The effect of acute ammonia exposure on selected immunological parameters of Daphnia similoides (Cladocera)

Cladocerans have been widely used as bioassay organisms to evaluate the impact of toxic substances. In this study, the activities of selected immunological enzymes and MDA level were investigated to characterize Daphnia similoides' immune response to ammonia stress. The activity of ACP and CAT showed no significant change during the test. The activity of AKP was significantly increased in the 0.19 and 0.38 mg/l NH3-N exposure groups after 6 h. After 24 h, a significant depression occurred in the high concentrations. After 24 h, significant decreases in SOD activity were observed at the concentrations of 0.38, 0.57 and 0.76 mg/l NH3-N. After 24 h, a significant change in MDA was also observed in 0.57 and 0.76 mg/l. These results suggest that changes in whole-body immune parameters of Daphnia similoides are effective to predict sub-lethal ammonia toxicity and useful as an early warning tool in monitoring studies of natural environments.