Acidic oceans pose future threat to shellfish

US ocean scientist Dr Todd Capson considers the challenge of ocean acidification. Photo by Craig Baxter.
US ocean scientist Dr Todd Capson considers the challenge of ocean acidification. Photo by Craig Baxter.
There is no room for complacency about the threat ocean acidification poses to New Zealand's lucrative shellfish industry.

That warning came yesterday from a leading United States ocean scientist and policy adviser, Dr Todd Capson, of the US-linked Sustainable Fisheries Partnership.

Dr Capson is in Dunedin to give a talk today on ''Protecting our global ocean heritage'' at the University of Otago's 49th annual Foreign Policy School.

Dr Capson, of Washington, DC, helped initiate a joint US-New Zealand ocean acidification workshop held in Nelson last year. Since a major blow in 2007 to aquaculture efforts in the US northwest, including Washington State, the US industry had been well aware of the dangers posed by ocean acidification, he said.

New Zealand was not facing immediate damage to its $350-million-a-year aquaculture industry, but there was growing concern within the New Zealand industry and among government agencies about the need to avoid future problems.

''A lot of people see it as a tsunami,'' he said.

It was not a question of if ocean acidification would affect New Zealand, but when, and that could be within five to 10 years.

''This is Chemistry 101- it's entirely straightforward,'' he said.

Excessive human production of carbon dioxide, including through burning fossil fuels, increased the amount of carbon dioxide absorbed in the world's oceans, increasing in carbonic acid production.

And then there was a reduction in the carbonate needed to create the calcium carbonate used to build shells for shellfish.

Much was to be gained through international collaboration, and New Zealand was developing a world-leading coastal network to monitor acidification levels, he said.