Archer, S. D. CCMS, Plymouth Marine Laboratory,
Stelfox, C. D. CCMS, Plymouth Marine Laboratory,
Burkill, P. H. CCMS, Plymouth Marine Laboratory,

Microzooplankton herbivory is one process by which dimethylsulfoniopropionate (DMSP) contained in phytoplankton, is converted to dimethylsulfide (DMS). Several previous studies have illustrated the extent of conversion of algal DMSP to DMS as a result of grazing by microzooplankton in laboratory cultures. However, few if any studies have demonstrated or quantified this process in natural waters. We have developed a new model in the laboratory that has been applied to natural waters to quantify DMS production by microzooplankton. The model is based on the dilution technique that is used routinely to determine the impact of microzooplankton grazing on phytoplankton. Two DMSP-rich Prymnesiophyte taxa, Phaeocystis spp. and Emiliania huxleyi, produce intense blooms in northern temperate waters during the spring and summer, respectively. During field studies in the southern North Sea and northeast Atlantic in 1998, we found that microzooplankton are active grazers in waters containing E. huxleyi and Phaeocystis spp. Our modified dilution technique was used to quantify this grazing impact and to budget the production of dissolved DMSP and DMS that resulted from the grazing. The experiments confirm the importance of bacterial processes to dissolved DMSP and DMS turnover and provide an indication of these rates in relation to grazing-mediated production. We suggest that the technique provides a useful means by which some of the complex processes involved in the production of DMS in natural waters can be quantified and modelled.
Day: Friday, Feb. 5
Time: 11:15 - 11:30am
Location: Sweeney Center
Code: SS37FR1115S