The corall reefs are dying but why?

The number of colourless corall reefs has increased in the last decade. If a corall reef loses his colour it’s almost dead. The reason for this process are warmer oceans and water pollution. Coralls are living togehter with tiny oranism that give them their colour and help them to grow. This system is very fragile and they can’t deal with warmer oceans. Corall reefs are the second most popular habitat for animal species on the earth. They are very important for animal welfare and aswell a beautiful retreat for fish.