Incubations were performed during the flooded periods in mudflats and saltmarshes (water level was between 30 and 100 cm above the chamber lids). Incubation Were conducted in dark conditions (n=6 each treatment), by wrapping chambers with opaque aluminum foil. At the end of the incubation, the volume of water inside each chamber was determined by measuring chamber height (i.e., water height) with a ruler. Chambers in treatments B and B + C were placed in such a way that one burrow was included into each chamber (burrow diameter: ~ 3.6 cm; burrow depth N40 cm). Given the chamber area (0.0201 m2), this was a burrow density of ~50 burrows m−2. This density was higher than the mean burrow density but remained within the range reported for SW Atlantic soft-bottoms. For these chambers, burrow volume was measured at low tide by adding a measured quantity of water into each burrow, and this volume was added to each chamber volume.