thewisegardener.com continues as your portal to still more exotic tropical discovery by, this month, taking you on a cyber-tour of that fascinatingly unique treasure and Queensland's pride: The Great Barrier Reef Marine Park!! A true silenced awe is instilled when one tries to fathom the scope of The Great Barrier Reef!! It literally is a universe of life under (and on!) the waves of the tropical Coral Sea just of NE Queensland, Australia! A bit of geography, first, for those unfamiliar with the State of Queensland, Australia.
If you mixed Florida with a little bit of southern California, and then took out almost all the big cities, you’d have something like an American version of the state of Queensland. It’s where Australians go to play “tropic-truant”: to escape winter, to surf, to lie on the beach, and to visit the reef. Vacation villages and resorts of every type are strung along the coast and scattered throughout nearby islands.Unlike some ecosystems known for their diversity—a rain forest, for instance, where much of the life is shy, nocturnal, or hidden in the treetops—the Great Barrier Reef is a staggeringly accessible spectacle, yours for the looking. There is so much to see, swimming by or waving in the current or just spread out in a sunlit tableau, that a newcomer can suffer a sort of sensory shock at the profligacy of beauty.
Great Barrier Reef Quick Facts
What's a coral reef, and why it's SO amasing!!
A coral reef is composed of calcium carbonate, or limestone, derived from the water by the reef organisms: colonies of coral polyps and coralline algae. Most of this structure, the underlying foundation of the reef, is dead, made up of layer upon layer of coral skeletons. Coral animals are called polyps: tiny, primitive marine organisms. Each coral polyp is an individual organism, and the reef is made up of colonies of these organisms.
Individual reefs are composed of the accumulated skeletal remains of plants and animals, supporting a veneer of living plants and animals. An estimated 1500 species of fish and more than 300 species of hard reef-building corals, 4000 mollusc species, and 400 species of sponge have been identified.
At certain times of the year, a strange event occurs on the reef - a synchronised mass spawning. Sperm and eggs are released by the parent polyps, and the fertilised eggs drift in the water and develop into larvae. Millions upon millions of larvae are produced.
The living reef is just a veneer, but it's this living part that continually adds new construction. Though coral looks like a plant, it's really an animal: or rather, a colony of animals that belong to the cnideria (the same group as jellyfish and sea anemones). There are a multitude of different kinds of coral, about 350 species including both hard and soft varieties, on the Great Barrier Reef. Their shapes are very different, and their colours come in the hundreds!
It takes this huge production of sperm and eggs to ensure that just a small percentage of larvae will survive. The predators are overloaded - but even so, almost all larvae are eaten. The timing of the spawning is crucial. Tide and water temperature need to be just right, to ensure larvae survive. Those larvae that survive attach themselves as quickly as possible to anchorages like rocks or dead coral, and start to build new colonies. The polyp builds its own skeleton by secreting calcium carbonate.
Corals are frequently the dominant group on the reef because they have evolved to overcome the problem of low energy levels. They draw most of their energy from photosynthesis, from the algae that live in the tissues of corals, and supplement by feeding on microscopic animals that they catch with expanding tentacles. The tentacles contain stinging cells that immobilise the prey, which is then drawn to the polyp's mouth. The coral polyps feed, and grow, and eventually they die, and become part of the base structure of the reef.
From above, it’s apparent that the Great Barrier Reef is not one solid structure but an association of smaller reefs, sometimes close together, sometimes widely separated. There are upwards of 2,500 individual reefs within the Great Barrier Reef. The shallower water over each reef shimmers an iridescent turquoise, paler than the blue of the surrounding depths.
Paul, "The Wise Gardener!"
Great Barrier Reef Links: