WHAT did the ecosystem historically look like?
Although the Great Barrier Reef dates back 600,000 years, the current structure of the reef did not begin forming until 15,000 years ago. Unlike most barrier reefs, which begin with volcanic eruption, the Great Barrier Reef began forming during the Ice Age. The retention of water in glaciers caused sea levels to be between 200 and 400 feet lower than the sea levels we are experiencing today. Due to these circumstances, coastal planes, or what would be later known as the Great Dividing Range, were exposed as landmasses. Along these coastlines, reefs began to form. They resembled what we refer to as fringe reefs. As the Ice Age ended, and glaciers began to melt, sea levels began to rise and these landmasses were again submerged. As the ice melted, the coral continued to grow on the old, dead coral as well as on the formerly exposed landmasses. The coral continually grew towards the surface as the ice continued to melt in search of sunlight which the zooxanthellae in coral need to survive. Eventually, the sea level stabilized, and wind and water began to erode the coral, which peaked through the surface of the water. At this point, the reef began to grow outward, and the modern structure of the reef began to take shape.
What Does the Great Barrier Reef Look Like Today?
This photo shows both the location and the scale of the Great Barrier Reef. The reef stretches over 2,300 kilometers. Due to the expanse of the reef and the sources of human impact, this information covers a regional spatial scale.
Over thousands of years, the Great Barrier Reef has developed into an enormous ecosystem. It is located off the Coast of Australia. Its span is more impressive than the Great Wall of China, stretching over 2,300 kilometers and it is the only living organism that is visible from space (1). It is one of the most diverse ecosystems in the world with over 600 coral species, over 1,500 species of fish, and 3,000 types of mollusks. (2)This is not to mention the endangered species of sea turtles and dolphins this ecosystem supports. This biodiversity hotspot is traditionally categorized into three sections: the Northern Reef, the Central Reef and the Capricorn Reef. The Northern Reef is the closest to the equator, has the most biodiversity and is primarily comprised of ribbon reefs (long, thin reefs) with patch reefs falling in the shallow waters between the ribbon reefs and the land. The Central Reef is farther from land, and expands over a wider area. This exemplifies what we normally think of as a barrier reef. This area gets the most tourism because it is the easiest to get to. As you go into the southern section, the reef continues to widen until it starts to become sparse and eventually disappears when the waters get too cold to support the coral population.(3) Today, the Great Barrier Reef is considered one of the seven wonders of the natural world and has been labeled a World Heritage Site. However, human impacts are having drastic impacts on this beloved landmark.
- "About the Great Barrier Reef." Australia's Great Natural Wonder: The Great Barrier Reef. Great Barrier Reef Organization. Web. 22 Nov 2013. <http://www.greatbarrierreef.org/about.php>.
- "Biodiversity." Great Barrier Reef Marine Park Authority. N.p.. Web. 22 Nov 2013. <http://www.gbrmpa.gov.au/about-the-reef/biodiversity>.
- Horton, Jennifer. "How the Great Barrier Reef Works."How Stuff Works. Discovery. Web. 22 Nov 2013. <http://adventure.howstuffworks.com/great-barrier-reef4.htm>.
http://www.the-great-barrier-reef-experience.com/great-barrier-reef-history.html
http://www.gbrmpa.gov.au/about-the-reef/facts-about-the-great-barrier-reefhttp://eoimages.gsfc.nasa.gov/images/imagerecords/54000/54930/S2000239014054_md.jpg
Written by Sydney Young