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Friday, June 26, 2009

Coral Reefs and the Great Barrier Reef

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In seas and oceans, there exist many waves -resistant walls of lime stone. These walls are called as Coral Reefs. Who makes coral reefs? Well, a big team of coral polyps…. But what are coral polyps? Coral Polyps are solitary or colonial marine animals with soft and sac like bodies. These tiny animals secrete Aragonite, a type of lime stone which accumulates to form high ridges called as reefs. Thus we can define a coral reef as - massive wave- resistant walls of corals built by coral polyps in oceans. In some areas of an ocean, coral reefs grow high enough to take the shape of a barrier in the ocean. The example of such an oceanic barrier is the Great Barrier Reef, which can be seen even from the space. It stretches itself 1,200 miles off of the east of Queensland; Australia.

The Great Barrier Reef is the largest marine preserve in the world. It harbors about 500 species of beautifully coloured corals; 4000 kinds of shell fish, and 1,500 types of other fish species; besides vast varieties of algae and millions of varieties of consumers.

Coral reefs provide shelter to specific algae that live inside them in mutually beneficial relationship called as symbiosis. Besides algae, varieties of colorful fishes also receive shelter in coral reefs. These reefs are so rich in animals that these are called as "rain forests of the sea". A number of sea-slugs, sea- anemones, sea- urchins, worms, parrot fish, angel fish, damselfish, and butterfly fish, and star fishes move around coral reefs and often take shelter in them. Thus coral reefs support an extraordinary biodiversity. Different colours of coral reefs are due to different colours of algae living in them. Now, what are algae? Algae is a plural of alga which means – variously coloured delicate plants found in water, having no distinction of true roots, stems, leaves etc.

The famous English poet Jein Morris has composed a beautiful poem about coral reef a few lines of which are –


"Cradle to Myriads of species
Millennia to create
Moments to destroy…"

The famous conservationist of the world Rachel Carson has written –
"There has long been a belief that sea, at least, was inviolate, beyond man's ability to change and to
despoil. But this belief, unfortunately, has proved to be naïve".

Both of these writings and many more by the world famous conservationists show that the treasure of our oceans – the coral reefs are in danger now. Here are some important facts about coral reefs –

(i). 10 percent of the world's coral reefs have been destroyed completely.
(ii). Over 70 percent of the coral reefs have been destroyed in Philippines alone.

There are two broad reasons behind the destruction of coral reefs- direct human activities and indirect human activities. The direct human activities that destroy coral reefs include- dynamite fishing which is the act of blowing up a coral reef with explosives and then catching all the stunned fish swimming around. The dynamite fishing destroys not only the coral reefs; it kills the coral polyps also that make the coral reefs.Indirect human activities that cause destruction of coral reefs include activities of land development, pollutions of land and water, destruction of mangrove vegetation, soil erosion along river- banks, global warming due to increasing concentration of carbon dioxide gas in the atmosphere,, extensive fish catch by way of using sodium cyanides, and ocean acidification by increasing carbon dioxide in oceans. The increasing absorption of carbon dioxide in the oceanic water forms carbonic acid which tends to dissolve the
materials of coral reefs.

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