Thermal stress-induced metabolic reprogramming in two hard coral species

Coral reefs are increasingly impacted by marine heatwaves that disrupt the symbiosis between corals and their symbiotic dinoflagellates. Using untargeted LC-MS metabolomics, we investigated heat-stress responses at the coral holobiont level in Stylophora pistillata (S. pistillata) and Pocillopora damicornis (P. damicornis) from the northern Red Sea. Under control conditions (25 degrees C), the two species exhibited distinct baseline metabolic profiles, indicating different energy-metabolism strategies. After 10 days at 31 degrees C, both the corals showed pronounced metabolic reprogramming but with contrasting responses, P. damicornis increased amino acid metabolism, redox buffering, and ammonia recycling, consistent with enhanced cellular defense. In contrast, S. pistillata reduced central carbon metabolism and shifted toward alternative energy pathways and lipid remodeling. These findings show that closely related corals can adopt divergent holobiont-level metabolic strategies under thermal stress, highlighting metabolic plasticity as an important component of coral responses to ocean warming.