Catastrophic Coral Die-Off on Great Barrier Reef During 2016 Heatwave

Australia՚s Great Barrier Reef suffered “catastrophic die-off” of coral during extended heatwave in 2016, threatening broader range of reef life than previously feared. Scientists have recorded worst mass coral bleaching event on Australia՚s Great Barrier Reef.

Threats to Coral Reefs Climate Change
  • Scientists said some 30% of reef՚s coral died in heatwave from March to November 2016,1st of unprecedented 2 successive years of coral bleaching along 2,300-km World Heritage-listed reef off Australia՚s northeastern coast.
  • Central & southern sections of reef are fared far better, with only 6% & 1% of coral dead, respectively.

Corals Reefs

  • Coral reefs result from natural work of little polyps (few millimeters long) is budded on top of one another. They are most biologically diverse ecosystems of planet.
  • Over centuries, shells (mostly made up of Calcium Carbonate) of these corals combine to form exotic shapes of coral reefs.
  • Tiny differences in anatomy of each polyp species mainly affect shape of their shells & produce exotic shapes of each reef.

Conditions for Growth of Corals

  • Warm tropical oceans w⟋min. temp. of 20 degree. They are primarily located b⟋w 30 degree north & 25 degree south latitudes where water temp. favours growth of coral organisms; Transparent parts of ocean bodies Oceanic water must free of sedimentation; it should have relatively low salinity.
Conditions for Growth of Corals

Coral Bleaching

  • Coral bleaching causes corals to expel tiny photosynthetic algae, draining them of their colour. It calcifies corals to turn into white.
  • Algae are vital to coral, which uses organic products of photosynthesis to help it grow. Loss of algae makes it vulnerable to disease & it will eventually die.
  • When coral bleaches, it is not dead. They can recover if water temperature drops & algaeare able to re-colonise them.
  • Reasons: It occurs when abnormal environmental conditions, such as warmer sea temperatures.
  • In recent times unusual warm ocean water is mainly heated by man-made climate change & natural El Niño climate pattern.

Great Barrier Reef

  • It is biggest coral reef system in world composed of over 2,900 individual reefs. It was recorded as World Heritage site in 1981.
  • Reef is located in Coral Sea, north east of Australia & covers area of approx. 348,000 sq km.
  • It is credited as world՚s biggest single structure made by living organisms & is visible from outer space.

Examrace Team at Aug 21, 2021