UPSC Prelims 2012 · Question 50 of 98

UPSC Prelims 2012 question on Ocean Acidification

The acidification of oceans is increasing. Why is this phenomenon a cause of concern?

1. The growth and survival of calcareous phytoplankton will be adversely affected.

2. The growth and survival of coral reefs will be adversely affected.

3. The survival of some animals that have phytoplanktonic larvae will be adversely affected.

4. The cloud seeding and formation of clouds will be adversely affected.

Which of the statements given above is/are correct?

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

Answer: A. 1, 2 and 3 only

Verdict

Correct Answer: 1, 2 and 3 only

Analysis

Ocean acidification occurs when oceans absorb excess atmospheric carbon dioxide, leading to a fall in seawater pH.

It mainly affects marine organisms that depend on calcium carbonate shells or skeletons.

Statement by statement

1. The growth and survival of calcareous phytoplankton will be adversely affected — Correct

Calcareous phytoplankton, such as coccolithophores, need carbonate ions to build calcium carbonate shells.

Ocean acidification reduces carbonate ion availability, making shell formation difficult.

2. The growth and survival of coral reefs will be adversely affected — Correct

Corals build calcium carbonate skeletons.

Acidification reduces calcification, weakens coral skeletons and makes reefs more vulnerable to erosion and damage.

3. The survival of some animals that have phytoplanktonic larvae will be adversely affected — Correct

Many marine animals have larvae that are sensitive to changes in seawater chemistry.

Ocean acidification can affect larval growth, development and survival.

4. The cloud seeding and formation of clouds will be adversely affected — Incorrect

This is not a direct or well-established primary impact of ocean acidification for this question.

Do not confuse indirect research links with standard biological impacts of ocean acidification.

Extra UPSC info

* Ocean acidification is often called the “other CO2 problem”.

* Oceans absorb a large share of atmospheric carbon dioxide.

* Dissolved CO2 forms carbonic acid, which increases hydrogen ion concentration.

* Increased acidity reduces carbonate ions needed by corals, molluscs and plankton.

* Acidification can disturb marine food chains because plankton form the base of many marine ecosystems.

* Coral reefs are also threatened by ocean warming, bleaching, pollution and destructive fishing.

How to crack it

Ocean acidification mainly threatens calcifying plankton, coral reefs and sensitive marine larvae, but cloud formation is not a standard direct concern in this context.

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