Comparison of patterns of spatial variation of microgastropods between twocontrasting intertidal habitats

Small-scale spatial variation in the distribution of the macrofauna. of mar ine intertidal shores has long been recognized, but there have been few qua ntitative studies about the scales of patchy distribution of the microbenth os on rocky shores. Patchiness has important implications for comparative a nd descriptive studies of distribution and abundance because it confounds c omparisons of abundance at the largest spatial scales unless the smaller sc ales are appropriately incorporated into the sampling designs. Spatial vari ation in the distribution of a number of species of intertidal microgastrop ods across 2 different habitats (sediment and coralline turf) in Botany Bay , Australia, is described using a nested, hierarchical sampling design. Sig nificant variation was detected mainly at small scales, ranging from less t han 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 re lation between these patterns and the taxonomic relations of the species. T hese data illustrate the scales of variability that must be considered when planning long-term or baseline investigations of microbenthos to assure th at the study adequately represents different habitats and that subsequent e cological inferences are valid.