Survival pressure and tolerance of juvenile greater amberjack (Seriola dumerili) under acute hypo- and hyper-salinity stress

Salinity is an important abiotic factor in aquaculture because of its significance in the multiple physiological progress of marine fish. The liver is the main organ involved in energy metabolism, supplying energy to other body tissues and organs. Greater amberjack (Seriola dumerili) is characterized by fast growth and is an important aquatic export product in China. In this study, the greater amberjack was cultured in varying salinity levels, i.e., from 5 to 40 ppt, for 72 h. Notably, all fish under 5 ppt salinity died within 24 h because of limited tolerance ability. A comparative transcriptome analysis was performed to explore the molecular response mechanism of the liver, a non-osmoregulatory organ, when fish was subjected to hypo- (10 ppt) and hyper-salinity (40 ppt) stress. A total of 100 and 5 DEGs were identified under hypo- (10 ppt) and hyper-salinity (40 ppt) stress, respectively. The DEGs were involved in lipid metabolism, glycine, serine, and threonine metabolism, and in various signaling pathways, including Calcium, PPAR and adipocytokine, and adrenergic signaling in cardiomyocytes. The mRNA expression levels of acsl5, lipin1, and apoeb in the liver were down-regulated under 10 ppt salinity, suggesting an elevation of fatty acids oxidation and energy requirement in response to the hypo-salinity stress. Similarly, there was a decrease in the expression levels of atp1b1b and cftr, responsible for the reduced Na+, K+ movement and Cl- ion secretion, under hypo-salinity stress. This study provides important basic data for the optimal artificial breeding of greater amberjack, and reveals the osmotic regulation mechanism of the liver in response to salinity stress. •Greater amberjack was more sensitive to the hypo-salinity than hyper-salinity.•Greater amberjack died within 24 h under less than 6 ppt salinity stress, because of limited tolerance ability.•A total of 100 and 5 DEGs were identified under hypo- (10) and hyper-salinity (40 ppt) stress, respectively.•An elevation of fatty acids oxidation and energy requirement, and reduce of ion movement and secretion in hypo-salinity group.