Global warming may hurt oysters

Acid threatens delicacy

Global warming could put Bluff oysters at risk from a new marine threat as acidity levels in oceans continue to rise, according to scientists.

A Royal Society of New Zealand report says concerns exist about ocean acidification and its potential, within decades, to severely affect marine organisms, food webs, biodiversity, and fisheries.

Oceans are becoming more acidic as they store more carbon dioxide from the rising levels in Earth's atmosphere, the report says.

University of Otago climate change expert Professor Keith Hunter said carbon dioxide was also more soluble in colder water and that could put Bluff oysters, from the chilly waters of Foveaux Strait, at the top of a hit list of vulnerable species. "It depends on the organisms, but the earliest we might expect to see if something is vulnerable to ocean acidity will be 2030."

Carbon dioxide-saturated oceans pose a threat to corals, crustaceans and shellfish because they may thin the calcium carbonate shells of both adult and juvenile organisms, Professor Hunter said.

Mussels, Pacific and Bluff oysters, paua, and scallops make up a $300 million industry.

The society is planning to hold a workshop on the issue in Wellington on September 9.

Prof Hunter said its purpose was to make the Government and agencies with interests in the marine environment aware of the potential problem and discuss ways it could be addressed.

Barnes Oysters manager Graeme Wright was not aware of the report when contacted by The Southland Times but said it would likely be raised at the next Bluff oyster fisheries planning group meeting later this year.

It was too early to speculate about how the industry could be affected but he would be pay close attention to what came out of the September workshop, he said.

"At the end of the day, it's tied in with climate change and I don't know if we can do anything about it. We can't go round putting masks on all the oysters."

Prof Hunter said Australian research had shown Sydney rock oysters could be selectively bred to tolerate higher levels of acidity. "There may be some future for the aquaculture industry to adapt," he said.

- © Fairfax NZ News