Marine ecosystems could be radically altered by ocean acidification resulting from increasing levels of atmospheric CO2, say researchers presenting at the Society for General Microbiology's spring meeting.

As a result of it's impact on fish stocks and erosion of coral reefs, researchers say ocean acidification could also have serious socioeconomic ramifications as well. 

The team simulated ocean acidification as predicted by current trends of carbon dioxide (CO2) emissions and found that the decrease in ocean pH (increased acidity) resulted in a sharp decline of a biogeochemically important group of bacteria known as the Marine Roseobacter clade.

"This is the first time that a highly important bacterial group has been observed to decline in significant numbers with only a modest decrease in pH," said lead author Michael Maguire.

The Marine Roseobacter clade is responsible for breaking down a sulphur compound called dimethylsulfoniopropionate (DMSP) that is produced by photosynthesising plankton. This end product is taken up and used by numerous bacteria as an important source of sulphur.

 A fraction of DMSP is turned into Dimethylsulfide (DMS) – a naturally occurring gas that influences the Earth's climate. DMS encourages the formation of clouds which reflect solar radiation back into space leading to a cooling of the earth's surface.

It's possible, the authors say, that the decline of the Marine Roseobacter clade through ocean acidification may alter the release of DMS into the atmosphere and affect the amount of available sulphur. This could have a significant impact on the ocean's productivity and the overall global climate system.