Coral bleaching is the loss of algae causing the coral to turn white. What causes coral bleaching?

• Climate change which has drastically raised the temperature of ocean water has caused the corals to bleach

• Excess greenhouse gas especially CO2 absorbed by seawater causing ocean acidification dissolved the algae in the coral causing bleaching

Which of the above statements is/are correct?
a) 1 only
b) 2 only
c) Both 1 and 2
d) Neither 1 nor 2

Ans- [a]

Explanation– Water temperatures above than normal often results in coral bleaching. When water is too warm, corals expels the algae (zooxanthellae) living in their tissues causing them to turn completely white. When a coral bleaches, it is not dead. Corals can survive a bleaching event, they are just under huge stress.

This image very well explains it.

Ocean acidification slows down the growth of coral. Ocean absorbs one-third of the atmosphere’s excess carbon dioxide. This makes the ocean acidic which reacts with limestone skeleton of corals and dissolves them. In order for a coral reef to grow, it must produce limestone at a rate that is faster than the reef is being eroded. This slows down the growth.