The Idefix project

CONTEXT AND MAIN ISSUES

Nitrogen is an essential element for all living beings. In the ocean, it directly conditions the growth of phytoplankton, the basis of all marine food chains and a major player in the capture of atmospheric CO2. This availability of nitrogen is based on a key natural process: nitrogen fixation, carried out by micro-organisms known as diazotrophs, capable of transforming nitrogen (N2) dissolved in water into a form that can be assimilated by living organisms.

While this mechanism is fundamental to ocean functioning and climate regulation, it remains poorly understood, particularly in certain regions of the globe. The Indian Ocean, which is warming faster than any other ocean basin, is a natural laboratory of the highest priority for understanding the links between nitrogen, biological productivity and climate.

GOALS

Decipher the role of nitrogen (N2) fixation according to monsoon seasons and discover new species of diazotrophs specific to the Indian Ocean.

METHOD

The IDEFIX project is based on oceanographic campaigns carried out in the Indian Ocean, notably during the Second International Indian Ocean Expedition. Researchers are studying the dynamics of nitrogen fixation over the monsoon seasons, combining in situ observations, biogeochemical analyses and microbiological approaches. This methodology makes it possible to link the activity of diazotrophs to the specific environmental and climatic conditions of the region, while identifying new species as yet unknown to science.

HOW IS THIS PROJECT INNOVATIVE?

IDEFIX is one of the few projects to study nitrogen fixation on a seasonal scale in the Indian Ocean, a key yet underexplored basin. By linking monsoons, microbial diversity and the biogeochemical functioning of the ocean, it provides new insights into a process central to climate regulation, and paves the way for a better understanding of the ocean’s response to global warming.