what causes coral bleaching

Coral bleaching is the process when corals lose their vibrant colors and turn white due to various stressors, such as changes in temperature, light, or nutrients. The leading cause of coral bleaching is climate change, which results in rising ocean temperatures. When water is too warm, corals will expel the algae (zooxanthellae) living in their tissues, causing the coral to turn completely white. Other causes of coral bleaching include extremely low tides, pollution, or too much sunlight. Coral bleaching matters because once these corals die, reefs rarely come back, and entire reef ecosystems, on which people and wildlife depend, deteriorate. Coral reefs are natural barriers that absorb the force of waves and storm surges, keeping coastal communities safe. Without them, we must rely on manmade seawalls that are expensive, less effective, and environmentally damaging to construct.