Biological production of methyl bromide in the coastal waters of the North Sea and open ocean of the northeast Atlantic

Two separate studies in different oceanic regions provide evidence for the production of methyl bromide (CHBr) by the prymnesiophyte Phaeocystis. A sampling program to study the seasonal cycle of CHBr in a coastal area demonstrated that the seawater was supersaturated with respect to CHBr for over 3 months of the year. The greatest saturation was observed during a bloom of Phaeocystis. Also, in situ field measurements demonstrated that CHBr was supersaturated over a large region of the northeast Atlantic. A positive correlation was observed between CHBr and dimethylsulphoniopropionate (DMSP), indicating that there was a source common to both compounds. An accessory pigment, hexanoyloxyfucoxanthin, which indicates the presence of prymnesiophytes, also correlated positively with CHBr.