Francesco D'Ovidio (LOCEAN – IPSL,  Université Pierre et Marie Curie, Paris, France): “The structuring role of horizontal stirring on marine ecosystems: a Lagrangian approach”

10:30 Meeting Room, IC3
C/ Doctor Trueta, 203
08005 Barcelona


The open ocean upper layer is characterized by a complex transport dynamics occuring over different spatiotemporal scales. At the scale of 10-100 km - which covers the so called mesoscale and part of the submesoscale - in situ and remote sensing observations detect strong variability in physical and biogeochemical fields like sea surface temperature, salinity, and chlorophyll concentration. The calculation of Lyapunov exponent and other Lagrangian diagnostics applied to the surface currents have allowed to show that an important part of this tracer variability is due to horizontal stirring. Thanks to novel in situ datasets and satelite-derived products, it is now possible to extend this analysis to marine ecosystems. For primary producers, transport features induced by stirring are able to structure the phytoplanktonic community in fluid dynamical niches of dominant types, where competition can locally occur during bloom events. Such niches are an important driver of phytoplankton diversity, but also quasi-isolated environments were biogeochemical processes can be monitored for extended times (weeks to months) with only minor contamination from environmental waters. Such sampling strategy has been exploited in particular by iron fertilization campaigns like EIFEX, LOHAFEX, and KEOPS2. The effect of stirring on marine ecosystems is also become apparent for higher trophic levels, through the analysis of biologging data. In perspective, these relations between transport structures and marine ecosystems may help to monitoring hotspots of biodiversity and trophic interactions from remote sensing, contributing to our understanding of the biophysical coupling in the global ocean and contributing to the management of marine resources.