Production of Dimethylsulfide After Deposition of Increasing Amounts of Emiliania Huxleyi onto Sediments in Marine Microcosms

Summary

Rapid release of dimethylsulfoniopropionate (DMSP) and subsequent production of dimethylsulfide (DMS) may occur after deposition of DMSP-containing algae onto sediments, potentially causing a temporal accumulation of DMS. This relation between sedimentation and DMS formation was studied by supplying increasing amounts of the marine microalga Emiliania huxleyi to anoxic marine sediment microcosms, resulting in initial DMSP concentrations of 950 nM, 1600 nM and 5300 nM. In all experiments, rapid formation of DMS was observed, the highest concentrations were reached after 2 to 5 days. The DMS concentrations remained high for more than 5 days, suggesting a slow response of anaerobic DMS consuming bacteria. In a control experiment, in which the algae were kept in suspension, the release of DMS was an order of magnitude lower, and more gradual. It was therefore concluded that sedimentation of DMSP containing algae to anoxic sediments can lead to emission of DMS to the water column. The ratio between DMS produced and DMSP added was highest at the highest algal density. This may indicate an increasing importance of the cleavage of DMSP under increasing substrate concentrations. Hence, benthic DMS formation after sedimentation of algae is most likely to occur in eutrophic, coastal areas, where large amounts of algae are deposited onto very reduced sediments.