人为排放硝态氮加剧珊瑚热白化

Core Insights - The research conducted by Hainan University's Coral Reef Ecology International Joint Research Center reveals that two common nitrogen pollutants, nitrate and ammonium, have opposing effects on corals under thermal stress [1][2] - The study provides a new perspective on how climate change and nutrient pollution jointly impact coral reef ecosystems and establishes a nitrate concentration threshold for seawater quality management [1] Group 1: Effects of Nitrogen Pollutants - Nitrate exacerbates coral bleaching by intensifying oxidative damage to symbiotic algae (zooxanthellae) and disrupting the stability of photosynthesis-related membrane structures, ultimately leading to a breakdown of the symbiotic relationship [1] - In contrast, ammonium enhances corals' heat resistance by boosting their antioxidant capacity and promoting the synthesis of lipids necessary for photosynthesis, thereby alleviating oxidative stress caused by high temperatures [1] Group 2: Management Recommendations - The research identifies a protective threshold for nitrate concentration at 0.13 mg/L (approximately 9 micromoles/L), below which coral bleaching under high temperatures can be effectively mitigated [2] - It emphasizes the need for strict local water quality management to control anthropogenic nitrate emissions, particularly in coastal areas like the Great Barrier Reef and Caribbean, where nutrient enrichment is primarily driven by nitrate [2] - The findings suggest that while climate change remains the greatest threat to coral reefs, managing nitrate pollution is crucial for enhancing the resilience of coral ecosystems against global climate change [2]