Seabed drag coefficient over natural beds of horse mussels (Atrina zelandica )

摘要

Measurements of seabed drag coefficient, C_100, were made under tidal currents at four sites in Mahurangi Harbour, New Zealand. At the first three sites the dominant roughness element was the pinnid bivalve, Atrina zelandica (horse mussel). At the fourth site, which was devoid of horse mussels but covered in cockle shells, patches of seaweed and crab burrows, C_100 was smallest (0.0055), but still twice as large as the value typically applied to abiotic, flat, cohesionless seabeds (0,0025). The mean drag coefficient plus-or-minus standard error at the three sites with horse mussels was: 0.0082±0.0010 (site 1); 0.0096±0.0009 (site 2); 0.0115±0.0016 (site 3).