Comparative Metabolomic Analysis Reveals the Impact of the Photoperiod on the Hepatopancreas of Chinese Grass Shrimp (Palaemonetes sinensis)

The photoperiod is a key environmental factor that in crustaceans influences development, feeding, and metabolism. In this study, liquid chromatography-tandem mass spectrometry was used to examine metabolic changes in Palaemonetes sinensis under different photoperiods. Our results showed that key metabolic pathways, such as linoleic acid metabolism, axon regeneration, pyrimidine metabolism, and cortisol synthesis, were significantly altered under both constant light (24L:0D) and constant darkness (0L:24D) compared with natural light conditions. The photoperiod notably affected the digestive and metabolic functions of P. sinensis. Most metabolic pathways were downregulated under full darkness and full light conditions, suggesting that inhibition of metabolism is a potential adaptive response. Furthermore, enzyme assays revealed significant variations in trypsin, lipase, and amylase activity across different photoperiods, highlighting the profound impact of light conditions on digestive functions. These findings suggest that extreme light conditions may negatively impact the metabolic and digestive functions of P. sinensis. This study provides new insights into the adaptive mechanisms of P. sinensis in response to photoperiod changes and offers valuable information for optimizing aquaculture practices to enhance the health and growth performance of this crustacean.