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Ocean Acidification a Real Threat to Shellfish

NEW ZEALAND - Bluff's oyster fisheries in Foveaux Strait may be at the top of a hit list of species vulnerable to increasing acidity levels in the oceans, New Zealand scientists say.

But reports, distributed by the New Zealand Press Association, say that the global phenomenon of ocean acidification may pose a threat not only to New Zealand's fisheries and aquaculture industries, but to marine ecosystems around the world, according to the national science academy, the Royal Society.

A National Institute of Water and Atmospheric Research (Niwa) scientist at the university, Dr Philip Boyd, said kina, mussels, oysters, and paua were among important coastal species which could be affected.

In the open ocean micro-organisms such as some plankton at the base of global food webs may be left with weaker and thinner shells.

"We will see a significant 'tipping point' in terms of ocean chemistry by as early as 2030," said Dr Boyd. "We may see the shells of some of these 'calcifiers' dissolve".

Both scientists emphasised there were huge gaps in knowledge of how marine life and ecosystems would change, but said the only plausible way to slow down the changes was to reduce emissions of carbon dioxide.

Coastal organisms may have extra resilience because the conditions in which they live vary naturally, and corals in the southern fjords may also have some adaptions in place because of acidic tannins in bush run-off.

But Antarctic ecosystems will be very vulnerable, because colder water can take up more carbon dioxide, and many cold-water organisms such as corals are slow-growing.

Proposals for helping aquaculture adapt have included breeding species capable of tolerating acidity, reducing the acidity of water in which larval stages develop, and changing the species farmed.

the Fish Site Editor

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