What causes ocean acidification and what is a key ecological impact?

What causes ocean acidification and what is a key ecological impact?

• A. Decreased CO2 dissolves to form carbonic acid
• B. Increased CO2 dissolves to form carbonic acid, lowering pH
• C. Increased salinity causes acidity
• D. Sunlight breaks down carbonic acid

Answer: (B)

Rising atmospheric CO2 dissolves in seawater and forms carbonic acid, which releases hydrogen ions and lowers pH. This shift also reduces the availability of carbonate ions needed by calcifying organisms to build shells and skeletons. As a result, calcification slows, shells and skeletons become weaker, and reef-building organisms like corals struggle to grow, impacting reef structure and marine ecosystems. The other ideas don’t fit because decreasing CO2 would lessen carbonic acid, salinity isn’t the primary driver of ocean acidification, and sunlight doesn’t break down carbonic acid in seawater.

Rising atmospheric CO2 dissolves in seawater and forms carbonic acid, which releases hydrogen ions and lowers pH. This shift also reduces the availability of carbonate ions needed by calcifying organisms to build shells and skeletons. As a result, calcification slows, shells and skeletons become weaker, and reef-building organisms like corals struggle to grow, impacting reef structure and marine ecosystems. The other ideas don’t fit because decreasing CO2 would lessen carbonic acid, salinity isn’t the primary driver of ocean acidification, and sunlight doesn’t break down carbonic acid in seawater.