Abstract: The rates of respiration of immature Fugu obscurus were measured in freshwater under conditions of different water temperature and DO.The results show that the variations of water temperature and DO can both cause the relative changes of respiratory rate.The water temperature become a major factor affecting the rates of respiration when DO saturation≥65%,and water temperature ranges between 10～32℃.The higher the temperature,the faster breathing is.The rates of respiration change from 47times·min^-1to 177times·min^-1with temperature rising from 10℃ to 32℃.The variations of the respiratory rates are also corresponding to the changes of water DO.The rate of respiration change from 120times·min^-1to 177timese·min^-1at water temperature 22℃,and from 125·min^-1to 180·min^-1at 24℃ respectively. When the amount of water DO declines from 8～2.1mg·min^-1L^-1.Inaddition,the movement of immature Fugu obscurus appear obviously weak,slowly moving,or motionlessly staying at the bottom of aquarium.Then a pre-suffocative reaction occurs when the DO decreases continuously to less than 2.1mg·L^-1at the temperature 22℃ and 24℃.

Key words: Cunninghamia lanceolata, cut-over land, soil dissolved organic carbon and nitrogen, soil microbial biomass, tree species.