The EMSO-Azores deep-sea observatory: towards an integrated and pluridisciplinary understanding of hydrothermal systems on a slow-spreading ridge from the sub-surface to the water column.

Faced with the increasing interest for ocean resources exploitation in a changing ocean, there is an urgent need for a comprehensive assessment of the health and status of deep-sea ecosystems. Hydrothermal vents constitute areas of important thermo-chemical exchanges between the lithosphere and the hydrosphere and host a unique biodiversity. Understanding their natural dynamics is key to evaluating and predicting the impacts and ecosystem responses to disturbances caused by natural and anthropogenic changes, and their consequences on the global ocean health. Since 2010, the EMSO-Azores observatory connects a large range of sensors at 1700 m water depth at the Lucky Strike Hydrothermal Field (LSHF) along the mid-Atlantic ridge. The infrastructure, combined with repeated yearly sampling, aims at understanding the feedbacks between geological processes and hydrothermalism at a slow spreading mid-ocean ridge, and the coupling between the hydrothermal ecosystem and sub-seabed processes.

The last 13 years of monitoring showed that tidal modulation is the main process driving vent heat flux variability, species behaviour and physiology while over decadal timescales, results point to a relative stability of the vent system across varying spatial scales, challenging the paradigm that hydrothermal vents are highly dynamic and ephemeral habitats. These results have strong impact in terms of resilience of these systems to large scale disturbance such as deep-sea mining. In addition, the infrastructure and the associated Momarsat maintenance cruises supported a large number of mediation projects, art and science productions, public outreach events, inter- and trans-disciplinary collaborations and citizen science projects showing the strong scientific and societal impact of the observatory over time.

In this talk we will summarise 13 years of integrated study at LSHF, training opportunities and discuss the leverage effect and the societal impact of the observatory.