Fig. 7. An example of the sterile, aerated sediment used for determinations of the oxygen uptake rates of buried fish by method 1. (A) Before burial of the fish, (B) alignment of the fish (arrow) in the sediment, (C,D) progressive deoxygenation of the sediment due to oxygen-depleted water leaving the gills, percolating into the adjacent interstice and replenishing the oxic porewater. C is approximately 1 h after the fish buried, while (D) is taken about 4 h later. To minimize the likelihood of cutaneous oxygen uptake from the sediment, only images obtained after the fish had been buried for 4–5 h were used for calculations of oxygen uptake rates, i.e. when local anoxia had evolved around the fish, as illustrated by D.