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PROTISTAN PLANKTON DIVERSITY AND SPECIES-SPECIFIC CONTRIBUTION TO OCEANIC CARBON EXPORT IN THE CALIFORNIA CURRENT ECOSYSTEM REVEALED BY DNA METABARCODING

The biological pump refers to the vertical export of photosynthetically fixed organic matter to the ocean’s interior, whereby contributing to carbon sequestration. The quantity and quality of the particulate organic matter exported depends on the diversity and structure of the microbial community. However, beyond a coarse taxonomic perspective, little is known about the specific composition of sinking biological material. In this study we applied DNA metabarcoding (V4 region of 18S rDNA) to investigate the molecular diversity and taxonomic composition of the eukaryotic community sinking out of the euphotic zone across contrasting water masses of the CCE. We analysed the chemical and biological composition of particulate organic matter collected in floating sediment traps drifting at 100 and 150 m during 5 Lagrangian experiments. Rhizarian sequences represented the majority of reads retrieved from sediment traps, but different Radiolaria taxa dominated during different deployments. Despite evidence of their abundance in the euphotic zone gathered from the underwater video profiler, the relative abundance of rhizarian sequences in discrete water column samples was much lower, suggesting a disproportionately large role in export. The water column protistan community was dominated by dinoflagellates (50% of reads), followed by prasinophytes clade VII (20%), while diatoms sequences (5%) were retrieved in much lower proportions than expected. The consistent contribution of rhizarian sequences to the organic matter of eukaryotic origin intercepted by sediment traps, suggests an important role in vertical carbon export for this lesser-studied group of silicified plankton.

Authors

Gutierrez Rodriguez, A., NIWA, New Zealand, agutierrez2001@gmail.com

Stukel, M. R., Florida State University, USA, mstukel@fsu.edu

Lopes dos Santos, A., Station Biologique de Roscoff, France, lopesas.ufrj@gmail.com

Biard, T., Station Biologique de Roscoff, France, tristan.biard@hotmail.fr

Vaulot, D., Station Biologique de Roscoff, France, vaulot@gmail.com

Landry, M. R., Scripps Institution of Oceanography, USA, mlandry@ucsd.edu

Not, F., Station Biologique de Roscoff, France, not@sb-roscoff.fr

Details

Oral presentation

Session #:006
Date: 02/28/2017
Time: 10:45
Location: 313 A

Presentation is given by student: No