OXYGEN-CONSUMPTION AND AMMONIA-N EXCRETION OF PENAEUS-JAPONICUS ADOLESCENTS EXPOSED TO AMBIENT AMMONIA

1. Oxygen consumption and ammonia-N excretion Of Penaeus japonicus adolescents (4.0487 +/- 0.420 g) increased with increased ambient ammonia-N in the range of 0.031-5.006 mg/l, however, ammonia-N excretion decreased as they were exposed to 10,085 mg/l ammonia-N in 30 ppt at 26-degrees-C. 2. Oxygen consumption as a function of ambient ammonia-N was expressed as Log OC = Log a + b Log C, where OC is oxygen consumption (O2 mg/g/hr) and C is ambient ammonia-N (mg/l). 3. Oxygen consumption of the shrimp exposed to control (0.031 mg/l) and 5.006 mg/l ammonia-N was 0.276. and 0.364 O2 mg/g/hr, respectively. 4. Ammonia-N excretion of the shrimp exposed to 0.031, 5.006 and 10.085 mg/l ammonia-N was 0.022, 0.160 and 0.055 mg/g/hr, respectively. 5. Ammonia-N excretion was inhibited as the shrimp was exposed to 10.085 mg/l ammonia-N after 1 hr. 6. A reversal of normal Na+/NH4+ exchange may occur following exposure to ambient ammonia-N higher than 10 mg/l.