More acidic ocean could spell trouble for marine life's earli...( Increasingly acidic conditions in th...)

Increasingly acidic conditions in the oceanbrought on as a direct result of rising carbon dioxide levels in the atmospherecould spell trouble for the earliest stages of marine life, according to a new report in the August 5th issue of Current Biology, a publication of Cell Press. Levels of acidification predicted by the year 2100 could slash the fertilization success of sea urchins by an estimated 25 percent, the study shows.

" If other marine species respond similarlyand there's no evidence yet that they don'tthen we're in trouble," said Jon Havenhand of the University of Gothenburg in Sweden. "The analogies are quite simple: we observed a 25 percent reduction in fertilization success at reduced pH, which is equivalent to a 25 percent reduction in the spawning stock of the species. Apply equivalent changes to other commercially or ecologically important species, such as lobsters, crabs, abalone, clams, mussels, or even fish, and the consequences would be far-reaching. It could be enough to "tip" an ecosystem from one state to another." However, he emphasized, more data about the response of growing acidic conditions on more species is needed before any such extrapolation can be made.

Widely cited estimates show that the average level of acidity in the oceans has risen by about 25 percent in the last 150 years, since the advent of fossil fuel burning, Havenhand explained. The most recent data show that levels of ocean acidification predicted for the end of this centuryabout a three-fold increase over current levelshave already been measured in some coastal waters.

More acidic surface waters eventually will sink to the bottom of the ocean, but it's a process that takes some 1,000 to 1,200 years. That long-term overturning circulation of the ocean has accommodated much higher atmospheric carbon dioxide levels in the past without resulting in the pH changes seen today. "The current problem is being caused by the rate of increase
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