Response of antioxidation and immunity to combined influences of ammonia and temperature in red swamp crayfish (Procambarus clarkii)

As important environmental factors, ammonia and temperature have important effects on aquatic crustaceans. The combined effects of ammonia and temperature on the anti-oxidation and immunity of Procambarus clarkii were examined using the factorial experimental design in this study. A total of 9 ammonia-temperature combinations (3 replicates for each combination) were set up with each factor having 3 regimes. The results showed that most indicators varied quadratically with ammonia concentration and temperature in the ranges of the two factors. The interaction between ammonia and temperature was significant on most indicators, demonstrating that ammonia and temperature affected the anti-oxidation and immunity of P. clarkii in a combined manner. Ammonia accumulation and oxidative stress occurred more likely under the combined influences of ammonia and temperature. The enzymatic activities and gene expressions that are closely related to the antioxidation and immunity were easier to be activated or inhibited due to presence of the interaction between ammonia and temperature. This study provides new insights into the mechanism for adaption of P. clarkii to the combined impacts of ammonia and temperature. The results contribute to increased immunity and resistance of this commercially important species against diseases through improvement of multiple culture conditions.