The Great Barrier Reef is located off the coast of Australia and is over 2,300 kilometers long. It is home to over 1,500 species of fish, 400 species of coral, and 133 species of sharks and rays.

Coral bleaching is caused by a rise in water temperature. When the water temperature gets too high, the coral expels the symbiotic algae that live in its tissues. This causes the coral to turn white and become more susceptible to disease and death.

Sewage contains high levels of nutrients, which can cause algal blooms. Algal blooms can block sunlight from reaching the coral, which can lead to coral bleaching and death.

Herbivorous fish eat algae, which helps to keep the coral reef clean and healthy. When herbivorous fish are removed from the reef, the algae can overgrow and smother the coral.

All of the above actions are necessary to protect coral reefs. Reducing greenhouse gas emissions will help to slow the rate of climate change and reduce coral bleaching. Reducing pollution will help to improve water quality and reduce the risk of disease. Reducing overfishing will help to maintain a healthy balance of fish populations on the reef.