Diatoms (Bacillariophyceae, Heterokontophytes) are essential aquatic eukaryotes. Their role in the structure and ecology of most of the aquatic ecosystems is crucial. Especially, their photosynthetic activity is responsible for about a quarter of the Earth's primary productivity as large as the most productive terrestrial ecosystems, even though they represent only few percents of the total plant biomass on the planet. Both planktonic and benthic diatoms tend to dominate in ecosystems characterised by a high turbulence of the water (coasts and estuaries). As a consequence, they have to cope with an underwater light climate with high frequency fluctuations in irradiance coupled with large amplitude. The observation that diatoms grow and dominate under a fluctuating light regime regularly punctuated with excess light exposure, which can be harmful for photosynthesis