UPSC Prelims 2014 · Question 81 of 100

UPSC Prelims 2014 question on Coral Reefs India

Which of the following have coral reefs?

1. Andaman and Nicobar Islands
2. Gulf of Kachchh
3. Gulf of Mannar
4. Sundarbans

Select the correct answer using the code given below.

  1. 1, 2 and 3 only
  2. 2 and 4 only
  3. 1 and 3 only
  4. 1, 2, 3 and 4
Show answer

Answer: A. 1, 2 and 3 only

Verdict

The answer is 1, 2 and 3 only. The Andaman and Nicobar Islands, the Gulf of Kachchh and the Gulf of Mannar have coral reefs; the Sundarbans does not.

Analysis

Statements 1, 2 and 3 are CORRECT. These are three of India's four major reef areas, the fourth being Lakshadweep. Statement 4 is INCORRECT. The Sundarbans is a deltaic mangrove ecosystem where the Ganga and Brahmaputra discharge enormous volumes of fresh water and silt. Corals need clear, warm, saline, sediment free water with light reaching the zooxanthellae in their tissues, and a turbid delta provides the opposite of every one of those conditions.

Source

India Year Book and reporting on threats to Indian reef ecosystems.

How to crack it

Rule out reef locations by physical conditions rather than by recall. Corals fail where rivers deliver fresh water and silt, so any delta or major river mouth is automatically out. That one test removes the Sundarbans without knowing anything else, and it also explains why India's reefs cluster in island groups and in shallow gulfs away from big river discharge. Learn the four reef areas as a set and the physical reason behind them, and the whole family of questions becomes deducible.

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