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Climate Change and Coral Skeletons

As early as during their larval stage, corals are affected by ocean warming and acidification. Researchers show that exposure of coral larvae, Acropora millepora, to the conditions predicted to prevail by the end of the century weakens and distorts the skeletons of polyps derived from these larvae. Over time, they will have to revise their interpretation of the chemical composition of corals in terms of surface temperature and ocean pH.
Published on 4 July 2017

Some coral reefs get bleached as the acidity and temperature of the ocean increases, which is a threat to ecosystems that are highly productive and diverse. In this context, the first step of coral reproduction, the larval stage, is an interesting area of investigation.

In Australia, researchers have collected larvae of Acropora millepora, a species resilient to climate change, and grew them in culture in water (27 °C and 29 °C) at acidity conditions corresponding to those expected if the level of carbon dioxide in the atmosphere reaches 750 ppm by the end of the century.

As the precipitation of calcium carbonate is modified under these conditions, the polyp skeleton becomes brittle and its shape asymmetrical. Another effect is the disruption of the coral geochemical tracers commonly used in paleoclimate reconstructions.

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