Toxicity of Ammonia and Its Effects on Oxidative Stress Mechanisms of Juvenile Crucian Carp (Carassius auratus)

The rapid increase in concentration of ammonia in lake water during the degradation of algal blooms may cause acute toxicity to aquatic organisms. The purpose of this study was to assess the acute toxicity of ammonia and its effects on oxidative stress mechanisms of juvenile crucian carp (Carassius auratus), a model organism for investigating antioxidant responses to different kinds of stress. The lethal concentrations of ammonia to 50% of juvenile crucian carp decreased significantly with time and fit a hyperbolic decay model. Ammonia also induced antioxidant defenses of juvenile crucian carp. Catalase (CAT), superoxide dismutase (SOD), and glutathione (GSH) in the livers of the fish fluctuated with time and ammonia concentration and had similar trends. There was a statistically significant interaction between time and ammonia concentration on activities of CAT and SOD.