A strong dependence was recognized between the scales of roughness due to bioturbation and the roughness scales resulting from a subsequent energetic flow event . In other words, biological activity generated roughness which initiated bedforms. This work was designed to substantiate the formation of ripples in the immediate vicinity of biogenic mounds and identify the mechanisms responsible. The flume channel is 17 meters long and 60 cm wide. Flow depth was approximately 12 cm for all experiments.
Water is recirculated through a return pipe by a centrifugal pump.
Bed topography elevation and plan shape were measured with a point-gauge and bed photographs. The sediment used was moderately well-sorted sand with a median grain size of 290 m m. This ejected sediment, which is only loosely bound, forms a cone-shaped mound next to a feeding pit. Feeding Activity or Mound Presence Laboratory flume studies explored the generation of bedforms downstream of groups of Cistenides . Experiments with worms, but no mounds, resulted in no ripples.