Transcriptomic and lipidomic analysis provide insights into ovarian development of the mud crab Scylla paramamosain under high-temperature and strong illumination conditions.

Environmental factors such as temperature, salinity, illumination intensity, and photoperiod exert profound influences on the physiology and reproduction of aquatic crustaceans. In this study, female mud crabs (Scylla paramamosain) were exposed to combined high-temperature and strong illumination stress (30 °C, 6000 lx) or maintained under control conditions (25 °C, 600 lx) for 30 days. To elucidate the impact of combined high-temperature and strong illumination stress on ovarian development, we conducted integrated analyses of transcriptomic data (RNA-Seq) from the hepatopancreas and ovary, alongside lipidomic profiles of the hepatopancreas and hemolymph. The hepatopancreas exhibited downregulation of lipid synthesis genes (e.g., Fasn, SCD5) and upregulation of lipid catabolism genes (e.g., BBOX1, Pnlip), which was associated with reduced lipid storage. Enrichment of sphingolipid signaling and autophagy pathways in hemolymph, along with elevated phosphatidylethanolamine species, indicated activation of protective mechanisms to maintain systemic balance. The ovary contained 1,457 differentially expressed genes, including upregulated stress-related genes (e.g., Lrp1b, Tcab1) and downregulated reproduction-related genes (e.g., Igf1r, LENG9), reflecting a trade-off between reproductive suppression and stress adaptation. In conclusion, these findings provide new insights into the adaptation of the mud crab to dual environmental stressors through coordinated molecular adjustments, offering valuable information for aquaculture management in response to sudden weather changes.