Diatoms were sampled from artificial substrates immersed at three sites in the Morcille river (Beaujolais vineyard area, SE France) during the pesticide spreading period (April-May 2008). From up- to downstream, we observed a gradient of trophic (mainly orthophosphate) and diuron pollution. Biofilm communities were allowed to settle on glass slides for 4 or 8 weeks at each site. After a 4-week colonisation some samples from the two contaminated downstream sites were transferred upstream to evaluate their restoration trajectories. Periphytic communities were characterised through biomass accrual and qualitative taxonomic identifications: brown algae always dominated. From up- to downstream, periphytic biomass and species richness decreased; the samples transferred upstream recovered quite well, most descriptors reaching a level comparable to that of the communities grown for 8 weeks at the pristine site. The taxonomic composition of the samples varied between dates and along the gradient. The communities transferred upstream did not recover a pristine structure but the increase in diversity, associated with the settlement of sensitive species, suggested elevated resilience potential.