Enhanced production of oceanic dimethylsulfide resulting from CO2-induced grazing activity in a high CO2 world

Abstract

Oceanic dimethylsulfide (DMS) released to the atmosphere affects the Earth’sradiation budget through nucleation of cloud condensation and growth of nuclei over the oceans. However, it is as-yet-known about 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 pCO2 of ~900 ppmv at ambient temperature conditions, and a pCO2 of ~900 ppmv at a temperature ~3°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 should be expected in high CO2 oceans in the future.