Thermal Stress During Embryogenesis Alters the Metabolome of Zebrafish Larvae

Global warming has led to continuous increases in marine surface temperatures, posing significant challenges to aquatic ecosystems and the aquaculture industry. Thermal stress during early development can profoundly alter physiological, morphological, and metabolic process in fish, with potential long-term consequences for growth, behavior, and survival. In this study, we investigated the effects of elevated temperature during zebrafish embryogenesis on developmental timing, morphological phenotypes, larval behavior, and metabolic regulation. Embryos were exposed to control and thermal stress conditions, and subsequent phenotypic and biochemical analyses were conducted from hatching through the larval stage. Thermal stress accelerated hatching to within 48 hpf, but this was accompanied by morphological abnormalities. At the late larval stage, larvae exposed to thermal stress exhibited significantly increased swimming velocity and distance with altered spatial occupancy patterns. Untargeted metabolomic profiling via UPLC-QTOF-MS elucidated alterations in purine metabolism, amino acid turnover, nucleotide metabolism, and phospholipid composition. Notably, phosphatidylethanolamines and phosphatidylserines were significantly depleted and phosphatidylinositols was elevated, implicating disruptions in pathways involved in membrane integrity, autophagy regulation, and ferroptosis. These findings demonstrate that thermal stress during embryogenesis elicits coordinated physiological, behavioral, and molecular responses in zebrafish, providing mechanistic insights into the vulnerability of aquatic organisms to climate change-driven temperature fluctuations.