Primary Study On The Physiological Function Of The Fish Under The Environmental Stress

Environmental stress is a pressure on the existence of the fish. The stress can break the balance and harmony between environment and the fish. The stress also can cause the physiological disorder of the fish body. Various stresses can make different harm to the fish and further mutual effects among these harmful environmental factors increase the damage. Therefore, it is very important to make a better understanding on the process and mechanism of the physiological function of the aquatic under the environmental stress. The study in this field will supply the necessary references to the concentrating healthy aquiculture. This thesis takes Sebastes schlegeli as the central object. During the experiments, experimental ecology, physiology and histology methods are used to study the changes of physiological, biochemical indexes of fish blood, the structure and the ultrastructure of the gills and kidneys under the environmental stress are observed as well.During the experiment of transportation stress, after 40 minutes transportation, the plasma glucoses of Sebastes schlegeli and Lateolabrax maculatus increase remarkable. It is reported that the changes of plasma glucoses are related with the habits and behaviors of the fish; the active Lateolabrax maculatus has high plasma glucose level after transportation and recovers slowly. Sebastes schlegeli with lower swimming capability shows a good tolerance to transportation stress, the level of the fish recovers quickly after the same transportation. Seasonal temperature changes are the main reason which causes the difference of the plasma glucoses under the transportation stress in spring and winter. The level of plasma glucose in spring (April) is about 1.4 times of that in winter (November).In the experiment of temperature stress, the plasma glucose of Sebastes schlegeli is elevated gradually along with the increasing temperature, however after the temperature exceeds 20℃, the level of plasma glucose is decreased. ESR keeps increasing during the temperature stress experiment. During the experiment of exposed to air which based on the temperature experiment, because of the accessional anoxia and capture stress, the level of plasma glucose is increased dramatically, ESR is decreased slightly. The tendency of plasma glucose and ESR are similar to those of the temperature stress experiment. This study results are considered as the complicated effects among the temperature, anoxia and capture stress.In the chronic salinity experiment, salinity can take great effects of the growth of Sebastes schlegeli. Under slighter stress, Sebastes schlegeli grows faster and has higher body growth rate and the total growth rate. In addition, the proper salinity transition can mitigate the stimulation of the salinity stress on Sebastes schlegeli and improve the growth rate and the survival rate. In the acute salinity stress experiment, the level of plasma glucose is decreased, ESR keeps increasing and GOT activity is higher than the result obtained before the stress.Accompanying the changes of the salinity, the structure of chloride cell in the fish gill alters remarkably and the kidney shows good adaptability to the salinity changes. Under the high salinity stress, tubule system in the chloride cell in the fish gill is developed, the number of mitochondria is increased and cell clearance is enhanced. Glomerulus becomes atrophic; the figure of renal tubule becomes illegible; brush border appears abnormal turgor; the number of mitochondria is increased. When the low salinity stress increase, chloride cell in the fish gill has more RER and the space between membranous tubules is increased. At the same, the numbers of mitochondria and lysosome in epithelial cell are increased, the vacuolization of the mitochondria was observed as well..In the crowding stress experiment, Sebastes schlegeli in low density group has high body growth rate and total growth rate. The final body weight, specific growth rate (SGR) and growth efficiency (GE) are all decreased greatly with the increasing of cultu...