Before the drifting of the Australian continent into the tropics coral and reef growth would only have taken place in the north where temperatures would have been more favourable. Only when the area of the Discovery Coast had drifted far enough into warmer waters, about 2 million years ago, corals started to grow building reefs here.

Coral growth at high sea levels about 30000 years ago

Apart from warm waters, temperatures around 22 to 29 degrees C, corals require clear water, stable salinity, low sedimentation and low nutrient and also a firm substrate to cling to.

Lowest sea level, 120 metres below prestent levels; 18000 years ago

As living corals make only the top few millimetres of the reef structure there are three stages of development of reef growth. Juvenile reefs which are still growing until they reach sea level, mature reefs which have reached sea level and have started to fill in with sediment, senile reefs which are filled in with sediment and have often formed coral cays.

Stabilized sea level, 6000 to 3000 years ago

Todays sea level, some reefs reached surface, cays have developed

A coral reef is a complex interweaving of life forms which depend on each other in the quest for food, the need for defence and successful reproduction. The reef is constructed by the actions and reactions of marine organisms. Sunlight is the powerhouse supplying the energy for these organisms to convert carbon dioxide and water into oxygen and carbohydrates (photosynthesis). This organic material feeds the herbivores (plant eaters) and herbivores then provide food for the carnivores (animal eaters) and both are the diet for the omnivores (plant and animal eaters). Scavengers and bacteria clean up by feeding on dead organisms (animals, plants and wastes) recycling organic matter back to carbon dioxide and nutrients.

However, not all of the carbon dioxide is used to produce plants through photosynthesis, about one quarter of it is needed for the production of limestone by corals and marine algae. This forms the basis and the continued growth of a reef which in itself is the home of a myriad life forms.

The island houses the Heron Island Research Station which is Australia's largest university marine research facility. It plays an importent role in research into, and education about, marine science and the marine environment. For over 30 years the Station has been the major field centre on the Great Barrier Reef.

World Heritage. In 1975 the Australian Government provided for a framework for the protection

of the Great Barrier Reef by passing the Great Barrier Reef Marine Park Act. In 1981 the Great Barrier Reef Marine Park and adjacent coastal areas and islands were inscribed on the World Heritage List. Australia's international obligations are to protect, conserve, present and transmit the Great Barrier Reef World Heritage Area to future generations.
 

How does a Coral Reef grow • Description of Reefs and Islands • Aquatic Life • Back to the Bunker Group