Avgoustidi V, Nightingale PD, Joint I, Steinke M, Turner SM, Hopkins FE, Liss PS
DMS, mesocosm, acidification, review
The oceans have absorbed approximately half of theCO2 produced by human activities and it is inevitable thatsurface seawaters will become increasingly acidified. The effect of lower pH on marine organisms and ocean–atmosphereexchanges is largely unknown but organisms with CaCO3 structural components are likely to be particularly affected.Because calcifying phytoplankton are significant producers of dimethyl sulfide (DMS), it is vital to understand how lowerseawater pH may affect DMS production and emission to the atmosphere. Here we show, by mesocosm (Raunefjorden,Norway, April–May 2003) and in vitro studies, that the net production of DMS and its cellular precursor dimethylsulfoniopropionate(DMSP) is approximately halved in microbial communities subjected to doubled CO2 levels. Our findingsprovide evidence that the amount of DMS entering the atmosphere could decrease in the future. Because atmosphericoxidation ofDMScan lead to climate cooling by increasing cloud albedo, a consequence of reducedDMSemissions from alower pH ocean would be an enhancement in global warming.