Simó, R. Institut de Cičncies del Mar (CSIC), rsimo@icm.csic.es
Pedrós-Alió, C. Institut de Cičncies del Mar (CSIC), cpedros@icm.csic.es
Massana, R. Institut de Cičncies del Mar, ramonm@icm.csic.es
Díez, B. Institut de Cičncies del Mar (CSIC), bdiez@icm.csic.es

 
SHORT-TERM VARIABILITY IN THE BIOLOGICAL CYCLING OF DMS IN THE OPEN OCEAN
 
Speciation and turnover of dimethylated sulfur compounds were measured during a lagrangian experiment in the North Atlantic during June/July 1998. Surface samples were taken once a day to obtain a time series of DMS, DMSPp, DMSPd, DMSOp and DMSOd concentrations in the same water mass. DMS production and consumption rates were measured with the 'inhibitor addition' technique (DMDS) in dark incubations. DMSP consumption rates were estimated from net concentration curves in the non-inhibited incubations. Among the most significant results, good correlation between DMSPp and DMSOp was apparent, with a mean DMSPp/DMSOp ratio of ca. 8. Also, we observed a short-term variability of the transformation rates of both DMSP and DMS, which gave rise to daily couplings and decouplings of DMS production and consumption, and daily changes of the DMSP-to-DMS conversion efficiency.Closer examination of a 24-h microcosm experiment revealed that such changes can also occur on a diurnal scale. Speciation and turnover rates are compared with air-sea exchange rates, and with the abundance, activity and diversity of eukaryotic and prokaryotic microorganisms. To our knowledge, this is the first time that the short-term variability of the DMS cycling rates has been examined. Our results indicate that the biological processes that control DMS occurrence in seawater are even more dynamic than previously suggested.
 
Day: Friday, Feb. 5
Time: 08:45 - 09:00am
Location: Sweeney Center
 
Code: SS37FR0845S