Oysters will fail the acid test

SYDNEY oyster lovers are in for an unpalatable surprise. A global conference in Monaco next week on the rising acidity of the world’s oceans will hear research that shows a detrimental effect on local oyster species.

The chemistry of seawater has been changing as a result of burning fossil fuels and the soaring amounts of carbon dioxide that have entered the atmosphere.

A Sydney marine biologist, Laura Parker, will tell the conference that the Sydney rock oyster will be especially vulnerable to the rise in seawater acidity that is expected to take place over the next few decades.

Ms Parker’s experiments found the fertility levels of the Sydney rock oyster and the Pacific oyster plummet when they are exposed to a small rise in seawater acidity. When she combined rising acidity with the rise in water temperature expected as a result of climate change, the abnormalities in the offspring were even worse.

“I thought they would have an impact but not as badly as the results showed,” Ms Parker told the Herald yesterday just before leaving for the world conference, which is supported by UNESCO.

Ms Parker has been working with a senior scientist at the NSW Department of Primary Industries and deliberately focused her research on the famous oyster to alert people to the growing problem of ocean acidification.

The Sydney rock oyster industry is the most valuable fishery in NSW, earning about $38 million a year. But it is just one of many fisheries around the world that scientists fear will be threatened by the changing chemistry.

The Monaco conference will bring together ocean scientists from Australia, Britain, France, Germany, the US, Japan, Spain and many other nations hoping to understand the phenomenon of ocean acidification, a term that was coined only in 2004.

Scientists from the Australian Antarctic Division and the University of Hobart who have led efforts at investigating acidification in the Southern Ocean will also be attending.

Scientists say the problem comes on top of global warming, which is also caused by rising emissions of carbon dioxide and other greenhouse gases.

The ocean absorbs about 30 per cent of the carbon dioxide humans release in the burning of fossil fuels and other activities. When the carbon dioxide dissolves in seawater, it forms carbonic acid.

Marian Wilkinson, The Sydney Morning Herald, 4 October 2008. Article.

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