Diversity in Xanthophyll Cycle Pigments Content and Related Nonphotochemical Quenching (NPQ) Among Microalgae: Implications for Growth Strategy and Ecology

Xanthophyll cycle‐related non‐photochemical quenching, which is present in most photoautotrophs, allows dissipating excess light energy. Xanthophyll cycle‐related NPQ depends principally on xanthophyll cycle pigments composition and their effective involvement in non‐photochemical quenching. Xanthophyll cycle‐related NPQ is tightly controlled by environmental conditions in a species/strain specific manner. These features are especially relevant in microalgae living in a complex and highly variable environment. The goal of this study was to perform a comparative assessment of non‐photochemical quenching ecophysiologies across microalgal taxa in order to underline specific involvement of non‐photochemical quenching in growth adaptations and strategies. We used both published results and data acquired in our laboratory to understand the relationships between growth conditions (irradiance, temperature and nutrient availability), xanthophyll cycle composition and xanthophyll cycle pigments quenching efficiency in microalgae from various taxa. We found that in diadinoxanthin‐containing species, the xanthophyll cycle pigment pool is controlled by energy pressure in all species. At any given energy pressure, however, the diatoxanthin content is higher in diatoms than in other diadinoxanthin‐containing species. XC pigments quenching efficiency is species‐specific and decreases with acclimation to higher irradiances. We found a clear link between the natural light environment of species/ecotypes and quenching efficiency amplitude. The presence of diatoxanthin or zeaxanthin at steady state in all species examined at moderate and high irradiances suggests that cells maintain a light‐harvesting capacity in excess to cope with potential decrease in light intensity

From plankton functional traits to marine ecosystem functions: Assessing functional diversity of plankton communities from high throughput -omics data and its impact on oceanic biogeochemical cycles

International audienc

From plankton functional traits to marine ecosystem functions: Assessing functional diversity of plankton communities from high throughput -omics data and its impact on oceanic biogeochemical cycles

International audienc

Assessing functional diversity of plankton communities from high throughput –omics data

International audienc

Community-Level Responses to Iron Availability in Open Ocean Plankton Ecosystems

Predicting responses of plankton to variations in essential nutrients is hampered by limited in situ measurements, a poor understanding of community composition, and the lack of reference gene catalogs for key taxa. Iron is a key driver of plankton dynamics and, therefore, of global biogeochemical cycles and climate. To assess the impact of iron availability on plankton communities, we explored the comprehensive bio-oceanographic and bio-omics data sets from Tara Oceans in the context of the iron products from two state-of-the-art global scale biogeochemical models. We obtained novel information about adaptation and acclimation toward iron in a range of phytoplankton, including picocyanobacteria and diatoms, and identified whole subcommunities covarying with iron. Many of the observed global patterns were recapitulated in the Marquesas archipelago, where frequent plankton blooms are believed to be caused by natural iron fertilization, although they are not captured in large-scale biogeochemical models. This work provides a proof of concept that integrative analyses, spanning from genes to ecosystems and viruses to zooplankton, can disentangle the complexity of plankton communities and can lead to more accurate formulations of resource bioavailability in biogeochemical models, thus improving our understanding of plankton resilience in a changing environment