Day-night alternation exerts an obvious rhythmic forcing on photochemical and photobiological processes, which may result in diel oscillations of the chemical-microbe networks, with consequences for biogeochemical fluxes. In the case of the algal metabolite DMSP and the trace gas DMS, previous studies have revealed that their local diel balance in the surface ocean depends on the fine interplay between microbial activities and physical forcing. We investigated the diel patterns in the production and loss rates of DMSP and DMS, sampling in lagrangian mode every 4 hours over 48 hours in open surface waters of the NW Mediterranean Sea. Incubations under natural full light and darkness allowed determination of microbial DMSP consumption rates (radioisotope addition), DMS production and consumption rates (inhibitor addition), and DMS photolysis rates (filtered seawater). These were compared with the variability of bacterial heterotrophic production and the diel transcription patterns of the known relevant genes. 

Primary Presenter: Rafel Simó, Institut de Ciencies del Mar, CSIC (rsimo@icm.csic.es)

Authors:

Rafel Simó, Institut de Ciències del Mar, ICM-CSIC  (rsimo@icm.csic.es)

Marta Masdeu-Navarro, Institut de Ciències del Mar, ICM-CSIC  (masdeu@icm.csic.es)

Jean F. Mangot, Institut de Ciències del Mar, ICM-CSIC  (mangot@icm.csic.es)

Jose González, University of La Laguna  (jmglezh@ull.edu.es)

Clara Cardelús, Institut de Ciències del Mar, ICM-CSIC  (ccardelus@icm.csic.es)

Steve D. Archer, Bigelow Laboratory for Ocean Sciences  (sarcher@bigelow.org)