[en] This study investigates the turnover of polysaccharides by heterotrophic bacterioplankton in the northern Bay of Biscay, a productive marine system on the shelf-break of the temperate Atlantic Ocean. Field studies were conducted along the shelf-break south of Ireland and west of France (47° 07' 83'' N, 6° 92' 01'' E and 51° 34' 42'' N, 10° 49' 95'' E) during the development of phytoplankton blooms in late spring. Bacterial biomass production (BBP) near the surface ranged from 0.5 to 27.4 nmol C L-1 h-1 in both years. A direct relationship between BBP and the concentration of total polysaccharides strongly suggests the dependence of bacterial growth on the availability of semi-labile organic matter. Concentrations of combined glucose as well as rate constants of extracellular glucosidase activity and glucose uptake were determined to estimate the actual carbon fluxes from bacterial polysaccharide turnover. Results reveal that the degradation of polysaccharides n the upper 100 m of the water column sustained on average a glucose flux of 2.6 mmol C m-2 d-1 i that was available for bacterial uptake. The mean turnover time for polysaccharides was 170 and 165 days for alpha- and beta-glycosidic linked polymers, respectively. Free glucose, the labile hydrolysate of polysaccharides, had a mean turnover time of 4.5 days and supported 2.2 to 18.4% of BBP. The incorporation of glucose into bacterial biomass was stimulated by the availability of inorganic nitrogen. Overall, our results demonstrate that the bacterial recycling of polysaccharides in the Bay of Biscay generates a relevant flux of organic carbon in microbial food-webs and biogeochemical processes.