Environmental control on the variability of DMS and DMSP in the Mauritanian upwelling region

• Main Authors: C. Zindler, I. Peeken, C. A. Marandino, H. W. Bange
• Format: Article
• Language: English
• Published: Copernicus Publications 2012-03-01
• Series: Biogeosciences
• Online Access: http://www.biogeosciences.net/9/1041/2012/bg-9-1041-2012.pdf
• ISSN: 1726-4170; 1726-4189

Dimethylsulphide (DMS) and dissolved and particulate dimethylsulfoniopropionate (DMSP<sub>d</sub>, DMSP<sub>p</sub>) were measured in near-surface waters along the Mauritanian coast, Northwest Africa, during the upwelling season in February 2008. DMS, DMSP<sub>d</sub> and DMSP<sub>p</sub> surface concentrations of up to 10 nmol L<sup>−1</sup>, 15 nmol L<sup>−1</sup> and 990 nmol L<sup>−1</sup>, respectively, were measured. However, the DMS concentrations measured are in the low range compared to other upwelling regions. The maximum DMSP<sub>p</sub> concentration is the highest reported from upwelling regions so far, which might indicate that the Mauritanian upwelling is a hot spot for DMSP. Within the phytoplankton groups, dinoflagellates were identified as important contributors to DMS concentrations, while other algae seemed to have only a minor or no influence on DMS and DMSP concentrations. A pronounced switch from high DMSP to high DMS concentrations was observed when the nitrogen to phosphorus ratio (N:P) was below 7. The high DMS/DMSP ratios at N:P ratios <7 indicate that nitrogen limitation presumably triggered a switch from DMSP to DMS independent of the species composition. Our results underline the importance of coastal upwelling regions as a local source for surface seawater sulphur.