Will shellfish soon be a thing of the past?

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You might like a big plate of them to ‘get you in the mood', but a new report is warning that animals such as oysters and mussels may be wiped out in years to come due to the acidification of the oceans.

Coming hot on the heels of a paper that suggests corals may be highly affected by acidification, Dr John Baxter, principal advisor in marine ecology for Scottish Natural Heritage, presented a report entitled 'Ocean Acidification: Questions Answered' earlier this month.

The report found that as levels of carbon dioxide released into the atmosphere increase due to a rise in industrialisation, acid levels in the waters of the world are gradually changing. 

If the trend continues, this will start to have a knock-on effect on the calcium carbonate shells of thousands of marine species as their shells are gradually eroded by the acid. This in turn will have a huge effect on other fish and marine life including certain types of plankton and species throughout the food chain.

While some species will adapt to the changing levels, others will be wiped out. As lobsters and crabs have shells with a different chemical composition, it is not clear how they will be affected by increasingly acidic sea water, the report says.

The last time the world witnessed serious ocean acidification, 55 million years ago, around 80% of sea species became extinct.

Over 440 billion metric tons of CO2 has been released into the atmosphere since the end of the first industrial revolution in the 1830s - with half of this generated in the past 30 years. The first major marine areas to be affected, says the report, are the northern oceans, while the Arctic Ocean is expected to be the first to reach a dangerous level of acidification with 10% of its area hitting the threshold at which damage will occur by the end of this decade.

Dr Baxter said: "The only way around this is for the amount of CO2 being released into the atmosphere to be reduced.

"To a certain extent, this can be done by carbon capture - when carbon released from power stations is trapped underneath the seabed and stopped from being released into the atmosphere - but, other than that, we just have to start using less fossil fuel."

The alternative is pretty worrying. Frighteningly, Dr Baxter predicts that if levels of atmospheric and oceanic CO2 continue to rise at current rates, by 2100 it is likely that the entire Arctic Ocean will be in a state that can dissolve unprotected calcium carbonate structures. There is even evidence already the shells of one species - the planktonic foraminifera - are now 30-35% lighter than their pre-industrial-era counterparts, demonstrating that the effect has already begun.