The bioavailability of trace metals in sediments is function of many factors such as the targeted metal, its colloidal, dissolved and particulate partition, sediment physico-chemical characteristics or Acid Volatile Sulphide (AVS) contents. Moreover, organisms activity in sediments induce both a modification of redox conditions disturbing particulate and dissolved partition and an increase of metal diffusion at the sediment interface. It was shown that passive samplers such as Diffusive Gradient in Thin films (DGT) represent a powerful tool to assess metal availability in sediments (Dabrin et al., 2012). In order to asses the impact of bioturbation on metal availability at the sediment interface, we used DGT-probes to measure labile metals at the water-sediment interface with a sub-centimetric resolution on a sediment with different density of organisms. Experiments were conducted on sediment introduced in PVC tubes allowing to use DGT probes and to introduce organisms at environmental relevant density (6000 to 18000 ind. m-² Goedkoop and Peterson, 2003). Two kind of organisms were tested; an insect larvae (Chironomus riparius), mainly living in the first centimeter of the sediment and oligochetes (Tubifex tubifex), living more deeply in the sediment. Sediment columns were specifically used for millimetric oxygen, pH and redox potential measurements and for AVS measurements