Oxygen uptake and ammonia-N excretion of juvenile Penaeus japonicus during depuration following one-day exposure to different concentrations of saponin at different salinity levels

Abstract

Oxygen uptake (O-2, mg g(-1) h(-1)) and ammonia-N excretion (ANE, mu g g(-1) h(-1)) of Penaeus japonicus juveniles (0.28 +/- 0.04 g), which had been exposed individually to control (0), 1, 5, 10 and 20 mg l(-1) saponin for one day at seawater of 18, 26 and 34 practical salinity units (psu), were measured after depuration for 6 h in clean seawater at each salinity level. Both oxygen uptake and ammonia-N excretion of shrimps increased with decreasing salinity, and increased directly with previous saponin concentration. P. japonicus, which had been previously exposed to saponin as high as 20 mg l(-1) for 24 h, was considered to increase its respiration rate and metabolism during 6 h depuration process. (C) 1997 Elsevier Science B.V.