A comparative study of differences among species and patches of habitat on movements of three species of intertidal gastropods

Information about how animals move through complex and patchy habitats is crucial to understanding how animals utilize habitat, spatial and temporal patterns of distribution and abundance, population dynamics and patterns of biodiversity. Dispersal may be influenced by many factors, including intrinsic characteristics of a species (e.g. its mobility, specificity for different resources or its ability to perceive the quality, size or structure of patches of habitat) and/or the features of the habitat itself. It is important to understand the relative importance of these different factors. Comparative studies of movements of different species across habitats of different structure will increase our understanding of the relative importance of speciesor habitat-characteristics in determining dispersal and the extent to which patterns of movement can be generalized across co-existing species or different patches of habitat. In this study, movement of three species of intertidal gastropods across patches of habitat that varied in cover of standing water, algae and topographic complexity was measured over three different periods of time in three replicate experiments. Movements were generally randomly orientated, but the linear distances displaced differed in complex ways. Over 24 h, distances displaced differed among species. Over 2 weeks, differences among species disappeared and distances moved were determined by the complexity of the topography. At intermediate times (1 week), there were no clear patterns and the results varied from one experiment to another. For 24 h and 2 weeks, patterns were consistent among experiments. For no species could patterns of movement be related to use of micro-habitats during low tide. The importance of replicating experiments and incorporating numerous temporal scales in studies of movement are discussed.  2000 Elsevier Science B.V. All rights reserved.