Effects of nitrite on mortality, ion regulation and acid-base balance of Macrobrachium rosenbergii at different external chloride concentrations

The 96 h LC50 of nitrite-N to juvenile Macrobrachium rosenbergii was 8.49, 11.21, and 12.87 mg l(-1) at 15, 24 and 34 mg Cl- per liter of water, respectively. hi. rosenbergii which had been exposed individually to 0 (control), 2, 5, 10 mg nitrite-N per liter for 24 h at 15, 33, 50 mg Cl- per liter were analyzed for hemolymph oxyhemocyanin, protein, acid-base balance, osmolality and ion concentrations. At 15 mg Cl- per liter, hemolymph oxyhemocyanin, protein, hemolymph pH, HCO3-, TCO2, osmolality, Cl-, Na+, K+ and Mg2+ levels were negatively correlated with external nitrite-N. Hemolymph nitrite N and PO2 levels were directly related to nitrite-N, but inversely related to external Cl-. (C) 1997 Elsevier Science B.V.