Reef communities are being impacted by global impacts such as ocean warming and acidification, as well as local impacts like overfishing and nutrient pollution. These stressors prompt physiological responses in coral reefs, leading to bleaching, which affects their reproduction, calcification, and persistence, compromising the entire ecosystem. Although coral reefs in the South Atlantic have historically been less susceptible to mass bleaching events than reefs in the Indo-Pacific and Caribbean, a strong heatwave combined with El Niño in 2024 caused a second mass bleaching event in Brazilian reefs. To understand how global impacts combined with local stressors affect the health of Siderastrea stellata, an abundant species in northeastern Brazilian reefs known for its tolerance to environmental variations, we simulated conditions of thermal stress and, nutrient pollution (nitrogen enrichment) in healthy and bleached colonies, in three different treatments: Elevated Temperature (30°C), Elevated Temperature and Nutrient Enrichment (> 8 µM), Nutrient Enrichment, and the control treatment where the temperature was maintained at 27°C and the nutrient concentration was not altered. Overall, the colonies showed no significant changes in their health status, as indicated by analyses of photosynthetic efficiency and coloration using the Coral Watch Coral Health Chart. We are now quantifying the total protein quantification and density of endosymbionts to investigate the cellular mechanisms associated with the species' resistance and resilience patterns facing climate change.

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