ANNUAL CYCLE OF THE PRODUCTION AND FATE OF DMS AND DMSP IN A MARINE COASTAL SYSTEM

The production of DMSP by phytoplankton and the fate through the marin e system of both DMSP and DMS were followed for a period of 21 mo in t he natural environment by studying a Wadden Sea tidal inlet. The major production and emission of DMS appeared to be Limited to a period of only 2 mo, which was closely linked to the presence of phytoplankton b looms. The production of DMS in the water column was not well correlat ed with chlorophyll a concentrations or plankton species composition. It was however, found to be closely related to the start of a Phaeocys tis bloom early in spring. Contrary to our expectations, the senescenc e phase of this Phaeocystis bloom did not result in high DMS accumulat ion. It is postulated that this phenomenon could be the result of a ba cterial consumption which increased with time in combination with a de creasing DMSP-lyase activity of Phaeocystis. A simple model, into whic h the overall DMSP consumption could be introduced, could very well im itate the measured concentrations of DMS in the water column of the na tural system studied.