Reefs. Where they occur

All similar yet all very different, most reefs fall into three categories:

1. fringing reefs, which occur around the edges of the continental islands that were once a part of the mainland.

2. ribbon or outer, barrier reefs which grow on the edge of the continental shelf.

3. platform or patch reefs, which support a cay, or island formed by sedimentary debris swept onto the reef.

One of the major reasons the reef holds such a fascination for scientists and tourist alike is its infinite variety. Some reefs are a little more than a few thousand metres in area while others could be spread over 120 square kilometres. Shapes vary from round, oblong, crescent and indescribable. Some of the very outer reefs are up to 25 kilometres long. At low tide some of the reefs expose themselves while others remain fully submerged. An aerial fly over is a must to appreciate the full extent of the reef.

About 2800 species of fish are known to live in the reef region. Of the 500 or so species of reef building corals found throughout the Indian and Pacific Oceans, about 350 are known to be on the Barrier Reef. It could be decades before scientists have a complete list of all the plants and animals found on any one reef. Many species are still to be identified and named. This clearly shows a staggering diversity of life.

Coral Facts

The world's first coral reefs occurred about 500 million years ago, and the first closeAerial Picture of a coral reef relatives of modern corals developed in southern Europe about 230 million years ago. By comparison, the Great Barrier Reef is relatively young at just 500,000 years old. The current reef's structure is much younger at less than around 8,000 years old.

Most modern reefs have formed on hard surfaces in the ocean, such as a base of an old reef that died during a period when sea level was lower, or the edge of a rocky island. Depending on how they start out, several types of reefs can form. Some coral reefs form in the deep ocean and are called atolls. The theories on how coral reefs form were first put forward by Charles Darwin (of The Origin of Species fame) who proposed that atolls form around the edges of high volcanic islands that gradually submerge beneath the sea with changes in sea level or subsidence of the land. Thus an atoll starts life as a fringing reef, then becomes more of a ring growing on the shrinking land-mass, until the land disappears and just the coral circle remains. In some cases, the coral growth is unable to keep pace with the sinking island, and sunken dead reefs have been found.


Class: Anthozoa [includes corals, anemones and sea pens]

Habitat: Coral reefs are found in shallow water, ranging to depths of 60 m. Some species prefer either cooler temperate water while others are found along tropical reefs, such as the Great Barrier Reef, with waters ranging in temperatures from 18 - 33 °C.
Living in colonies: They generally occur in large numbers as colonies of individual polyps linked by tissue. Resources, such as food, are then shared amongst the individuals in the colony.

Coral Size: Individual polyps range from 3 - 56 mm in diameter or height; while colony size varies from 75 mm -1500 mm (1.5 m) in width, height or length.

Some corals have a mutualistic relationship with algae called zooxanthellae. A mutualistic relationship is one where both parties benefit from their partnership. The algae use sunlight and the polyp’s waste products to make oxygen and food. These substances leak into the surrounding tissues of the polyp and can provide up to 98% of the polyp’s dietary requirements. These corals are found in shallow water, as they require sunlight to survive. They are generally fawn, brown or green in colour, due to the yellow-brown colour of the zooxanthellae.


Stinging cells: All Cnidarians have characteristic stinging cells called nematocysts in the tentacles and body wall. Each nematocyst cell contains a coiled thread under pressure, which is ejected from the cell when triggered by touch. These stinging cells are used for catching prey and for defense, some having barbed ends connected to poison sacs, while others are sticky.

Summary:

Coral polyps: Coral reefs consist of hundreds and thousands of soft-bodied, invertebrate animals, having no backbone. These animals are called coral polyps. The individual polyp is radially symmetrical and has a tubular body with tentacles surrounding the mouth at the upper end. Each polyp’s body wall consists of two layers of cells, an outer layer called the ectoderm and an inner endoderm layer. A gelatinous material called mesogloea is found in between these two layers.

Hard corals: Hard corals build reefs by growing atop the stony skeletons of previous coral colonies. They consist of limestone cases made by coral polyps extracting calcium from seawater. These limestone cases form a ‘house’ for the coral polyp, consisting of a floor, outer walls and a number of internal partitions. Inside corals’ clear outer tissues live microscopic algae, which transform sunlight into sugars through Photosynthesis The hosts help themselves to some of the sugars and gain some colour through the process.

Reproduction: Corals reproduce in two ways: asexually and sexually. Coral Spawning Some corals divide to form new individuals. This is known as asexual reproduction. Sexual reproduction takes place as mass spawning, where polyps release millions of eggs and sperm. Polyps are either male or female or both male and female. After the eggs and sperm are released, they float to the surface. The fertilised eggs that escape predation by other animals hatch into larvae and drift with the plankton. The tiny percent that survive and settle on the reef then begin new coral colonies.

Major Natural Predator:

The Crown-of-Thorns Seastar was once an animal of great controversy causing terrible damage to the coral reefs of the Great Barrier Reef. Many believed that this seastar was a pest species invading the coral reef habitat predating on and killing corals in great numbers. Research has indicated that the Crown-of-Thorns Seastar is only found in this habitatPicture of Crown of Thorns Starfish and a native species to Australian waters. The role that the sea star plays by eating coral polyps forms a population control, making more room for new coral reefs to form. Plague proportions are thought to coincide with rainfall and increases in nutrients from rivers during floods, and often occur cyclically every 17 years. Further scientific studies are still in progress to determine whether these plaques can be controlled.

Scuba diving & snorkeling is the most sought after outing onto the reef. With so much to see like ship wrecks, coral gardens, the thousands of species of marine animals and under water canyons. Cairns has many qualified scuba diving courses available and are amongst the safest in the world, with strict guidelines that trainers must follow. You can easily become a certified scuba diver and enjoy all the underwater attractions that the reef has to offer.

Information Sources: Australian Marine Life, by G.J.Edgar Steve Parish: Amazing Facts about Australian Marine Life Encyclopedia Britannica and www.reef.crc.org.au

A natural world wonder

The Great Barrier Reef is the largest coral reef in the world, roughly parallel to the coast of Queensland, Australia, for almost 2,000km. Australia has almost 1/5th of the world's reef area and most is located in the (GBR) Great Barrier Reef.

Reefs form where temperatures don't fall below 18 degrees Celsius (64 degrees Fahrenheit) for long periods, so are usually found between 30 degrees north and south of the equator. Most require very saline water, also the water must be very clear so light penetrates.
Corals found in the Great Barrier Reef contain algae and the relationship between the algae produce oxygen and help the coral to remove wastes. When this relationship breaks down, the coral suffers and becomes bleached. Bleaching is a major worry for those looking after reef health, as coral dies if bleaching is prolonged.

Washed by the warm waters of the South-West Pacific Ocean the perfect environment is created for the world's largest system of coral reefs. The Great Barrier Reef is of such pristine condition that it was listed by the World Heritage Trust as a protected site and is therefore managed by the Great Barrier Reef Marine Park Authority to ensure that its beauty is maintained for many generations to come.

Visitors in their thousands come to the Great Barrier Reef to marvel at the spectacular sight seeing opportunities that is unique to our area. The Wet Tropics World Heritage listed Rainforest on one side and the Great Barrier Reef on the other. No other place in the world offers such diversity so close to each other.

The primary Tourism uses are:-
1. dive operators
2. large vessels operating to pontoons moored at attractive off-shore reef sites
3. island resorts
4. cruise ships
5. charter vessels
6. airplane and helicopter scenic joy flights
7. bareboat self-skipper charter

History of tourism use

The earliest instance of organised tourism on the Great Barrier Reef was in the 1890s when Green Island became a destination for pleasure cruises offshore of Cairns. By the 1930s tourist resorts had begun to develop at Green Island off Cairns and at Heron Island further south. During the first half of the 20th century, most tourist activity was inshore and close to regional centres, being limited by boating technology and sub standard transport links to southern capitals.

The 1960s and 1970s produced a steady growth in visitor numbers, most natably at Green Island and in the Whitsundays. By the end of the 1970s new, faster marine vessels extended the range of a day trip to the Reef to between 15 and 20 nautical miles.

Great Barrier Reef tourism grew rapidly in the 1980s and early 1990s, assisted by improved air access to a number of regional centres and vastly improved road transport links. In the early 1980s visitor numbers to the Marine Park were increasing by about 30% per year. There was also a steady growth in the number of operations over this time, and the capacity, range and diversity of products offered expanded markedly. High-speed modern vessels extended the range of a day trip to the reef to over 50 nautical miles.

Tourism today

Tourism is now the largest commercial activity in the Great Barrier Reef Marine Park. Generating over $1b per annum, the marine tourism industry is a major contributor to the local and Australian economies.

About 1.6 million tourists now visit the Great Barrier Reef Marine Park each year. This number has remained relatively static since the mid 1990s. About 85% of tourists visit the Marine Park in the area offshore of Cairns and in the Whitsundays, a combined area of less than 10% of the Marine Park.

There are approximately 730 tourism operators and 1,500 vessels and aircraft permitted to operate in the Great Barrier Reef Marine Park. About 60% of these permitted operators are actively undertaking a tourism operation in the Marine Park.

There is a diverse range of tourism operations catering to the differing needs of visitors to the Great Barrier Reef. Activities typically include: snorkelling; scuba diving; fishing; glass-bottomed boat viewing, semi-submersibles and educational trips to learn about the marine environment.

The marine tourism industry plays an important role in presenting the World Heritage area to a wide range of visitors. For many visitors to coastal Queensland, the tourism fleet is their primary means of experiencing the Great Barrier Reef and learning about its World Heritage values.

Managing tourism use of the Great Barrier Reef

Keeping the Barrier Reef ‘Great’ for future generations requires the cooperative effort of the Great Barrier Reef Marine Park Authority, the Queensland Parks and Wildlife Service, other government agencies, the marine tourism industry and other stakeholders. By working together, the diversity, integrity and productivity of the Great Barrier Reef can be maintained and the impacts of all activities in the Marine Park can be minimised. The goal is to provide for the protection, wise use, understanding and enjoyment of the Great Barrier Reef in perpetuity.

In managing tourism use of the Marine Park, particular attention is given to:

protecting coral reefs and other habitats such as seagrass from anchor damage, poor diving practices, waste disposal, reef walking and collecting
protecting turtles and seabirds from disturbance, especially during nesting seasons

respecting the cultural importance of the Great Barrier Reef to Aboriginal and Torres Strait Islanders

minimising conflicts in access within this multiple use Marine Park
informing the community about the Great Barrier Reef and its World Heritage values
encouraging the adoption of best practices within tourism operations
assisting the marine tourism industry to contribute to management initiatives and monitoring programs.

Fundamental to management is the Great Barrier Reef Marine Park Act 1975 (Cwlth). Its regulations provide the framework for the establishment, care and ongoing management of the Marine Park. There is also a reef-wide system of zoning which defines in broad terms a set of management objectives for each zone along with a description of what activities, especially extractive activities, may or may not take place, including those that require a permit. Permits are required for all tourism activities in the Marine Park. It is through these permits that the activities that may be undertaken by each operator are defined and any necessary conditions described.

Management issues relating to tourism use of a specific region can be further addressed through plans of management. Such plans have been developed for the Cairns Area and Whitsundays (the two major tourism nodes in the Marine Park). These plans are designed to manage:

environmental protection of these high-use sites
separation of different uses
resolution of conflicting use
limiting use where necessary.

Tourism use is also managed on a finer scale through specific management initiatives for popular reefs and bays. Here the focus is on localised issues, and any plans and management strategies are developed in close consultation with local users.

A set of best practices has been developed to guide the activities of tourism operators and visitors in the Marine Park. Many of the tourism associations have developed voluntary codes of conduct to ensure that their members’ operations are sustainable. The Great Barrier Reef Marine Park Authority communicates information about management requirements and sustainable use through a range of quality information products and training opportunities. New zoning within areas of the reef during 2004 and 2005 has added extra protection to the natural beauty of the reef while still allowing the marine tourism industry to thrive.

Increasingly, the Great Barrier Reef Marine Park Authority is recognising the important role the marine tourism industry plays in presenting the area to the general public and its potential to work in partnership with managers to achieve best practice, sustainable use of the Marine Park. Through working cooperatively with the marine tourism industry, we aim to ensure a sustainable and vibrant future for tourism on the Great Barrier Reef.


References

Great Barrier Reef Marine Park Authority 2000, Tourism Operator’s Handbook for the Great Barrier Reef, Great Barrier Reef Marine Park Authority, Townsville.

Harriott V (in press), Marine Tourism Impacts and their Management on the Great Barrier Reef, CRC Reef Research Centre Technical Report No. 46, CRC Reef Research Centre, Townsville.

Ilett A, Aiello R, Power M, Recchia C & Saunders L 2000, 'The Great Barrier Reef World Heritage area - Ecotourism in the world’s largest marine protected area’, in T Charters & K Law (eds), Best Practice Ecotourism in Queensland, Tourism Queensland, Brisbane, pp. 65-80.

Ilett A, Skeat H, Thomas C, Bonanno V & Green E (in press), Managing Tourism Sustainably - lessons learned on the Great Barrier Reef, Australia, Proceedings of the Ninth Meeting of the International Coral Reef Symposium, Bali.

Off the Cairns coastline are outer edge ribbon reefs which may be up to 25 kilometres long. This is the outer limits of the continental shoreline of prehistoric times. The ribbon reefs can be seen by taking one of the daily outer reef cruises offered by local operators. One of the best ways to view the reef is to take a low flying scenic flight over it, especially at low tide where you'll see the breadth and diversity of this great living wonder.

The waters of the Great Barrier Reef provide the world's busiest and most varied marine habitats. Marine life is in abundance. From the many species of coral to the sought after Black Marlin and all sizes and species of fish in-between. The varied colours of the reef's fish and other marine life will astound the visitor with colour combinations that artists haven't even dreamed of. It is the largest of the world’s 552 World Heritage Areas, covering 347,000 km There are more than 2800 catalogued reefs in the area.

Although stretching more than 2000 kilometres offshore from Queensland, it is only at Cape Tribulation, just north of Port Douglas that the reefs come right to the shore and meets the tropical rainforests of the Wet Tropics. With over 1000 islands which are easily accessible from North Queensland and coastal cities like Cairns and Port Douglas. The coral islands are very popular tourist attractions. Some even have varied vegetation including rainforest and are encircled by the coral reefs. Accommodation on the islands that are inhabited ranges from camping grounds to bungalows and luxurious resorts.