The Great Barrier Reef, Australia – October 6th, 2008
The Great Barrier Reef, located in the Coral Sea off the coast of Queensland (northeast Australia), is the world’s largest coral reef system. It is made up of more than 3000 individual reef systems and 900 islands, and extends for 2,600 kilometres (1,600 mi) over an area of approximately 344,400 square kilometres (133,000 sq mi). It is the largest single structure made by living organisms; bigger than the Great Wall of China and so large that it is the only living thing on the planet visible from space.
The Great Barrier Reef is actually composed of billions of tiny organisms, called coral polyps. In fact, 400 species of corals (both hard and soft) can be found there.
It also supports a great diversity of life, including 30 species of whales, dolphins and porpoises, 6 species of sea turtles which use the reef for breeding, salt-water crocodiles, 125 species of shark, stingray, skates and chimera, almost 5000 species of mollusk, 1500 species of fish, 9 species of seahorse, 17 species of sea snake, and 7 species of frog. There are also 15 species of seagrass and 500 species of marine algae or seaweed. On the islands, 215 species of birds can be observed roosting or nesting. The islands also have 2195 plant species. Many of the species populating the reef ecosystem are either considered vulnerable or endangered.
In the image on the left we can observe a huge algal bloom that stretches from the coastal city of Mackay to Townshend Island.
The Great Barrier Reef Marine Park protects a large portion of the reef, limiting the impact of human use and thus protecting it from problems such as overfishing and tourism. Other environmental problems affecting the reef are runoff (particularly chemical runoff from farms), which affects the water quality, cyclic outbreaks of crown-of-thorns starfish, which prey on the coral polyps, shipping accidents and oil spills, tropical cyclones, and climate change, which is accompanied by mass coral bleaching.
In the lower central part of the image, an artificial basin next to the Boyne Island Aluminium Smelter, the largest aluminium smelter in Australia, is clearly visible as an orange splotch. Aluminium smelters contribute to climate change.