How Was the Great Barrier Reef Formed?
How was the Great Barrier Reef formed? In order to form, a reef needs clean, shallow water and sunlight. Corals grow and form a colony and each coral polyp is associated with an alga. The photosynthesis of the alga helps the coral form a coral skeleton. These form the foundation on which the reef grows. There are many aspects to understanding the Great Barrier Reef and how it was formed.
The Great Barrier Reef was formed because of the relationship between coral and alga. After the coral skeleton is made, then the alga (zooxanthella) produces calcium carbonate to seal two coral skeletons together.
Over one million years ago, there was a huge change in the Earth’s climate. The sea levels rose and fell over time. When the sea levels rose, the continental shelf of Australia was flooded. This allowed the coral that were growing on the edges of the shelf to grow and begin forming the Great Barrier Reef.
What Is the Great Barrier Reef?
The Great Barrier Reef is the largest coral reef system in the world. It is actually a series of smaller reefs. It took between 50,000 and 100,000 years for it to form off the northeastern coast of Queensland, Australia. It is one of the seven natural wonders of the world and is 1250 miles long.
The Great Barrier Reef acts as a buffer between the strong waves of the Pacific and the shores of Australia. Reefs have to have clean and shallow water, sunlight, and a water temperature between 18 and 30 degrees Celsius. Four hundred species of coral have been found there, as well as 4000 species of mollusk and 2000 different kinds of fish.
Types of Reefs
There are three kinds of reefs:
- The barrier reef - A lagoon always separates a barrier reef from the coast
- The fringing reef - Forms in shallow waters along the shore
- The atoll reef - A circular reef that often has a lagoon in the center. As the waves of the lagoon cover the submerged island, the reef grows in layers over the island.
Many parts of the Great Barrier Reef have islands made of coral sand that have piled up to make them.
Scientists define a reef as a rigid biological construction. Reefs form on hard surfaces. Most of the reefs of today grew on an old reef that died during a time when the sea levels were lower or on the edge of a rocky island. Reefs are made of coral, sand, or rock and form underwater.
Global Warming and the Great Barrier Reef
If ocean temperatures increase by 1.5 degrees Celsius as scientists are predicting, then the Great Barrier Reef could lose 95% of its living coral by 2050. This would have catastrophic socioeconomic and ecological ramifications. When the ocean water temperature rises, it causes coral bleaching. That means that the symbiotic alga inside the coral polyps dies, which causes the polyps to turn white and eventually die.
Coral reefs are fragile ecosystems and are extremely sensitive to water temperature, so any changes can have an effect. As with any ecosystem, the reefs can recover from a certain amount of bleaching, but there will come a point when they will not recover.
From an economic standpoint, 500 million people live within 100 km of a reef and losing reefs will have a big impact on the world economy. Also, barrier reefs play an important role of sheltering the coastline from the full effect of the ocean’s waves. If the reef crumbles, the coastlines are exposed to damaging waves and the people there would have to deal with erosion and wave action, and low-lying structures could be at risk.