Intertidal assemblages across boulders and rocky platforms: a multi-scaled approach in a subtropical island

Abstract

Rocky intertidal communities have proved to be tractable systems for experimental ecology, contributing much to our general understanding of population and community ecology. Physical environmental factors are usually considered strong structuring elements for these assemblages. In this study, we adopted a mixed model sampling design to study the effects of substratum type and shore orientation (i.e. different wave exposure) on intertidal assemblages of Madeira Island (NE Atlantic) across time. We included both macrofauna and macroalgae and compare their abundance and distribution in boulders and rocky platforms on north and south coasts of the island. Generally, assemblages moderately differed between boulders and rocky platforms whereas orientation had little influence on the distribution of most taxa. A high variability was observed across a range of spatial and temporal scales, suggesting that interactions of both physical variables and biological parameters may be influencing distribution of intertidal organisms. The results obtained provide pioneer quantitative data on intertidal assemblages of Madeira.