Poor design of behavioural experiments gets poor results: examples from intertidal habitats

Many patterns of distribution and abundance of intertidal animals are expla ined by processes of movements of animals, selecting particular habitats or levels on the shore, or interacting with other species. Movements of inter tidal animals have therefore been studied over many years. During this long history, much intertidal ecology has changed in focus from broad-scale to small-scale patterns and processes, although there has been recent refocus on a combination of many scales. Simultaneously, there has been an increase in the incidence of field experiments and growing recognition that behavio ur is more flexible than originally thought. This review examines changes i n the ways that experiments on movements on intertidal animals have been an d are being done, taking into account these changes in emphasis. Although s ome progress has been made, there is still a long way to go. The idea is st ill prevalent that behaviour is simple, rather invariant and that the anima ls respond to broad-scale cues that have traditionally been of interest to many investigators. This means that many experiments are still designed to minimise (or ignore) natural variation in behaviour rather than to measure it and thar any associated disturbances are considered irrelevant and there fore not evaluated. Understanding the rot that behaviour has in establishin g and maintaining many of the patterns observed on intertidal shores is cru cial to our understanding of the ecology of these habitats. Better experime nts, designed logically with appropriate controls to evaluate realistic pro cesses and to measure how behaviour varies among places and from time to ti me can only improve this understanding. (C) 2000 Elsevier Science B.V. All rights reserved.