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?

Ocean acidification is primarily caused by the absorption of excess carbon dioxide by the oceans, leading to a decrease in pH. This phenomenon has several critical impacts on marine ecosystems.

1. The growth and survival of calcareous phytoplankton will be adversely affected. Correct. Ocean acidification reduces the availability of carbonate ions, which are essential building blocks for organisms that form shells or skeletons from calcium carbonate (calcification). Calcareous phytoplankton, such as coccolithophores, rely on these ions and will struggle to grow and survive.

2. The growth and survival of coral reefs will be adversely affected. Correct. Coral reefs are built by corals that secrete calcium carbonate skeletons. Reduced carbonate ion availability makes it harder for corals to build and maintain their structures, leading to slower growth, weakened skeletons, and increased vulnerability to erosion.

3. The survival of some animals that have phytoplanktonic larvae will be adversely affected. Correct. If calcareous phytoplankton (a crucial part of the marine food web) are negatively impacted, the food source for many marine larvae that feed on phytoplankton will diminish. This can lead to reduced survival rates for these larval stages, impacting the populations of various marine animals.

4. The cloud seeding and formation of clouds will be adversely affected. Incorrect. While there are complex interactions between ocean biology and atmospheric processes (e.g., some marine organisms produce aerosols that can influence cloud formation), the direct and primary concern of ocean acidification is not the adverse effect on cloud seeding (an artificial process) or natural cloud formation in the same direct and significant way as the biological impacts described in statements 1, 2, and 3. This is not considered a primary or immediate concern of ocean acidification.

Therefore, statements 1, 2, and 3 are correct.

The final answer is A