Environmental enrichment improves survival and growth of Portunus trituberculatus in recirculating aquaculture system by reducing energy expenditure and stress responses

Abstract

Barren rearing environment of recirculating aquaculture system (RAS) is a stressful situation that may result in high mortality rate of the swimming crab Portunus trituberculatus, an important economic seawater crab species in China. Environmental enrichment can mitigate stress to animals held in captivity. However, the physiological responses as well as survival and growth phenotype of the swimming crabs in the enriched RAS are currently unknown. Here, we examined the changes in the survival and growth performance as well as metabolic and immune features after 28 day-environmental enrichment using sand and polyvinylchloride (PVC) tube in RAS. We observed that sand enrichment improved survival and growth performance accompanied by reduced stress to crabs. The reduced stress subsequently attenuated the glucolipid metabolism and enhanced the accumulation of glycogen and triglyceride. This in turn mitigated oxidative stress and knock-on positive effects on immunity and apoptosis of the swimming crabs. PVC tube induced the similar but less significant effects on the swimming crabs to/than sand. Overall, environmental enrichment using sand and PVC tube improved survival and growth performance of the swimming crabs by reducing stress of RAS, glucolipid metabolism, oxidative damage and apoptosis, as well as enhancing accumulation of energy substances and immunity. The application of environmental enrichment techniques in RAS is urgently required to improve the yield of the swimming crabs.