The Laurentian continuum spreads all along the River, the Estuary and the Gulf of St. Lawrence (Canada) and is one of the greatest and most productive aquatic systems worldwide. Increasing anthropization of this continuum since two centuries had still poorly assessed ecological consequences. Environmental and ecological observatory networks are now monitoring with accuracy a large set of hydrobiological parameters but the oldest data only go back to the late 1990s. This is insufficient to get insights about the impacts of mankind and global change on this ecosystem. In this context, the main goal of the project ARCHivES is to build annually-resolved chronologies of multi-decadal to multi-centennial variations in environmental parameters (temperature, phytoplankton dynamics, pollution). This goal will be achieved by deciphering the structural and geochemical information archived in shells of long-lived bivalve species. Three marine species (Arctica islandica, Mactromeris polynyma, Cyrtodaria siliqua) will be collected (both live and dead) from the maritime estuary to Saint-Pierre-et-Miquelon and analyzed for their growth patterns and geochemical composition. This sclerochronological approach will provide insights about spatial and temporal variability of anthropogenic impacts. It will therefore go towards overcoming the scarcity of long-term observation time-series that are, yet, essential for accurate regional-scale climate predictions.