Effects of sulfate content and salinity on growth, oxygen consumption, Na+/K+-ATPase activity, and hepatopancreas histopathology of Pacific white shrimp Litopenaeus vannamei

Inland culture of shrimp integrated with irrigation could be one of the most feasible livelihood options for many households nearby saline land. Compared with seawater and most of reported brackish water used for shrimp culture, the sulfate content was higher in both surface and ground water in the central Asia. We evaluated the effects of salinity, the SO42-/Cl- ratio and their interaction on the growth, oxygen consumption, Na+/K+-ATPase activity, total antioxidant capacity (T-AOC), and hepatopancreas histology of Litopenaeus vannamei reared in artificial seawater. The experiment lasted for 30 d, two salinity levels (20 and 10) and four SO42-/Cl- ratios (0.14, 0.577, 1.127, and 2.225 mg/mg) of waters were set. Results show no significant differences in survival among groups. Salinity and its interaction effects with SO42-/Cl- ratio did not significantly affect the final body weight, weight gain, and specific growth rate of shrimps, whereas the SO42-/Cl- ratio did (P<0.05). Shrimp mean weight gain and specific growth rate at water SO42-/Cl- ratio of 2.225 were significantly lower than at ratio of 0.14. At salinity 20, the shrimp final body weight at water SO42-/Cl- ratio of 2.225 was significantly lower than at other ratios (P<0.05), whereas there was no significant difference in final body weight among treatments at salinity 10 (P>0.05). Oxygen consumption, Na+/K+-ATPase activity, and T-AOC increased with increasing SO42-/Cl- ratio at both salinities. L. vannamei exposed to water SO42-/Cl- ratio of 2.225 at salinity 20 showed severe histopathological changes. This study indicated that L. vannamei has strong tolerance to sulfate in brackish water environment. The shrimp is more adaptable to SO42-/Cl- ratios below 2.225 at lower salinity, and the optimal SO42-/Cl- range for the growth is 0.14-0.577 (mg/mg) regardless of salinity level.