Estuaries are composed of a mosaic of habitat providing various ecological functions for many biological communities and many goods and services to society. At the interface between continents and oceans, estuaries in general, and particularly large estuaries, are also environments which concentrate important ecological issues but also many environmental climatic and anthropogenic pressures. The Gironde estuary, one of the largest European estuaries, is thus an emblematic case. Historically, it has undergone major evolutions of its hydromorphosedimentary characteristics due to impacts of climate change and human activities. The aim of this work is to assess the ecological consequences of these changes through the study of the evolution of surfaces of estuarine available habitats and the knowledge of ecological functions associated with these habitats. To do this, we propose to combine two approaches: ecological and hydromorphosedimentary. First, work was undertaken to determine, from scientific literature, tolerances and preferences of representative species of the ecosystem for each of the parameters determining estuarine aquatic habitats (depth, salinity, sedimentary facies ...). Thus, combining available map data and results from a hydrodynamic model implemented in the Gironde, we can map the spatial distribution of these species in the estuary using a geographic information system (GIS). Then, we characterized the ecological functions associated with each habitat (eg. nursery role for sole, migration for eels ...). On the other hand, old maps of the environment have been digitized and analysis was undertaken to characterize the evolution of morphology, hydrological and sedimentary dynamics of the estuary in recent decades. The potential distribution maps we obtained allowed defining a kind of ecological potential that can be used as a reference for assessing effects of development issues, management measures or climate change scenarios. Results highlighted small changes in functional habitats distributions but high vulnerability of some of them (nursery grounds).