Keller, M. K. Bigelow Laboratory for Ocean Sciences, email@example.com
PRODUCTION AND DYNAMICS OF DMSP AND DMS IN UPPER SEA ICE PROTISTS
Total DMSP concentrations of 84-97 nM were observed in the upper 60 cm of annual land-fast ice in McMurdo Sound during late September and October. The samples were dominated by dinoflagellate cysts and chrysophyte statocysts. In early November, when temperatures in the upper ice rose, average DMSP concentrations in the ice abruptly increased to 293-996 nM. At this same time, chlorogenesis was observed in dinoflagellate cysts, indicating metabolic activity. These observations suggest that DMSP may be synthesized in resting stages of sea-ice flagellates and that a dramatic increase in DMSP may occur just prior to excystment. DMSP has not previously been reported in association with cysts. A very high level of DMSP, 6.57 mM, was observed in 136 psu brine collected from the ice in mid November, suggesting that DMSP may be lost from the ice during spring brine drainage. Laboratory observations of high DMSP concentrations in isolates of microalgae isolated from the sea ice support the potentially important role of brine protists in DMS release. A brine dinoflagellate isolated from the ice had intracellular levels of DMSP that were an order of magnitude higher than ice diatoms. High levels of DMSP in the brine may also support an active microbial community and microbial loop. These aspects will be discussed.