Digestive microbiota provides a wide range of beneficial effects on host physiology and are therefore likely to play a key role in marine intertidal bivalve ability to acclimatize to the intertidal zone. This study investigated the effect of intertidal levels on the digestive bacterial microbiota of oysters Crassostrea gigas and clams Ruditapes philippinarum, two bivalves with different ecological niches. Based on the 16S rRNA region sequencing, digestive glands, seawater and sediments harbored specific bacterial communities, dominated by OTUs assigned to the Mycoplasmatales, Desulfobacterales and Rhodobacterales orders, respectively. Field implantation modified digestive bacterial microbiota of both bivalve species according to their intertidal position. Rhodospirillales and Legionellales abundances increased in oysters and clams from low intertidal level, respectively. After a 14-day depuration process, these effects were still observed especially for clams, while digestive bacterial microbiota of oysters were more subjected to short-term environmental changes. Nevertheless, 3.5 months stay on intertidal zone was enough to leave an environmental footprint on the digestive bacterial microbiota, suggesting the existence of autochthonous bivalve bacteria. When comparing clams from the three intertidal levels, 20% of the bacterial assemblage was shared among the levels and it was dominated by OTU affiliated to the Mycoplasmataceae and Spirochaetaceae families.