André, M. Listening to the deep-ocean environment in a changing climate Proceedings of the 23rd Annual Conference of the European Cetacean Society, Istanbul, Turkey, p.58, Mar 2009 Résumé: Oceans exert a pervasive influence on the Earth’s environment, most notably as a regulator of climate. Understanding the link between natural and anthropogenic processes and ocean circulation is essential for predicting the magnitude and impact of future changes in Earth’s climate. Deep-sea observatories have the potential to play a key role in the assessment and monitoring of these changes. ESONET is a European Network of Excellence of deep-sea observatories that includes 55 partners belonging to 14 countries. ESONET NoE will provide data on key parameters from the subsurface down to the seafloor at representative locations and transmit them in real time to shore. The strategies of deployment, data sampling, technological development, standardisation and data management are being integrated with projects dealing with the spatial and near surface time series. LIDO (Listening to the Deep Ocean environment) is one of these projects and proposes to establish a first nucleus of a regional network of multidisciplinary seafloor observatories contributing to the coordination of high quality research in the ESONET NoE by allowing the real-time long-term monitoring of Geohazards and Marine Ambient Noise in the Mediterranean Sea and the adjacent Atlantic waters. Specific activities are addressed to a long-term monitoring of earthquakes and tsunamis and the characterisation of the ambient noise induced by marine mammals and anthropogenic noise. Here, we present the development of LIDO and its ongoing results with a special emphasis on cetacean bioacoustics and the realtime display of acoustic data and statistics. Projet: LIDO, Listening to the Deep-Ocean Environment Projet: ESONET, Network of Excellence