What are coral reefs? What is their significance? Explain in detail the threats faced by them.

Corals are animals in the same class as jellyfish and anemones. They consist of individual polyps that get together and build reefs. They are important hotspots of biodiversity in the ocean.
Significance of Corals:

• They support a wide range of species.
• They maintain the quality of the coastal biosphere.
• Corals control the level of carbon dioxide in the water by converting it into a limestone shell.

Threats faced by Coral Reefs:

• Coral reefs are threatened by�climate change.
• Coral Bleaching: When�the sea surface temperature increases beyond a tolerable limit, they undergo a process of bleaching. The corals expel a certain algae known as�zooxanthellae, which live in the tissues of the coral in�a symbiotic relationship. When�a coral bleaches, it does not die but comes pretty close to it.
• These are also threatened by Plastic pollution in seas.

Recently it was found that�Sea surface temperature ranged from 28.7�C to 31�C in the August 2018-February 2019 period and there was no bleaching seen then. When the temperatures rose to between 32�C and 36�C between March 2019 and May 2019, researchers observed a pattern of bleaching in corals.