Biological performances (growth and reproduction) of intertidal bivalves mainly rely on environmental factors such as water temperature and food sources. Both quality and quantity of bivalve food sources, however, are not easy to determine because of complex features of coastal ecosystem functioning, such as high spatial heterogeneity. This is particularly critical for oyster (Crassostrea gigas) culture in France when quantifying and explaining the variability in growth performances of oysters among culture sites at a large spatial scale. In this context, insights for new operational tools to characterise trophic features of coastal ecosystems are needed. The aim of the present study is to couple natural isotope tracers and DEB modeling to describe and quantify bioenergetic processes and isotope dynamics in oyster tissues under varying environmental conditions (temperature, food sources). The model will be tested and validated on carbon and nitrogen isotope data of oyster tissues measured in experimental controlled mesocosms. Once validated, the resulting DEB-isotopes model will be used in inverse method to provide biological indicators (e.g. nutrition level, food sources, availability of reserves, maintenance, growth rate) about oysters cultured in different shellfish areas and to allowcomparison of yields among culture sites.