Objective
This study aimed to investigate the effects of CO2-induced seawater acidification on the biochemical composition and digestive enzyme activities of mantis shrimp (Oratosquilla oratoria).
Method
A 49-day aquaculture experiment was conducted. Three acidified treatment groups (pH 7.90, pH 7.70, pH 7.50) were established by introducing CO2 gas into seawater, using natural seawater (pH 8.10) serving as the control.
Result
(1) Under acidified conditions, the muscle moisture content of O. oratoria increased with decreasing pH levels. From day 21 onward, the moisture content in the pH 7.70 and pH 7.50 groups exhibited significantly higher than that in the control group (P < 0.05). Conversely, the contents of ash, crude protein, and crude lipid contents decreased with pH reduction. All acidified groups displayed significantly lower ash content than the control from day 7 onward (P < 0.05). The crude protein levels in respective acidified groups became significantly lower than those in the control starting on days 28 (pH 7.90 group), 14 (pH 7.70 group), and 7 (pH 7.50 group), respectively (P < 0.05). All acidified groups showed significantly reduced crude lipid content compared to the control from day 7 onward (P < 0.05). (2) Pepsin and trypsin activities showed an initial increase followed by a decrease, while lipase activity exhibited a gradual increasing trend. Although acidified groups exhibited marginally higher pepsin and trypsin activities than the control at day 7, these enzymes showed declining trends subsequently, with significant inhibition observed in pepsin by day 21 and trypsin by day 35, respectively (P < 0.05). Lipase activities in the acidified groups became significantly elevated compared to the control starting on day 28 (pH 7.90 group), day 7 (pH 7.70 group), and day 7 (pH 7.50 group), respectively (P < 0.05).
Conclusion
When seawater acidification reached pH levels of 7.50–7.30, it induced a stress response in the mantis shrimp (Oratosquilla oratoria). After 7–14 days of exposure, energy reserves such as crude fat and crude protein were mobilized to cope with the acidic conditions. Although the activities of digestive enzymes including pepsin, trypsin, and lipase were temporarily enhanced, this response failed to alleviate the stress caused by seawater acidification.
Zhang Z., Sun P., Wen J., Li X., Wang J., Xue J., Chang Y., Qin Y., Yin Z. & Chen L., 2026. Analysis of the effects of seawater acidification on the biochemical composition and digestive enzyme activities of Oratosquilla oratoria. Journal of Anhui Agricultural University 53(1): 48-54. Article.
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