| Trachinotus ovatus were widely cultured in the southern coast of China, which was one of the main species marine cage culture of fish in the region, making a great profit on economics in recent years. This dissertation mainly studied respiration and ammonia excretion of juvenile T. ovatus and influence of environmental factors on oxygen consumption and ammonia excretion of juvenile, the oxygen consumption of embryo and early larva, the oxygen consumption of gill tissue in vitro the juvenile.The main results were showed as follows:1 Oxygen consumption and ammonia excretion of the juvenile T. ovatusThe effects of body weight and stocking density on oxygen consumption and ammonia excretion of T. ovatus were determined by the closed flow experimental methods. The results showed that the oxygen consumption of juvenile T. ovatus decreased as its weight increasing (P<0.05). Light had significant effects on oxygen consumption and ammonia excretion. The oxygen consumption and ammonia excretion of the fry under dark condition was 25.18%～40.76% and 16.28%～40.28% lower than that in the natural light conditions. The oxygen consumption of T. ovatus increased with the increase of stocking density, and ammonia excretion of T. ovatus showed the trend of hyperbola with stocking density increasing (P<0.05). Diurnal variation of oxygen consumption rate and ammonia excretion rate in T. ovatus was significant, average oxygen consumption and ammonia excretion in day time were higher than that at night, oxygen consumption in valley bottom value being 69.68% of that of peak value and ammonia excretion in valley bottom value being only 30.91% of that of peak value. The asphyxiation point of juvenile T. ovatus was 0.991±0.058 mg/L.2 Influence of environmental factors on oxygen consumption and ammonia excretion of juvenile T. ovatusThe effects of temperature,salinity,pH and water velocities on oxygen consumption and ammonia excretion of T. ovatus were determined by the closed flow experimental methods. The results showed that the oxygen consumption and ammonia excretion of juvenile T. ovatus showed the trend of hyperbola with water temperature increasing, and reached a peak value in water temperature 27℃. Water temperature had significant effects on oxygen consumption and ammonia excretion (P<0.01). The oxygen consumption and ammonia excretion of juvenile T. ovatus was decreased with the increase of salinity, and salinity also had significant effects on the oxygen consumption and ammonia excretion (P<0.01). As the pH increases, the oxygen consumption did not change obviously, pH on the oxygen consumption was not significant (P>0.05). The ammonia excretion was increased from the first, and then decreased with pH increase, and pH had significant effects on the ammonia excretion (P<0.05). Oxygen consumption and ammonia excretion of juvenile T. ovatus increased gradually with increasing water velocities and there was a peak appeared at 150 ml/min, and then oxygen consumption and ammonia excretion decreased gradually. The effects of water velocities on oxygen consumption and ammonia excretion in juvenile T. ovatus were significant (P<0.01).3 Study on oxygen consumption of embryo and early larva T. ovatusUsing SKW-3 instrument, the oxygen consumption in main development stages of T. ovatus embryos and early larval were determined, as well as its influences of temperature, salinity, pH and the different concentration levels of copper, cadmium were studied. The results show that under the conditions of 25±0.5℃, the oxygen consumption of embryos and early larval T. ovatus increased gradually with advancing development, and became the maximum when embryos were in pre-stage of hatching. The stages of gastrula and hatching were sensitive especially to dissolved oxygen content in water. Embryonic oxygen consumption increased gradually with temperature, salinity and pH increasing, reaching the maximum value at the water temperature of 25℃, salinity 35 and pH 8, and then declined gradually. The oxygen consumption showed the trend of hyperbola with the rise of concentration of copper. The oxygen consumption of embryos became the highest when the concentration of copper in water was 0.01 mg/L. Embryonic oxygen consumption decreased with the rise of concentration of cadmium.4 Influences of temperature,salinity and pH on oxygen consumption of gill tissue in vitro juvenile T. ovatus Using SKW-3 instrument, we mensurate the oxygen consumption of gill tissue invitro and oxygen consumption of per unit respiratory area gill tissue in vitro juvenile Trachinotus ovatus, and we also researched the influences of temperature, salinity, and pH about them. The results showed that with the temperature, salinity and pH increasing, there were enhancement on the oxygen consumption of gill tissue in vitro and oxygen consumption of per unit respiratory area gill tissue in vitro juvenile T. ovatus. When the water temperature reaching 27℃, salinity 28 and pH 8.5, the oxygen consumption of gill tissue in vitro arrived at maximum value and then decline gradually; while the water temperature reached 27℃, salinity 23, pH 8.5, the oxygen consumption of per unit respiratory area gill tissue in vitro had the same situation as above. Water temperature, salinity and pH have significant effects on the oxygen consumption of gill tissue in vitro (P<0.05). Temperature and salinity also had evident effects on oxygen consumption of per unit respiratory area (P<0.01). The pH had obviously impacted on the oxygen consumption of per unit respiratory area too (P<0.05). During the salinity of 18 and 33,there was no significant effects on the oxygen consumption of gill tissue in vitro juvenile T. ovatus (P> 0.05). |
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