| The stability of intertidal sediments may be greatly influenced by the presence of organisms associated with the sediment surface. This study examined the effects of empty Littorina littorea (Mollusca: Gastropoda) shells on the erosion of a cohesive clay bed subjected to increasing current velocities in an annular mini-flume. Empty littorinid shells were collected from the shoreline near the Queen's Wharf at Fort Anne, Nova Scotia and cleaned prior to use in the study. Experiments were conducted to examine the effects of shell size and shell number on the erosion threshold and erosion rate. Effects due to shell size were examined by placing seven different sized shells (ds = <3 to 22mm) separately into the mini flume and recording the resulting suspended sediment concentrations occurring at seven different velocities. Similarly, the effects due to shell number were examined by placing from 1 to 7 shells of the 10–12mm shell size class into the mini-flume. Each experiment was recorded with VHS, and the tapes were examined to identify times when shells began to roll (intermittently or continuously) or to saltate (i.e. leave the bed). (Abstract shortened by UMI.)... |
