Lionel Guidi, winner of the CNRS bronze medal in 2018

© John Proscedu / CNRS

Researcher in oceanography and bio-geochemistry at the Villefranche Oceanographic Laboratory (LOV), Lionel Guidi is a specialist in the carbon cycle and biological pump who joined the Tara Oceans adventure in 2009. In October 2018, he was awarded the CNRS bronze medal for his innovative work on the planktonic organisms involved in the ocean’s key function as climate regulator: the biological pump.

In an article published in the science journal Nature on February 10, 2016 (entitled “Plankton Networks Driving Carbon Export in the Oligotrophic Ocean”), Lionel Guidi presented new details on the biological pump, one of the main biological processes responsible for carbon sequestration in the ocean on the scale of geological time.

This process involving plankton (viruses, bacteria, uni- and multicellular eukaryotes) has been studied since the 1980s. Many previous studies pointed out that the effectiveness of the biological pump is directly correlated with the abundance of certain planktonic species. Lionel Guidi’s research shows that the organization of planktonic communities involved in carbon sinks remained largely unknown until now.

Zooplankton-mix-Galapagos-CSZooplankton © Christian Sardet / Tara Expeditions Foundation

I had the great opportunity to participate at an early stage in analyzing the data collected during the Tara Oceans expedition. Thanks to this project, I am part of a multidisciplinary universe composed of oceanographers, ecologists, biologists, and computer scientists, all brought together to study the Ocean system as a whole“, he explains.

Through computer analysis, the first “plankton social network” associated with carbon export was described for nutrient-poor regions. If some photosynthetic algae – in particular diatoms and copepods (microscopic shrimps) – were already known, the involvement in carbon export of specific micro-organisms such as unicellular parasites, cyanobacteria, and viruses, was largely underestimated until now.

2_oceans_francis_latreille-tara-oceans-sous spi-logo© Francis Latreille / Tara Expeditions Foundation

The Tara Oceans database enabled us to establish that the abundance of a small number of bacterial and viral genes is responsible for the variability of carbon export in the deep ocean.

Collaborations developed over these past years allowed me to integrate biological complexity and various measurement techniques (imaging and meta-omics) into a global vision of the biological pump. These approaches led me to link the structuring of planktonic communities (the “plankton Facebook”) and their genetic composition with the effectiveness of this pump that contributes to carbon sequestration in the ocean“.

Lionel Guidi in a few dates:

  • 2008 : Double doctorate in Environmental Sciences at the Paris Sorbonne University (France) and Texas A&M University (USA)
  • 2008-2011 : Post-doctoral fellowship at the Center for Microbial Oceanography: research and education (University of Hawaii, USA)
  • 2011-2013 : Post-doctoral fellowship at the Villefranche Oceanographic Laboratory on the Tara Oceans project
  • 2013 : Joined the CNRS – Research fellow at the Villefranche Oceanographic Laboratory
  • 2017 : Member of the steering committee of EMBRC-France

 

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