Hemolymph oxygen content, oxyhemocyanin, protein levels and ammonia excretion in the shrimp Penaeus monodon exposed to ambient nitrite

Abstract

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 oxygen and carbon dioxide, bicarbonate concentration, oxyhemocyanin and protein levels, and whole animal ammonia-N excretion and nitrite-N uptake were determined. Ammonia-N excretion and hemolymph oxygen partial pressure increased, whereas hemolymph pH, HCO3-, oxyhemocyanin, protein and the ratio of oxyhemocyanin/protein levels decreased with increasing ambient nitrite-N. It is suggested that accumulated nitrite of P. monodon following exposure to ambient nitrite causes reduction of oxyhemocyanin, protein and the ratio of oxyhemocyanin/ protein in the hemolymph, and affects nitrogen metabolism and acid-base balance at low hemolymph pH.