HEMOLYMPH OXYGEN-CONTENT, OXYHEMOCYANIN, PROTEIN-LEVELS AND AMMONIA EXCRETION IN THE SHRIMP PENAEUS-MONODON EXPOSED TO AMBIENT NITRITE

Subadult Penaeus monodon (21.03+/-3.19 g) were exposed individually in sea water (30 mg.ml(-1)) to 0.02 (control), 1.04, 5.02, 10.11 and 20. 06 mg.l(-1) nitrite-N for 24 h. Hemolymph pH, partial pressures of oxy gen and carbon dioxide, bicarbonate concentration, oxyhemocyanin and p rotein levels, and whole animal ammonia-N excretion and nitrite-N upta ke were determined. Ammonia-N excretion and hemolymph oxygen partial p ressure increased, whereas hemolymph pH, HCO3-, oxyhemocyanin, protein and the ratio of oxyhemocyanin/protein levels decreased with increasi ng ambient nitrite-N. It is suggested that accumulated nitrite of P. m onodon following exposure to ambient nitrite causes reduction of oxyhe mocyanin, protein and the ratio of oxyhemocyanin/ protein in the hemol ymph, and affects nitrogen metabolism and acid-base balance at low hem olymph pH.