Physiology and Molecular Response Mechanisms in the Gills of Macrobrachium rosenbergii Under Acute NaHCO3 Alkaline Stress

As an important freshwater economic shrimp, <i>Macrobrachium rosenbergii</i> (<i>M. rosenbergii</i>) possesses a certain tolerance to saline/alkaline conditions. Analyzing the damage mechanism and stress response of <i>M. rosenbergii</i> in saline/alkaline environments will provide a scientific basis for promoting ecological restoration through the utilization of saline/alkaline water resources for aquaculture. In the first experiment, the 96 h median lethal concentration (LC₅₀) of NaHCO₃ was determined for juvenile <i>M. rosenbergii</i>. A second experiment then exposed the shrimp to a control group and an alkaline water group set at 60% of the established LC₅₀. After 96 h of exposure, gill tissue samples were collected from both groups for analysis. The aim was to clarify both the damage mechanisms induced by NaHCO₃ and the response mechanisms. The current results indicated that acute NaHCO₃ exposure reduced antioxidant enzyme activity and induced gill tissue damage in <i>M. rosenbergii</i>. In response to the stress caused by NaHCO₃, <i>M. rosenbergii</i> activated immune-related enzymes as well as immune-related differentially expressed genes involved in endocytosis, autophagy, and the toll-like receptor signaling pathway. In summary, the current research provided reference information for understanding the adverse effects caused by saline/alkaline water stress and for the breeding of <i>M. rosenbergii</i> in saline/alkaline water environments.