How does ocean acidification primarily affect marine life?

Ocean acidification primarily affects marine life by decreasing the availability of carbonate ions in seawater. This phenomenon occurs when carbon dioxide (CO2) from the atmosphere is absorbed by the ocean, leading to a chemical reaction that forms carbonic acid. This acid then dissociates, resulting in a lower pH level in ocean water and a decrease in carbonate ion concentration.

Carbonate ions are essential for many marine organisms, especially those that build calcium carbonate structures such as mollusks, corals, and some plankton species. Without sufficient carbonate ions, these organisms struggle to form their shells and skeletons, which can ultimately lead to decreased populations and biodiversity in marine ecosystems. For example, corals rely on carbonate ions to secrete their calcium carbonate skeletons; if their availability diminishes, it affects coral growth and structural integrity, further impacting the marine environment.

The other options presented are not consistent with the scientific understanding of ocean acidification. Improved fish reproduction rates, increased plankton populations, and enhanced coral growth are not supported by evidence, as these outcomes would typically result from more favorable environmental conditions rather than the adverse effects of ocean acidification. Therefore, the primary mechanism through which ocean acidification impacts marine life is by reducing carbonate ion availability, making