Fish swimming amongst the CoralWhat is a coral reef? Coral reefs are like underwater cities built from living animals (coral polyps) which usually live together in colonies. Hard corals, which are the only types of corals to form coral reefs, produce limestone skeletons. Amazingly, they do this with the help of tiny microscopic plants that actually live inside them. These plants give the corals their colours and capture energy from the sun by photosynthesis - just like plants in your garden! The sugars and oils they produce are also used by the corals.

Why are they important? Coral reefs form important homes for hundreds of colourful fish (more than 500 species live in Ningaloo Marine Park), sea stars, crabs, marine worms with their colourful feeding tentacles, exquisite shellfish, and a myriad of other animals. At Ningaloo Marine Park, the world’s biggest species of fish, the whale shark, arrives soon after the reef’s mass coral spawning. If coral reefs die all the animals that depend on them will disappear too.

What does a coral reef look like? Coral reefs may look quite different to one another, depending on the species they are made up of. They come in a fantastic range of shapes and colours. There are staghorn corals with delicate branching structures that look a little like the horns of stags, mushroom corals, bubble corals, cabbage corals, honeycomb corals, brain corals, plate corals, blue corals and many many more. Sometimes a reef may be formed mostly of one particular type and sometimes you can see lots of different species living together. In WA, some of the most beautiful coral reefs are found in the Rowley Shoals Marine Park, the proposed Dampier Archipelago Marine Park, Montebello Islands Marine Park, Ningaloo Marine Park and the Muiron Islands Marine Management Area.

Shark wimming amongst the Coral

Where are they found? Coral reefs only thrive in warm, clear water with few nutrients (which is why water pollution kills corals) so they generally only grow in the subtropics and tropics. Western Australia’s coral reefs are amazing and unique, because they grow much further south, in much colder waters, than reefs elsewhere in the world. At the Houtman Abrolhos Islands, offshore from Geraldton, there are well-developed and stunningly beautiful coral reefs where they should not (in theory) be growing. There is even a beautiful pink coral reef at Pocillopora Reef at Rottnest Island, offshore from Perth. WA reefs are able to thrive in these temperate-water areas because of the Leeuwin Current, a band of warm water that starts in the tropics and travels south down our coast in the winter.

Interesting facts: Coral reefs grow less than three centimetres each year, so it takes many, many years for a large reef to form. Coral reefs have existed for more than 200 million years.

How you can help protect coral reefs: The world’s coral reefs are under threat. Coral bleaching caused by climate change has already caused widespread death of corals and huge areas of reefs around the world are under threat. Even Western Australia’s fairly healthy coral reefs are threatened. As climate change is caused by increased carbon emissions into the atmosphere you can help by doing simple things such as switching off lights and riding your bike to school. If you visit areas with corals (like Ningaloo Marine Park or Pocillopora Reef at Rottnest Island) you can collect information for Coral Watch. Visit their website www.coralwatch.org and find out more about coral bleaching and how you can help monitor coral health.