5. Answer Around the world, reefs generally occur only where temperatures remain above 18° Celsius (64° Fahrenheit) most of the time. This means that they are usually located in this region, which is within 30° North and 30° South of the equator.
9. The Great Barrier Reef can be seen from outer space and is the world's biggest single structure made by billions of these tiny living organisms. Answer
18. The rivers of north eastern Australia provide significant pollution of the Reef during tropical flood events with over 90% of this pollution coming from this source. Answer