Comparison of patterns of spatial variation of microgastropods between two contrasting intertidal habitats

Small-scale spatial variation in the distribution of the macrofauna. of marine intertidal shores has long been recognized, but there have been few quantitative studies about the scales of patchy distribution of the microbenthos on rocky shores. Patchiness has important implications for comparative and descriptive studies of distribution and abundance because it confounds comparisons of abundance at the largest spatial scales unless the smaller scales are appropriately incorporated into the sampling designs. Spatial variation in the distribution of a number of species of intertidal microgastropods across 2 different habitats (sediment and coralline turf) in Botany Bay, Australia, is described using a nested, hierarchical sampling design. Significant variation was detected mainly at small scales, ranging from less than 1 to 10 m. Moreover, the species showed different patterns of variation depending on the type of habitat and the time of sampling. There was no relation between these patterns and the taxonomic relations of the species. These data illustrate the scales of variability that must be considered when planning long-term or baseline investigations of microbenthos to assure that the study adequately represents different habitats and that subsequent ecological inferences are valid.