Shading Acropora kenti during doldrum-like conditions can reduce mortality risk during high-thermal stress events

Climate change is threatening the health of coral reefs, particularly through elevated water temperatures, which can interact with excessive light to exacerbate coral bleaching. Shading interventions, such as seawater fogging, have been proposed to mitigate the effects of light stress during low-wind, doldrum-like conditions. A critical assumption of this type of intervention is that shading corals only during these doldrum-like conditions, as they occur during a marine heatwave, is sufficient to affect overall mortality outcomes. This study investigated the impact of shading on the bleaching and mortality of Acropora kenti during high-thermal stress events. An 11-week experiment was conducted to simulate two doldrum-like events, manipulating light intensity and water temperature, with shading applied only during short periods of the doldrums. Elevated thermal stress significantly impacted coral pigmentation and enzymatic antioxidant responses, with mixed responses to shading. However, corals shaded at a 30% light reduction were 31% more likely to survive compared to unshaded and 15% shaded corals. Thus, shading during doldrum-like conditions can alter the bleaching response and reduce mortality in thermally stressed Acropora kenti . These findings support the potential of shading interventions, such as seawater fogging, to enhance coral resilience. They also highlight the critical importance of managing high light and temperature stress, particularly during recurrent summer doldrum periods when conditions favour mass bleaching.