excretory system is present in human body which discharge out the waste material time to time. basically when a cell in a body breaks down they produce various waste material like carbohydrates eliminates carbon dioxide while digestive system eliminates through feces. any malfunctioning can cause serious problem like constipitation kidney failure and kidney stones
The coral reef is experiencing succession, so over time the coral will continue to die off gradually as the zooxanthellae algae leaves the coral polyps.