Coral Bleaching

coral reefs

Coral reefs are large underwater structures composed of the skeletons of colonial marine invertebrates called corals. Even though they may appear as colourful plants, they are, in fact, made up of tiny animals called polyps. These polyps secrete limestone skeletons, or calicles, to protect their delicate bodies by adding support.

coral reefs formation

Calicles secreted by the polyps connect to one another, creating a colony that acts as a single organism. As these colonies grow over thousands of years, they become reefs that can grow multiple hundred miles long. The largest coral reef is Australia’s Great Barrier Reef, which began growing about 20,000 years ago, and spans over 1,200 miles today.

coral bleaching

Coral Bleaching, in simple words, is the loss of colours from the polyp, resulting in them turning white. The bright and vibrant colours of the corals, like green, brown, pink, yellow, red, purple and blue come from the microscopic algae present in them, called zooxanthellae. Even the slightest of environmental changes can result in the coral expelling the algae and therefore, losing its colour.

Causes

The corals lose their colour on stress, which occurs mainly due to the water turning very warm. The water can turn warm due to extreme heat conditions, overexposure to the heat of the sun, and thermal pollution caused by industries. If the temperature were to rise by even 2 degrees Fahrenheit, the coral fades and looks as though it has been bleached. Coral once bleached, can return to its original colour only if conditions are reversed, but this process can take up to three years.

Solution

The main cause of coral bleaching is global warming. The solution to this is none other than reducing our carbon footprint and replacing fossil fuels with sustainable energy.

Corals are known as the “Rainforest of the Ocean” and it is a pity that they are getting bleached all across the globe due to global warming, from the Great Barrier Reef of Gold Coast in Australia to the North-western Hawaiian Islands of the United States.