Séminaire de Alberto BaudenaSéminaire
The role of fine scales, from fish dispersion to plastic pollution, through a Lagrangian approach
Alberto Baudena, Sorbonne Université, CNRS, Laboratoire d’Océanographie de Villefranche, Villefranche-sur-Mer
In the ocean, everything is continuously on the move. Indeed, currents shape the seascape and transform it regularly. In particular, circulation features at the fine scale (1-100 km, few days to several weeks) affect marine processes in manifold ways. Understanding their role is therefore pivotal in a context of climate change and increasing anthropic pressure on marine systems. Following the path of water parcels in time, through a Lagrangian approach, is central to shed some light on these mechanisms. In this presentation, I will describe some of the processes through which fine scale currents regulate marine ecosystems, with a special attention on mid trophic levels, notably fish. By regulating the distribution of lower trophic levels, fine scale structures can foster strong fish aggregations. Subsequently, I will illustrate the role of ocean circulation on the dispersion of passive tracers such as larvae or pollutants. I will expose this paradigm in the study of plastic debris dispersal in the Mediterranean Sea. A specific Lagrangian diagnostic, the crossroadness, can reveal peculiar hotspots for plastic dispersal, highways of plastic passage. These regions can represent a novel framework to study plastic debris and, more generally, tracer transport, and can provide essential information for remediation strategies or marine spatial planning.