Grim warning on ocean shells

Global warming could dissolve the shells of marine life as oceans become more acidic, scientists in Hobart said yesterday.
Shell-life in the Southern Ocean will face the acid test first, because colder waters will become acidic faster.

Researchers investigating the effects of ocean acidity left Hobart aboard the Aurora Australis yesterday — its first voyage for the summer season.

A major focus of research in Antarctica this season will be the future of shells in an increasingly acidic environment.

Scientist Dr Andrew Davidson, who left for his 15th expedition, said the forecast was that in the next 20 to 30 years some Antarctic marine life would be unable to make shells. Eventually shells in all oceans could be under threat.

He said oceans were becoming more acidic as a direct result of more carbon dioxide in the atmosphere.

Dr Davidson said carbon dioxide dissolved in sea water, forming carbonic acid — leaving the ocean more acidic.

“The resulting increase in ocean acidity interferes with the formation of calcium carbonate, a major structural component of the shells of many important planktonic organisms,” he said.

Dr Davidson said these tiny sea creatures would be unable to form shells in an acidic ocean because their shells would dissolve as they were trying to form.

He said the ramifications were huge, with all Antarctic marine life potentially affected if there was a threat to the marine microbes at the bottom of the food chain.

“The colder the ocean is, the more carbon dioxide it can dissolve. Therefore the impacts of ocean acidification will appear first in the icy Southern Ocean,” he said.

He said the research would investigate the affects of ocean acidity on microbial communities of phytoplankton, protozoa and bacteria.

The research will also investigate the affects of global warming on snow depth and ice thickness.

Voyage leader Dr Tony Worby, who is on his 16th voyage, said a team would be developing a remote instrument to measure ice depth from an aircraft.

He said global warming could have affects on snow and how much of it settled on the ice.

Snow depth is important because it determines the amount of light filtering through to the marine life in the sea ice.

Anne Mather,, 13 October 2008. Article.

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