Question

Imagine a marked increase in dissolved carbon dioxide in warm shallow waters, where coral reefs exist. How could the increase in dissolved carbon dioxide MOST LIKELY affect the diversity of this ecosystem?
Responses
A Some organisms are unable to withstand the reduced pH levels and die.Some organisms are unable to withstand the reduced pH levels and die.
B These are perfect conditions for coral reefs, which support a vast diversity of living organisms.These are perfect conditions for coral reefs, which support a vast diversity of living organisms.
C Aquatic plants die because they are unable to carry out photosynthesis under the new conditions.Aquatic plants die because they are unable to carry out photosynthesis under the new conditions.
D The increased carbon dioxide causes an increase in dissolved oxygen also and more animals migrate to the area.The increased carbon dioxide causes an increase in dissolved oxygen also and more animals migrate to the area.
E There will be an increase in the aquatic plants growing in the area because of the increased carbon dioxide.

Answer 1

A

Increased dissolved CO2 causes ocean acidification (more H+ ions, lower pH), which reduces calcification and can directly stress or kill corals and other pH‑sensitive organisms. That loss of reef builders lowers habitat complexity and reduces overall biodiversity. Options B, C, D, and E are incorrect because higher CO2 harms (not helps) coral calcification, does not stop photosynthesis broadly, does not raise dissolved O2, and although some algae might grow more with extra CO2, the net effect on reef diversity is negative.