Context: The Mumbai civic body recently received the green signal from the Principal Chief Conservator of Forests (Wildlife), Nagpur, for translocating the corals off the coast of Mumbai for the Rs 12,700-crore Mumbai Coastal Road Project.

More on the news:

  • Corals in Mumbai: The Mumbai coast hosts a tiny population of corals. The corals found across rocky patches along the Mumbai coastline are mostly fast-growing and non-reef building corals.
  • The National Institute of Oceanography (NIO), appointed to study the presence of marine biodiversity along with the Coastal Road project area, has identified 
    • Six coral species at Worli and Haji Ali:
    • Two species of the Rhizangiidae family (Oulangia and one unidentified species), 
    • 18 colonies were documented across 0.251 square meters in Worli; along with another species (Dendrophylliidae family) , Rhizangiidae across 1.1 square foot area at Haji Ali.

The translocation of corals

  •  Survival rate of translocated corals:
    • Some experts are of the view that for a high survival rate, it is important to translocate corals in a place with similar environmental characteristics such as depth, current flow, amount of light, and pressure.
    • Experts have suggested to the NIO and BMC to undertake the translocation post-monsoon, when the colonies would likely be healthy.
  • Experiments along the Indian coastline:
    • In India translocation of corals is at a nascent stage.
    • Pilot projects at the Lakshadweep islands, and off the coast of Kutch and Tamil Nadu have been undertaken to study the survival rate, method and site of translocation, and creation of high heat-resistant coral colonies, etc.
    • In a project in Sindhudurg, corals were cultivated fragments of corals were taken and attached to concrete frames with the help of nylon threads and then left on ocean beds at a depth suitable for their growth.
    • In a project at the Andaman islands, ReefWatch Marine Conservation has transplanted coral fragments on to nine artificial structures, totalling a 20-square-metre area. 


About Corals

  • They exhibit characteristics of plants, but are marine animals that are related to jellyfish and anemones.
  • Coral polyps: 
    • They are tiny, soft-bodied organisms. 
    • At their base is a hard, protective limestone skeleton called a calicle, which forms the structure of coral reefs.
  • Construction of reefs:
    • Reefs begin when a polyp attaches itself to a rock on the seafloor, then divides, or buds, into thousands of clones. 
    • The polyp calicles then connect to one another, creating a colony that acts as a single organism.
    • As colonies grow over hundreds and thousands of years, they join with other colonies and become reefs.
  • Types of corals: There are soft corals as well, which are non-reef-building, and resemble bushes, grasses, trees.
  • Significance:
    • Coral reefs maintain the quality of the coastal biosphere and support a wide range of species.
    • Corals convert the carbon dioxide in the water into a limestone shell and thus control the level of carbon dioxide in the water. 
    • This maintains the amount of carbon dioxide in the ocean water and thus saves ecological niches from destruction.
    • Coral reefs also act as ‘wave breaks’ between the sea and the coastline and minimise the impact of sea erosion. 
    • In India, they are protected in the same way as the tiger or elephant, under Schedule I of the Wildlife Protection Act (WPA), 1972.
  • Threat to coral reefs:
    • Climate change remains one of the biggest threats to corals.
    • Around the world, this threat has been visible in the “bleaching” of coral
      • Bleaching of corals is a process during which corals, under stress from warm weather, expel the algae that give corals their brilliant colours and live in their tissues and produce their food. 
      • Few examples of beaching are as follows
        • The Great Barrier Reef off the coast of Australia, has suffered six mass bleaching events due to warmer than normal ocean temperatures: in 1998, 2002, 2006, 2016, 2017, and now 2020.
        • Experts have documented bleaching of the corals along Mumbai’s coastline as well.