Coral reefs occupy less than 0.1% of the ocean floor, but they rival the rainforest in terms of biodiversity as they are highly complex ecosystems. They support nearly 25% of all known marine species. They are most commonly found at shallow depths in tropical waters, but deep water and cold water corals also exist on smaller scales in other areas. Constructed by living organisms, coral reefs are home to some of the most fascinating plants and animals in the world.
These ecosystems have huge ecological and social value, providing food and income for millions of people worldwide. They also protect coastal communities from damaging storms and cyclones.
Coral reefs are very fragile, partly because they are very sensitive to water temperature. They are under threat from various tourism activities, overfishing or damaging fishing techniques, climate change, oceanic acidification, agricultural runoff and water pollution, to name a few.