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.

QUESTION

Hard

Environment & Ecology

Prelims 2012

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

The growth and survival of calcareous phytoplankton will be adversely affected.
The growth and survival of coral reefs will be adversely affected.
The survival of some animals that have phytoplanktonic larvae will be adversely affected.
The cloud seeding and formation of clouds will be adversely affected.

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Explanation

Statement 1 is Correct: Calcareous phytoplankton, such as coccolithophores, rely on carbonate ions to build their calcium carbonate shells. Ocean acidification reduces the availability of these ions, which adversely affects their ability to calcify, grow, and survive.

Statement 2 is Correct: Coral reefs are primarily composed of calcium carbonate. Increased ocean acidity lowers the calcium carbonate saturation state, making it harder for corals to build their skeletons and potentially causing existing reef structures to dissolve.

Statement 3 is Correct: Many marine invertebrates (like mollusks and echinoderms) have planktonic larvae that are highly sensitive to changes in seawater chemistry. Acidification can impair their development and shell formation during these vulnerable early life stages, leading to increased mortality.

Statement 4 is Incorrect: While some scientific research suggests a complex link where acidification might reduce the production of dimethyl sulfide (DMS)—a gas that contributes to cloud condensation nuclei—this is considered an indirect climatic feedback rather than a primary direct impact. According to the official UPSC answer key, this statement is excluded from the correct causes of concern.

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