Augustin Lafond is a 1st year PhD student at Mediterranean Institute of Oceanography and is co-advised by Bernard Quéguiner and Karine Leblanc. The aim of his PhD project is to improve our understanding of the mechanisms linking the diversity of siliceous marine planktonic organisms, including diatoms that account for 40% of primary marine production, in the modulation of carbon and silica biogoechemical fluxes by comparing two contrasted polar ecosystems in which factors that limit the development of diatoms are different. He is involved in the MOBYDICK program (Marine Ecosystem Biodiversity and Dynamics of Carbon around Kerguelen: an integrated view), whose field campaign will be conducted on board the R.V. Marion Dufresne over the Kerguelen Plateau in March 2018. He will also work on the GREENEDGE program, whose field missions have already been carried out in 2015 and 2016, and were located in Baffin Bay in the Arctic.