0 1998, by the American Society of Limnology and Oceanography, Inc Biological production of methyl bromide by cultures of marine phytoplankton

Methyl bromide production was followed in cultures of a selection of marine phytoplankton species throughout their growth cycle. The cultures were species common to coastal and(or) open ocean areas, as well as originating from various latitudinal bands. Methyl bromide was produced by 13 out of 19 species tested, with production rates ranging from 1.7 to 30.1 pg CH,Br,ug- ’ Chl a d-l. Species that are strictly coastal or more abundant in coastal areas appeared to be stronger producers of CH,Br than species that are more abundant in open ocean areas. The prymnesiophyte Phaeocystis sp., a bloom-forming, ubiquitous species, showed the highest daily production rate normalized to Chl a of 30.1 pg CH,Br pg- ’ Chl a d-l. The range of methyl bromide production by the phytoplankton cultures tested suggests that the input of methyl bromide by marine phytoplankton can be significant in coastal oceans. Methyl bromide (CH,Br) is the most abundant form of gaseous bromine in the atmosphere (Khalil et al. 1993; El-liott and Rowland 1993; Schauffler et al. 1993). Average concentrations of CH,Br in the atmosphere are- 10 parts per trillion by volume (pptv, 10-12) (Khalil et al. 1993; Lob