Time series data for the major compounds in the cycle of dime thylsulfide in open ocean water will be integrated with experimental studies to address controlling processes. DMS, DMSP, and DMSO will be measured in Bermuda waters in conjunction with the time-series studies at the Bermuda Atlantic Time-Series program. Complementary chemical and biological data collected as part of the JGOFS program will provide insights into the importance of blooms and phytoplankton speciation to the DMS cycle. Specific processes involved in the cycling of DMS, its precursors an its products, will be investigated in coordinated laboratory experiments. Time-series measurements and laboratory experiments will be linked by a series of short but intensive process-oriented field studies at the Bermuda site to test hypotheses derived from time-series and laboratory work. The major goal of the project is to identify and quantify the key controlling processes throughout the annual cycle.