Topics and Objectives

The conference aims to develop a transdisciplinary approach (including chemistry, biogeochemistry, biochemistry, physiology, genomics) to better understand and model silicification and silicifiers.

Silicifiers are among the most important living organisms of planet Earth. They are able to take advantage of the abundance of silicon (silicon is the second-most-abundant element in the Earth's crust) to build silicified architectures, which in particular can help for protection against predators, for motility, or for facilitating the penetration of light and nutrients to the cells.

This transdisciplinary conference focuses on the marine realm, for which numerous unknowns remain regarding the global marine silica cycle. Marine diatoms vs. siliceous sponges and radiolarians rose to prominence about 100 Myears ago. Today diatoms play a key role in the trophic networks of the most productive coastal or open-ocean ecosystems, as well as in the biology-mediated transfer of CO₂ from the surface to the ocean interior (the so-called biological pump of carbon). The physiology and biochemistry of pelagic diatoms have been extensively studied but many gaps remain regarding the silicification mechanisms and their variations due to environmental changes. The link between Si and C cycles also needs to be re-evaluated using newly developed genomic and geochemical tools.  Moreover, benthic diatoms and their role in coastal ecosystems have been largely overlooked despite their 40% contribution to coastal primary production. Along the same vein,  the key role of other siliceous organisms, such as benthic sponges, in the silica cycle has only been demonstrated at regional scales and needs to be quantified at the global scale. Accumulation of silica by non siliceous picocyanobacteria has been evidenced but the reasons and mechanisms behind such accumulation are still unidentified. Similarly, the formation of siliceous compounds in some flagellates of the nanoplankton remains to be quantified. The understanding of all these processes closely associated with the metabolism of such a diversity of silicifiers should now benefit from the use of genomics.

Since 2000 the genomes of several diatom species have been sequenced and genomics can now be used to formulate new hypotheses and research strategies for explaining the role of different silicifiers in coastal and open-open ecosystems, and their control of C, N, P, and Si biogeochemical cycles. More knowledge must now be acquired about interactions between diatoms and other organisms, at the cell/species level, and their consequences for nutrient cycles and ecosystem functioning. Genomics can help understanding such processes, and the availability of new resources, (such as from the Tara Oceans expedition and from the Gordon and Betty Moore Foundation’s MMETSP programme) make this a pivotal moment to exploit new opportunities to explore the biology of ocean silicification processes.

The objectives of the conference are:

(1) to favour the convergence of chemistry, biochemistry, physiology, biogeochemistry and genomics to better understand silicification processes and the role of silicifiers in the marine ecosystems,

(2) to organise an open dialogue between top-level senior scientists and early-stage researchers through a Gordon-like conference format, offering to senior scientists opportunities to confront their ideas to new points of view, and to the early-stage researchers a unique opportunity to improve their research skills and to gain a more global vision of these thematics,

(3) to built a niche for preparing new research proposals, to be submitted to national and European research agencies.

 With the support of Labex-Mer the conference welcomes students of the Master of marine sciences of the European Institute for Marine Studies (IUEM/UBO-CNRS-IRD) and of the Doctoral School of Marine Sciences (EDSM) of the University of Brest.