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Coastal Ocean More Acidic Than Anticipated

Ocean water along the continental shelf of western North America is becoming more acidic and will likely have negative impacts on marine ecosystems, such as the corrosion of calcium carbonate exoskeletons in many organisms, according to Feely et al. in Science 22 May 2008.

By using data from 13 survey lines stretching from the waters of central Canada to northern Mexico, Richard A. Feely and colleagues found lower pH levels in seawater closer to the surface than researchers had predicted. They suggest that this is due to increased levels of human-induced carbon dioxide emissions, which are responsible for the phenomenon known as "ocean acidification," and are causing more dramatic effects earlier than ever anticipated. The reaction of carbon dioxide with seawater reduces the availability of carbonate ions that are necessary to make calcium carbonate, the compound that a number of marine organisms' skeletons and shells are made of. Previous studies show these marine organisms to be sensitive to such changes in their environment, and more information is now required to assess the scope of potential damage to these marine fragile ecosystems.

''Obviously, this situation will get worse with time as we continue to release more fossil CO2 into the atmosphere'' says Richard Feely.

While a consensus is reached that acidification may negatively impact ocean ecosystems, the species shift may not be as easy to determine among calcifying pelagic organisms. A recent study by Iglesias-Rodriguez et al. suggests that coccolithophorids may be more resistant to lower ocean pH than previously thought (more…).

IMAGE The distribution of the observed surface seawater temperture during our cruise along the Pacific continental margin in May-June 2007. The very low temperatures near the coast of northern California is indicative of the upwelling signal along the coast. These cold waters, which are enriched-CO2 and have very low pH values, form the core of the upwelled waters that are corrosive to aragonitic shells. [Courtesy of Dana Greeley and Simone Alin of PMEL]

Reference
R.A. Feely, C.L. Sabine, J.M. Hernandez-Ayon, D. Ianson, B. Hales, 2008. Evidence for Upwelling of Corrosive 'Acidified' Water onto the Continental Shelf, Science 22 May

RELEVANT LINKS:
- Bleak future for acid oceans - Nature 6 June 2008
- Ocean Acidification – an EUROCEANS film in French and English with the participation of James Orr and Jean-Pierre Gattuso
- Ocean Acidification Network - http://www.ocean-acidification.net/
- Ocean Acidification – An information outlet on ocean acidification moderated by Jean-Pierre Gattuso http://oceanacidification.wordpress.com/



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