Taurine Supplementation Enhances the Resistance of Litopenaeus vannamei Postlarvae to Low-Salinity Stress

In aquaculture, Pacific white shrimp (Litopenaeus vannamei) growth in low-salinity waters is limited by osmoregulatory stress; therefore, improving resistance to low-salinity stress via nutritional modulation is key. In the present study, shrimp postlarvae were provided with a taurine supplement under low-salinity stress, and then the survival rate, the histology, the Na⁺/K⁺-ATPase (NKA) expression pattern and transcriptomic sequencing were investigated to evaluate the postlarval responses. The results showed that the postlarva survival rate in low-salinity water was only 61.11%, which is significantly lower than that for postlarvae reared in saline water (92.67%). However, taurine supplementation significantly increased the postlarva survival rate in low-salinity culture to 76.67% and also increased the shrimp body length. Moreover, immunofluorescence and enzyme activity assays indicated that taurine alleviated NKA overactivation in the shrimp postlarvae under low-salinity stress. Furthermore, a GO enrichment analysis of differentially expressed genes suggested that the overactivation of hormone and receptor signaling under low-salinity stress was significantly downregulated after taurine supplementation. On the other hand, taurine supplementation may promote epithelial cell proliferation in shrimp postlarvae by negatively regulating the Wnt signaling pathway. These findings suggest that taurine may enhance the shrimp postlarval osmoregulatory capacity, thereby improving their ability to acclimatize to low-salinity environments.