Coral bleaching is primarily caused by increased water temperature, which is often a result of climate change. When water temperatures rise, corals expel the symbiotic algae that live in their tissues, causing them to turn white and become more susceptible to disease and death.

Symbiotic algae, known as zooxanthellae, live in the tissues of corals and provide them with food through photosynthesis. They also give corals their color, as the algae contain pigments that absorb and reflect light.

When corals bleach, they expel the symbiotic algae that live in their tissues, causing them to turn white and become more susceptible to disease and death. If the stress that caused the bleaching persists, the corals will eventually die.

Coral bleaching can have a number of long-term effects, including loss of biodiversity, damage to coral reefs, and reduced food security. Coral reefs are home to a wide variety of marine life, and when corals die, it can disrupt the entire ecosystem. Coral reefs also provide food and shelter for many fish species, and when they are damaged, it can reduce the amount of food available for these fish.

To prevent coral bleaching, it is important to reduce greenhouse gas emissions, which contribute to climate change and rising water temperatures. It is also important to protect coral reefs from pollution, which can make them more susceptible to bleaching. Finally, it is important to limit overfishing, as this can reduce the number of fish that eat algae, which can lead to an increase in algae growth and competition for space on coral reefs.