Great Barrier Reef - Courtesy Tourism Queensland
The Great Barrier Reef, off Australia's east coast, is one of the wonders of the natural world. It is World Heritage listed and is one of Australia's, and the world's, premier holiday destinations. The combination of glorious weather (be aware that it rains a lot in the wet season!), pristine rainforest, white sandy beaches, and an ocean varying in hue from blue to turquoise to green, ensures it's where the world wants to go to lie on the beach, swim, surf, snorkel, sail, bushwalk and birdwatch.
The area abounds with wildlife, including dugong and green turtles, varieties of dolphins and whales, more than 1500 species of fish, 4000 types of mollusc and more than 200 species of birdlife. The Great Barrier Reef system consists of more than 3000 reefs which range in size from 1 hectare to over 10,000 hectares in area. The reef is scattered with beautiful islands and idyllic coral cays and covers more than 300,000 square kilometres.
The coral has, over the years, brought many ships to grief - Cook's own Endeavour hit the reef and almost foundered - if it had, and Cook and his crew had perished, Australian history would be quite a different story. One of the most famous wrecks is that of the HMS Pandora, which foundered in 1791.
The corals which make up the various reefs and cays, and which are the base for this variety of sea and animal life, consist of individual coral polyps - tiny live creatures which join together to form colonies. Each polyp is a tiny jelly-like blob crowned by tentacles, and looks not unlike an anemone, but much smaller. Each polyp lives inside a shell of aragonite, a type of calcium carbonate which is the hard shell we recognise as coral. The polyps join together to create forests of coloured coral in interesting fan, antler, brain and plate shapes.
There are many different types of coral, some are slow growing and live to be hundreds of years old, others are faster growing. The colours of coral are created by algae. Only live coral is coloured. Dead coral is white.
The ideal environment for coral is shallow warm water where there is a lot of water movement, plenty of light, where the water is salty and low in nutrients.
Reefs are sensitive to climate change, to changes in patterns of water movement, and to physical damage - so problems like global warming, El Nino, the building of moorings or breakwaters, any additional nutrients running off land from human habitation, may well have a negative effect on the reef system, and thus on the sea and land animals which depend upon it for survival.
Tourism may also have a negative impact, with fragile corals broken by reef walking, dropped anchors or by boats dropping fuel and other sorts of pollution. Even the number of people in the water with the associated run-off of sweat and suntan lotions may well have a negative impact on the fragile reef environment.
One tourist who cares little for the beauty and diversity of the Great Barrier Reef system is the Crown of Thorns starfish. Since the 1960s the Crown of Thorns has been destroying the corals which make up the reef. Crown of Thorns outbreaks go through a series of stages which can take from 1 to 15 years. The impact of a Crown of Thorns infestation on sea and bird life can be significant as the corals, which support and sustain this life, die.
The latest scourge of the reef is bleaching, where corals have died in large numbers. This phenomenon is not exclusive to Queensland's Great Barrier Reef, but has been observed on reefs throughout the world. It is thought the bleaching has been caused by rises in water temperature related to the El Nino effect, although the evidence is not conclusive.
Even with these problems and challenges the Great Barrier Reef is still one of the natural wonders of the world - an environment of extraordinary beauty and richness, with a diversity of plant, animal and sea life which makes it essential we conserve and preserve it, and maintain it as great place to relax and experience part of Australia's natural heritage.