The Great Barrier Reef is the world’s largest coral ecosystem. It is comprised by a complex of reefs, shoals, and islets that are located in the Coral Sea, off the coast of Queensland, Australia. This is the world’s largest single geographical feature that is completely made up of living organisms and/or their remains, and can even be seen without visual aids from outer space. Billions of coral polyps and their skeletal remains form the building blocks of the reef, which in turn supports a large variety of biodiversity within its unique coral ecosystems. In 1981, the Great Barrier Reef was assigned the status of being a World Heritage Site by the United Nations' UNESCORTED, while CNN labelled it as one of the "seven natural wonders of the world".
The formation of the Great Barrier Reef dates back to millions of years ago. The reef was formed from the skeletal waste of a mass of living marine creatures. The calcareous remains of the coral polyps forms the framework of the Great Barrier Reef, while the cementing material holding the remains together was formed by deceased bryozoans and coralline algae. Although human contacts with the reef were believed to have first commenced well before the arrival of Westerners, as the indigenous inhabitants of Australia would make their voyages into these same waters near the reef for fishing, the first recorded human contact with the Great Barrier Reef took place in 1770 when Captain James Cook ran his ship aground upon it. The Great Barrier Reef Expedition between 1928 and 1929 contributed a significant deal of knowledge to the scientific community regarding the structure and biodiversity of the reef. Presently, a modern laboratory on Heron Island near the reef is actively conducting several ongoing studies on the Great Barrier Reef's ecosystems.
The Great Barrier Reef is a very productive ecosystem which supports a tremendous degree of biodiversity, and is also of immense importance to humankind. Coral reefs of the world, including the Great Barrier Reef, are vital to the world’s fisheries, acting like nurseries for around a quarter of the world’s fisheries as fish come to them to lay eggs and raise their young. About a billion people around the world either directly or indirectly depend on the coral reefs for their food and incomes. Tourism revenues generated by the Great Barrier Reef are also highly significant, which amount to nearly over $1 billion USD annually. The Great Barrier Reef also provides coastal protection by acting as a barrier capable of reducing the impact of the cyclones, tropical storms, and tsunamis in the coastal regions.
The Great Barrier Reef supports a rich diversity of life, including many species that have been registered as either threatened, vulnerable, or endangered by the IUCN's Red List of Threatened Species. The reef and the seas around it host around 1,500 species of fish, 4,000 species of molluscs, one-third of the world’s corals, 800 species of echinoderms, 1,500 species of sponges, 23 species of marine mammals, 500 species of seaweed, and 6 species of marine turtles. Marine mammals common in this region include the Indo-Pacific humpback dolphin, the humpback whale, and the dwarf minke whale. Clown fish, red bass, coral trout, and snapper are some of the fishes common to these reefs. Endangered sea turtles, like the green sea turtle, Olive Ridley, loggerhead sea turtle, and others, breed on the reef as well. 215 species of birds also visit the reef and nest on the nearby islands. Around 2,195 species of plants are also supported by the Great Barrier Reef.
Threats and Disputes
There are a large number of growing threats to the Great Barrier Reef, many of which are threatening to damage the entire network of ecosystems in the region. Climate change is by far the most serious threat to the coral ecosystem. Coral bleaching, involving the death of vibrantly coloured algae inhabiting the corals, results when water temperatures rise. The death of these algae in turn results in the deaths of those creatures that depend on algae for food, and the entire food chain of the ecosystem is thus disrupted. Besides coral bleaching, the rise in water temperatures is believed to affect the coral ecosystem in many more ways, possibly to such a point that it could potentially diminishes life as we know it on the reef as soon as by the year 2030. Though the Great Barrier Reef Marine Park Authority has rendered large areas of the reef off-limits to commercial fishing, trawling for prawns and molluscs in the nearby waters has often led to the death of marine species unique to the reef as bycatch of commercial fishing expeditions. The huge burden of tourists on the reef is also disturbing the ecology of the region, often doing so in unintended, yet still devastating, ways. Frequent shipping accidents and accidental oil spills in the region over the past several decades have also affected the reef and marine life in the surrounding waters. Since 1987, 283 spills have been reported in the waters in and around the reef.