Coral Bleaching & Acidification

Question 1

Which short explanation correctly describes both how higher water temperature makes corals turn white and how increased carbon dioxide in the ocean hurts their skeletons?

Accepted Answer

When water gets too warm, coral polyps become stressed and push out the zooxanthellae that give them color, so they turn white. At the same time, the extra CO₂ turns into carbonic acid, which lowers the seawater’s pH and slowly melts the calcium‑carbonate skeletons.

Answer

Higher water temperature makes zooxanthellae multiply, giving corals brighter colors, while CO₂ makes the water more basic, helping the skeleton grow faster.

Answer

Warm water causes corals to release oxygen, which turns them white, and the CO₂ reacts with salt to create a protective coating on the skeleton.

Answer

When the ocean warms, corals eat more zooxanthellae for energy, but the CO₂ only changes the water’s temperature, not its chemistry.

Question 2

Which brief statement best explains both why a rise in sea temperature makes corals turn white and how increasing carbon dioxide weakens their calcium‑carbonate skeletons?

Accepted Answer

Higher water temperature stresses coral polyps, causing them to expel their zooxanthellae, which makes the coral look white; at the same time, more CO₂ dissolves in seawater, forming carbonic acid that lowers pH and slowly dissolves the calcium‑carbonate skeleton.

Answer

Warmer water makes the zooxanthellae grow faster, turning the coral white, and the extra CO₂ makes the water more alkaline, which strengthens the coral skeleton.

Answer

Heat causes corals to release their zooxanthellae, so they lose color, and the CO₂ reacts with the skeleton directly, turning calcium carbonate into a harmless gas.

Answer

When water gets warm, corals die instantly and lose their skeleton, while CO₂ removes all the oxygen from the water, making it impossible for any marine life to survive.

Question 3

Which explanation best describes (1) why a coral that experiences a 3 °C rise in water temperature loses its color, and (2) how an increase in atmospheric CO₂ to about 450 ppm weakens the coral’s calcium‑carbonate skeleton?

Accepted Answer

The higher temperature stresses the coral, causing it to expel the photosynthetic zooxanthellae that give it color, so the tissue looks white; the extra CO₂ dissolves in seawater to form carbonic acid, lowering pH and reducing carbonate ions, which makes the calcium‑carbonate skeleton dissolve more easily.

Answer

The heat kills the zooxanthellae, so they stop making pigment and the coral turns white; the added CO₂ reacts with calcium in the water to create solid calcium carbonate that blocks the coral’s pores.

Answer

Warmer water makes the coral’s own cells stop producing pigment, causing bleaching; the increased CO₂ directly corrodes the skeleton like a battery acid, independent of pH.

Answer

The temperature rise forces the coral to release its sugars, which makes it appear white; the higher CO₂ simply makes the water more acidic, which dissolves the coral’s proteins, not the skeleton.

Try three questions

Which short explanation correctly describes both how higher water temperature makes corals turn white and how increased carbon dioxide in the ocean hurts their skeletons?

Which brief statement best explains both why a rise in sea temperature makes corals turn white and how increasing carbon dioxide weakens their calcium‑carbonate skeletons?

Which explanation best describes (1) why a coral that experiences a 3 °C rise in water temperature loses its color, and (2) how an increase in atmospheric CO₂ to about 450 ppm weakens the coral’s calcium‑carbonate skeleton?

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