Physical irrigation of relict burrows: Implications for sediment chemistry

Relict biogenic structures are common in some areas of the sea floor, particularly the deep-sea, and are potentially irrigated by flow induced by overlying water currents. Such physically induced irrigation could have major effects on sedimentary solutes and influence interpretation of their measured distributions. Experiments show that the rate of flow through these uninhabited burrow structures is in some cases comparable to irrigation rates by animals. Even at the very low mean current velocities expected in the deep-sea boundary layer, induced irrigation is often sufficient to hold the concentrations of solutes in the burrow water close to that of the overlying water. As a result, these relict structures may in some ways be functionally equivalent to inhabited burrows with respect to modification of sediment chemistry.