ANNUAL MONITORING OF DMS-PRODUCING BACTERIA IN TOKYO BAY, JAPAN, IN RELATION TO DMSP

The population of dimethylsulfide (DMS)-producing bacteria together wi th the DMS and dimethylsulfoniopropionate (DMSP) concentrations were m onitored from July 1995 to August 1996 in Tokyo Bay, Japan. The concen tration of DMS varied widely in the range from 2 to 130 nM, and the to tal, dissolved and particulate DMSP concentrations varied from 5 to 22 0 nM, from below the detection Limit to 75 nM, and from 5 to 200 nM, r espectively. The observed particulate DMSP concentration was well expl ained by the DMSP attributable to Dinophyceae, estimated from the spec ies-specific DMSP per cell contents. The population of DMS-producing b acteria enumerated by the Most Probable Number method was in the range from 1.6 x 10(3) to 9.2 x 10(4) cells ml(-1). A positive relationship was found between the population of DMS-producing bacteria and the to tal DMSP concentration in some months, suggesting an important role of bacteria in DMS production. However, some other data points showed th e small population of DMS-producing bacteria in spite of the high conc entrations of DMS and total DMSP. These data did not agree with the ab ove relationship and suggest a contribution of non-bacterial DMS produ ction under certain circumstances.