Processes driving seasonal variability in DMS, DMSP, and DMSO concentrations and turnover in coastal Antarctic waters

Abstract

This study presents new measurements of the concentrations and turnover rates of dimethyl sulfide (DMS), dimethylsulfoniopropionate (DMSP), and dimethyl sulfoxide (DMSO) in coastal waters near Palmer Station, Antarctica, during the spring and summer of 2012–2013. Using several novel analytical and experimental techniques, we document variability in DMS, DMSP, and DMSO (DMS/P/O) concentrations and quantify dominant production and removal terms in the mixed layer DMS budget. Our results demonstrate considerable seasonal variability in the concentration of DMS (range 0–20 nM), total DMSP (8–160 nM), and total DMSO (4–160 nM). Over the seasonal cycle, dissolved DMSP concentrations were well correlated with total DMSP concentrations and the abundance of Phaeocystis antarctica, while DMSO concentrations (total and dissolved) were well correlated with DMS concentrations. DMSP cleavage from the dissolved pool (mean rate = 5.5 nM d−1) and release from microzooplankton grazing (mean 5.6 nM d−1) were the dominant sources of DMS, with smaller DMS production rates associated with DMSO reduction from the dissolved pool (mean 2.6 nM d−1) and krill grazing (mean 0.82 nM d−1). Specific rate constants for DMSP cleavage were inversely related to net primary production. Bacterial uptake was a primary contributor to DMS removal (mean −12 nM d−1), and we observed a significant correlation between bacterial production and gross DMS loss rate constants. Estimated sea‐air flux and photo‐oxidation constituted secondary DMS sinks. Our experimental and analytical methods provide insight into the DMS/P/O cycle at Palmer Station, and a starting point for future studies examining inter‐annual DMS/P/O variability in coastal Antarctic waters.

Variability and change in the west Antarctic Peninsula marine system: Research priorities and opportunities

“…The latest Southern Ocean climatology indicates that the WAP is not a particular hotspot of DMS production (Jarníková and Tortell 2016), although this may reflect a shortage of published datasets, particularly from the marginal ice zone. Two time series from the Palmer LTER show highest DMS concentrations in January between 5 and 15 nM (Asher et al 2017;Herrmann et al 2012), which compare well with the climatological mean for January of 10.8 ± 6.9 (SD) nM for the whole Austral Polar province (Lana et al 2011). A recent continuous 5-year time series at Rothera shows large seasonal fluctuations in northern Marguerite Bay, with considerably higher concentrations in January, reaching an average of 24 ± 35 (SD) nM and a maximum of 160 nM in January 2015 (Webb et al in review).…”

The Roles of Suspension-Feeding and Flux-Feeding Zooplankton as Gatekeepers of Particle Flux Into the Mesopelagic Ocean in the Northeast Pacific

“…Zooplankton play diverse roles in the cycling of many elements in the ocean including iron, zinc, sulfur, and mercury (Fowler, 1977;Asher et al, 2016;Baines et al, 2016;Schmidt et al, 2016;Gorokhova et al, 2018). However, their greatest importance to global biogeochemistry is likely derived from their roles in the biological carbon pump (BCP; Buitenhuis et al, 2006;Turner, 2015;Steinberg and Landry, 2017).…”

Acrylic acid and related dimethylated sulfur compounds in the Bohai and Yellow seas during summer and winter

“…In summer, the average concentration order was AAd > DMSPt > DMS > DMSPd along the three transects; this result was consistent with the order in the surface seawater (Table 1). Higher values of DMS than DMSPd might be produced through the intracellular cleavage of phytoplankton DMSPp catalyzed by the enzyme DMSP lyase and the photochemical and biological reduction of dimethylsulfoxide (DMSO) to DMS (Asher et al, 2017). In contrast, the higher values of AAd than DMSPt indicated that there were terrestrial sources of AAd aside from the contribution of in situ DMSP degradation along the three transects.…”