Abstract:To determine the influence of temperature and ammonia on the oxygen consumption rate and ammonia excretion rate of the red claw crayfish (Cherax quadricarinatus), a single factor experimental design and closed flow method were used to analyze the influence of temperature and ammonia concentration on the oxygen consumption and ammonia excretion rates of crayfish of three sizes (S, M, and L representing small, medium, and large crayfish, respectively). The results were as follows. Temperature had significant effects on the oxygen consumption and ammonia excretion rates of crayfish. The oxygen consumption rate increased with the increase in temperature (15℃~35℃), and at 35℃, the oxygen consumption rate reached the maximum, wherein the rate of the S group was 0.777 mg/(g·h), significantly higher than that of the other two size classes. The ammonia excretion rate of the crayfish increased first and then decreased with increasing temperature, and reached a maximum at 30℃; among the size classes, the ammonia excretion rate of the S group was 0.061 mg/(g·h) and was significantly higher than the other two sizes. Temperature had a significant effect on the oxygen/nitrogen ratio of the crayfish. 2 The level of ammonia significantly affected the oxygen consumption and ammonia excretion rates of the crayfish. The oxygen consumption and ammonia excretion rates increased with an increase in the ammonia concentration, and then decreased. The oxygen consumption rate reached a maximum at an ammonia concentration of 8 mg/L, which was 0.663, 0.332, and 0.195 mg/(g·h) in the S, M, and L groups, respectively, whereas the ammonia excretion rate reached a maximum at an ammonia concentration of 12 mg/L, which was 0.123, 0.049, and 0.034 mg/(g·h) in the S, M, and L groups, respectively, and was significantly higher than those of the other groups. Furthermore, the ammonia concentration had a significant effect on the oxygen/nitrogen ratio of the crayfish. The Q10 values for the oxygen consumption and ammonia excretion rates ranged from 1.102~3.361 and 0.346~3.417, and at the minimum values were at 25℃~30℃ and 30℃~35℃, respectively.
