The physiology of dimethylsulfoniopropionate (DMSP) production in phytoplankton

Dimethylsulfoniopropionate (DMSP) is the precursor of dimethyl sulfide (DMS), the primary volatile organic sulfur compound released from the world's oceans. DMS flux from the oceans is estimated currently at {approximately}1.2 Tmol S.y{sup {minus}1}, or about half the amount of sulfur resulting from anthroprogenic activities, and has been implicated in important global atmospheric processes. Significant production of DMSP is confined to a few classes of marine phytoplankton, primarily the Dinophyceae and Prymnesiophyceae. In these groups, DMSP can account for up to 80% of total organic sulfur. DMSP remains intracellular and fairly constant over the growth cycle until late stationary phase when extracellular levels begin to rise, suggesting leakage. We have examined the effects of a number of environmental variables on DMSP production and release in several marine phytoplankton. In particular the effects of perturbations in light, temperature and nutrient status have been determined. These results will be discussed in relation to marine sulfur chemistry, with ancillary comments on freshwater phytoplankton.