International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.6, 260-266 http://ecoevopublisher.com/index.php/ijmec 261 This study will introduce the mechanism of heat stress and coral resilience, explore the impact mechanism of heat stress on corals, analyze the bleaching patterns and influencing factors, and expound the resilience mechanism of corals. Meanwhile, discuss the evolution and ecological mechanisms of coral adaptation to heat stress; In light of global changes, propose management and intervention strategies. This study aims to provide a theoretical basis for coral protection and point out the direction for future research. 2 The Mechanism of the Impact of Heat Stress on Corals 2.1 Direct effects of seawater temperature rise The increase in seawater temperature is the main cause of coral heat stress. When the temperature exceeds a certain limit, the balance between corals and their symbiotic algae will be disrupted. High temperatures will accelerate the respiration and metabolism of algae, and at the same time affect their photosynthetic capacity. Some mathematical models, such as bioenergy models, indicate that an increase in temperature will accelerate metabolism. However, high temperatures can also damage the photosynthetic organs and metabolic processes of algae, thereby reducing the amount of carbon that algae transfer to corals. Over time, this imbalance can damage the relationship between corals and algae and trigger coral stress (Figure 1) (Pfab et al., 2024). Figure 1 The model describes the effect of temperature on a coral host and its algae symbiont (Adopted from pfab et al., 2024) Image caption: Increased temperature is assumed to accelerate metabolic processes and damage the photosynthetic machinery of the symbiont (Adopted from pfab et al., 2024) 2.2 ROS (reactive oxygen species) generation and cell damage mechanism Reactive oxygen species (ROS) play a key role in the process of heat stress. Heat stress can cause symbiotic algae and hosts to produce excessive ROS, including superoxide anion (O₂⁻), hydrogen peroxide (H₂O₂), etc. (Doering et al., 2023). When these ROS exceed the processing capacity of the clearance system (such as superoxide dismutase and catalase), they can cause oxidative damage to cells, membrane damage and signal imbalance. Especially H₂O₂, the relationship between its dynamic changes and albinism is more complex at high temporal resolution. Some studies have pointed out that its concentration fluctuations are not necessarily the direct cause of albinism (Schlotheuber et al., 2024). 2.3 Symbiotic relationship breakdown and albinism process With the imbalance of ROS generation and metabolism, the coral-symbiotic algal system may enter a stage of breakdown. Heat stress can disrupt the photosynthesis of symbiotic algae, reducing their efficiency in transferring carbon to the host. Meanwhile, ROS signaling may induce the host to expel the symbiotic algae (Brown et al., 2024). To reduce internal environmental pressure, corals will decrease the density of symbiotic algae by shedding, expelling or digesting them, which leads to the forced interruption of symbiotic relationships. As the number of symbiotic algae significantly decreases, the transparency of coral tissue increases, presenting a white appearance, which is known as bleaching. After that, the sharp decline in energy supply will further expose corals to the risk of death in the face of food scarcity, disease attacks or continuous high temperatures.
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