The Australians scientists on 29 November 2016 announced that the Great Barrier Reef suffered from its worst coral die-off ever recorded.
The scientists stated that warm seas around the Great Barrier Reef have killed two-thirds of a 700 kilometers stretch of coral in the past nine months.
The northern region of the reef had escaped with minor damage in earlier bleaching events in 1998 and 2002.
• The reef suffered its most severe bleaching in recorded history, due to warming sea temperatures during March 2016 and April 2016.
• The underwater surveys and aerial studies revealed that a 700-kilometre stretch of reefs in the less-accessible north lost two-thirds of shallow-water corals in the past eight to nine months.
• Most of the losses in 2016 have occurred in the northern part of the Great Barrier Reef.
• There is a minimal damage in the central and southern regions, including major tourist areas around Cairns and the Whitsunday Islands, of the reef.
How did it get damaged?
• Bleaching of the 2300-kilometre long reef was one of the foremost reasons of the damage.
• Bleaching occurs when abnormal environmental conditions, such as warmer sea temperatures, cause corals to expel tiny photosynthetic algae, which in turn drain them of their colour.
• The coral uses the organic products of photosynthesis to help it grow. Therefore, algae are vital for them.
• The loss of algae makes the host vulnerable to disease, which will eventually make them die.
• However, coral can recover if the water temperature drops and the algae are able to recolonise them.
Will the damaged part ever recover?
• Scientists estimate that the northern region will take at least 10-15 years to regain lost corals. However, they are also are concerned that a fourth major bleaching event may occur before that, which will impede the recovery.
• Earlier in 2016, the reef studies centre have also warned that if greenhouse gas levels keep rising, then similar events would be the new normal.
• The reefs, which take plenty of time to recover from severe bleaching, it is likely to lose large parts of the Great Barrier Reef in just 20 years.
About Great Barrier Reef
• The Great Barrier Reef is the world's largest coral reef system.
• It is composed of over 2900 individual reefs and 900 islands.
• The reef is located in the Coral Sea, off the coast of Queensland, Australia.
• The reef is so vast that it can be seen from outer space.
• It is also the world's biggest single structure made by living organisms.
• This reef structure is composed of and built by billions of tiny organisms, known as coral polyps.
• In 1981, it was selected as a World Heritage Site.
• A large part of the reef is protected by the Great Barrier Reef Marine Park, which helps to limit the impact of human use.
• A study published in October 2012 by the Proceedings of the National Academy of Sciences revealed that the reef has lost more than half its coral cover since 1985.