支、呼吸代谢、行为选择及不同组织器官的氧化应激参数影响的实验研究,主要研究结果如下：1.第一部分实验对中国明对虾不同温度下的低氧耐受能力及其在缺氧水体中的行为及代谢反应进行了研究。共设计了4个实验对中国明对虾在不同温度下的窒息点、对不同溶解氧含量水体的探测和逃避和在不同溶解氧含量水体中的代谢率进行了观察和测定。结果表明水温高于20℃时,实验虾窒息点随水温上升而提高,回归分析推算得出实验虾最低窒息点和出现水温分别为0.59 mg/l和14.7℃；实验虾能探测到低氧区域的存在、完全避开DC<2.0 mg/l的区域并很少进入DO为2.0～2.5 mg/l的区域；在D0<4 mg/l时,实验虾的耗氧率和排氨率随DO降低而下降,O：N随溶解氧降低而上升；长期处于低氧水体的实验虾其能量代谢率和排泄能损失率都随DO降低而下降,由能量代谢率和排泄氮推算得到的O：N则未受到溶解氧含量的显著影响；长期处于低氧水体的实验虾身体水分含量升高,蛋白质、脂肪、能量和糖类能量含量显著降低。以上研究结果表明,中国明对虾对低溶解氧非常敏感,属于有限的溶解氧调节型,其临界溶解氧含量(COL)在4.0mg/l左右。在水体溶氧低于COL时,中国明对虾短期内可以改变代谢底物组成以获得更高的氧利用效率,而长期缺氧时代谢底物主要来源于食物,其组成不受溶解氧降低的影响。2.第二部分实验研究了5个溶解氧梯度下(2.09±0.15、3.10±0.29、4.13±0.25、4.73±0.12、5.48±0.09 mg/l)中国明对虾幼虾的生长及其能量学机制,实验共持续30 d。结果表明当水体DO低于4.13 mg/l时实验虾生长受到抑制。在较低DO处理,实验虾摄入能分配到代谢能、蜕皮能及排泄能的比例较高,而分配到生长能的比例较低,同时能量代谢率较低,导致其饲料转化效率及摄食率较低。在低DO处理组实验虾蜕皮能较高、存活率较低,死亡实验虾甲壳薄软、残食等现象较多,说明缺氧会延缓实验虾蜕皮后的恢复,导致残食和高死亡率。实验结果表明缺氧会使中国明对虾幼虾生长受到抑制、死亡率升高,由此推断缺氧是影响其群体数量和适合度的重要因素之一。3.第三部分实验对中国明对虾受低溶氧(DO 3.11±0.13、2.08±0.21 mg/l)胁迫10d后的补偿生长现象及能量学机制进行了研究,实验共持续50 d。研究发现实验虾在低氧胁迫期间代谢能和蜕皮能占摄入能比例较对照组高,但日能量代谢率(J/g/d)相对低,这导致饲料转化效率和摄食率降低,实验虾生长受到抑制。恢复正常溶解氧(5.59±0.19、5.63±0.22 mg/l)后20 d和30 d,两组实验虾分别出现完全补偿生长,主要原因是恢复阶段过量摄食效应,同时饲料转化效率提高也起到了一定作用。在恢复阶段,低氧胁迫后实验虾日能量代谢率比对照组高(P<0.05),意味着胁迫后实验虾有更多的能量可用于与摄食相关的行为。能量收支分析表明实验虾主要通过减少分配到排粪和蜕皮的能量来增加饲料转化效率。结果表明如果有足够的时间恢复生长,短期非致死低氧胁迫不会影响中国明对虾幼虾后期的生长；中国明对虾能承受和适应一定程度的溶解氧波动,短期非致死低氧胁迫对天然、放流或养殖群体产量不会有明显影响。4.第四部分实验通过测定3-24 h低氧暴露(DO 2.0±0.1 mg/l)和随后3-24 h恢复正常溶氧(DO 6.0±0.2 mg/l)期间中国明对虾肌肉、鳃、肝胰脏和血浆中乳酸含量、脂质过氧化物丙二醛含量、抗超氧阴离子活力及总抗氧化能力,对短期低氧胁迫及溶氧恢复过程中中国明对虾组织器官的抗氧化状态和氧化损伤进行了初步研究。对照组和各处理组实验虾各组织器官中所测得的氧化应激参数均存在一定差异。低氧胁迫6h和12h实验虾血浆和肌肉中的乳酸含量显著增加,胁迫24 h时乳酸含量降到对照组水平；肌肉的乳酸含量在溶氧恢复后升高,12h显著增加；低氧胁迫对实验虾肝胰脏及鳃中乳酸含量、肌肉、鳃及肝胰脏中总抗氧化能力、肝胰脏及鳃中抗超氧阴离子活力、肌肉、肝胰脏、鳃及血浆中的丙二醛含量均无显著影响,而恢复正常溶氧后肝胰脏总抗氧化能力、鳃的抗超氧阴离子活力、肌肉、鳃及血浆中的丙二醛含量在不同时间显著增加,可能会造成不同程度的氧化损伤,表明实验虾在恢复正常溶氧后比低氧胁迫时的氧化应激反应强烈；恢复正常溶氧24 h时,除肌肉中的乳酸含量、鳃的抗超氧阴离子活力、鳃及血浆中的丙二醛含量高于对照组,其余指标均与对照组无显著差异。结果表明中国明对虾在水温26.0±1.0℃、盐度30～31、pH7.9±0.2的条件下,对DO为2.0±0.1 mg/l的急性低氧胁迫和溶氧恢复有一定的耐受和调节能力。更多还原

【Abstract】 The domestic and foreign research advances regarding the effects of hypoxia on physiological ecology in crustacean were reviewed in this thesis. Menthods of ecology, energetics, and physiology were used to investigate the effects of low dissolved oxygen (DO) content on the growth, compensatory growth, energy allocation, oxygen consumption, metabolism, behavior, and oxidative stress of Chinese shrimp, Fenneropenaeus chinensis. The main results are as follows:1 Tolerance and response of behavior and metabolism to low dissolved oxygen of Chinese shrimp, Fenneropenaeus chinensisThe tolerance of low DO content and the responses of behavior and metabolism to hypoxia are important strategies for aquatic organisms to adapt to variable DO in water environment. In this chapter, four experiments were designed to investigate the tolerance of low DO and the responses of behavior and metabolism to hypoxia of Chinese shrimp, F. chinensis. The results of experiment I showed that the lethal dissolved oxygen (LDO) content of small shrimp (2.29±0.06 g) and large shrimp (12.21±0.09 g) were positively related to temperature above 20℃. The regression analysis showed that the temperature at minimum LDO (0.59 mg/l) was 14.7℃for small shrimp. In experimentⅡ, the small (9.03±1.32 g) and the large (19.21±1.86 g) shrimp could detect hypoxic water area and absolutely avoided the water area with DO below 2.0 mg/l. The shrimp seldom entered the water area with DO 2.0～2.5 mg/l. In experimentⅢ, the oxygen consumption and ammonia excretion of the shrimp (15.69±0.91 g) exposed to different DO for eight hours was measured. The oxygen consumption and ammonia excretion were positively related to DO below 4 mg/l. However, O:N was negatively related to DO. In experimentⅣ, an energy budget method was adopted to calculate the daily energy metabolic rate (R, J/g/d), daily energy lost rate of nitrogen excretion (U, J/g/d), and O:N. R and U diminished as DO decreasing and no significant effects of DO on O:N. Being exposed to hypoxic water for 30 days induced an increase of moisture content of the shrimp and decrease of protein, lipid, energy, and energy of glucide. The above results indicated that F. chinensis was sensitive to low DO content and it should be a limited oxygen-regulator. The critical dissolved oxygen (COL) content was about 4.0 mg/1 and when DO was below COL for a short period, F. chinensis could adjust the composition of metabolic substrate to achieve a higher oxycalorific coefficient. But for a long term low DO, the metabolic substrate was from feed and its composition would not be changed by DO decrease.2 Effects of limited dissolved oxygen supply on the growth and energy allocation of juvenile Chinese shrimp, Fenneropenaeus chinensisInformation about the effect of hypoxia exposure on energy allocation is helpful for better understanding how aquatic animals tolerate and adapt to the hypoxic environment. The growth, molting, and energy allocation were investigated in juvenile F. chinensis exposed to five different dissolved oxygen seawaters (DO 2.09±0.15,3.10±0.29,4.13±0.25,4.73±0.12, and 5.48±0.09 mg/1) for 30 days. When DO was below 4.13 mg/l, the growth of shrimp was depressed. Feeding rate and feed conversion efficiency decreased with DO decrease. Less feed ingestion was caused by lower daily metabolic energy. Higher proportion of ingested energy lost in metabolism, exuviations, and nitrogen excretion caused lower feed conversion efficiency. More energy lost in exuviations, lower survival rate, soft carapaces of dead shrimp, and cannibalism were found in oxygen deficient groups and it implicated that hypoxia could delay the shrimp recovering from molting and cause cannibalism and higher mortality. The results indicated that hypoxia was an important factor affecting the amount and fitness of shrimp stock because it could cause a high rate of mortality and growth depression.3 Compensatory growth of Chinese shrimp, Fenneropenaeus chinensis following hypoxic exposureCompensatory growth following stress is a strategy which aquatic animals use to adjust themselves to a variable environment. Studies on the recovery growth of aquatic animals are not only of theoretical value in ecophysiology and evolution, but also important to applications in aquaculture and fisheries resource management. In this experiment, juvenile F. chinensis with an initial average body weight of about 3.72 g were exposed to hypoxic water (DO about 2.08 and 3.11 mg/1) for 10 days and then switched to normoxic water (DO about 5.63 and 5.59 mg/1). Compared to the juveniles in normoxia, juveniles in the hypoxia period allocated a greater proportion of energy to metabolism and exuviations, but allocated less energy to daily metabolism per gram shrimp weight (J/g/d). This reduced feed conversion efficiency and feeding rate. Finally, F. chinensis suffered growth depression. The juveniles completely compensated for hypoxia-induced growth depression in 30 days after being switched into normoxic water and the compensation was achieved mainly by hyperphagia and slightly by improvement of feed conversion efficiency. During the recovery period, the hypoxic-stressed shrimp showed higher daily metabolic energy (J/g/d) than controls (P<0.05). This means the stressed shrimp had more energy for feeding-related activities. So hyperphagia was observed. Energy analysis indicated that F. chinensis improved feed-conversion efficiency mainly by reducing the percentage of energy lost in feces and exuviations. The results showed that short-term non-lethal hypoxia would not affect the growth of juvenile F. chinensis if there were enough time for the stressed shrimp to recover. It suggested F. chinensis was able to adapt to DO fluctuation to some extent and short-term non-lethal hypoxia would not have an obvious effect on natural, released, and cultured shrimp stock.4 Hypoxia and recovery perturb oxidative stress of Chinese shrimp, Fenneropenaeus chinensisThe effects of hypoxia exposure 3-24 h and following normoxic recovery 3-24 h on the levels of lactic acid, lipid peroxidation (malondialdehyde), activities of anti-superoxide radical and the total antioxidant capacity status were measured in muscle, gill, hepatopancreas, and plasma of the Chinese shrimp, F. chinensis. Results indicated differences among tissues, even under control conditions. Under hypoxia 12 h and 6 h, lactic acid levels in muscle and plasma were increased significantly, but decreased to the same levels as control in hypoxia 24 h. Followed by 12 h of normoxic recovery, lactic acid levels in muscle increased significantly. Hypoxia exposure did not show a significant effect on the lactic acid levels in hepatopancreas and gills, total antioxidant capacity status in muscle, gills and hepatopancreas, activities of anti-superoxide radical in hepatopancreas and gills, malondialdehyde levels in muscle, hepatopancreas, gills and plasma. But during reoxygenation, the total antioxidant capacity status in hepatopancreas, activities of anti-superoxide radical in gills, and levels of malondialdehyde in muscle, gills and plasma increased significantly at different time, which could cause tissue damage. The results showed that the oxidative stress during normoxic recovery was greater than during hypoxia exposure. After 24 h of normoxic recovery, most parameters were at the same levels as control, but the lactic acid levels in muscle, activities of anti-superoxide radical in gills, malondialdehyde levels in gills and plasma were still higher than control groups. Under the condition of 26.0±1.0℃, salinity 30～31, pH 7.9±0.2, Chinese shrimp showed a certain degree of ability to to tolerate and adapte to acute hypoxia (DO 2.0±0.1 mg/l) and following reoxygenation.更多还原