Question.
Give a reasoned account of Coral Bleaching. ( UPPSC 2020)
Answer.
Coral polyps are marine micro animals and they form symbiotic relationships with algae that provide 90% of the food for coral polyps. Coral polyps and algae together make up the colorful highly productive ecosystem of the ocean, also known as the tropical rainforest of the ocean.
What is Coral bleaching?
Under certain environmental conditions, corals expel the algae from their tissue and the coral appears white, this situation is called coral bleaching. Coral bleaching can be of short duration or of long duration. Coral polyps die after prolonged coral bleaching.
The following are the causes of coral bleaching:
- Warming of seawater
- Ocean acidification
- Increase in ocean pollution
- Increased sedimentation on seawater
Warming of seawater:
- A water temperature of 24 to 29 degrees centigrade is ideal for coral polyps to live in. Due to global warming or other reasons, if the seawater temperature increases by more than 29 degrees centigrade, then large-scale coral bleaching occurs.
For example, in 2016-17, large-scale coral bleaching occurred in the Great Rift Barrier in Australia due to warming ocean waters.
Ocean Acidification:
- Coral polyps can only survive in saltwater, but acid rain and the release of chemicals into ocean waters cause ocean acidification that causes coral bleaching.
Increase in ocean pollution:
- Due to human activities and pollution runoff, pollution of the ocean increases, due to which coral bleaching occurs.
Increase in sedimentation on seawater:
- Coral survive in sedimentary and mud-free waters, large-scale sedimentary water deposits called coastal areas due to river and surface runoff, which lead to coral bleaching.
- Give an account of recent observations on coral bleaching with reference to Clive Wilkinson's report. (UPSC 2014, 200 words, 15 marks)
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