Venice Lagoon benthic macrofauna, in an experimental laboratory system (0.3 × 0.4 × 0.8 m), significantly affected nutrient exchange at the sediment-water interface. After macrofauna addition, the inorganic nitrogen release rate from the sediment increased by an order of magnitude compared with the values obtained in the undisturbed experimental system (from 1.7 to 23 mmol m-2 day-1), while a two- to three-fold increase was observed for reactive phosphorus (from 0.26 to 0.7 mmol m-2 day-1). In this system, the sediment redox potential and nutrient concentrations in the interstitial waters were similar to those observed in situ in the lagoon.