| DMS, DMSP, and DMSO concentrations along with phytoplankton community composition (assessed by pigments) were measured from December 2004 through January 2005 in the Ross Sea, Antarctica. Data were analyzed using both univariate and multivariate statistical techniques. I found increased ratios of DMSPp, DMS and DMSO to Chl a under shallow mixing conditions. BIO-ENV analysis showed that the variability observed in DMSPp, DMSPd, DMS, and DMSOd was best explained by the combined concentrations of the xanthophyll cycle pigments diadinoxanthin and diatoxanthin. This result indicates that dimethylated sulfur speciation is responding the same environmental stimuli as DD+DT, namely light and nutrient stress. The results presented here support the hypothesis of an antioxidant function for DMSP, DMS, and DMSO. Additionally, I found evidence of recurring sub-ML populations of P. antarctica in otherwise diatom-dominated waters as indicated by both high Hex-Fuco:Chl a and high DMSPp:Chl a below the pycnocline, which could impact the biogeochemical sulfur cycle in the Ross Sea by exporting DMSP out of the ML. I also found that in extremely shallow mixed layers, bacterial processes were dominant in shaping dimethylated sulfur speciation. |
