Short-term air exposure triggers redox metabolic shifts in the reef-building coral Pavona cactus

Coral reefs are ecosystems that provide essential services, including coastal protection, fisheries, and biotechnological resources. Nearshore coral species are often exposed to environmental stressors such as aerial exposure during low tides, leading to functional hypoxia. While many invertebrates under aerial exposure have been extensively studied for their redox responses, cnidarians remain poorly understood in this context. This study investigates the metabolic and redox responses of the coral Pavona cactus during short-term aerial exposure (30 min) and subsequent re-immersion (+30 min). We observed a significant 4.2-fold reduction in metabolic rate during aerial exposure, followed by a 3.4-fold recovery upon re-immersion, indicating a state of functional hypoxia and reoxygenation. Catalase activity increased by 18% during aerial exposure and remained elevated during re-immersion, suggesting the preparation for oxidative stress (POS) strategy. Lipid peroxidation levels (TBARS) increased by 37% during aerial exposure but normalized upon re-immersion, while DNA damage was significantly elevated during re-immersion, indicating oxidative stress during the reoxygenation phase. Protein oxidation remained unchanged throughout the experiment. These findings demonstrate that P. cactus responds rapidly to aerial exposure with increased antioxidant capacity, exhibiting metabolic suppression and oxidative stress despite the brief emersion. The pronounced shifts in oxygen consumption and oxidative damage highlight its sensitivity to environmental fluctuations, and the activation of the POS strategy demonstrates how rapidly this species responds to acute stress conditions.