Destination Uncharted: The Great Barrier Reef

July 30,2013

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This undated photo shows a colorful scene on the Great Barrier Reef off Australia's northeastern coast. (AFP/Getty Images)

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The Great Barrier Reef is a unique and beautiful natural wonder. The reef is 2,300 km (1,426 miles) long, encompassing a total area of over 300,000 square km (186,000 square miles), and is reportedly the only living structure on Earth visible from space.

Coral reefs are formed when coral animals, or polyps, attach to a hard surface and build a cup-shaped exoskeleton, or calyx, by excreting calcium carbonate. The polyps will occasionally detach from their calyx and secrete a new one above it, causing the coral structure to grow slowly over time, according to the National Oceanic and Atmospheric Administration. The origin of the Great Barrier Reef can be traced back to an ice age that occurred roughly 15,000 years ago, when much of the Earth's water was locked in glaciers, and sea levels were 300-400 feet lower than they are today. Coral polyps settled along Queensland's continental shelf, which was exposed to air at that time, and as the glaciers melted and the sea level rose, the coral structures were able to grow fast enough to keep the coral polyps in the lighted surface waters where they were able to survive, marinebio.net reports.

The Great Barrier Reef contains close to 400 different types of corals, the Australian Great Barrier Reef Marine Park Authority states, which form structures in an amazing variety of shapes and colors, making the reef a place of incredible beauty, resembling a rainforest in an alien landscape.

In fact, coral reefs are often called rainforests of the sea because of their biodiversity, and even though they consist of less than .01% of the Earth's oceans, they provide a home for 25% of all marine species, the dailymail.co.uk reports. The Great Barrier Reef, the largest reef structure in the world, contains 500 seaweed species, 215 species of birds, 16 species of snakes, 4,000 species of mollusks and 1,500 different species of fish, according to the Sydney Sea Life Aquarium.

In addition, the reef also provides a home for over 30 different species of marine mammals for at least part of the year, including Indo-Pacific humpback dolphins, Australian snubfin dolphins, spinner dolphins, pan-tropical spotted dolphins, killer whales, short-finned pilot whales, sperm whales, and humpback whales, which return to the reef from May to September in order to have their calves and build up strength for their return trip to the Antarctic, states greatbarrierreef.org. Six of the seven species of sea-turtles also dwell in the confines of The Great Barrier Reef, and the reef provides a protected home for the iconic dugongs, also known as sea cows, endangered marine mammals which were at least partially responsible for the legends of mermaids when they were first seen by early sailors, according to the Australian Great Barrier Reef Marine Park Authority.

The reef is extremely important to humans as well. Majestic marine mammals, the riot of color from the many diverse species of fish, the unearthly beauty of the coral "forest", and the warm gentle ocean currents all contribute to making the Great Barrier Reef a popular tourist destination, and other parts of the reef supports a large commercial fishing industry that is vital to the Australian economy, as well as fishing in the reef providing food for indigenous people, the Great Barrier Reef Marine Park Authority reports. The GBRMPA is responsible for insuring that the waters of the reef are not overfished, as well addressing other threats to the reef such as pollution from the millions of tourists who visit each year, in order to make sure this delicate ecosystem is not harmed.

The most powerful threat to the reef seems to come from the forces of nature. Intense hurricanes can cause massive damage to the reef. The Great Barrier Reef seems to have lost half of its coral cover in the past 27 years, with loss being attributed to the following causes: storm damage - 48%, crown of thorns starfish - 42%, and coral bleaching - 10%, according to researchers from the Australian Institute of Marine Science. The CEO of the AIMS goes on to say if the starfish proliferation could be halted, the reef could start to recover, growing at a rate of 0.89% per year. Coral bleaching is a phenomenon in which ocean conditions, such as temperature or acidification, cause the corals to expel the algae which give them their color, and while corals can survive bleaching, they become more vulnerable when it occurs, according to NOAA.  According to another study that was reported on weather.com from Institut Pierre Simon Laplace and Stanford University, ocean acidification, which the study states is a condition in which the ocean becomes more acidic as a result of CO2 emissions, may result in the death of all shallow-water coral reefs in the next 100 years.