Greenspeak

By: Rebecca Evered, Curriculum & Content Director, Greenspeak International

A reef is a rock, sandbar or other feature that lies just below the water’s surface. Most reefs form by geological processes, but coral makes the best-known reefs Biotic (living) reefs take a second name due to their position in relation to the land. They may be called barrier, fringing or atoll reefs. Barrier reefs form a hard wall around an island protecting the shore from the ocean, while a fringing reef is a reef that is attached to an island. An atoll is a ring reef with no land close by. The reef front (ocean side) is a rougher area, with a lot of wave action whereas the lagoon inside will be calmer.

The Great Barrier Reef is the largest coral reef in the world, made up of over 2,900 individual reefs and 900 islands. It is over 3,000 km (1,600 miles) long. The reef is located in the Coral Sea off the coast of Queensland in northeast Australia. It is so big that it can be seen from space, and is listed as one of the seven natural wonders of the world.

Four hundred species of corals, both hard and soft are found on the reef. The majority of these breed in mass spawning events that are controlled by warmer sea temperatures of spring and summer, the moon cycle and day lengths. Reefs in the inner Great Barrier Reef spawn during the week after the full moon in October, but the outer reefs spawn in November and December.

A large part of the reef is protected by the Great Barrier Reef Marine Park, which helps to limit human impacts, such as over-fishing and tourism. Other environmental pressures to the reef include water quality from chemicals used on the land (such as fertilizers), climate change accompanied by mass coral bleaching from rising sea temperatures, and outbreaks of the introduced crown-of-thorns starfish.