scholarly journals Phytoplankton community structure and productivity along the axis of the Mississippi River plume in oligotrophic Gulf of Mexico waters

2004 ◽  
Vol 35 ◽  
pp. 185-196 ◽  
Author(s):  
B Wawrik ◽  
JH Paul
2005 ◽  
Vol 41 (2) ◽  
pp. 305-310 ◽  
Author(s):  
Jason H. See ◽  
Lisa Campbell ◽  
Tammi L. Richardson ◽  
James L. Pinckney ◽  
Rongjun Shen ◽  
...  

2004 ◽  
Vol 31 (9) ◽  
pp. n/a-n/a ◽  
Author(s):  
Jinchun Yuan ◽  
Richard L. Miller ◽  
Rodney T. Powell ◽  
Michael J. Dagg

2016 ◽  
Vol 13 (2) ◽  
pp. 280 ◽  
Author(s):  
Jessie Motard-Côté ◽  
David J. Kieber ◽  
Allison Rellinger ◽  
Ronald P. Kiene

Environmental contextDimethylsulfoniopropionate (DMSP) comprises an important fraction of the organic carbon produced by phytoplankton, and is a major source of carbon and sulfur for heterotrophic bacteria. Here, we show that a non-bioavailable fraction of DMSP recently discovered in coastal waters also exists in oligotrophic open-ocean waters. Taking account of the non-bioavailable pool improved estimates of cycling rates of DMSP and its contribution to bacterial nutrition. AbstractMicrobial cycling of dissolved dimethylsulfoniopropionate (DMSPd) and the fate of DMSP-sulfur were measured in the northern Gulf of Mexico off the Louisiana coast in September 2011 using the tracer 35S-DMSPd. Salinity ranged from 31.2ppt in the Mississippi River plume to 36.5ppt offshore. Total DMSP concentrations were significantly higher at the river-influenced stations (12–27nM) than offshore (6–14nM). From 8.7 to 27% of the measured DMSPd, equivalent to 0.1 to 0.23nM, was refractory (i.e. non-bioavailable). We subtracted refractory DMSPd from the measured DMSPd concentrations when calculating DMSPd consumption rates with the tracer 35S-DMSPd. DMSPd consumption and bacterial production were respectively 8 and 7 times higher in the river plume compared with offshore. Incorporation of DMSP-sulfur into biomass was almost three times higher in river-influenced water, whereas the dimethylsulfide (DMS) yield was 3.5 times lower in the river plume compared with offshore. Accordingly, DMSP contributed over 3 times more to the bacterial demand for both carbon and sulfur in the river-influenced water. Despite lower DMS yields in the river plume, the fast DMSP turnover resulted in a 2.7-times higher DMS production compared with offshore waters. Mississippi River inputs and the resulting high productivity led to a rapid turnover of DMSP and high DMS production in the river plume compared with oligotrophic Gulf of Mexico waters. Failure to account for refractory DMSPd when using the 35S-DMSP method will lead to significant overestimation of the DMSPd turnover flux and its contributions to C and S cycling.


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