Historically, the earth's ocean had a pH of 8.2. In recent years, it has dropped to 8.1. How might this change affect the ocean environment?

A. The skeletons of coral will become soft due to increased acidity.

B. The rise in alkalinity will make the ocean unfit for certain ocean plants.

C. At 8.1, the ocean has reached neutral pH, making it identical to pure water.

D. The ocean's CO2 content will decrease, improving the environment for animals.

The answers are the letter A. The skeletons of coral will become soft due to increased acidity. and the letter B. The rise in alkalinity will make the ocean unfit for certain ocean plants. The acidification of the water is the alteration of the pH of the water up to values considered acidic. It is a serious problem of aquatic ecosystems. Many organisms are not able to survive in an acidic environment (low pH values), which increases their mortality. Additionally a considerable part of the oceans' plant and animal life, from phytoplankton (which is the basis of the marine food chain) to coral reefs and a variety of shellfish and molluscs form their shells by fixing calcium and carbonate from seawater to form calcium carbonate. As the pH of the seawater decreases, the availability of carbonate drastically decreases. Below certain pH levels it becomes practically impossible for these organisms to form their shells and skeletons.