Enhanced Production of Oceanic Dimethylsulfide Resulting from CO2-Induced Grazing Activity in a High CO2 World

Oceanic dimethylsulfide (DMS) released to the atmosphere affects the Earth's radiation budget through the production and growth of cloud condensation nuclei over the oceans. However, it is not yet known whether this negative climate feedback mechanism will intensify or weaken in oceans characterized by high CO2 levels and warm temperatures. To investigate the effects of two emerging environmental threats (ocean acidification and warming) on marine DMS production, we performed a perturbation experiment in a coastal environment. Two sets of CO2 and temperature conditions (a pCO(2) of similar to 900 ppmv at ambient temperature conditions, and a pCO(2) of similar to 900 ppmv at a temperature similar to 3 degrees C warmer than ambient) significantly stimulated the grazing rate and the growth rate of heterotrophic dinoflagellates (ubiquitous marine microzooplankton). The increased grazing rate resulted in considerable DMS production. Our results indicate that increased grazing-induced DMS production may occur in high CO2 oceans in the future.