The cultivation of Pacific white shrimp (Litopenaeus vannamei) in low-salinity or freshwater systems is a growing trend in global aquaculture. However, this practice presents a considerable challenge: osmoregulatory stress. As marine organisms, shrimp must expend a significant amount of energy to maintain their internal ionic balance in a low-salt environment, often resulting in lower survival rates and reduced performance.
In response to this problem, nutritional modulation emerges as a key tool. A recent study, published in the journal Biology by researchers from Huazhong Agricultural University and the Guangxi Academy of Fishery Sciences, investigated the role of a functional amino acid, taurine, as a dietary supplement to enhance the resilience of L. vannamei postlarvae to low-salinity stress. The results are promising and offer a new perspective for optimizing cultivation under these conditions.
Key findings
- Taurine supplementation significantly increased the survival rate of shrimp postlarvae in low-salinity water, raising it from 61.11% to 76.67%.
- Postlarvae that received taurine exhibited greater body length compared to the control and non-supplemented low-salinity groups.
- Taurine helped balance the shrimp’s ionic system, alleviating the over-activation of the key enzyme Na+/K+-ATPase (NKA), which is induced by low salinity.
- At a microscopic level, taurine reversed the structural damage caused by osmotic stress, resulting in more compact muscle fibers and better-defined organs.
- Transcriptomic analysis demonstrated that taurine mitigates the overactivation of stress-induced hormonal signaling pathways and promotes epithelial cell proliferation, suggesting a protective and reparative effect.
The challenge of low salinity for shrimp
Litopenaeus vannamei is known for its ability to adapt to a wide range of salinities (euryhaline). However, a rapid transition or cultivation in very low-salt (hyposaline) water forces the shrimp to activate complex physiological mechanisms to prevent salt loss and water gain. This process, known as osmoregulation, is energetically costly and can compromise other vital functions such as growth and immunity. The study showed that cultivation in low salinity (4‰) drastically reduced postlarval survival to just 61.11%, compared to 92.67% observed in saline water (18‰).
How the study was conducted
To evaluate the effect of taurine, researchers designed an experiment with three groups of shrimp postlarvae:
- Control Group (C): Reared in saline water (18‰) with a standard commercial diet.
- Low-Salinity Group (L): Reared in water where salinity was gradually reduced from 18‰ to 4‰, fed the standard diet.
- Taurine Group (T): Subjected to the same low-salinity conditions as group L, but their diet was supplemented with taurine (0.3% of the feed’s dry weight).
After one week, survival and body length were measured, tissues were analyzed (histology), the activity of a key osmoregulatory enzyme was assessed, and a transcriptomic analysis was performed to observe the response at the genetic level.
The protective impact of taurine
Increased survival and growth
The most direct and significant result was the increase in survival. The postlarvae in group T, which received taurine, achieved a survival rate of 76.67%, a substantial improvement over the 61.11% of group L, which did not receive the supplement. Furthermore, taurine promoted growth, as the postlarvae in this group were significantly longer than those in the other two groups.
Tissue-level protection
Low-salinity stress left visible marks at the microscopic level. Histological analyses of group L showed an expansion of spaces between muscles and blurred boundaries between internal organs, indicative of cellular damage from osmotic imbalance. In contrast, taurine supplementation had a clear restorative effect: muscle fibers regained their compactness, and organ boundaries became much more defined, similar to those of the control group.
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The osmoregulatory factor: Taurine as a stabilizer
To maintain their saline balance, shrimp rely on a molecular “pump” called Na+/K+-ATPase (NKA). This enzyme actively transports sodium and potassium ions across cell membranes, a vital process in osmoregulation.
The study revealed that under low-salinity conditions (group L), both the expression of the NKA protein and its enzymatic activity increased significantly. This “over-activation” is an emergency response by the shrimp to combat salt loss, but it consumes a great deal of energy.
This is where taurine made a difference. In group T, the NKA enzyme activity showed no significant difference from the control group in saline water. This suggests that taurine acts as an osmolyte—a molecule that helps maintain water and saline balance within cells—reducing the need for the shrimp to overload its ion-pumping system.
A deeper look: What the genes reveal
The transcriptomic analysis, which studies which genes are “turned on” or “turned off,” offered a detailed view of the molecular mechanisms.
- Calming the Stress Response: In group L, hyposaline stress activated genes related to hormonal activity and receptor signaling—a general alarm response in the organism. Notably, in group T, taurine decreased the expression of these same genes, indicating that the supplement helps mitigate the perception of stress at a molecular level.
- Promoting Tissue Repair: Low salinity inhibited genes associated with the proliferation of epithelial cells (those lining tissues like the gills and intestine) through the Wnt signaling pathway. Taurine, conversely, downregulated this pathway, promoting cell proliferation. This is crucial, as it suggests that taurine not only protects but also actively contributes to the repair of epithelia that are fundamental for osmoregulation.
Conclusion and implications for aquaculture
This study conclusively demonstrates that dietary taurine supplementation is an effective strategy for improving the resilience and performance of Litopenaeus vannamei postlarvae in low-salinity cultivation. By acting as an osmolyte, taurine alleviates the energetic burden on the osmoregulatory system, protects tissues from cellular damage, and modulates gene expression to reduce stress and encourage repair.
For producers operating in freshwater systems or areas with salinity fluctuations, incorporating taurine into postlarval diets could translate into higher survival rates, better growth, and ultimately, greater profitability.
Reference (open access)
Wang, H., Du, X., Zou, J., Wang, M., Lei, Y., Zhang, B., Zhao, Y., Jiang, L., Chen, X., & Wang, Q. (2025). Taurine Supplementation Enhances the Resistance of Litopenaeus vannamei Postlarvae to Low-Salinity Stress. Biology, 14(8), 1082. https://doi.org/10.3390/biology14081082
Editor at the digital magazine AquaHoy. He holds a degree in Aquaculture Biology from the National University of Santa (UNS) and a Master’s degree in Science and Innovation Management from the Polytechnic University of Valencia, with postgraduate diplomas in Business Innovation and Innovation Management. He possesses extensive experience in the aquaculture and fisheries sector, having led the Fisheries Innovation Unit of the National Program for Innovation in Fisheries and Aquaculture (PNIPA). He has served as a senior consultant in technology watch, an innovation project formulator and advisor, and a lecturer at UNS. He is a member of the Peruvian College of Biologists and was recognized by the World Aquaculture Society (WAS) in 2016 for his contribution to aquaculture.
