Campaign Summary Report - Mission Microbiomes from Punta Arenas (2022-03-06) to Cape Town (2022-04-21) on board AtlantECO flagship SV Tara

The seascape is composed of a non-linear combination of processes that cover spatial scales from millimeters to thousands of kilometers, on times ranging from seconds to millennia [McWilliams, 2016]. A critical scale is the one associated with major current perturbations, the so-called mesoscale and associated submesoscale processes, such as eddies, filaments, and fronts. These phenomena are known to impact bulk primary production, mostly via vertical movements that bring nutrients to the photic zone and promote lateral and vertical mixing [Mahadevan 2016, Levy et al., 2018]. However, much less is known about the impact of submesoscale processes on plankton taxonomic and functional diversity and associated vertical export of organic matter [Kavanaugh et al., 2016]. In Tara MM, we are addressing the following questions: (a) What is the effect of physical segregation and mixing on competition and exclusion? and (b) Do submesoscale downward and upward vertical fluxes restructure communities by favouring some species, inducing a fast response to the changing environment? Given the ubiquity of meso/submesoscale processes, these unknowns limit our current capacity to model biogeochemical cycles and, more broadly, to constrain the role of the ocean microbiome in a changing climate. The reason behind the lack of knowledge is the ephemeral nature of these phenomena, typically lasting from a few days to a few weeks, and their unpredictable nature, due to the high nonlinearity of the physical processes that cause them. The outcome is a dramatic lack of in situ observations of the biological responses. This experiment thus aims to address these observational stumbling blocks by combining recent technological advances in marine biology (-omics) with automated in-line sampling, and state-of-the-art satellite missions in an innovative field experiment.