The Impacts of Coral Bleaching

What are corals?

Corals are made up of hundreds to thousands of tiny coral creatures called polyps. Each soft-bodied polyps secretes a hard outer skeleton of limestone (calcium carbonate, CaCO3) that attaches either to rock or the dead skeletons of other polyps. The calcium carbonate is insoluble in water and hence form an impervous coating on the coral reef which protect the coral animals from predators and also offer a substrate on which new coral polyps can attach themselves.

What is coral bleaching?

When corals are stressed by changes in conditions such as temperature, light, or intake of nutrients, they expel the algae (zooxanthellae) living in their tissues, causing them to turn completely white. When a coral bleaches, it does not mean it is dead yet. If the bleaching is not severe, corals are able to recover. If the algae loss is prolonged and the stress continues, corals will eventually die. 

The leading cause of coral bleaching is climate change. As our Earth warms up, our oceans are also gradually warming, and a change in water temperature, as little as 1 degree Celsius, can cause coral to drive out algae.

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What is the rate of death of Coral reefs?

Half of the Great Barrier Reef has been bleached to death since 2016.   Thirty percent of the coral perished in 2016, another 20 percent perished in 2017.

How does coral bleaching impact wildlife?

Coral reefs support some of the most biodiverse ecosystems on Earth. Thousands of marine animals depend on coral reefs for survival. Coral reefs provide shelter, spawning grounds, and protection from predators. They also support organisms at the base of ocean food chains. As reef ecosystems collapse, endangered species may face extinction.   

How does coral bleaching impact humans?

Coral bleaching impacts peoples’ livelihoods, food security, and safety. Coral reefs are natural barriers that absorb the force of waves and storm surges, keeping coastal communities safe especially during any natural events. Without them, we must rely on man-made walls that are expensive, less effective, and environmentally damaging to construct. Bleached coral also add on to the overfishing crisis by removing links in the food web and depriving some marine species of a place to spawn and develop. Anyone relying on these animals as a primary source of food will face food shortage. Finally, reef tourism brings in billions of dollars each year and supports thousands of jobs. Bleached coral reefs, devoid of magnificent marine species, will jeopardise the people holding such jobs and the economy of the country. 

How can we help to reduce coral bleaching?   

We can start with small, daily actions such as reducing our carbon footprint by taking public transport instead of private transport. However in order to really save the corals, the issue of climate change must be addressed globally. Deforestation must be stopped. Businesses and consumers should use renewable energy instead of non-renewable energy. Each country’s government should also take the initiative to come up with some policies to tackle climate change issues. 

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