Coral Bleaching

Coral Bleaching Latest News

Recently, the seventh Status of Coral Reefs of the World report by the Global Coral Reef Monitoring Network (GCRMN) said that Coral bleaching events are becoming more frequent and recovery periods have shortened dramatically. 

About Coral Bleaching

• It occurs when corals experience stress in their environment due to changes in temperature, pollution or high levels of ocean acidity.
• Process of Coral Bleaching
  • Under stressed conditions, the zooxanthellae or food-producing algae living inside coral polyps start producing reactive oxygen species, which are not beneficial to the corals.
  • So, the corals expel the colour-giving zooxanthellae from their polyps, which expose their pale white exoskeleton, giving the corals a bleached appearance.
  • This also ends the symbiotic relationship that helps the corals to survive and grow.

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What Causes Coral Bleaching?

• Change in Ocean Temperature: Increased Ocean temperature caused by climate change is the leading cause of coral bleaching.
• Runoff and Pollution: Storm generated precipitation can rapidly dilute ocean water and runoff can carry pollutants, which can bleach near shore corals.
• Overexposure to sunlight: When temperatures are high, high solar irradiance contributes to bleaching in shallow water corals.
• Extremely low tides: Exposure to the air during extremely low tides can cause bleaching in shallow corals.

What are Corals?

• Corals are marine invertebrates or animals not possessing a spine.
• Each coral is called a polyp and thousands of such polyps live together to form a colony, which grows when polyps multiply to make copies of themselves.
• Corals share a symbiotic relationship with single-celled algae called zooxanthellae.
• The algae provide the coral with food and nutrients, which they make through photosynthesis, using the sun’s light.
• In turn, the corals give the algae a home and key nutrients. The zooxanthellae also give corals their bright colour.

Source: DTE