Offshore wind farms (OWFs) modify the hydro-sedimentary environment on a local scale and possibly regional scale. Around their foundations, wind turbines are colonized by numerous bentho-pelagic species, creating a reef e_ect. The presence of these species, which released large number of planktonic larvae in presence of hydrodynamics features due to uid-structure interactions, increases larval dispersal and retention between OWFs, impacting the connectivity of species. So, this study is focused on hydrodynamic impacts of OWFs on larval dispersal and species connectivity for the Bay of Seine (France), where three OWFs are under development, using numerical modelling. An ocean circulation model, MARS3D, under met-ocean forcings (tide/wind/temperature) is combined with a Lagrangian model, Ichthyop, for simulating the behavior of four benthic species known to colonize wind turbine foundations. Hydrodynamic forcings from MARS3D are computed in three-dimensions using three nested grids and with the sub-grid scale parameterization of Rivier et al. 2016 1 to account for the hydro-sedimentary e_ects of wind turbine foundations. First results have shown that the parameterization, initially developed for monopile foundations, can reproduce uid-structure interactions for gravity-based using a regional model. The velocity immediately behind foundations is reduced and the turbulent intensity in the wake is increased. The distance between the foundations within the three OWFs keeps the wake-foundation interactions low. Larvae are dispersed within the OWFs, particularly along the turbulent wake, and retention effects are being investigated.