HEMOLYMPH PCO2, HEMOCYANIN, PROTEIN-LEVELS AND UREA EXCRETIONS OF PENAEUS-MONODON EXPOSED TO AMBIENT AMMONIA

Subadult Penaeus monodon (21.985 +/- 3.546 g) were exposed individually in 30 ppt seawater to 0.060 (control), 0.994, 4.631, 9.593 and 20.728 mg/l ammonia-N for 24 h. Hemolymph pH, PO2, PCO2, hemocyanin and protein levels, and whole animal ammonia-N, urea-N and nitrite-N excretions were determined. Urea-N excretion and nitrite-N excretion increased, whereas ammonia-N excretion and hemolymph PCO2 level decreased with increased ambient ammonia-N. P. monodon exposed to ambient ammonia-N greater than 4.631 mg/l, net ammonia-N uptake occurred, and caused significant reduction of hemocyanin and hemolymph protein and their ratio. In addition, there was a shift from ammonotelic to ureotelic excretory pattern of shrimps following exposure to ambient ammonia-N greater than 4.631 mg/l.