Nitrite toxicity toLitopenaeus schmitti(Burkenroad, 1936, Crustacea) at different salinity levels

Litopenaeus schmitti juveniles (total length 15 ± 0.4 cm) were exposed to different concentrations of nitrite using the static renewal method at different salinity levels (5‰, 20‰ and 35‰) at pH 8.0 and 20 °C. The 24, 48, 72 and 96 h LC50 values of nitrite in L. schmitti juveniles were 40.72, 32.63, 24.63, and 19.12 mg L−1 at 5‰; 53.52, 38.60, 27.76, 25.55 mg L−1 at 20‰; 54.32, 47.87, 41.67 and 38.88 mg L−1 at 35‰ salinity. As the salinity decreased from 35‰ to 5‰, susceptibility to nitrite increased by 33.4%, 46.7%, 69.2% and 103.3%, after 24, 48, 72 and 96 h of exposure respectively. Furthermore, we found that exposure of shrimp to nitrite caused an increase in oxygen consumption by 137.3%, 99.2% and 81.4% and an increase in the ammonia excretion level by 112.5%, 87% and 64.3% with respect to the control with decreasing salinity levels.