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

Litopenaeus schmitti juveniles (total length 15 +/- 0.4cm) were exposed to different concentrations of nitrite using the static renewal method at different salinity levels (5 parts per thousand, 20 parts per thousand and 35 parts per thousand) at pH 8.0 and 20 degrees C. The 24, 48, 72 and 96h LC50 values of nitrite in L. schmitti juveniles were 40.72, 32.63, 24.63, and 19.12mgL(-1) at 5 parts per thousand; 53.52, 38.60, 27.76, 25.55mgL(-1) at 20 parts per thousand; 54.32, 47.87, 41.67 and 38.88mgL(-1) at 35 parts per thousand salinity. As the salinity decreased from 35 parts per thousand to 5 parts per thousand, susceptibility to nitrite increased by 33.4%, 46.7%, 69.2% and 103.3%, after 24, 48, 72 and 96h 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.