Corals – Coral Reefs – UPSC GS1

  • Australia’s Great Barrier Reef, the world’s largest coral reef system, could suffer a bleaching event every two years by 2034 under the current level of greenhouse gas pollution, finds a new study.
What are Corals?
  • Corals are 500 million years old. Starting off as simple, solitary organisms, they have come a long way before evolving into the reefs we know today.
  • Over the years, corals formed colonies when conditions were favourable.
  • They withered in mass extinctions, only to reappear after each event in a different shape and form.
  • They have come and gone throughout the geological record. About 210 million years ago during the Triassic Period, things began to change.
  • A massive worldwide coral-reef expansion was taking place and the hitherto lonely corals met algae.
  • Corals began to offer algae shelter, while in return, the latter offered nutrients from photosynthesis.
  • Algae added colour to corals’ life. This symbiotic relationship has kept corals, algae and coral reefs alive all along.
  • Many times corals have had to expel algae for various reasons, mostly due to ocean warming.
  • And every time they expelled algae, the corals lost their colour ( bleached). The marine life that made the reefs their home have been left in the lurch. But they have always got back together, once the corals recovered. - Corals
Threat to Corals
  • But the bleaching experienced in the recent past has been different.
  • Scientists have predicted that the back-to-back severe bleaching events will leave little chance for recovery, especially in Australia’s Great Barrier Reef. This means two-thirds of the reef are dying.
  • According to a recent study published by the Climate Council, it has been found that the Great Barrier Reef could suffer a bleaching event every two years by 2034 under the current level of greenhouse gas pollution.
  • According to the study, 70 % of coral reefs will be at risk of long-term degradation by 2100 if the global temperature rises by 1.5 degrees Celsius above pre-industrial levels.
Significance of Corals
  • Coral reefs provide habitats for one in four marine species.
  • Reefs also form crucial barriers protecting coastlines from storms.
  • They provide billions of dollars in revenue for countries from tourism and fishing.
  • Many of the compounds are used in human medicines.

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