Influence of sampler shape and orientation on density estimates on intertidal macrofauna

The variability in density estimates of intertidal, infaunal benthos due to the shape and tidal orientation of sampling devices is discussed. Although all intertidal sampling devices are fundamentally of the same design, three different cross-sections were investigated, square, circular and rectangular, with the first two of common use in intertidal sampling. Results demonstrated that tidal orientation of the sampling device does not induce variability in density estimates. Furthermore, no difference in density estimate could be detected between the square and circular cores, both having a very similar cross-section. In contrast, some species exhibited significant differences when comparing rectangular vs square/circular cores combined. It is postulated that these are caused by species-specific small-scale spatial patterns.