great-barrier-reef
Liveaboard, Australia’s Great Barrier Reef the World’s largest Coral Reef covering over 350,000 square kilometres of the sea off the the tropical North Queensland coast of Australia in the Coral Sea

The Great Barrier Reef is on in the Coral Sea, off the coast of Queensland, north east Australia. It is the largest coral reef in the world and in 1981 was selected as a World Heritage Site because of the diversity of life living in the Great Barrier Reef.

The reef has the greatest diversity of life including the vulnerable and the endangered species.

Whales, dolphins and porpoise, 30 species in all have been recorded. Large dugongs live there as well as 1500 fish species

The Great Barrier Reef and its lagoon offer a wide variety of habitats for fishes and other marine organisms.  The outer part of this massive reef, where the clearest water is generally found, is divided into  zones.

Typically there is a broad outer reef flat, the inner part of which may be covered with fleshy algae and the outer part with encrusting coral line algae.  The reef flat is exposed during low spring tides.

At the Outer edge where the surf breaks, there is coral line algae rim, then the broad spur-and groove zone subject to strong surge from incoming waves and the scouring action of sand and rubble in the grooves from powerful water movement.  The grooves may extend as deep as 20 m.

Below the spur-and-groove zone there is usually an abrupt vertical escarpment which drops to 30 m or more this is followed by a gradual slope to the abyss.

Each of these zones has its characteristic assemblage of corals, algae an associated marine life.  The channels and passages through the reef both shallow and deep, provide still more habitats for which current is a major parameter.

On the sheltered side of the outer reef, as the water deepens slightly there’s is a zone of elongate patches of coral coral line algae, about 1-2 m wide and 20 m or more in length, separated by channels.

Then a broad zone of sand grading into depths of the lagoon.  Isolated on the sand substratum there are usually many small coral heads *called bommies in Australia), each a microcosm of marine organisms.

Within the deeper lagoon a variety of coral formations occur, some rising pinnacle-like form the deep water.

Corals growing in the sheltered lagoon water are often delicately branched.  Also in the lagoon are broad expanses of sea-grass beds.

Moving towards the mainland of Queensland, silty sand and mud habitats tend to dominate the lagoon floor.

The islets and larger islands of the Great Barrier Reef complex provide still more habitats such as rocky inter-tidal areas, sandy shores, and mangrove swamps.

Just as the outer reef zones harbour characteristic fish communities, so also do the lagoon habitats and many of the fishes seen there will not be found on exposed reefs.

The Great Barrier Reef is an ideal location to take a liveaboard scuba dive or snorkel trip.

There are many liveaboard trips that depart from the North Queensland coast for one night or a multiple of nights