A database of 15,617 point measurements of dimethylsulfide (DMS) in surface waters along with lesser amounts of data for aqueous and particulate dimethylsulfoniopropionate concentration, chlorophyll concentration, sea surface salinity and temperature, and wind speed has been assembled. The database was processed to create a series of climatological annual and monthly 1°×1° latitude‐longitude squares of data. The results were compared to published fields of geophysical and biological parameters. No significant correlation was found between DMS and these parameters, and no simple algorithm could be found to create monthly fields of sea surface DMS concentration based on these parameters. Instead, an annual map of sea surface DMS was produced using an algorithm similar to that employed byConkright et al.[1994]. In this approach, a first‐guess field of DMS sea surface concentration measurements is created and then a correction to this field is generated based on actual measurements. Monthly sea surface grids of DMS were obtained using a similar scheme, but the sparsity of DMS measurements made the method difficult to implement. A scheme was used which projected actual data into months of the year where no data were otherwise present.

Concentrations of dimethylsulphide (DMS) and its precursor compound dimethylsulphoniopropionate (DMSP), two sulphur compounds that are involved in the formation of clouds, were measured for mucus ropes, coral mucus, surface films and sediment pore waters collected from three coral reefs in the Great Barrier Reef, Australia. The concentrations of DMS (61–18 665 nm) and DMSP (1978–54 381 nm) measured in mucus rope samples are the highest yet reported in the marine environment. The values exceed concentrations of DMS and DMSP reported from highly productive polar waters and sea ice algal communities. Concentrations of DMSP in coral mucus ranged from 1226 to 25 443 nm, with mucus from Acropora formosa containing the highest levels of DMSP. Dimethylsulphide and DMSP in surface microlayer samples from three coral reefs were two to four times subsurface (0.5 m) concentrations. In coral-reef sediment pore waters, concentrations of DMS and DMSP were substantially higher than water-column concentrations, suggesting that coral sediments may be a significant source of these two compounds to reef waters. Overall, the results strongly suggest that coral reefs in the Great Barrier Reef are significant sources of these two sulphur substances.