Nature Climate Change - Southern Ocean Acidification On Track For Food Chain "Avalanche" By 2030

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The Southern Ocean is acidifying at such a rate because of rising carbon dioxide emissions that large regions may be inhospitable for key organisms in the food chain to survive as soon as 2030, new US research has found. Tiny pteropods, snail-like creatures that play an important role in the food web, will lose their ability to form shells as oceans absorb more of the CO2 from the atmosphere, a process already observed over short periods in areas close to the Antarctic coast.

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Below a certain pH level, shells of such creatures become more brittle, with implications for fisheries that feed off them since pteropods appear unable to evolve fast enough to cope with the rapidly changing conditions.

"For pteropods it may be very difficult because they can't run around without a shell," Professor Timmermann said. "It's not they dissolve immediately but there's a much higher energy requirement for them to form the shells." Given the sheer scale of the marine creatures involved, "take away this biomass, [and] you have avalanche effects for the rest of the food web", he said.

As carbon dioxide levels rise, the impacts seen in the Southern Ocean – and its counterpart regions in the northern hemisphere – can be expected to spread closer to the equator.

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http://www.smh.com.au/environment/climate-change/abrupt-changes-in-food-chains-predicted-as-southern-ocean-acidifies-fast-study-20151030-gknd2g.html