Physiological effects of ocean acidification and nano-silver on juvenile jellyfish Rhopilema esculenta

Ocean acidification and nanometals pose a threat to marine animals,but the effects of ocean acidification and nanometal stress on jellyfish have not been reported. This study took the large edible jellyfish Rhopilema esculenta from the coastal China as the research object,and the physiological effects of acidification and AgNPs stress on the juvenile jellyfish were studied. The juvenile jellyfishes were exposed to two levels of pH(8.10 and 7.60)and three concentrations of AgNPs(0,20,and 200 mug /L)for 14 days,and their growth,swimming behavior and physiological indicators were measured. The results indicated that seawater acidification could significantly enhance the activities of catalase(CAT)and ion transport enzymes(Ca~(2+)-ATPase and Na~+K~+-ATPase),thereby alleviating the oxidative stress caused by AgNPs on juvenile jellyfish. AgNPs inhibited the activities of acid phosphate phosphatase(ACP),alkaline phosphatase(AKP)and superoxide dismutase(SOD)of juvenile jellyfish and affected energy metabolism,resulting in slow growth rate and redusced pulsation rate. With the increase of AgNPs exposure concentration,acidification led to higher levels of lipid peroxidation and a significant increase inmalondialdehyde(MDA)in jellyfish. This study identified the different physiological responses of juvenile jellyfish to the acidification and AgNPs and provided a reference for evaluating changes in Rhopilema esculenta populations under changing marine environments