Radial profiles of electrostatic fluctuations and fluctuations-inducedtransport have been measured in the proximity of rational surfaces inthe plasma boundary region of the TJ-II stellarator. Structures inplasma profiles linked to the location of low-order rational surfaces(n = 8/m = 5, n = 4/m = 2) have been observed. Local turbulent E×Bdriven fluxes are significantly modified in the proximity of rationalsurfaces. In the case of low-order rationals (n = 4/m = 2) turbulenttransport reverses from radially outwards to radially inwards. Thesechanges are due to a modification in the phase relation between densityand electric field fluctuations.