Supplementation of dietary astaxanthin alleviated oxidative damage induced by chronic high pH stress, and enhanced carapace astaxanthin concentration of Chinese mitten crab Eriocheir sinensis

Abstract The Chinese mitten crab Eriocheir sinensis is subjected to high pH stress and a shortage of astaxanthin (AX) via the natural food chain when individuals are reared in ponds. The aim of this study was to investigate the response of Chinese mitten crab to chronic high pH stress, focusing on the antioxidant capacity and oxidative damage response of the crab; the potential improvement in color due to AX supplementation in the diet was also explored. Twelve tanks (400 L) were used to store 30 crabs (56.5 ± 2.3 g) each. The pH of the water in 6 of the tanks was modulated to 9.5–10.0 (high pH), and another 6 tanks had a pH range of 7.5–8.1 (normal pH). Diets with or without 68 mg/kg of astaxanthin were fed to crabs, with 3 tanks for each diet at each pH level. After 4 weeks, reactive oxygen species (ROS) produced in hemolymph cells, activity of total superoxide dismutase (T-SOD), total antioxidant capacity (T-AOC), activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the serum, apoptotic ratio of hemolymph cells, hepatopancreas histology, hepatosomatic indices (HSI) and carapace AX concentration were analyzed. The results showed that when crabs were fed a diet without AX, high pH stress induced an increase ( P P P