Coral Reefs

Otherwordly images reveal coral skeleton-building

Pupa Gilbert

Coral reefs are under constant threat from climate change.

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Major storms and heat waves can cause corals to bleach, making them even more vulnerable.

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We hear about ocean acidification as another threat to corals — but some but some corals seem resistant to acidification.

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A new paper in the Proceedings of the National Academy of Sciences has shed new light on the skeleton-building process and suggests that rising temperatures — not acidification — should be our first concern.

Pupa Gilbert

Using a special kind of microscope, the scientists witnessed corals building their skeletons up close.

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Coral reefs are made of a mineral called aragonite, a crystalline form of calcium carbonate.

Pupa Gilbert

They build their skeletons by absorbing carbonate, bicarbonate, and calcium from seawater and creating calcium carbonate.

Ocean acidification is thought to hinder this process.

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Pupa Gilbert

It’s been previously assumed that the coral skeleton is in direct contact with seawater as the skeleton develops, and that more acidic seawater can hinder skeleton-building.

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But the new images show that skeleton-building takes place in between the coral’s living tissue and its skeleton — separate from seawater.

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"If there are to be coral reef remediation strategies, they should not focus on countering ocean acidification, they should focus on countering ocean warming,” lead author Pupa Gilbert says in a statement.

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Gilbert is a physicist who specialises in biominerals. “To save coral reefs we should lower the temperature,” not focus on regulating the acidity of the oceans, she says.

Read more science and nature stories here.

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