Great Barrier Reef Scuba Dive Australia - Snorkel & Dive Great Barrier Reef - Overnight Liveaboard Diving Expeditions - Scuba Dive Courses

THE GREAT BARRIER REEF

The Great Barrier Reef is the world’s largest World Heritage area and the biggest tropical marine reserve. Only the Heard Island and McDonald Islands Marine Reserves in the Australian sub-Antarctic are larger. It is approximately 347,800 square kilometres in area and approximately 2,300 kilometres long, running from just north of Frazer Island near Bundaburg through to the tip of the Cape York Peninsula. When it comes to length, the Belize Barrier Reef (off the Caribbean coast of Belize) is a distant second at only 290 kilometres and Ningaloo Reef, off the coast of Western Australia, is just 280 kilometres.

The reef contains over 2,900 reefs which includes 760 fringing reefs, and 300 coral cays. There are also 618 continental islands, which were once part of the mainland.

As the world's largest coral reef ecosystem, the Great Barrier Reef is home to approximately 1,500 species of fish, 400 species of corals, 4,000 species of molluscs, 500 species of seaweed, 215 species of birds, 16 species of sea snake, six of the world's seven species of threatened marine turtles and some of the largest populations of dugong in the world.

There are more different species of animals and plants in a cubic metre of the Great Barrier Reef, than in any other environment in the world, including tropical rainforests.

"Coral spawning"
Every year over one third of the reef's 350 species of coral reproduce sexually during a mass spawning event. The majority of inner reefs spawn around November with the outer reefs spawning later in December. Spawning always takes place at night, and follows any time up to six days after the full moon. Eggs and sperm are released into the water where they eventually combine to form a free swimming planktonic larval stage.

SPECIES GALLERY

Hard corals:
Each no bigger than a fingernail, hard corals build reefs by growing atop the stony skeletons of previous coral colonies. Assuming such shapes as plates, domes, and branches, coral colonies have created the largest structures ever made by living things. But like any masterpiece, a coral reef takes time, growing about a half inch (1.3 centimetres) a year. Armed with tentacles that help them “fish” for meals of minute plankton, the individual corals, or polyps, are tubelike animals related to jellyfish and sea anemones. Unlike most of their cousins, though, corals harbour their own built-in food factories. 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 even gain a bit of added colour.

HUMAN THREATS

Overfishing
This type of grouper may be overfished in some parts of the Great Barrier—at least partly due to its popularity in Asia, where diners often order it live from restaurant aquariums. Concerns for the coral trout aside, fishing is strictly regulated on the Great Barrier, but countless other reefs aren’t so lucky. Elsewhere many are obliterated by blast fishing—in which reefs are often blown to bits in hopes of an easy catch—and cyanide poisoning, the dark secret of the aquarium trade. In cyanide fishing, divers generally squirt the toxin onto coral reefs, then search the newly dead reef for live-but-stunned fish—or so they hope. More than half of all fish caught this way die in the poisoning process or in shipping.

NATURAL THREATS

Crown-of-thorns sea star
Armed with poison spikes and an appetite for hard coral, adult crown-of-thorns sea stars can kill a reef. By projecting their stomachs out of their mouths and wrapping them around coral, they slowly devour it—or not so slowly if they’re out in force, which is increasingly the case. No one’s quite sure why crown-of-thorns epidemics are on the rise. Some believe they’re part of a natural cycle, like wildfires. Others think humans inspire the outbreaks, possibly by overfishing species that cull juvenile crown-of-thorns sea stars. Divers are sometimes trained to kill sea stars at popular dive sites, but there doesn’t seem to be a large-scale, responsible weapon against crown-of-thorns epidemics. For now, conservationists watch and wait—and hope afflicted areas bounce back.

Warming
When stressed, corals expel the algae that live in their transparent outer tissues, exposing the corals’ limestone skeletons. The most common cause of this bleaching is abnormally high ocean temperatures. Other culprits: inflows of fresh water, high ultraviolet radiation, and changes in salinity. Bleached coral isn’t necessarily dead coral, though, and it often regains its healthy colour when conditions return to normal. But prolonged bleaching can lead to coral death—one more way global warming and periodic climate shifts such as El Niño can change the face of the Earth.

You just can’t beat snorkelling and scuba diving on the Great Barrier Reef off Cairns, Queensland Australia. It’s one of the most amazing and diverse scuba diving locations in the world. From beginners to experienced divers, snorkellers and non-swimmers, there are dive trips and great barrier reef tours available to suit all budgets and levels of experience.

For personalised help with organising your 'Great Barrier Reef Experience' please contact us on:
info@great-barrier-reef-dive.com.au