TURNOVER OF DIMETHYLSULFONIOPROPIONATE AND DIMETHYLSULFIDE IN THE MARINE-ENVIRONMENT - A MESOCOSM EXPERIMENT

The production of dimethylsulfoniopropionate (DMSP) by marine phytopla nkton and the fate of the produced DMSP and dimethylsulfide (DMS) were studied in 4 pelagic mesocosms during an algal bloom over a period of 1 mo. Bacterial numbers, concentrations of particulate and dissolved DMSP, DMS, and chlorophyll a were monitored, as well as the turnover r ates of DMS and DMSP. Of the total amount of DMSP produced, only a fra ction could be detected as DMS in the water column. DMS production in the water column did not necessarily correlate with algal senescence, but also occurred during the maximum of the algal bloom. The flux of D MS to the atmosphere played a minor role as a sink for DMS. Evidence i s presented that shows bacterial consumption to be a major sink for DM S, under conditions of both high and low DMS water concentrations. DMS P was degraded either via cleavage or via demethylation; the results i ndicate a predominant role for the latter route.