Scientists Explore Risks of Ocean Acidification

By EASTON, Paul

NEW ZEALAND scientists have met at the University of Otago to explore the threat more acidic oceans might pose to the health of marine life.

The meeting followed mounting international concerns that oceans are absorbing increasing amounts of carbon dioxide, causing seawater to become more acidic.

The workshop was New Zealand’s first on ocean acidification and its implications, co-organiser Catriona Hurd said.

Two dozen scientists from the university, Niwa and other organisations met to discuss the issues and identify the top research priorities for New Zealand.

“Ocean acidifications’ future impact on marine eco-systems and fisheries could be huge. The more acidic sea water becomes, the more it threatens to dissolve the carbonate skeletons that protect many marine organisms.”

Over the past couple of centuries the average ocean pH has lowered from 8.2 to 8.1.

With carbon dioxide being soaked up in ever-larger amounts, this trend was projected to continue, said Dr Hurd.

Coral reefs are vulnerable to the effects of acidification, as are important New Zealand fisheries such as green-lipped mussels. Phytoplankton, vital to the marine food chain, is also threatened by the phenomenon.

“This is doubly concerning because not only are they a primary source of food for higher organisms, phytoplankton blooms also play an important role in removing CO2 from seawater.”

Coralline algae, which provide chemical cues for the larvae of paua and kina to settle, was also susceptible, she said.

These algae make up about 80 per cent of the cover for Otago’s sub-tidal rock shelves.

Researchers from the university’s botany, chemistry and marine sciences departments gathered with Niwa scientists from Greta Point and representatives from Victoria University and the Fisheries Ministry at the workshop.

“We hope that this cross- disciplinary meeting of minds will lead to the establishment of a long- term collaborative research effort,” said Dr Hurd.

No work has previously been done on what ocean acidification might mean for the New Zealand marine environment, which ranges from sub- tropical to sub-Antarctic.

As the effects of acidification were more marked in colder waters, Otago was a perfect base from which to study the phenomenon, she said.

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