Coral Reefs- What Are They & Threats to Them

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Known to thrive well in the tropical oceans, coral reefs are one of the most beautiful and spectacular ecosystems in the world displaying varied colors and are home to diverse marine plants and animals. Of these , the great barrier reef off the coast of north eastern Australia has a special distinction of being the largest living structure on the earth, stretching for more than 2000 Km, and is even visible from outer space. Such is it’s  aesthetic significance that it is counted as one of the seven natural wonders of the world.

Thousands of tiny living organisms, called coral polyps, together form a colony or a coral reef. They control the level of carbon dioxide in the ocean waters by using it to make hard limestone  skeletons. The increased levels of CO2 in the oceans, if not used up by these tiny beings, can adversely affect both human beings and other animals. The term ” barrier” in the Great barrier reef is significant as it protects the coastline from wave action. The reef acts as a hindrance to the fast moving waves and lowers their speed, thereby protecting the life and property along the coastlines. The diversity of plants and animals inhabiting this ecosystem are an important source of both food and income globally.

Corals are animals and are unable to prepare their own food while a photosynthetic micro algae called zooxanthellae is in search of a protected habitat. This makes both of them enter into a symbiotic relationship mutually benefiting each other. The algae lives in the tissues of the corals and provides it with essential nutrients. The incredible colors of the coral reefs are also attributable to the presence of this micro algae without which they would have appeared ghostly.

Climate change due to the ever increasing use of fossil fuels is showing its impact on these underwater creatures as well. Burning of fossil fuels has increased the levels of dissolved CO2 in the oceanic waters and has also soared the underwater temperatures. Zooxanthellae, has the capacity to tolerate only very narrow ranges of both temperature and pH levels. Dissolved levels of CO2 creates weak carbonic acid which makes the ocean waters more acidic beyond its range of tolerance. Once the conditions become unfavorable, the algae tends to leave the corals and starts looking for more favorable conditions. This leaves the corals colorless with no source of food. Such a state when corals become stressed and white with little or no nutrients is called coral bleaching. The corals in this case do not die but only become weak because of food deficiency. But with time, if favorable conditions are not restored, they are burdened by the piling up of brown-green algae and other organisms and eventually die.

According to a survey of the great barrier reef, 93% of the reefs have been bleached as a result of mining activities and the burning of fossil fuels. Moreover, the permission given by the Govt. of Australia to Adani Group for its mining activities in Queensland has raised  concern from various stakeholders who have taken a legal route to counter the decision. Strict norms need to be enforced and awareness about this fragile ecosystem needs to be created to reverse the growing trend of coral bleaching. Avoiding excess of nutrients from entering the oceans can prevent harmful algal blooms, which have an adverse effect and can even kill the reefs.

The recent discovery of a coral reef at the mouth of the Amazon River is a news worth rejoicing but it is to be seen that it does not meet the same fate as the Great Barrier Reef. Efforts to protect this newly found reef from human intervention should be taken in advance before the signs of bleaching occur.

Industrialization, increasing rapidly in the developing countries cannot be stopped altogether but should be done in a responsible manner with the least possible use of fossil fuels. The developed countries, which have already benefited from industrialization,  should come forward and provide both financial and technological aid to the developing ones. Renewable energy has to be given topmost priority so that there is minimum damage to the environment and the increasing temperatures could be arrested.

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