Marine life faces ‘acid threat’

Man-made pollution is raising ocean acidity at least 10 times faster than previously thought, a study says.

Researchers say carbon dioxide levels are having a marked effect on the health of shellfish such as mussels.

They sampled coastal waters off the north-west Pacific coast of the US every half-hour for eight years.

The results, published in the journal PNAS, suggest that earlier climate change models may have underestimated the rate of ocean acidification.

Ocean pH

Professor Timothy Wootton from the department of ecology and evolution, University of Chicago, in Illinois, says such dramatic results were unexpected as it was thought that the huge ocean systems had the ability to absorb large quantities of CO2.

“It’s been thought pH in the open oceans is well buffered, so it’s surprising to see these fluctuations,” he said.

The findings showed that CO2 had lowered the water pH over time, demonstrating a year-on-year increase in acidity.

The research involved taking daily measurements of water pH levels, salinity and temperature, off the coast of Tatoosh island, a small outcrop lying in the Pacific Ocean, just off the north-western tip of Washington state, US.

As well as measuring physical factors, the health of marine life present in the coastal ecosystem was also tracked.

Professor Wootton says biological factors were missing from previous models of ocean climate systems – and that life in the ocean, or in this case on the ocean edge, can also affect seawater pH.

Julian Siddle, BBC News, 25 November 2008. Article.

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