Thursday, October 7, 2010
The future of oceans: 'toxic jellyfish and algae'
Acidifying oceans spell marine biological meltdown 'by end of century'
The Geological Society: 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 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.'...
'At a mean pH level of 7.8, calcified organisms begin to disappear, and non calcifying ones take over. We are headed towards that being the case in this century. The big concern for me is that unless we curb carbon emissions we risk mass extinctions, degrading coastal waters and encouraging outbreaks of toxic jellyfish and algae.'
Oceans are acidifying 10 times faster today than 55 million years ago when a mass extinction of marine species occurred
Ocean dead zones 'devoid of fish and seafood' are poised to expand and 'remain for thousands of years'
Image: pH trend vs. CO2 trend around Station ALOHA; source here.