DIMETHYLSULFIDE IN A LARGE-SCALE COCCOLITHOPHORE BLOOM IN THE GULF OF MAINE

Blooms of the coccolithophore, Emiliania huxleyi, are common phenomena in the Gulf of Maine in early summer, as revealed by AVHRR imagery. It is known from laboratory cultures and some field studies that the production of the important volatile sulfur compound, DMS, and its precursor, DMSP, are confined largely to a few classes of phytoplankton, specifically the Dinophyceae and the Prymnesiophyceae, which includes the coccolithophores. In the Gulf of Maine, concentrations of DMS and DMSP were as much as an order of magnitude higher within a E. huxleyi bloom than at stations outside the bloom area, including stations with high phytoplankton biomass of other taxa. Values of both DMS and DMSP were highest in the mixed layer, with depth maxima associated with the chlorophyll maxima, generally at 10-15 m. In addition, higher levels of DMS and dissolved DMSP were associated with older parts of the bloom, as determined by numbers of loose coccoliths. This is the first example in nature where DMS production is related, not only to a given species of algae, but also to the stage of the bloom.