Shellfish farming structures such as intertidal racks, trestles or longlines may alter the
hydrodynamics of an area (Kaiser et al., 1998), though such changes have been rarely
documented (Crawford, 2001). Anecdotal evidence suggests that the effects of racking on
hydrodynamics can be seen in some culture areas in Tasmania, with organic buildup
evident underneath farm structures in areas of high current flow. Additionally, Thorne
(1998) proposed that sediment accretion around racks at Pipeclay Lagoon in south-eastern
Tasmania may be due to hydrodynamic modifications. Sediment accretion and
compaction may also result from heavy machinery use in shellfish growing areas
(Crawford, 2001). De Graves et al. (1998) concluded that the compaction and dispersal
of sediments by heavy vehicle traffic may affect the composition and abundance of
benthic species.