Profiles of DMSP, algal pigments, nutrients and salinity in pack ice from eastern Antarctica

Concentrations of dimethylsulphoniopropionate (DMSP) were measured in seven pack ice cores from three sites in eastern Antarctica to determine their relation to algal pigments, nutrients (nitrate, silicate and phosphate) and bulk salinity. The algal groups haptophytes, dinoflagellates and diatoms were identified in surface, interior and bottom assemblages in the pack ice cores using the photosynthetic marker pigments 19′-hexanoyloxyfucoxanthin (HEX), peridinin (PER) and fucoxanthin (FUC), respectively. DMSP concentrations were significantly correlated (P<0.01, Pearson) with chlorophyll-a (r=0.58), HEX (r=0.75), PER (r=0.79) and FUC (r=0.63) concentrations. The pool of DMSP within the pack ice (mean 107 nM) was contributed mainly by interior and bottom algal assemblages (mean 94 and 268 nM, respectively), whilst the surface algal assemblages were minor contributors (mean 18 nM). DMSP production and/or accumulation appears to differ between surface, interior and bottom pack ice algal assemblages due to differences in biomass, class composition, and possibly the unique environmental conditions experienced by each assemblage. In pack ice, diatoms appear to be important producers of DMSP, due to their dominance of algal assemblages.