What is a major effect of ocean acidification?

The correct choice highlights that ocean acidification significantly harms marine ecosystems and organisms. Ocean acidification occurs when excess carbon dioxide (CO2) from the atmosphere is absorbed by the oceans, leading to a decrease in pH levels. This process creates a more acidic environment that negatively impacts marine life, particularly organisms that depend on calcium carbonate to build their shells and skeletons, such as corals, mollusks, and some plankton species.

As these organisms struggle to maintain their calcium carbonate structures, there can be far-reaching consequences for the entire marine food web and ecosystem. Coral reefs, which are vital habitats for many marine species, suffer from reduced growth rates and increased susceptibility to disease in acidic conditions. Consequently, the health of marine ecosystems is compromised, leading to declines in biodiversity and the overall functioning of these environments.

In contrast, the other options do not align with the well-documented impacts of ocean acidification. Increased fishing yields, enhanced coral reef growth, and improved oceanic air quality are unlikely outcomes in the context of rising ocean acidity.