Acidity @ Ocean Thermal Vents Comparable To Projected Ph By 2100 Destroyed 20 Of 24 Foram Species

ScienceDaily (Aug. 31, 2010) — A unique 'natural laboratory' in the Mediterranean Sea is revealing the effects of rising carbon dioxide levels on life in the oceans. The results show a bleak future for marine life as ocean acidity rises, and suggest that similar lowering of ocean pH levels may have been responsible for massive extinctions in the past.

The scientists, from the University of Plymouth and the University of Santa Catarina, Brazil, studied a single celled organisms called Foraminifera around volcanic carbon dioxide vents off Naples in Italy. The study, published in the September issue of the Journal of the Geological Society, found that increasing CO2 levels caused foram diversity to fall from 24 species to only 4.

'Previous studies have shown a reduction in diversity of 30%, but this is even bigger for forams', said Dr Jason Hall-Spencer, one of the study's co-authors. 'A tipping point occurs at mean pH 7.8. This is the pH level predicted for the end of this century'.

Rising carbon dioxide levels acidify the ocean, which has a particularly devastating effect on organisms that have calcium carbonate shells, like Foraminifera. 'Forams are well preserved in the fossil record, which is why we chose to study them', says Dr Hall-Spencer. 'We knew the results were likely to show a decline in foram diversity but we weren't expecting such a seismic shift'. Forams record past events in the geological record -- in particular, the effect of the Palaeocene-Eocene Thermal Maximum (PETM), a period of massive carbon release and rapid warming, 55 million years ago, accompanied by extinctions in marine life. It is also thought to have seen a period of ocean acidification.

EDIT

http://www.sciencedaily.com/releases/2010/08/100825093651.htm