Crabs and urchins fight back against acid seas

A thin skin may be all that is required for corals, oysters, mussels and other marine organisms with shells to defend themselves from the looming threat of ocean acidification, say researchers (Frank Pope writes).

An organic layer covering the skeletons and shells of certain species can protect them from corrosion by seawater whose chemistry has been changed by atmospheric carton dioxide, even allowing them to build shells more rapidly.

Jason Hall-Spencer, a marine biologist at the University of Plymouth and colleagues looked at the effect of increased acidity on corals, mussels and limpets by transplanting them to a volcanic “natural laboratory” off Italy, where
conditions mimic the surface ocean chemistry predicted to occur around the world by the end of this century.

According to the established chemistry of “calcifiers”, all of them should have suffered thinner shells as a result of the increased acidity. But some species, such as lobsters, crabs and urchins, left, are able to lay down more calcium carbonate.

“We found that the species that are able to calcify at higher CO2 levels are able to do so “if they protect themselves with a periostracum — a varnish-like skin,” Dr Hall-Spencer said. “If you feed mussels and oysters plenty of food they can cope with CO levels beyond those that are expected to occur.” The findings are published in the journal Nature Climate Change

The Times (Scotland), 22 August 2011. Paper web site.

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