Plankton networks driving carbon export in the oligotrophic ocean

Lionel Guidi1, Samuel Chaffron2, Lucie Bittner3, Damien Eveillard4, Jeoren Raes2, Eric Karsenti5, Chris Bowler6 and G Gorsky1, (1)CNRS, Laboratoire d'Océanographie de Villefranche-sur-Mer, Villefranche-sur-Mer, France, (2)Rega Institute, Department of Microbiology and Immunology, Leuven, Belgium, (3)Sorbonne Universités, Institut de Biologie Paris-Seine, Paris, France, (4)University of Nantes, Nantes, France, (5)European Molecular Biology Laboratory, Heidelberg, Germany, (6)Institut de Biologie de l’Ecole Normale Supérieure (IBENS), Ecology and Evolutionary Biology, Paris, France
Abstract:
The biological carbon pump is the process by which CO2 is transformed to organic carbon via photosynthesis that sinks to the deep ocean as particles where it is sequestered. While the intensity of the pump correlates with plankton community composition, the underlying ecosystem structure and interactions driving the process remain largely uncharacterised. Here we use environmental and metagenomic data gathered during the Tara Oceans expedition to improve our understanding of the underlying processes. We show that specific plankton communities correlate with carbon export and highlight unexpected and overlooked taxa such as Radiolaria, alveolate parasites, as well as Synechococcus and their phages, as lineages most strongly associated with carbon export in the subtropical oligotrophic ocean. Additionally, we show that the relative abundance of just a few bacterial and viral genes can predict most of the variability in carbon export in these regions. Together these results help elucidate ecosystem drivers of the biological carbon pump and present a case study for scaling from genes-to-ecosystems.