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Corals - Shanmugam IAS academy in coimbatore - UPSC/TNPSC


What’s in news?

An inspection was on corals growing on tables in the Red sea as a part of research carried out by the Interuniversity Institute for Marine Sciences near the Southern Israeli city of Eilat.

Key data’s:

  • As coral reefs around the world face growing danger from a changing climate, scientists are researching new interventions that have the potential to slow coral reef damage from warming and acidifying oceans. 
  • A new report from the National Academies of Sciences, Engineering, and Medicine examines these resilience tools and provides decision-makers with a process they can follow in considering whether to use one or more of the novel approaches.

What are corals?

  • Corals are a kind of calcareous rock, chiefly made of the skeletons of minute sea organisms called ‘polyps’.
  • Though they are very tiny creatures, their ability to secrete calcium carbonate within their tiny cells has given rise to a particular type of marine landform. The landforms are popularly known as coral reefs.
  • Coral reefs and atolls are formed due to the accumulation and compaction of the skeletons of these lime secreting organisms.
  • Corals reefs are one of the most diverse habitats in the ocean. It is commonly known as the rainforest of oceans.
  • There are two major types of corals: hard corals and soft corals, such as sea fans and gorgonians. Only hard corals build reefs. While the majority of coral reefs are found in tropical and sub-tropical waters, there are also deep water corals in colder regions. 
  • According to the United Nations Environment Programme, there are more cold-water coral reefs (largest cold-water coral reef is the Rost Reef off Norway) worldwide than tropical reefs.

Conditions for Growth of Coral Reefs:

  • The surface water temperature of the ocean must not be less than 20 degrees Celsius. The condition virtually limits the areal distribution of corals to the tropical, and sub-tropical zones.
  • Corals can live only in saline water, and for their proper growth the average salinity should be between 27 to 40%.
  • For the growth of coral the depth of the water should not exceed 200m. Most vigorous growth is confined to shallow water less than 50 m. deep.
  • Corals also require sediment-free, clean water, which is disturbed by ocean waves and currents is beneficial for the corals.
  • In the open seas it is necessary to have platforms which may act as foundations for the corals. These platforms should not be deeper than 90 m.

Types of Coral Reefs:

The three main types of coral reefs include,

  • Fringing Reefs
  • Barrier Reefs
  • Atolls

Importance of Coral Reefs:

  • It is a source of food for millions of marine species.
  • It protects coastlines from storms and erosion.
  • It is a source of new medicines.
  • It assists in carbon and nitrogen fixing as well as helping with nutrient recycling.

Coral Bleaching:

Bleaching refers to the paling of coral color. It occurs when

  • The density of zooxanthellae residing inside the reef’s declines.
  • The concentration of photosynthetic pigments within the zooxanthellae fall.


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