Dimethyl sulfide and dimethylsulfoniopropionate profiles from winter sea ice - Influence of physical parameters and speciation

• Main Authors: Uhlig, Christiane, Rintala, J., Tison, J.-L., Carnat, G., Dieckmann, Gerhard, Delille, B., Damm, Ellen
• Format: Conference Object
• Language: unknown
• Published: 2014
• Subjects: Antarc*; Antarctic; IPY; Sea ice; Weddell Sea
• Online Access: https://epic.awi.de/id/eprint/35829/; https://hdl.handle.net/10013/epic.43751

Due to the physico-chemical conditions given, i.e. the high salinity and the icy matrix, sea ice as habitat favors production of high levels of dimethylsulfoniopropionate (DMSP) by the inhabiting microalgae. DMSP and DMS (dimethylsulfide) are frequently found in high concentrations in sea ice during spring and summer. Records from winter are yet scarce, but of importance for global budgeting. Our study presents profiles of the DMS(P) in sea ice cores collected during the AWECS (Antarctic Winter Ecosytem Climate Study) cruise on RV Polarstern (ANT29-6) in the Weddell Sea. Results show that DMS(P) production in sea ice in the Weddell Sea is also significant during winter. This stands in contrast to previous measurements in Arctic winter sea ice (CFL-IPY cruise in the Circumpolar Flaw Lead Polynya), where DMS(P) concentrations were very low. Possible explanations for the differences between DMS(P) levels in the Arctic and Antarctic might be the different snow cover and thus insulation, light regimes and also microbial community structure within the ice. The DMS profiles mirrored the permeability of the sea ice following DMSP in the impermeable areas while showing losses to the ice surface and ice-water interface in the more permeable regions. DMS(P) levels were generally correlated with chlorophyll A concentrations, although the details are complex and seem to be influenced by species composition and species specific DMSP/Chla ratios. Three mayor trends determined in situ with values of 136 (±93), 32 (±15) and 5 (±2) mmol DMSP / g ChlA resemble the published values for cultures of dinoflagellates, haptophytes and diatoms. Preliminary microscopy data confirm that dinoflagellate dominated sea ice layers display higher DMSP/ChlA ratios than diatom dominated ones.