Particle Resuspension in the Benthic Boundary Layer Induced by Flow around Polychaete Tubes

Abstract

The effect of the projecting tubes of Lanice conchilega (Terebellidae) on particle flux in the benthic boundary layer was studied in laboratory flume experiments. Intact tubes, worms, and flume sediment were collected from an ebb channel of the Tay Estuary. Experiments were performed with dye and high contrast, near-neutral density particles to determine flow patterns and net particle movement in individual tube wakes. Projecting tubes produced characteristic vortex patterns which may increase resuspension of sediment particles. These vortex patterns were not strongly dependent on obstacle shape or flow regime and resulted in pronounced upward motion of fluid from the bed. Particle velocities within the wake were lower than ambient free stream velocity. Results of flume observations reported are consistent with detailed visualization studies of small-scale disturbances within a laminar boundary layer.Key words: resuspension, boundary layer, benthos, tubes, polychaete, Lanice conchilega, flow visualization