CHANGES OF OXYHEMOCYANIN AND PROTEIN-LEVELS IN THE HEMOLYMPH OF PENAEUS-JAPONICUS EXPOSED TO AMBIENT NITRITE

The concentrations of oxyhemocyanin, protein and urea in the hemolymph, and ammonia-N excretion of Penaeus japonicus (15.08 +/- 1.56 g) were examined, after the shrimp had been exposed individually in 30 ppt to 0.01 (control), 5.12, 10.46, 20.57 and 50.86 mg/l nitrite-N at 25 degrees C for 24 h. Accumulation of nitrite-N and urea-N in the hemolymph, and ammonia-N excretion of shrimp increased with increased ambient nitrite-N over the entire range. Nitrite-N uptake occurred, and increased with increased ambient nitrite-N in the range of 5.12-50.86 mg/l. Exposure of P. japonicus to elevated nitrite-N-affected nitrogen metabolism, and decreased the oxyhemocyanin and the ratio of oxyhemocyanin/protein. It is suggested that nitrite incorporated into the hemolymph of penaeids may decrease the oxygenation state of the hemolymph, and decrease the fraction of oxyhemocyanin.