Protective effect of dietary Aronia melanocarpa extract against ammonia stress in juvenile Eriocheir sinensis

Abstract

Ammonia is a major toxic pollutant that can affect the survival and performance of aquatic animals. Here, we examined the protective effect of Aronia melanocarpa extract (AME) against ammonia stress in juvenile Eriocheir sinensis. In Experiment 1, individuals of E. sinensis were exposed to 20.93 mg/L of total ammonia-N (or 0.4 mg/L NH3) and fed diets supplemented with AME at 0 %, 1 %, 3 %, and 5 % (CK1, AME1, AME3, and AME5, respectively) for four weeks to evaluate the protective effect of AME against ammonia stress. In Experiment 2, E. sinensis were fed diets supplemented with AME at 0 % and 3 % for four weeks after acute ammonia exposure (0.4 mg/L NH3, 72 h) to examine its effects on damage repair and E. sinensis growth after acute ammonia stress. During the experiments, the water temperature was maintained at 22 ± 0.5 ℃ and pH at 7.63 ± 0.44. AME supplementation increased the survival rate of E. sinensis under ammonia stress in a concentration-dependent manner. The AME3 group had the highest molting rate (MR) and weight gain rate. Compared with those in the CK1 group, the crude protein and lipid contents in the muscle tissue and superoxide dismutase, catalase, and peroxidase activities in the hepatopancreas of E. sinensis in the AME3 and AME5 groups significantly increased (p < 0.05), and the malondialdehyde (MDA) content in the hepatopancreas of E. sinensis in the AME3 and AME5 groups significantly decreased (p < 0.05). The AME3 group also had the highest antioxidant enzyme activities and lowest MDA content. Similar results were obtained in Experiment 2. Overall, these results indicated that AME supplementation at 3 % had the best effect on alleviating oxidative damage, improving MR, and promoting nutrient accumulation in E. sinensis during and after ammonia stress.