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. Ocean acidification refers to the ongoing decrease in the pH of the Earth's oceans, caused by the uptake of atmospheric carbon dioxide (CO2). This change in ocean chemistry poses significant threats to marine ecosystems. 2. Statement 1 is correct. Calcareous phytoplankton, such as coccolithophores, build their shells or plates from calcium carbonate. Increased acidity (lower pH) reduces the availability of carbonate ions, making it harder for these organisms to form and maintain their calcareous structures. This adversely affects their growth and survival. 3. Statement 2 is correct. Coral reefs are built by corals that secrete calcium carbonate skeletons. Ocean acidification directly hinders the ability of corals to calcify, leading to weaker skeletons, slower growth rates, and increased susceptibility to erosion. This severely impacts the growth and survival of coral reefs. 4. Statement 3 is correct. Many marine animals, including molluscs, crustaceans, and echinoderms, have planktonic larvae that often form calcium carbonate shells or skeletons early in their life cycle. These larval stages are particularly vulnerable to changes in ocean chemistry, and acidification can adversely affect their development and survival. 5. Statement 4 is generally considered incorrect as a primary, established concern of ocean acidification. While some phytoplankton produce dimethyl sulfide (DMS), which can influence cloud formation, the direct and significant impact of ocean acidification on cloud seeding and cloud formation across the globe is much less certain and established compared to the severe impacts on calcifying marine life. The primary concerns revolve around direct biological and ecological consequences.